Recommendations on Standards for the Design of Medical Diagnostic Equipment for Adults with Disabilities, Advisory Committee Final Report

5. Recommendations

5.1 Transfer Surface Height Recommendations

Description: The transfer height is set above the finished floor surface to permit transfers form mobility devices onto the transfer surface. This height is also critical for patients who use mobility aids such as walkers and canes and may find it difficult to get up onto or down from an examination chair or table or imaging bed platform, and for facilitating assisted transfers. The height provision is the same for MDE used by patients in supine, prone, or side-lying positions (M301) and patients in seated positions (M302).

NPRM Proposed Provision: M301.2.1 and M302.2.1 Height. The height of the transfer surface during patient transfer shall be 17 inches minimum and 19 inches maximum measured from the floor to the top of the transfer surface.

Advisory M301.2.1 and M302.2.1 Height. The transfer surface position may be outside of the specified height range when not needed to facilitate transfer.

NPRM Preamble Discussion: The technical criteria allow the height of transfer surfaces to be either fixed or adjustable within the 17 inches minimum and 19 inches maximum range. Based on the information discussed below (see NPRM discussion), the Access Board is considering requiring in the final standards that the height of transfer surfaces be adjustable from 17 inches minimum to 25 inches maximum during patient transfer.

5.1.1 Transfer Surface Height Adjustability Recommendation for M301 and M302

The Committee recommends adjustable height in small, virtually continuous increments.

Rationale for final recommendation

The Committee agreed that adjustability greatly increases the overall accessibility of equipment for all persons. Adjustable height MDE, such as exam tables, imaging tables and chairs, will make it possible to position the transfer surface near the height of the seat of the mobility device. For some, independent transfers are only possible when there is minimal or no change in vertical height between the seat of the mobility device and the transfer surface. People may prefer or, in some cases, require, transfer to a slightly lower surface moving the transfer surface lower than the seat of the mobility device; then adjusting the transfer surface to above the seat for the return transfer.

The Committee sought information on the range of seat heights of persons using mobility devices for this recommendation. The research documented a wider range in the seat heights of mobility devices than existed in the past. The Wheeled Mobility Anthropometry Project found a range of occupied seat heights from 16.3 inches to 23.9 inches for manual wheelchair users;16.2 inches to 28.9 inches for power wheelchair users; and 18.8 inches to 25.3 inches for scooter users. In determining these heights, project researchers measured the seat heights from underneath the buttocks at the center of the occupied seats, a spot likely to be lower than the front of the seat where a person transfers.^FF Some Committee members pointed out that this likely made the seat height measurements lower than the actual spot from where a person actually transfers. The adjustability of medical diagnostic equipment will facilitate transfers for all types of patient populations by providing the ability to “pair” the transfer surface of diagnostic equipment at or near the height of the mobility device. People who use wheelchairs, most of which have no adjustability, will directly benefit from medical diagnostic equipment that moves up or down; as will people who use scooters, some of which have height adjustable seats that swivel to assist with alignment for transfers. Persons who are older, have stability/balance issues, and use a walker or cane, will also benefit from adjustability of the equipment when getting on and off the equipment. Industry experts noted that adjustability is readily available in many existing products. Both electronic and manual pump chairs have the ability to stop at any position and are not limited to set points within the range. Thus, the committee adopted a standard of adjustability in small, virtually infinite increments.

Figure 5.1.1 Adjustable Height Medical Table/Chair
(SOURCE: Midmark Corporation)

The Committee recognized that some types of imaging equipment do not allow adjustability with today’s technology. Specific types of imaging equipment, DXA and some x-ray systems, have the imaging hardware below the table underneath the patient. Imaging industry members acknowledged, as new technologies develop, future generations of equipment might find a way to incorporate adjustability. In the meantime, industry proposed creating a System Accessibility Configuration to provide a means to achieve accessibility where equipment’s current design is limited or achieving accessibility is not technically feasible despite best efforts to redesign imaging equipment (see Section 7).

5.1.2 Transfer Surface High Height Recommendations for M301 and M302

The Committee recommends an adjustable height range with an upper height measuring at least 25 inches.

Rationale for final recommendation

The anthropometric data referenced above in the Wheeled Mobility Anthropometry Project shows seat heights for people who use mobility devices are above 19 inches. For manual wheelchair users seats measured up to 23.9 inches; for power wheelchair users up to 28.9 inches; and for scooter users to 25.3 inches. Seat heights for males were typically higher than for females. All the male manual wheelchair users and 92 percent of the male power wheelchair users had seat heights equal to or less than 25 inches. Therefore, transfer surfaces that are adjustable to a 25 inches maximum during patient transfer accommodate most patients who use mobility devices.

Since one key factor in ease of transfer is locating the transfer surface near or at the same height as the seat of the wheeled mobility device, moving the minimum high point for adjustability of transfer surfaces, improves access for many. This particularly benefits persons using powered mobility devices and scooters with higher seat heights.

5.1.3 Transfer Surface Low Height Options for M301 and M302

The Committee did not agree on a final low height recommendation.

Rationale for final recommendation (more detail provided in Section 6)

The Committee was unable to reach consensus regarding the transfer surface low height. The Committee considered various anthropometric data from research, clinicians, and Committee expertise but was never able to agree on a recommendation. The Committee shifted focus from a fixed height range between 17 to 19 inches as adjustability was accepted. Members focused on determining a specific low height absolute measurement.

A portion of the Committee recommended a height range of 17 inches to 25 inches.

A portion of the Committee recommended a height range of 18 inches to 25 inches.

A portion of the Committee recommended a height range of 19 inches to 25 inches.

The Stretcher Subcommittee recommended considerations for the height range of stretchers.

The Imaging Subcommittee recommended deferring this issue to the Table and Chairs Subcommittee.

5.1.4 Transfer Surface Height Measurement for M301 and M302

The Committee recommends capturing the transfer surface height at the highest point of the seat in an uncompressed state, inclusive of bolsters.

Rationale for final recommendation

Having an accessible transfer surface height is critical to facilitate independent patient transfers to equipment used by patients both in a supine, side-lying, or prone and seated position. To determine compliance, it is necessary to have a consistent point of measure. Since many transfer surfaces are not perfectly flat, measuring to the highest point in an uncompressed state provides this consistent point of measure. Identifying the highest point on the transfer surface will assure that all points on the transfer surface comply with the height criteria. This recommendation applies to exam tables and chairs and this measurement may not necessarily be at the centerline of the seat where there are higher points on the seat.

Figure 5.1.4 Illustration of Height Measurement
(SOURCE: Midmark Corporation)

5.2 Transfer Surface Size Recommendations

5.2.1 Transfer Surface Size Recommendations for M301

Description: The transfer surface is the part of the diagnostic equipment onto which patients who use mobility devices or aids transfer when moving onto and off the equipment. Depending on the configuration of the equipment, the transfer surface may occupy only a portion of an examination table or imaging bed platform. The technical criteria do not address the overall width and depth of patient support surfaces because of the diverse shape and size of these surfaces. The transfer surface size standard has two components: width and depth (see Figure 5.2.1.1)

NPRM Proposed Provision: M301.2.2 Size. The transfer surface shall be 30 inches wide minimum and 15 inches deep minimum.

5.2.1.1 Transfer Surface Width Recommendations for M301

The Committee recommends a transfer surface of 28 inches minimum width for equipment used by patients in a supine, side-lying, or prone position.

Rationale for final recommendation

The Committee considered the initial proposal of 30 inches and ultimately decided to decrease the width proposal by two inches. Currently, the only equipment existing with a 30-inch transfer surface width is bariatric equipment.

At the Committee’s December 2012 meeting, Dr. Edward Steinfeld, Director of the Center of Inclusive Design and Environmental Access at the University of Buffalo, gave a presentation on the Wheeled Mobility Anthropometry Project (AWM Project).^GG He provided a brief analysis of measurements of the width and depth of seating surfaces for individuals using wheeled mobility devices. This study obtained data from subjects seated in their mobility devices. The results of the AWM Project indicated that a seating surface could have a width of 28 inches and accommodate the 95th percentile of the population of wheeled mobility device users studied.

As part of the deliberations, Committee members examined tables and chairs from various manufacturers during its meetings. The equipment was present and members could sit on, look at, and operate equipment during the meeting and breaks. This allowed members to experience tables that were 28 inches wide along with the other elements of the equipment.

Some supported the 28-inch dimension noting there is little gain in usability by increasing the transfer surface width to 30. The significant gain in numbers of persons able to use the equipment is at the width of 36 inches. The discussion of transfer surface width triggered the decision to set aside the issues of equipment for very large or obese patients. The Committee members expressed concern about the need to assure that persons of larger size receive care but there is incomplete data to determine specific criteria at this time.^HH

In order to have equipment with a wide enough transfer surface to accommodate very large or obese patients, the transfer surface width would need to be at least 36 inches. Since the needs of very large or obese patients are not included in this round of recommendations, the Advisory Committee agreed that either a 28 or 30 inch width would be appropriate. The Committee decided to reduce transfer surface width to 28 inches, with a future determination of equipment dimensions for very large or obese patients.

During the discussion, healthcare providers with experience in assisting patient transfers pointed out that too wide a transfer surface is challenging to smaller sized persons. Making all equipment wide enough for a 36-inch transfer surface would create difficulty for many smaller persons to transfer. For persons needing to reach across the table and pull themselves onto the transfer surface, a wider table becomes a chasm, which will impair the ability of many to grasp the side facilitating transfer. The width measurement is from the center-point of each side of the transfer surface as shown in Figure 5.2.1.1.

Figure 5.2.1.1 Measurement of Depth and Width from Center-Point of Transfer Surface Sides
(SOURCE: Midmark Corporation)

Notes

^GG Analysis of Seat Heights for Wheeled Mobility Devices. The study is available at http://udeworld.com/analysis-of-seat-height-for-wheeled-mobility-devices.

^HH Of note, the committee also decided by consensus that extreme obesity was not within the scope of the committee’s work, but to instead use the data provided by Dr. Steinfeld’s study in determining their recommendation. See section 8.1 of this report for further discussion of extreme obesity, and its recommendation for future topics of research.

5.2.1.2 Transfer Surface Depth Recommendation for M301

The Committee recommends a minimum transfer surface depth of 17 inches for all M301 except imaging equipment.

Rationale for final recommendation

Concern about the adequacy of the size of the transfer surface led members to propose an increase in the minimum depth of the transfer surface from 15 inches to 17 inches. The Committee easily supported this increase as existing equipment already encompassed this dimension.

The Committee reviewed anthropometric data from a variety of sources. Dr. Edward Steinfeld, Director of the Center of Inclusive Design and Environmental Access at the University of Buffalo, reported that his research data suggested that a depth of 15 inches would provide an adequate seating surface for the average user in his sample. However, Committee members raised concerns that the proposed depth was too short. Although the minimum size indicated by the SUNY research was 15 inches, current design practice used on tables and chairs incorporates a minimum depth of 17 inches. Some Committee members suggested that a minimum 15 inches of depth was too little, and the Committee adopted the 17-inch minimum.

This depth measurement is from the center-point of the front and back of the transfer surface as shown in Figure 5.2.1.1.

5.2.1.3 Transfer Surface Size Recommendations for Stretchers (M301)

The Committee recommends a minimum transfer surface size of 28 inches wide by 17 inches deep for stretchers located on both long sides of the stretcher.

Rationale for the recommendation

The configuration of stretchers can accommodate the same transfer surface as those used by exam tables. An important element is the position at which the patient transfers onto the stretcher. The point of entry to the equipment is in the center. The length of the stretcher means a patient would transfer on in the middle. The patient would not use the short end as the point of entry because it would require the patient to slide a long distance to lie on the stretcher.

5.2.1.4 Transfer Surface Size Recommendations for Imaging Equipment (M301)

The Committee recommends a transfer surface size on imaging equipment be a minimum of 28 inches long by a minimum of 28 inches deep. Where the 28 inches minimum depth is technically infeasible, the depth may be no less than 21 inches. The transfer surface must be located so the 28-inch long dimension is parallel to the patient scanning/imaging side of the table.

Rationale for the recommendation

The Committee agreed to this proposal to compensate for the unique aspects of the transfer surface in diagnostic equipment. Patients access diagnostic imaging tables from one of the long sides of the table. Some imaging equipment have narrow tables due to functional necessity. When patients transfer on the long side, table depth may be equal to the transfer surface depth. Lack of table depth beyond the transfer surface increases the potential for patients to “overshoot” the table during transfer, falling off the side opposite transfer. To facilitate transfers and to mitigate this fall hazard, the Committee proposes the inclusion of transfer supports (M301.3).

For equipment with bores, both long sides of the imaging table may be available for transfer subject to room layout and other imaging components. Many x-ray system tables and all DXA tables have part of the equipment support located on one of the long sides making that side of the table unavailable for patient transfer. For these types of equipment, patient transfer is only on the other side of the table.

All X-ray tables meet the 28-inch table width. However, because of physical design constraints such as bore size, not all tables used with equipment with bores meet the 28 inch width criteria but all meet the 21-inch minimum.

Manufacturers must determine the location of the transfer surface to facilitate the patient’s transfer and positioning for the clinical functions of the diagnostic procedure.

Figure 5.2.1.4 Schematic of Transfer Surface Size for Diagnostic Imaging Equipment
(SOURCE:  GE Healthcare)

5.2.2 Transfer Surface Size Recommendations for M302

Description: The transfer surface is the part of the diagnostic equipment onto which patients who use mobility devices or aids transfer when moving onto and off the equipment. Depending on the configuration of the equipment, the transfer surface may coincide with the seat area of an examination chair. The transfer surface size has two components: width and depth. (See Figure 5.2.1.1)

NPRM Proposed Provision: M302.2.2 Size. The transfer surface shall be 21 inches wide minimum and 15 inches deep minimum.

5.2.2.1 Transfer Surface Width Recommendations for M302

The Committee recommends 21 inches for the minimum width of the transfer surface of examination chairs and other equipment primarily used by patients in a seated position as described in its proposed standard 302.2.2.

Rationale for final recommendation

The Committee considered the dimensions for rectangular seats in roll-in showers from the 2010 Standards; and the ideal chair width recommended in Architectural Graphic Standards for auditorium seating. The Committee also reviewed anthropometric data from a variety of sources.

5.2.2.2 Transfer Surface Depth Recommendation for M302

The Committee recommends a minimum depth requirement of 17 inches for equipment used by patients in seated positions.

Rationale for final recommendation

As discussed in previous sections, many members expressed concern about the adequacy of the transfer surface depth. Members proposed increasing the minimum depth of the transfer surface from 15 inches to 17 inches. The Committee easily supported this increase as existing equipment already meets or exceeds this dimension.

5.2.3 Transfer Surface Measurement Recommendation for M301 and M302

Description: The transfer surface size standard has two components: width and depth. The transfer surface dimensions do not include headrests, footrests, or similar supports for body extremities that do not support the patient’s overall body position.

The Committee recommends measuring the transfer surface from the center-point of each side of the transfer surface.

Figure 5.2.3 below indicates how these width and depth dimensions are measured for MDE used by patients in supine, prone, or side-lying positions (M301) and the seated position (M302)

Figure 5.2.3 Measurement of Depth and Width from Center-Point of Transfer Surface Sides
(SOURCE: Midmark Corporation)

5.3 Transfer Sides Recommendations

5.3.1 Permitted Obstructions to Transfer Sides for M301 and M302

Description: Transfer side provisions are the same for M301 and M302 and require the transfer surface to be located to provide options to transfer onto the short side and the long side of the surface. The provisions result in the transfer surface being located at a corner of the equipment and the two transfer sides adjoining at the edges of the equipment. The provision will coincide with the seat area design of most examination chairs.

NPRM Proposed Provision: M301.2.3 and M302.2.3 Transfer Sides. The transfer surface shall be located to provide options to transfer from a mobility device onto one short side (depth) and one long side (width) of the surface. Each transfer side shall provide unobstructed access to the transfer surface.
EXCEPTION: Temporary obstructions may exist where they can move out of the way to permit transfer.

NPRM Preamble Discussion: The Access Board is considering whether the final standards should permit equipment parts to extend horizontally 3 inches maximum beyond the edge of the transfer sides provided they do not extend above the top of the transfer surface. This would allow handholds and other features that may facilitate transfer to be located on the transfer sides. The 2010 Standards provide a gap of 3 inches between the edge of a shower seat and the shower compartment entry, and the gap does not appear to interfere with transferring onto and off the shower seat.

The Committee recommends a 3-inch maximum obstruction permitted at transfer sides.

Rationale for the recommendation

Transfer supports provide handholds on adjustable medical equipment to facilitate transfers onto and off the equipment. Some medical equipment types have components that create a gap between the transfer surface and the outer edge of the equipment on the side used for transfer. This standard places a limit on the size of the gap allowed.

To address this, the Committee used the provisions in the 2010 Standards on shower compartment seats. These seats allow a maximum of a 3-inch gap between the edge of a shower seat and the shower compartment entry.

The Committee considered anthropometric data from a research project that examined transfer experience with an adjustable height transfer surface. The two surfaces were placed at the same height and subjects transferred at gaps in increments of 3.5 inches. The result showed that 95% of subjects could transfer when seat and surface are at same height with a 3.5-inch gap. This data helped inform the recommendation since the 3-inch criteria is less than that used in the research and should assure effective transfers for most.

Figure 5.3.1 Permitted 3-Inch Maximum Obstruction at Transfer Side
(SOURCE: U.S. Access Board)

The 3-inch gap would accommodate a variety of supports including ones foldable, collapsible, removable, and articulating. A common example of an obstruction is the side rails on stretchers. Arm rests and footrests are examples of permitted temporary obstructions because they move out of the way of the transfer. The 3-inch maximum gap applies to two sides of medical diagnostic equipment with a rectangular shape, the long length (width) and the short length (depth), where the transfer surface is located.

Special considerations for Stretchers

Each transfer side shall minimize obstructions to the transfer surface. Obstructions shall not be vertically less than 1 inch nor be horizontally more than 3 inches from the edge of the patient support surface to provide unobstructed access to the transfer surface.

This provision incorporates the provisions of IEC 60601-2-52 establishing the maximum vertical obstruction at no less than 1 inch below the top of the transfer surface.

5.3.2 Transfer Sides Recommendations for M301

Description: The transfer side provision requires the transfer surface to be located to provide options to transfer onto the short side and the long side of the surface. The provisions result in the transfer surface being located at a corner of the equipment and the two transfer sides adjoining at the edges of the equipment (e.g., foot of an examination table). Patients who use mobility devices would have the choice to approach parallel to the deep dimension of the transfer surface, parallel to the wide dimension of the transfer surface, or at an angle to the corner of the transfer surface and be able to perform a variety of transfers. Locating the transfer surface at a corner of the equipment and providing unobstructed access to the two transfer sides also would facilitate assisted transfers.

NPRM Proposed Provision: M301.2.3 Transfer Sides. The transfer surface shall be located to provide options to transfer from a mobility device onto one short side (depth) and one long side (width) of the surface. Each transfer side shall provide unobstructed access to the transfer surface.

5.3.2.1 Transfer Sides Recommendation for Stretchers

On stretchers, the transfer surface is oriented along the long dimension of the surface on which patients are in the supine, prone, or side-lying position (see Figure 5.4.1.1).

For stretchers, the Committee recommends the transfer surface be located to provide the ability to transfer from a mobility device onto both long sides of the surface.

Rationale for the recommendation

This recommendation recognizes the configuration and use of stretchers. The configuration of stretchers typically does not allow access to a transfer surface on either end. As a result, with current stretcher design, a patient will access the long side of the transfer surface and the short side will be inaccessible. The location of the transfer side is on the patient right or left roughly midway between the two ends (head and foot). This transfer location places the patient at a desirable location along the length of the stretcher side so that when the transfer is complete, the patient is in the proper location as the backrest articulates.

5.3.2.2 Transfer Sides Recommendation for Imaging Equipment

On imaging equipment, the transfer surface is oriented along the long dimension of the surface on which patients are in the supine, prone, or side-lying position (see Figure 5.2.1.4).

The Committee recommends that imaging equipment provide transfer surfaces on at least one long side of the table.

Rationale for the recommendation

Patients access diagnostic imaging equipment from one of the long sides of the table. Patients would not transfer onto imaging tables from the head or foot end because the patient would need to scoot,” slide, or twist a long distance to get into the proper position for the exam, a difficult if not impossible feat. Recognizing this, imaging equipment provides the transfer surfaces on the short sides of the table. The Committee members recognized the option of transferring from either of the long sides of the equipment is optimum.
Imaging manufacturers noted that many X-ray system tables and all DXA tables with today’s technology have part of the imaging equipment support located on one of the long sides and all patient transfers happen on the opposite side. Many X-ray systems and all DXA systems as currently installed have equipment obstructions on one of the long sides. Industry agreed the best solution is to have transfer access where feasible within the medical equipment design on both long sides.

5.3.3 Transfer Sides Recommendations for M302

Description: Transfer side provisions are the same for M301 and M302 and require the transfer surface to be located to provide options to transfer onto the short side and the long side of the surface. The provisions result in the transfer surface being located at a corner of the equipment and the two transfer sides adjoining at the edges of the equipment. This provision will coincide with the seat area design of most examination chairs.

NPRM Proposed Provision: M302.2.3 Transfer Sides. The transfer surface shall be located to provide options to transfer from a mobility device onto one short side (depth) and one long side (width) of the surface. Each transfer side shall provide unobstructed access to the transfer surface.
EXCEPTION: The provision permits temporary obstructions if they can move out of the way to permit transfer.

5.3.3.1 Transfer Sides Recommendation for Exam Chairs with Fixed Footrests

Some examination chairs have footrests that get in the way of entry from the foot end, such as dental chairs and podiatry chairs.

The Committee recommends exam chairs with a fixed footrest have a transfer surface minimum of a 17 inch depth and a 21 inch width located on both sides of the chair to allow for a left or right transfer.

Rationale for the recommendation

As currently designed, some examination chairs have fixed footrests that facilitate the clinical functions for which the chair is used. The footrests obstruct access to the foot end of the chair. Examples of chairs that fit this category are most dental chairs and podiatry chairs. The current design allows only one long side for transfer, which limits some patient transfers where a patient can use only one side of the body due to paralysis on one side or other such conditions. To address this issue, the recommendation requires chairs with footrest obstructions to allow patient transfers from both sides of the chair. The solution creates the option for either a left or a right transfer. (see Figures 5.3.3.1(a) and 5.3.3.1(b))

Figure 5.3.3.1(a) Podiatry Chair
(SOURCE: Midmark Corporation)

Figure 5.3.3.1(b) Dental Chair
(SOURCE: Midmark Corporation)

5.4 Transfer Supports Recommendations

5.4.1 Transfer Support Location for M301 and M302

Description: Transfer supports assist individuals while making transfers on to the transfer area. Provisions require transfer supports be provided for use with the transfer sides and be located within reach of the transfer surface and not obstruct transfer onto the surface when in position.

NPRM Proposed Provision: M305.2.1 Location. Transfer supports shall be located within reach of the transfer surface and shall not obstruct transfer onto or off the surface when in position.

NPRM Preamble Discussion: The transfer support would be located on the side of the transfer surface that is opposite the transfer side (M301.2.3 and M302.2.3) similar to the provisions in the 2010 Standards for grab bars provided at bathtubs and shower compartments with seats. This would be a minimum requirement. Where possible, it is recommended that supports be provided on each side of the transfer surface that is 15 inches deep minimum for patients to maintain position after they have transferred onto the equipment, and that the supports be repositionable to permit transfer.

The Committee recommends transfer supports be required on both sides of the transfer surface and be movable or removable so the supports are out of way during transfer.

Rationale for the recommendation

Transfer supports or handholds on adjustable medical equipment facilitate transfers onto a transfer surface by giving the individual something to hold or grab onto while transferring. This recommendation for placement of the supports on both sides of the equipment will increase options during patient transfers.

Figure 5.4.1 Location and Length of Transfer Supports
(SOURCE: Midmark Corporation)

A: Table seat depth, 17 inches minimum
B: Transfer support length, 15 inches minimum
C: Distance between transfer support and transfer surface, 1 1/2" maximum
D: Minimum 80% overlap between the transfer support and transfer surface, 12” minimum*

* Note: The 80% overlap allows for the transfer support to be slightly forward or back of the front edge of the transfer surface

5.4.1.1 Transfer Support Location Recommendation for Stretchers

For Stretchers, the transfer surface is oriented along the long side of the surface.

Rationale for the recommendation

Patients access stretchers on either of the long sides rather than on its end (short side). The Committee proposes to flip the orientation of the transfer surface so that the long side of the transfer support is along the long side of the stretcher. This reflects the actual use since accessing it on the end (short side) would require scooting, sliding, or twisting a long distance to lie in the proper position on the stretcher. Transfer support will be located on the opposite side of the transfer side. (see Figure 5.4.1.1)

Figure 5.4.1.1 Transfer Support Location – Plan View
(SOURCE: Stryker Medical)

5.4.1.2 Transfer and Positioning Support Location Recommendations for Imaging Equipment with Transfer Surfaces

For imaging equipment with transfer surfaces, the Committee recommends adding transfer supports on tables with transfer depths of less than or equal to 24 inches and positioning supports for transfer depths greater than 24 inches. Both transfer and positioning supports are to be located opposite the transfer side.

Rationale for the recommendation

Imaging tables need some form of support on the opposite side of the table. Because of the size, diversity, and use of diagnostic imaging tables, this support will carry out different functions on different tables. The function dictates the design and load capability. This two-part recommendation recognizes the different use of the supports based on table width. The Committee used a 24-inch dividing point for table width to accommodate the dimensions for the maximum reach range.

For transfer surface depths on tables less than 24 inches wide, a transfer support must be available on the side opposite the entry to the transfer surface. Some imaging tables are narrow and may not have additional “table” surface beyond the transfer depth. For these narrow tables, a more substantial transfer support is necessary. This transfer support facilitates transfers and prevents patient falls over the opposite side of the table.

For transfer surface depths on tables greater than 24 inches wide, a positioning support must be available on the side opposite the entry to the transfer surface. For wider tables, a transfer support would not be functional because of its distance from the patient. If transfer is possible from either of the long sides of the table, then a positioning support must be available on the side opposite the transfer.

A positioning support requires a different load bearing capacity than a transfer support. Minimum load bearing requirements for supports are found in international standards (e.g. risk management ISO 14971; IEC60601-1; and use of IEC60601-2-52.) Generally, for positioning supports, the table is supporting the full weight of the patient rather than the support. In this situation, the load bearing requirements of the positioning support impose a different load rating. The location of this positioning support must accommodate the clinical use along with the patient’s positioning needs.

In some cases, current methods of imaging patients require table design that may not permit supports to attach to the table without compromising the diagnostic functionality of the table and/or requiring complete redesign of the table structural support. Some types of modalities capture images by using a table that moves. In those cases, attaching supports would likely impede the required movement. For example, some x-ray tables require bi-directional horizontal movement to perform the functions for the images. A new generation of equipment is necessary to address this.

Many/most imaging tables have a moving part and a stationary part dictated by diagnostic need. Many also move up and down. The tables must safely accommodate a wide range of patient sizes. These considerations factor into where the substantial support structure is located while still enabling the precise movement and imaging transparency of the table top/cradle. Therefore, in many cases, there currently is no feasible direct attachment point on the table for a support.

Any support design must take into consideration the risks associated with IV or other tubing, monitors and other such items entangling in the support as the table moves during the procedure. Support design must also assure sufficient clinician access to the patient during the exam for proper positioning, administration of imaging agents or drugs, patient monitoring, etc.

5.4.2 Transfer Support Length for M301 and M302

Description: Transfer support length applies to the gripping surface of the support, that portion of the support used to grasp or maintain balance against while performing a transfer. The purpose of a minimum length is to ensure that there is a minimum gripping surface available to support positioning and repositioning during a transfer. This is a linear measurement (see Figure 5.4.1).

NPRM Proposed Provision: Length not addressed.

NPRM Preamble Discussion: The Access Board is considering whether the following technical criteria would be appropriate for the location and size of transfer supports. The transfer support would extend horizontally the entire depth of the transfer surface and would be 15 inches minimum in length.

The Committee recommends 15 inches minimum length positioned so that the transfer support overlaps the minimum depth of the transfer surface by 80%.

Rationale for the recommendation

The length of the transfer support shall be a minimum of 15 inches long and positioned so that the transfer support overlaps the length of the transfer surface by 80% at a maximum distance from the transfer surface of 1½ inches. (See Figure 5.4.1).

5.4.2.1 Transfer Support Length Recommendation for Stretchers

On Stretchers, the transfer surface is oriented along the long dimension of the surface on which patients are positioned in the supine, prone, or side-lying position (see Figure 5.4.1.1).

For Stretchers, the Committee recommends transfer supports be 15 inches minimum length.

Rationale for the recommendation

The length provides continuous support for patients using the stretchers. This is to accommodate the articulation that is necessary for the head and back support on stretchers.

Figure 5.4.2.1 Transfer Support Location – Side View
(SOURCE: Stryker Medical)

5.4.2.2 Transfer and Positioning Support Length Recommendations for Imaging Equipment with Transfer Surfaces

On imaging equipment with transfer surfaces, the transfer surface is oriented along the long dimension of the surface on which patients are positioned in the supine, prone, or side-lying position (see Figure 5.2.1.4).

For imaging equipment with transfer surfaces, the Committee recommends a transfer support be 28 inches minimum length and that a positioning support be 12 to 16 inches in length.

Rational for the recommendation

A transfer support (for transfer surfaces less than or equal to 24” deep) is to extend horizontally along the side of the patient scanning/imaging table at least the minimum width of the transfer surface, a minimum length of 28-inches. It is to be located at the designated transfer location.

A positioning support (for transfer surfaces >24” deep) is to extend horizontally along the side of the patient scanning/imaging bed/table with a length of 12 to 16 inches and a height of 3 to 6 inches above the surface. It will be located at a position to accommodate the clinical use, with design inputs from users, for optimal positioning assistance.

Either a transfer support or positioning support may need to be separate from the patient-imaging table in cases where its attachment to the table is not possible. Specific discussion of these situations is in Section 7.

The two-part standard addresses various widths of tables. (see Section 5.4.1.2).

5.4.2.2 Schematic of Transfer Surface and Patient Support for Diagnostic Imaging Equipment
(SOURCE: GE Healthcare)

5.4.3 Transfer Support Height for M301 and M302

Description: Transfer support height applies to the vertical distance that the gripping area of the support is above the transfer surface (see Figure 5.4.3). The purpose of a minimum height is to ensure that the gripping surface is at an adequate height to facilitate positioning during a transfer.

NPRM Proposed Provision: Height not addressed.

NPRM Preamble Discussion: The Access Board is considering whether 6 inches minimum and 19 inches maximum above the transfer surface would be an appropriate height for transfer supports on diagnostic equipment used by patients in a supine, prone, or side-lying position, and diagnostic equipment used by patients in a seated position. The minimum height is consistent with the information provided by Midmark Corporation on examination tableside rails, and the maximum height is generally consistent with the height of grab bars above shower seats in the 2010 Standards.

The Committee recommends following the Access Board’s proposed height of 6 to 19 inches from the top of the transfer surface for transfer supports.

Rationale for the recommendation

The location of the transfer supports shall be a minimum of 6 inches to a maximum of 19 inches from the top of the transfer surface. Members of the committee also discussed IEC 60601-2-52, which defines specific requirements to prevent entrapment safety hazards on specific types of MDE (typically hospital beds and stretchers). Manufacturers of such equipment on the committee determined that this recommendation did not conflict with IEC 60601-2-52, allowing equipment to be designed to provide both accessibility and safety from entrapment hazards. The Committee also discussed height adjustability where equipment functions allow for adjustability of the transfer supports as this will increase design options as a best practice.

Figure 5.4.3 Height of Transfer Supports
(SOURCE: Midmark Corporation)

B: 6 inches minimum and 19 inches maximum from the top of the transfer surface
C: Transfer support length, 15 inches minimum

5.4.3.1 Positioning Support Height Recommendation for Imaging Equipment with Transfer Surfaces

For imaging equipment with transfer surfaces, the Committee recommends a positioning support 3 to 6 inches above the transfer surface.

Rationale for the recommendation

See above discussion on transfer supports for imaging equipment with transfer surfaces in Section 5.4.2.2. Manufacturers must locate the supports at a position designated for optimal positioning assistance.

5.4.4 Transfer Support Distance from Transfer Surface Recommendations for M301 and M302

Description: This minimum distance ensures that the transfer support is within reach of the transfer surface and can be effectively used to position during a transfer. The gripping surface measurement is horizontal from the adjacent edge of the transfer surface (see figure 5.4.1).

NPRM Proposed Provision: M305.2.1 Location. Transfer supports shall be located within reach of the transfer surface and shall not obstruct transfer onto or off the surface when in position.

NPRM Preamble Discussion: The Access Board is considering whether the following technical criteria would be appropriate for the location and size of transfer supports on diagnostic equipment used by patients in a supine, prone or side-lying position, and diagnostic equipment used by patients in a seated position:

• At least one transfer support would be provided on the side of the transfer surface that is 15 inches deep minimum. The transfer support would be located on the side of the transfer surface that is opposite the transfer side (see M301.2.3 and M302.2.3) similar to the provisions in the 2004 ADA and ABA Accessibility Guidelines for grab bars provided at bathtubs and shower compartments with seats. This would be a minimum requirement. Where possible, it is recommended that supports be provided on each side of the transfer surface that is 15 inches deep minimum for patients to maintain position after they have transferred onto the equipment, and that the supports be repositionable to permit transfer.

• The transfer support would extend horizontally the entire depth of the transfer surface and would be 15 inches minimum in length.

• The gripping surface of the transfer support should be located 1 ½ inches maximum measured horizontally from the adjacent edge of the transfer surface. This would ensure that the transfer support is within reach and can be effectively used during transfers.

The above technical criteria would likely result in the transfer surface being located at the foot end of examination tables and allow the use of transfer supports similar to the side rails described in the information provided by Midmark Corporation.

The Committee recommends the transfer supports be located at a maximum distance from transfer surface of 1 ½ inches.

Rationale for the recommendation

The Committee followed the NPRM proposal.

Refer back to Figure 5.4.1 Location and Length of Transfer Supports.

5.4.4.1 Transfer Support Distance from Transfer Surface Recommendation for Stretchers

The Committee recommends locating the transfer support along the long side of the of the transfer surface on the opposite side of the transfer. The horizontal distance from transfer surface should be no more than 3 inches from the edge of the patient support surface.

Rationale for the recommendation

Currently transfer supports are part of the side rail system on stretchers. To allow the side rail system to fold and store properly, the rails must be at a little less than 3 inches beyond the mattress surface edge (transfer surface edge). The Committee proposes that this horizontal dimension be included for stretchers under the proposed rule.

5.4.4.2 Transfer Support Distance from Transfer Surface Recommendation for Imaging Equipment

The Committee recommends a maximum distance of 1 1/2 inches from the transfer surface to the support (either transfer or positioning). The distance may extend up to 3 inches where the support must fold, collapse, come off, or articulate.

Rationale for the Recommendation

The Committee decided to follow the recommended 1 1/2inch proposal but included a 3-inch dimension to accommodate movement of the support. This standard parallels the recommendation for stretchers (see Figure 5.4.1.1).

5.4.5 Transfer Support Position Recommendation for M301 and M302

Description: Transfer support position refers to the placement of the gripping surface within the minimum and maximum vertical height ranges proposed. It addresses angled supports or contoured portions of horizontal supports often provided for ergonomics or equipment design considerations. This provision would apply along the support length and not to the cross-sectional profile of the gripping surface, see Figure 5.4.1.1.

NPRM Proposed Provision: position not addressed.

NPRM Question 17 e): Should angled or vertical transfer supports be permitted?

The Committee recommends a gripping surface be located within the minimum and maximum heights.

Rationale for the recommendation

The design process will determine the shape (contours and curves along length for ergonomics, not cross sectional profile) so that manufacturers can use creativity and flexibility as to the direction of positioning (i.e. horizontal, angled, etc.).

5.4.5.1 Transfer and Positioning Support Position Recommendation for Imaging Equipment

On imaging equipment, the transfer surface is oriented along the long dimension of the surface where patients lie in a supine, prone, or side-lying position (see Figure 5.4.2.2).

On imaging equipment with transfer surfaces, the transfer or positioning support must be oriented horizontally.

Rationale for the recommendation

A transfer support will extend horizontally along the side of the patient scanning/imaging table at least the minimum width of the transfer surface, but in all cases 28 inches minimum. It will be located at the designated transfer location.

A positioning support will extend horizontally along the side of the patient scanning/imaging bed/table and be 12 - 16 inches in length and 3 - 6 inches above the transfer surface. It will be located at a position designated by the manufacturer for optimal positioning assistance.

(see Figure 5.4.2.2 Schematic of Transfer Surface Size and Patient Support for Diagnostic Imaging Equipment)

5.4.6 Transfer Support Gripping Surface Cross Section and Clearances for M301, M302, and M305.2

Description: This provision prescribes a cross-sectional profile of the transfer support sufficient to enable individuals with disabilities to firmly grasp the gripping surface and support themselves during transfers. The provision addresses gripping surface diameter and perimeter of the support.

NPRM Proposed Provision: gripping surface cross section not addressed.

NPRM Preamble Discussion: The 2010 Standards specify the following dimensions for grab bars to enable individuals with disabilities to firmly grasp the grab bars and support themselves during transfers:

• Grab bars with circular cross sections must have an outside diameter of 1¼ inches minimum and 2 inches maximum.

• Grab bars with non-circular cross sections must have a cross section dimension of 2 inches maximum and a perimeter dimension of 4 inches minimum and 4.8 inches maximum.

The Access Board is considering whether the above cross section dimensions would be appropriate for the gripping surfaces of transfer supports on diagnostic equipment used by patients in a supine, prone, or side-lying position, and diagnostic equipment used by patients in a seated position.

The Committee recommends following the provisions for gripping surface cross section configurations contained in the 2010 Standards.

Rationale for the recommendation

The cross section dimensions contained in the 2010 Standards used for grab bars found in the built environment are those contemplated for use in MDE. The Committee expressed confidence in reliance on the cross-section dimensions in the 2010 Standards. Allowing both noncircular cross sections and circular cross sections gives manufacturers flexibility to employ the best configuration for use of the equipment, hand, grip strength, and power grab functions. While a majority of the Committee members supported a recommendation allowing both noncircular and circular cross sections, some members noted ergonomic considerations support the better functionality of circular cross section gripping surface.

Figure 5.4.6(a) Gripping Surface Circular Cross Section
(SOURCE: U.S. Access Board)

Figure 5.4.6(b) Gripping Surface Non-Circular Cross Section
(SOURCE: U.S. Access Board)

5.4.7 Transfer Support Gripping Surface Clearance Recommendation for M301 and M302

Description: A clearance around the gripping surface is necessary to ensure sufficient space for a person to grasp the transfer support. This clearance would allow the fingers and knuckles to clear adjacent equipment parts as they grip the support. This clearance location is around the cross section of the gripping surface (see Figure 5.4.7).

NPRM Proposed Provision: Gripping surface clearance not addressed.

NPRM Preamble Discussion: The Access Board is considering whether 1½ inches minimum clearance around the gripping surface would be appropriate for transfer supports on diagnostic equipment used by patients in a supine, prone, or side-lying position, and diagnostic equipment used by patients in a seated position.

The Committee recommends following the Access Board’s proposal in the preamble discussion allowing a 1½-inch clearance.

Rationale for the recommendation

As above, this provision is based on precedent of 2010 Standards and International Building Code Requirements (ICC/ANSI A117.1). The Committee found no reason to change this requirement for MDE.

Figure 5.4.7 Gripping Surface Clearance
(SOURCE: U.S. Access Board)

5.4.8 Transfer Support Gripping Surface Hazard Recommendation for M301 and M302

Description: Gripping surface hazards are sharp or abrasive elements that prevent an individual from sufficiently grasping the support and may pose an injury hazard during use. The provision would prevent such hazards.

NPRM Proposed Provision: Gripping surface hazards not addressed.

NPRM Preamble Discussion: Did not address.

The Committee recommends gripping surfaces be free of sharp or abrasive elements and have rounded edges.

Rationale for the recommendation

Gripping surface configurations must provide an effective and safe surface for patients to hold onto. Sharp edges or abrasive elements may injure and cause the patient to lose his/her grip during positioning or transfer. This provision, like those above, originates in the technical provisions for grab bars in the 2010 Standards

5.4.9 Interruptions along Transfer Support Gripping Recommendation for M301 and M302

Description: Transfer supports may contain elements to provide structural support or prevent patient entrapment. The elements, bars, pickets, spacers, panels, and similar features, connect to the transfer support and may interrupt the gripping surface. At the point of connection, these features impede the ability to grasp completely around the cross section of the gripping surface. The proposed provision seeks to balance the need for such features with an adequately usable transfer support.

NPRM Proposed Provision: Interruptions along gripping surface not addressed.

NPRM Preamble Discussion: Did not address.

The Committee recommends the bottom of the transfer support have no obstructions affecting more than 20% of its length.

Rationale for the recommendation

This recommendation assures that patients needing the use of the transfer support can easily grip the support. Gaps or interruptions along the bottom of the transfer surface may not obstruct more than 20% of its length per the 2010 Standards. Section 505.6 specifies that the gripping surface on the vertical support structure that is necessary for supporting the grip must not be discontinuous.

5.4.10 Transfer Support Fittings Recommendations for M301 and M302

Description: To ensure safe and effective transfers, transfer supports must not rotate within their fittings during use. The proposed provision uses technical criteria in the 2010 Standards for grab bars.

NPRM Proposed Provision: M305.2.3 Fittings. Transfer supports shall not rotate within their fittings.

The Committee recommends transfer supports not rotate when locked in place for patient transfer or use.

Rationale for the recommendation

Transfer supports that move when locked for use would create an unacceptable risk for patients relying on stable support. When the transfer supports latch into a locked position, the transfer supports must meet the required load conditions without movement.

To be useful, transfer supports will be of varying configuration and designs. Some may be removable, some foldable or articulating. In these cases, it is advantageous to allow the supports to perform needed movement but they should not do so when locked at loads below those prescribed in M305.2.2.

5.4.11 Transfer Support Structural Strength Recommendations for M301 and M302

Description: Transfer supports and their connections must be capable of resisting sufficient vertical and horizontal forces to remain stable during use. The proposed provision addresses these aspects of structural strength.

NPRM Proposed Provision: M305.2.2 Structural Strength. Transfer supports and their connections shall be capable of resisting vertical and horizontal forces of 250 pounds (1,112 N) applied at all points on the transfer support.

The Committee recommends transfer supports and connections contain the strength to resist vertical and horizontal forces of 250 pounds at locations determined by the intended use of the equipment.

Rationale for the recommendation

The Committee recommends a proposal that harmonizes the transfer support requirements with other provisions for transfer supports. The proposed technical criteria originated from provisions for grab bars in the 2010 Standards. During discussion manufacturers stated that industry is required to test the most vulnerable spots on the transfer support. Industry must follow testing parameters found in other standards. IEC60601-2-52: “Transfer Supports shall be designed to withstand the forces applied during reasonably foreseeable use without creating an unacceptable RISK.” Transfer supports will deform to some degree under these loads, it must remain stable enough for use. This clause should limit elastic deformation and prohibit permanent deformation or breakage. Product development manufacturers use risk management practices to avoid any unacceptable risk defined by the specific product designs. The most commonly followed standard for risk management is ISO 14971.

5.5 Armrest Recommendations

5.5.1 Armrest Provision for M302

Description: Diagnostic equipment used by patients in a seated position such as exam chairs typically have armrests. The proposed provision requires armrests as these enhance patient comfort and stability. However, this requirement does not supplant provisions for transfer supports. Today, some chair types contain armrests used for transferring and positioning.

NPRM Proposed Provision: M302.3.2 Armrests. Where patients are positioned in a seated position, armrests shall be provided.

The Committee recommends that armrests not be required but if provided they cannot obstruct transfer supports.

Rationale for the recommendation

The Committee recommends use of armrests. If provided, armrests cannot interfere with transfer supports during the transfer. This provision allows dual transfer support/armrest mechanisms as long as the resulting device meets all of the requirements for transfer supports.

Armrests serve a similar function, and occupy the same physical space, as the transfer supports as described in the NPRM. The NPRM requires transfer supports for all chairs, so the additional requirement for armrests for chairs was not only redundant, but could potentially create a physical conflict between the two devices. Although the NPRM infers that the transfer supports are only useful during transfer to/from the chair, the Committee felt that the transfer supports would adequately assist a user with repositioning on the chair during a diagnostic examination or procedure.

5.6 Stirrups Recommendations

5.6.1 Stirrups Provision for M301

NPRM Description: For patients with limited leg strength and control, thigh, knee and calf supports are necessary to maintain an appropriate position. Stirrups that support only the foot and require active user leg strength are insufficient. The proposed provision ensures a method of supporting, positioning, and securing the patient’s legs.

NPRM Proposed Provision: M301.3.2 Stirrups. Where stirrups are provided, they shall provide a method of supporting, positioning, and securing the patient’s legs.

The Committee recommends where equipment provides stirrups, it must also provide an alternate method to support, position, and secure the patient’s legs (specifically including sufficient support of the patient’s thigh, knee, and calf to stabilize the leg). This method will either supplement or serve as a substitute for the stirrups.

Rationale for the recommendation

For procedures that use stirrups and require the leg to be stable, there must be a method to support the patient’s legs. ANSI/AAMI HE75 recommends “[f]or patients with limited leg strength and control, instead of stirrups that support only the foot and require active user leg strength, leg supports that support both the foot and the leg should be used to assist patients in keeping their legs in an appropriate position.” In addition, some people with disabilities cannot use stirrups or any type of boot or heel rest device due to foot contractures.

Stirrups imply support of the foot only, whereas support of the calf, knee, and thigh might be required to stabilize the patient during the procedure. By recommending this addition, it requires use of methods to support areas for the patient’s thighs, knees, and calves to ensure adequate stabilization. When stirrups do not provide a method of supporting, positioning, and securing the patients legs, then a device that supports the calf, knee, and thigh is required. Note that this device may be a supplement to stirrups, or, may be a substitute for the stirrups.

Unique Considerations for Stretchers

When stirrups (also called foot supports) alone will not provide a method of supporting, positioning, and securing the patient’s thighs, knees and calves, the stirrups may be supplemented by or used in conjunction with a secondary accessory that provides this function.

5.7 Lift Compatibility Recommendations

5.7.1 Lift Compatibility Clearance in Base for M301

Description: For portable floor lifts to be effective, they must deploy at diagnostic equipment such that the boom of the lifts can maneuver far enough over the equipment to safely lower and raise the patient onto and off examination surfaces. The proposed clearance in the base provision allows the legs of a portable floor lift to fit under the base of the equipment. The proposed clearance around the base provision allows the legs of a portable floor lift to straddle the equipment base.

NPRM Proposed Provision: M301.4.1 Clearance in Base. The base of the equipment shall provide a clearance 44 inches wide minimum, 6 inches high minimum measured from the floor, and 36 inches deep minimum measured from the edge of the examination surface. Where the width of the examination surface is less than 36 inches, the clearance depth shall extend the full width of the equipment. Equipment components are permitted to be located within 8 inches maximum of the centerline of the clearance width.

5.7.1.1 Lift Compatibility Clearance in Base for Stretchers (M301)

The Committee recommends the equipment base provide a clearance of 39 inches wide minimum.

Rationale for the recommendation

The recommendation for stretchers is for a smaller clearance width than the 44-inch minimum for other equipment. The change harmonizes this provision with the international standards. IEC 60601-2-52 provides requirements for stretchers and includes a lift clearance at the 39 inch width.

For stretchers with a shorter wheelbase than “standard,” the clearance for a lift may use both the clearance in the base and the clearance around the base to position the lift around the stretcher for patient transfers. With a short wheelbase, one leg of a portable lift can extend through the base and the second leg can extend around the base. The size of the clearance is still consistent with the proposed recommendation but this illustrates a different use of the space configuration.

5.7.1.2 Lift Compatibility Clearance in Base for Imaging Equipment (M301)

The Committee recommends the use of alternative means of access by an overhead lift in place of clearances in and around the equipment base where portable lifts are not feasible.

Rationale for the recommendation

Overhead lifts can provide an alternate means of access instead of clearances around the bases of imaging equipment required for portable lifts. Table structural design and/or room layout may be such that providing the clearances in and around the base may be either technically difficult or impractical. In these cases, a ceiling-mounted lift may be a better method for some types of imaging equipment because the portable lift would need to access the diagnostic imaging table from the side or far end. Some imaging systems already use overhead lifts to assist patients.

Overhead lifts are not feasible in the MR exam room due to the magnetic fields. Some MR systems currently have detachable tables that can move away from the magnetic field to permit transfer elsewhere. In situations where an overhead lift would be impossible, detachable and portable imaging tables could move to the patient for transfers. A stretcher-based transfer provides another option. A stretcher-based transfer is also an alternate to lift-based transfers in the case of prone breast biopsy tables. This type of transfer effectively and safely achieves the patient position needed for the procedure.

Below is a picture of an existing CT room with a ceiling mounted overhead lift. This may offer flexibility over a portable lift because it can transfer the patient from either side placing the patient in the desired imaging orientation, and the ability to move completely out of the way when not needed.

Figure 5.7.1.2 An existing CT room with a ceiling mounted overhead lift
(SOURCE: GE Healthcare)

5.8 Wheelchair Spaces Recommendations for M303 Diagnostic Equipment Used by Patients Seated in a Wheelchair

5.8.1 Wheelchair Spaces on Raised Platforms Recommendations

Description: Proposed section M303 provides technical criteria for diagnostic equipment used by patients seated in a wheelchair. The provisions allow patients who use wheelchairs to position their devices at equipment typically used in a standing position such as mammography equipment, and applies to equipment specifically designed for patients seated in a wheelchair such as weight scales. Portable and fold-up weight scales with wheelchair spaces are also the ubiquitous example of diagnostic equipment with raised platforms. The proposed recommendations address considerations unique to these.

NPRM Proposed Provision: M303.2 Wheelchair Spaces. A wheelchair space complying with M303.2 shall be provided at diagnostic equipment.

M303.2.2 Width. Wheelchair spaces shall be 36 inches wide minimum.

M303.2.3 Depth. Where wheelchair spaces can be entered from the front or rear, the wheelchair space shall be 48 inches deep minimum. Where wheelchair spaces can be entered only from the side, the wheelchair space shall be 60 inches deep minimum.

NPRM Preamble Discussion: The Access Board is considering adding exceptions in the final standards to the minimum width in M303.2.2 and the minimum depth in M303.2.3 for diagnostic equipment with wheelchair spaces on raised platforms.

5.8.1.1 Clear Platform Size Recommendation

The Committee recommends a platform size with a minimum clear width of 32 inches and a minimum clear length of 40 inches.

Rationale for the recommendation

The platform size of 32 inches minimum width by 40 inches minimum length accommodates both manual and power wheeled mobility devices including small and mid-size scooters. This platform size may not accommodate some larger scooters with a 4-wheel base. The Wheeled Mobility Anthropometry Project recommends this platform dimension.^iv These study findings noted that a 36-inch length accommodates standard manual and power wheelchairs and most, if not all, large size-extra wide manual chairs. This size platform allows the person to maneuver and position the device even though many devices may not stop precisely in the middle of the platform.

To have an accurate weight, the entire wheelbase (either 3 or 4 wheels) of a mobility device must rest on and make contact with the platform. The foot pedals, footrests, scooter deck and tip wheels can overhang or extend beyond the platform and still get an accurate weight.^II

The Wheeled Mobility Anthropometry Project research summarizes wheelbase measurements on wheeled mobility devices shown in the table below.4

Table 5.8.1.1
Wheelbase Measurements on Wheeled Mobility Devices

Table ![sic]: Range and percentile values for wheelbase (inches) by mobility device type

[Click image above to view HTML version]

The Wheeled Mobility Anthropometry Project recommends a minimum flat surface of 40 inches length for platforms accommodating wheeled mobility devices including scooters and a minimum flat surface of 33 inches length for platforms accommodating wheeled mobility devices excluding scooters.

Figure 5.8.1.1 Clear Platform Size
(SOURCE: U.S. Access Board)

Notes

^II The IDeA Center in its research defined wheelchair wheelbase as the distance from the center of the primary drive wheel to the center of the caster measured parallel to the floor. It defines scooter wheelbase as the distance from the center of the primary drive wheels to the center of the back or front wheels measured parallel to the floor.

Section 5 References

^iv IDeA Center Study at the University of Buffalo, New York: Summary analysis of wheelbase measurements on wheeled mobility devices.

5.8.1.2 Entry to Wheelchair Spaces on Raised Platforms
Recommendations

Description: Entry to wheelchair spaces on raised surfaces greater than ¼ inch in height requires a transition via a bevel or ramp so that people using mobility devices will be able to maneuver onto and off it. The proposed provision includes technical criteria for changes in level at the entry of a wheelchair space. This change in level may occur on wheelchair weight scales with raised platforms. The technical criteria are consistent with the 2010 Standards.

NPRM Proposed Provision: M303.3 Entry. Where there is a change in level at the entry to a wheelchair space, the change in level shall comply with M303.3.

M303.3.3 Ramped. Changes in level greater than ½ inch high shall be ramped and shall comply with M303.3.3.

M303.3.3.1 Running Slope. Ramp runs shall have a running slope no steeper than 1:12.

M303.3.3.4 Edge Protection. Ramps with drop offs ½ inch or greater shall provide edge protection 2 inches high minimum on each side.

5.8.1.2.1 Ramped Entry Slope Recommendations

The Committee recommends that raised platforms have a ramp with slopes that do not exceed the following:

• At 0 to 1½ inches, the slope is 1:2
• At greater than 1½ to 2½ inches, the slope is 1:8
• At greater than 2½ inches, the slope is 1:12

Rationale for the recommendation

The Committee considered the needs of a ramped surface to access the platform on the accessible scale. Because there are different types of scales with different platform heights, the Committee developed a three tiered ramp slope proposal to fit different situations.

The Committee reviewed and discussed the provisions on slopes for ramps as they apply to architectural elements in the built environment. The maximum slope for a ramp in the 2010 Standards is a rise of 1 vertical inch for each 12 inches of horizontal distance slope. Under very limited conditions in the built environment, the 2010 Standards allow a steeper ramp for a limited rise. A ramp in the built environment to which this exception applies may use a 1:2 grade slope on a short rise ramp.

Industry experts spoke to the concern for facility space often expressed by healthcare entities. The space constraints affect the desirability of accessible scales since space is often expensive and tight in many medical facilities. Scales that can be wall mounted or portable enhance the flexibility of scales and allow use in tight environments. Currently, these types of accessible scales use the short rise ramp to facilitate easy storage or mounting.

Existing technology for weight cell load allows a for a platform profile to go as low as ¾ to 1½ inches. As the height of the platform lowers, the length of the ramp can decrease. The trend in the scale industry is to develop lower weight cell technology. However, industry currently does not know if lower profiles are possible.

Some Committee members pointed out that these provisions create exceptions from the existing 2010 Standards.

5.8.1.2.2 Single Ramped Entry - Edge Protection on the Platform and Platform Sides Recommendations

The Committee recommends a two-inch high edge protection on the back of the platform opposite the entry ramp and a minimum two-inch high edge protection on the sides of the platform.

Rationale for the recommendation

The edge protection adds a safety feature to prevent wheeled mobility device users from “over-shooting” the platform edges and tipping, falling, etc. Not all mobility devices stop immediately when braking to stop. The limitation on edge protection height will reduce the possibility that the edge protection will interfere with the patient’s footrest.

5.8.1.2.2 Single Ramp Scale with Edge Protection
(SOURCE: U.S. Access Board)

5.8.1.2.3 Double Ramped Entry - Edge Protection on the Platform sides Recommendations

The Committee recommends a minimum two-inch high edge protection on both sides of the platform for double ramped entry platforms.

Rationale for the recommendation

Edge protection provides an additional safety feature and guides users of wheeled mobility devices on the platform. The protection stops the mobility device from driving off either side of the platform.

5.8.1.2.3 Double Ramp Scale with Edge Protection
(SOURCE: U.S. Access Board)

5.8.1.2.4 Edge Protection on Platforms 1½ inches or less in Height Recommendations

The Committee recommends that no edge protection be required on platforms of 1½ inches or less in height.

Rationale for the recommendation

Edge protection on platforms of heights of 1½ inches or less is not required because the low height profile does not pose a safety hazard to users when on the platform.

5.8.2 Knee and Toe Clearance Recommendations under Breast Platform Recommendations

Description: The knee and toe clearance under the breast platform applies to mammography equipment for patients seated in a wheelchair. Knee and toe clearances are critical where patients seated in a wheelchair need to position their knees and toes next to or underneath a component of the diagnostic equipment. The proposed provision requires the depth of wheelchair spaces to include knee and toe clearance. Given the unique use of mammography equipment, the provision also contains a specific depth requirement under breast platforms.

NPRM Proposed Provision: M303.2.4 Knee and Toe Clearance. Wheelchair spaces shall include knee and toe clearance complying with M303.2.4. The depth of the wheelchair space shall include knee and toe clearance of 17 inches minimum and 25 inches maximum. Knee and toe clearance under breast platforms shall be 25 inches deep.

M303.2.4.1 Toe Clearance. Toe clearance shall be provided at a height of 9 inches above the floor to a depth of 6 inches maximum.

M303.2.4.2 Knee Clearance. Knee clearance shall be provided at a depth of 11 inches minimum and 25 inches maximum at 9 inches above the floor and at a depth of 8 inches minimum at 27 inches above the floor. Between 9 inches and 27 inches above the floor, the knee clearance shall be permitted to reduce at a rate of 1 inch in depth for every 6 inches in height.

NPRM Preamble Discussion: The dimensions for toe clearance in M303.2.4.1 and knee clearance in M303.2.4.2 are based on the 2010 Standards and are shown in the second column of the table below. The Wheeled Mobility Anthropometry Project showed that these dimensions do not accommodate many people in the sample and recommended alternative dimensions that would accommodate 95 percent of the people in the sample. The alternative dimensions recommended by Wheeled Mobility Anthropometry Project are below in the last column of the table. The Access Board is considering requiring in the final standards the dimensions for toe clearance and knee clearance recommended by the Wheeled Mobility Anthropometry Project.

Table 5.8.2(a)
Recommended Dimensions for Knee and Toe Clearances

The Committee recommends increasing the overall knee and toe space to a minimum 28 inches deep, from the initially proposed 25-inch absolute dimension; increasing the knee clearance directly underneath the breast platform to a minimum of 18 inches; and assuring unobstructed floor space in front of the base support at a minimum of 17 inches deep.

Rationale for recommendation

Each of these measurements creates a more accessible piece of imaging equipment while balancing the physical attributes and operation of the equipment.

The M303.2.4 proposed NPRM provision and the dimensions recommended by the Wheeled Mobility Anthropometry Project are based on an anthropomorphic model that defines knee and toe clearances based on measurements from the tip of a person’s foot. Industry suggested that using an anthropomorphic model that defines knee and toe clearances based on measurements from a person’s abdomen would be more appropriate because mammography procedures require a person’s chest to be flush with the front of the breast platform. Industry also indicated that the Committee would need to consider the range of travel of the breast platform and the impact that it has on the knee and toe space. The Committee reviewed the relevant anthropomorphic modelsand industry input on how these elements affect one another from a technical perspective. Below is an overview of the rationale for each of the final recommended dimensions affecting the knee and toe clearance underneath the breast platform. Figure 5.8.2 illustrates each of the critical dimensions. Further discussion of each of these dimensions follows in sections 5.8.2.1 – 5.8.2.7.

Figure 5.8.2 Overview of the Critical Dimensions that Define the Knee and Toe Space Underneath the Breast Platform.
(SOURCE: Hologic, Inc.)

Table 5.8.2(b) Critical Equipment Dimensions with the relevant Anthropomorphic Data

Section 5 References

^v IDeA Center at the University of Buffalo, New York: The Wheeled Mobility Anthropometry Project, Final Report, pages 89-92.

^vi D’Souza, et al. “Clearance Space Envelopes of Wheeled Mobility Device Users for Computer Workstations”. Proceedings of the Human Factors and Ergonomics Society Annual Meeting 2012.

^vii D’Souza, Steinfeld. “Revised Knee Clearance Depth and Footrest Clearance dimensions for sizing of mammography equipment.” Memorandum. April 23, 2013.

5.8.2.1 Height of Breast Platform at Time of Measurement
Recommendation

The Committee recommends measuring all knee and toe clearances when the top of the breast platform is set at 34 inches above the floor.

Rationale for the recommendation

The shape of the breast platform affects the shape of the knee and toe space. This shape varies across different pieces of equipment, and breast platforms do not have standard features that can be used to define the required knee clearance space underneath the breast platform. However, the top surface of the breast platform is a well-defined surface, and defines where the patient’s chest will be during the exam. When the top of the breast platform is at the height of the patient’s breasts, there must be sufficient clearance at the height of the patient’s knees, as is shown in Figure 5.8.2.1.

Figure 5.8.2.1 Illustration of the relationship between the breast platform height and the clearance required at the patient’s knees.
(SOURCE: Hologic, Inc.)

As indicated by the graphics key, the dotted lines reference the current ADA-ABA standard. Industry has laid an example mammography image over the relevant anthropomorphic modelvv.

The NPRM proposed measuring the knee clearance under the breast platform at 27 inches above the ground. Industry started with this dimension and determined the proportionate height of the breast platform to be 34 inches. The Committee agreed to this as a “set point” (Identified as “Breast Platform Height” in Figure 5.8.2.1). These dimensions (27 and 34-inch heights) are the same as those defined by the current 2010 Standards to accommodate wheelchair users at desks, which is outlined by the dotted lines in Figure 5.8.2.1.

The 27-inch and 34-inch dimensions help to define the breast platform requirements for a person with deep knees and a tall wheelchair. When the breast platform lowers to accommodate patients in shorter wheelchairs, there will be ample knee clearance for those patients. Conversely, as the breast platform moves up for patients who have longer torsos, the breast platform will just be moving away from their knees and legs, thus giving them ample space as well.

By defining the height of the breast platform as the “set point” for the other dimensions, all clearances have a static measurement point that assures maximum clearances during operation of the equipment. If there were not a defined method of measuring the clearances in relationship to the breast platform, then it would be possible for inaccessible equipment configurations to meet the clearance requirements.

5.8.2.2 Knee Clearance Depth at 27” Above the Ground

The Committee recommends increasing the knee clearance at 27 inches above the ground to 18 inches minimum.

5.8.2.3 Overall Knee and Toe Clearance Recommendation

The Committee recommends increasing the overall knee and toe space to 28 inches minimum.

Rationale for the recommendation

See Section 5.8.2.4 below.

5.8.2.4 Unobstructed Floor Space Recommendation

The Committee recommends the unobstructed floor space in front of the base support be a minimum of 17 inches deep.

Rationale for the recommendation

The overall knee and toe clearance and unobstructed floor space dimensions dictate how close a patient in a wheelchair can get to the mammography equipment. As was discussed above, the Committee considered anthropomorphic data that defined knee and toe clearances from a person’s abdomen. To consider overall knee and toe clearance, the Committee used female-only anthropomorphic data that defined abdomen-toe depths to ensure that a patient’s toes would not hit the gantry. To consider unobstructed floor space, the Committee used anthropomorphic data that defined abdomen-caster edge depths to ensure that the front caster wheels on a patient’s wheelchair would not hit the front of the base support.

The base support affects how close the patient can get to the mammography machine because it intrudes into the floor space. The purpose of the base support is to eliminate any instability caused by the weight of the cantilevered c-arm. Moving the c-arm further away from the gantry would increase the overall knee and toe clearance, but would also require an increase in the size of the base support in order to stabilize the equipment. The simultaneous increase in the size of the base support will minimize any gains from increasing the knee and toe clearance, since the base support obstructs the floor space. The Committee considered this balance when making final decisions about overall knee and toe space and unobstructed floor space.

While discussing these issues, the Committee also considered positioning methods for patients using wheelchairs. During a mammography procedure, the patient’s chest is flush with the front edge of the breast platform and the technician positions the patient’s breast on the breast platform. In order to image as much of the breast as possible, patients cannot be seated in the “natural” sitting position. They will need to sit up straight in order to situate as much breast tissue as possible on the breast platform. For patients seated in a wheelchair, a common positioning technique is to place towels, pillows, or other positioning aids behind the patient’s back in order to sustain an upright pose during imaging. This upright pose is necessary regardless of how close the patient can naturally get to the breast platform. The pose reduces the abdomen-toe and abdomen-caster edge dimensions by a couple of inches.

To accommodate 95% of female wheelchair users, the anthropomorphic data shows that 30.5 inches and 19.5 inches are the necessary minimum overall knee and toe clearance and unobstructed floor space dimensions, respectively. [Data is below in Tables 5.8.2.4(a) and 5.8.2.4(b)]. Members agreed on reducing these dimensions by 2.5 inches to adjust for the upright pose and to ensure technical feasibility and equipment safety. The final Committee recommendation is to require a minimum of 28 inches overall knee and toe clearance and a minimum of 17 inches unobstructed floor space. Looking purely at the anthropomorphic data, these dimensions accommodate 80% - 90% of the population. In adjusting for the needed upright pose, the dimension works for 95% of the population. Members recognized that these dimensions are an optimal blend of accessibility and technical feasibility .

Table 5.8.2.4(a). Abdomen Depth Data^vii to determine overall knee and toe clearance

Table 5.8.2.4(b) Abdomen-Caster Edge Depth^vii to determine unobstructed floor space 

Section 5 References

vii D’Souza, Steinfeld. “Revised Knee Clearance Depth and Footrest Clearance dimensions for sizing of mammography equipment.” Memorandum. April 23, 2013.

5.8.2.5 Toe Height Recommendation

The Committee recommends increasing the toe height to 18 inches minimum, measured above the ground when the top of the breast platform is 34 inches above the ground.

Rationale for the recommendation

The NPRM defined the toe clearance at a height of 9 inches. However, as the breast platform moves up and down, it may intrude on the toe space. Looking further at female-specific toe height data, the 95th percentile toe height is 13 inches for manual wheelchair users and 16.1 inches for power wheelchair users.^vi As such, the subcommittee recommended that the toe height be set to 18 inches (when the breast platform is at the 34 inch height discussed above). This higher 18-inch measurement (compared to the originally proposed 9-inch toe height) would also minimize the chance of the breast platform hitting patients’ toes when the breast platform moves to some of its lower heights.

A toe space dimension usually defines a static unobstructed space. However, in the case of mammography, as the breast platform moves up and down, the toe space changes. The 18-inch toe height is defined when the breast platform is at 34 inches above the ground. When the breast platform lowers to its required minimum height of 26 inches, the resulting toe height is 10 inches above the ground. When a patient needs the breast platform to be this low, she is likely to be lower to the ground and thus likely to have her feet closer to the ground as well. As such, a 95th percentile toe height (13 – 16.1 inches) does not need to be accommodated when the breast platform is at this minimum height. However, it is important to provide extra toe space for patients who are seated close to the ground but have their footrests positioned at more of an angle. The toe height defined here will provide this extra accommodation. Providing this dimension helps define the outer limits of the breast platform configuration in a way that maximizes the dimensions for accessibility.

Section 5 References

^vi D’Souza, et al. “Clearance Space Envelopes of Wheeled Mobility Device Users for Computer Workstations”. Proceedings of the Human Factors and Ergonomics Society Annual Meeting 2012.

5.8.2.6 Clearance Depth at Toe Height above the ground Recommendation

The Committee recommends 22 inches minimum clearance depth at toe height.

Rationale for recommendation

See Table 5.8.2(b).

5.8.2.7 Base Support Allowance Recommendation

The Committee recommends allowing a base support that obstructs the clear floor space if it fits within the allowed base support volume. Base supports can be a maximum of 1½ inches high. An additional sloped region above the base support is permitted at a depth of 25 inches from the front edge of the breast platform at 1½ inches above the floor, and can extend to a height of 4 inches above the floor at a depth of 28 inches from the front edge of the breast platform. Figure 5.8.2.7(a) illustrates this configuration below.

Figure 5.8.2.7(a) Illustration of final committee recommendation on proposed base support configuration. 
(SOURCE: Hologic, Inc.)

Rationale for the recommendation

The base support is of fundamental importance to mammography equipment and provides structural support, seismic stability, and installation safety. It does obstruct the floor space in front of the gantry and, thus, may limit how close a wheelchair can get to the equipment. To respond to this issue, industry proposed a configuration that would cause minimal obstruction to the floor space in front of the gantry and would allow footrests to ride over it.

To discuss the maximum base support height, the sub-committee looked at anthropomorphic data regarding footrest heights. The footrest height data measures the height from the floor to the top surface of the footrest at its proximal outside corner. To determine the necessary clearance for the footrests, the Committee used the footrest height data and subtracted the thickness of the footrests (~0.5 inch). The ~0.5inch thickness is the recommendation from the data supplied by Steinfeld and D’Souza7. The anthropomorphic data, as well as the calculated footrest clearances, is below in Tables 5.8.2.7(a) and 5.8.2.7(b).

Table 5.8.2.7(a). Anthropomorphic data on measured footrest heights

 Table 5.8.2.7(b). Actual footrest height clearances

Allowing a maximum base support height of 1.5 inches will provide room for the structural components necessary for an effective base support design and will also be accessible by around 92% of manual chair users and over 95% of power chair users.

Committee members noted that allowing the base support to encroach into the floor space creates an exception from the 2010 Standards. Since mammography equipment bolts or affixes to the floor of the facility, it becomes a fixture to the building. The Department of Justice considers fixtures to fall under the architectural elements covered by the 2010 Standards. The provisions for clear floor space generally do not allow an encroachment even with a maximum height of 1½ inches for the base support. However, the Committee agreed that since the base support is critical to the equipment’s stability and installation safety, the support must be configured to allow for maximum wheelchair accessibility.

The Committee also discussed adding an allowance for a sloped region at the base of the gantry. Many of the mammography machines today have important informational displays at the base of the gantry, on top of the base support (shown as the checkered region in Figure 5.8.2.7(b)) that display information such as compression force and compression thickness.

Figure 5.8.2.7(b) Checkered region shows location of informational displays and other mechanical and electrical components on many mammography machines.
(SOURCE: Hologic, Inc.)

The Committee discussed the additional sloped region. Several members felt strongly that the additional sloped region must be justified by structural stability since displays could be located elsewhere. Members commented that not all equipment has displays in this region, so it seemed possible for industry to redesign the displays to create less interference.

Industry input indicated that customer feedback was one of the major drivers to position the displays at that location. Technologists have reported that while positioning the patient’s breast, they are naturally looking downward, and by having the display at the base of the gantry, they could watch the compression force and breast thickness readout while positioning the patient. They suggested this location for the display as a method for improving workflow. On other machines, this region has other mechanical and electrical components that are not necessarily there for structural stability, but are important to the function of the equipment.

The Committee refined the configured allowance for the sloped region from 7 inches down to a height of 4 inches above the floor at a depth of 28 inches from the front edge of the breast platform. Industry worked with Committee members to optimize the accessibility of the base support configuration, shown in Figure 5.8.2.7(a) above. The Committee agreed to accept the refined configuration during the full discussion of the report with no reference to structural stability.

Figures 5.8.2.7(c) and 5.8.2.7(d) illustrate this region overlaid with the anthropomorphic data for manual and motorized wheelchairs, respectively. Steinfeld and D’Souza supplied these charts plotting their study’s findings on the depth of participant’s footrests and caster wheelsvii. The black lines show the areas with no interference between the footrests and caster wheels and the base support interface. However, based on the technical feasibility and clinical use considerations discussed in the above sections, industry proposed the overlay configuration in red in the figures.

Figure 5.8.2.7(c) Final Committee recommendation on allowable base support configuration overlaid with anthropomorphic data for manual wheelchairs. 
(SOURCE: Hologic, Inc.)

The black lines show the areas with no interference between the footrests and caster wheels and the base support interfacevii. However, based on the technical feasibility and clinical use considerations discussed in the above sections, industry proposed the overlay configuration in red.

Figure 5.8.2.7(d) Committee recommendation on allowable base support configuration overlaid with anthropomorphic data for power wheelchairs. 
(SOURCE: Hologic, Inc.)

The black lines show the areas with no interference between the footrests and caster wheels and the base support interface. However, based on the technical feasibility and clinical use considerations discussed in the above sections, industry proposed the overlay configuration in red.

The green dots in the scatter plot illustrations represent observed values for footrest height (on the vertical axis), and footrest depth (on the horizontal axis) measured for manual wheelchair users to the abdomen point. The footrest heights do not account for the 0.5-inch footrest thickness, so the required footrest clearances are 0.5 inch lower than the footrest heights plotted here. The footrest depth is the horizontal distance from the abdomen to the distal (forward-most) edge of the footrest. The person’s toes, however, will extend beyond the front edge of the footrests, so the Committee reviewed different data to determine the overall knee and toe clearance (see Section 5.8.2.3 above).

5.8.2.7.1 Mammography Chair Footrest Recommendation

The Committee recommends that the mammography chair meet the elements of M302 with the additional requirement that any footrests must accommodate and ride over the base support.

Rationale for the recommendation

The mammography chair is an essential piece of equipment allowing persons who are unable to stand or balance to sit for the diagnostic procedure. The chair must meet the elements of M302 with the additional requirement that any footrests must accommodate and ride over the base support.

5.8.2.8 Knee and Toe Clearance Recommendations Summary

Ultimately, all of the knee and toe clearance recommendations in sections 5.8.2.1 – 5.8.2.7 are summarized below, in Figure 5.8.2.8, which shows the measurements needed to determine if a certain piece of mammography equipment is accessible. For such a measurement, the top of the breast platform will be moved to 34 inches above the ground, and then the clearance dimensions will be measured just as they would be on any stationary piece of equipment, with allowance for slopes where shown.

Figure 5.8.2.8 Summary of Knee and Toe Clearance Measurements. 
(SOURCE: Hologic, Inc.)

The top of the breast platform would be moved to 34 inches above the ground, and then the clearance dimensions would be measured just as they would be on any stationary piece of equipment, with allowance for slopes where shown.

5.8.3 Breast Platform Recommendations

Description: In addition to providing knee and toe clearance at the breast platform (see 5.8.2 Knee and Toe Clearance Recommendations under Breast Platforms), the height of the breast platform is also critical to ensuring that mammography equipment is accessible to patients seated in a wheelchair. The proposed provision addresses the low and high heights that must be provided.

NPRM Proposed Provision: M303.4.1 Breast Platforms. The height of the breast platform shall be 30 inches high minimum and 42 inches high maximum above the floor when in use by a patient seated in a wheelchair

5.8.3.1 Breast Platform Height Recommendations

The Committee recommends decreasing the minimum height of the top of the breast platform to 26 inches above the floor. The upper height range for the breast platform was not controversial and remained as proposed. The final version of the criteria must clarify that the specified height range is a minimum range of travel.

Rationale for the recommendation

The subcommittee expressed conflicting perspectives on the minimum breast platform height with members either choosing to support the 26-inch or 28-inch minimum. While all other subcommittee decisions were by group consensus, the group required a formal vote on this issue. Although the subcommittee vote was for 28 inches, during the final public meeting, the full Committee supported the 26-inch minimum by a strong majority.

According to industry, equipment currently manufactured ranges anywhere between 25 and 28 inches for the lowest measurement of the breast platform. There were various reasons cited for each of the positions. Recommendations from accessibility experts who developed mammography protocols for women with disabilities identified a need for a breast platform height of 24 inches. Because this recommendation evolved from technologist experience on equipment with less knee space, disability advocates supported the rationale for 26 inches as the minimum. One member cited the diversity of body types and sizes for persons with disabilities as the rationale for the 26 inches. Another member emphasized the importance of considering patients of short stature in addition to considering patients seated in a wheelchair.

Many industry organizations supported the 28-inch minimum. Reasons cited included providing more flexibility for manufacturers and concern that the lower minimum could result in more leg injuries as the technologist lowered the breast platform so close to the lap of the patient using a wheelchair. Members disagreed with limiting the height as the method of minimizing the risk of injury since this could happen at any height depending upon the height of the knees of the person. Informal input from some technologists indicated no problems with imaging patients with disabilities at 28-inch minimum heights.

One member expressed support for the lower height in order to facilitate the Magnified Cranio Caudal (hereinafter “Mag”) view for person needing magnified views of tissue. Mag views require the breast to be located at a specific position in between the x-ray tube and the breast platform. To capture this view, providers place an accessory, often called a “Mag Stand”, on the breast platform, as shown in Figure 5.8.3.1. The provider will then position the patient’s breast on top of the mag stand so that the breast is at the correct position between the x-ray tube and the breast platform. The height of the mag stand can vary between 6 inches and 10 inches, depending on the characteristics of the x-ray beam and the degree of magnification desired. Since the technologist places this accessory on top of the breast platform, it effectively increases the height and thickness of the breast platform. Beginning with a lower breast platform height could help more patients to have access to the mag view. However, the more significant barrier to patients imaged from a seated position is the increased overall size of the platform (from lap to breast) during a mag view, since it would require the patient to have a very tall torso.

Figure 5.8.3.1 Illustration of an example mag stand on top of the breast platform.
(SOURCE: Hologic, Inc.)

5.9 Standing Support Recommendations for M304 Diagnostic Equipment Used by Patients in a Standing Position

Description: Many people who ambulate with a disability need support to maintain position and balance on diagnostic equipment used by patients in a standing position. The proposed provision requires standing supports be provided on each side of the standing surface. These standing supports may be provided in a horizontal position, vertical position, or a combination of horizontal and vertical positions, as long as the minimum length of gripping surface is provided for the support position used on each side of the standing surface.

NPRM Proposed Provision: M304.3 Standing Supports. Standing supports shall be provided on each side of the standing surface and shall comply with M305.3.

5.9.1 Standing Supports Recommendation In Reference To Mammography Equipment

The Committee recommends removing the requirement for standing supports on mammography equipment. Instead, positioning supports should be required. To be useful, positioning supports must be shaped for grasping, positioned within reach range of all users, and be 12 inches long minimum when located on the moving c-arm or 18 inches long minimum when in a fixed location.

Rationale for recommendation

The original criteria proposed in the NPRM included vertical standing supports on both sides of the equipment that were 18 inches in length. During discussion, there was general agreement that the real use of these supports is for positioning, and thus, not meant to support the full weight of the patient or to keep a patient in a standing position during the exam. Industry representatives posited that if a patient has limitations or balance issues severe enough to need standing assistance, then the healthcare provider should position her in a seated position for safe imaging. The primary use of these supports is for positioning of the arms during the imaging process to keep them out of the field of view of the image. For these purposes, the equipment criteria should designate these supports as positioning supports and be designed with the structural strength required for positioning activities.

Furthermore, since the supports mount to the c-arm on many types of mammography equipment, they will move up and down with the breast platform. In these cases, they do not need to be as long as 18 inches to provide sufficient flexibility for patients to reach them. Industry representatives also indicated that there are controls in the area where these positioning supports are located. It is important that the patients’ hands do not accidentally hit these controls when they are holding the positioning supports. For this reason, industry will sometimes intentionally shorten the length of these handholds to less than the 18-inch proposal. Considering these factors, the full Committee agreed that a 12-inch long positioning support would be sufficient if it moved with the movable breast platform.

5.9.2 Standing Supports on Ramped Entry Raised Platforms with Wheelchair Spaces Recommendations

5.9.2.1 Standing Supports on Single Ramped Entry Raised Platforms with Wheelchair Spaces Recommendations

The Committee recommends standing supports located on both sides of platforms, a minimum of 34 inches between supports, integrated into the platform, and 32-inch minimum length (at least 80% of the platform length) at the platform entry edge for a single ramp entry raised platform.

Rationale for the recommendation

The Committee recommends placement of standing supports on both sides for single ramp entry to a raised platform because the supports add safety. The user can hold onto something for stability when accessing or exiting the scale. Standing supports can also act as a guide to help the user to better position her or himself onto the platform.

A 34-inch minimum width between the supports will allow for adequate elbow space for a user of a wheeled mobility device to push the wheels onto the platform and does not infringe on the 32-inch platform.

A standing support must integrate into the platform so it does not interfere with weight accuracy.

The length of the standing supports must be 80% of the platform length or 32-inches minimum, from the platform entry edge. This dimension allows a user to grab it from any point on the platform. This dimension allows use during accessing the platform, positioning on the platform, and provides guidance during exiting (backing out) of the platform.

5.9.2.2 Standing Supports on Dual Ramped Entry Raised Platforms with Wheelchair Spaces Recommendations

The Committee recommends standing supports located on one side of the platform, integrated into the platform and stretching the full length of the platform (40-inch minimum) for dual ramped entry raised platforms.

Rationale for the recommendation

Users need to access either side of the ramp for entry. An individual accessing the ramp may have only one usable side due to conditions such as a stroke, or right or left side paralysis or weakness etc. The user can choose which side of the ramp to enter on and use the standing support as needed to help guide and position himself onto the scale platform.

A standing support must integrate into the platform so that it does not interfere with weight accuracy. The standing support spanning the full length of the platform, 40-inches minimum will provide maximum platform coverage for added safety and stability to users. The user can grab onto the standing support, gain access to the platform, position, and exit the platform.

Notes

^GG Analysis of Seat Heights for Wheeled Mobility Devices. The study is available at http://udeworld.com/analysis-of-seat-height-for-wheeled-mobility-devices.

^HH Of note, the committee also decided by consensus that extreme obesity was not within the scope of the committee’s work, but to instead use the data provided by Dr. Steinfeld’s study in determining their recommendation. See section 8.1 of this report for further discussion of extreme obesity, and its recommendation for future topics of research.

^II The IDeA Center in its research defined wheelchair wheelbase as the distance from the center of the primary drive wheel to the center of the caster measured parallel to the floor. It defines scooter wheelbase as the distance from the center of the primary drive wheels to the center of the back or front wheels measured parallel to the floor.

^JJ The concept of technical feasibility is one found in other areas of access. It recognizes that there may be physical factors that create limits to what functions can be achieved even with redesign. In mammography, the presence of the base support for the physical stability and operation of the equipment falls into this category. The committee recognizes that future visionaries may be able to “re-vision” new devices to provide greater clearances and smaller base supports.

Section 5 References

ⁱ http://udeworld.com/analysis-of-seat-height-for-wheeled-mobility-devices

ⁱⁱ ”The Impact of Transfer Setup on the Performance of Independent Transfers: Final Report”; Human Engineering Research Laboratories, VA Pittsburgh Healthcare System, University of Pittsburgh.

ⁱⁱⁱ ANSI/AAMI HE75 Standard Human factors engineering – Design of medical devices, Chapter 16 – Accessibility considerations, section 16.4.7 (g).

^iv IDeA Center Study at the University of Buffalo, New York: Summary analysis of wheelbase measurements on wheeled mobility devices.

^v IDeA Center at the University of Buffalo, New York: The Wheeled Mobility Anthropometry Project, Final Report, pages 89-92.

^vi D’Souza, et al. “Clearance Space Envelopes of Wheeled Mobility Device Users for Computer Workstations”. Proceedings of the Human Factors and Ergonomics Society Annual Meeting 2012.

^vii D’Souza, Steinfeld. “Revised Knee Clearance Depth and Footrest Clearance dimensions for sizing of mammography equipment.” Memorandum. April 23, 2013.