36 CFR Part 1195 Standards for Accessible Medical Diagnostic Equipment - Preamble

2. Equipment Clearances for Breast Platforms

The MDE NPRM proposed knee and toe clearance requirements for diagnostic equipment used by patients seated in wheelchairs that paralleled the knee and toe clearance requirements from the 2004 ADA and ABA Accessibility Guidelines. NPRM, 77 FR at 6929. The proposed rule included a requirement that 17 inches minimum and 25 inches maximum of the 48-inch wheelchair space depth include knee and toe clearance. The knee and toe clearance would be permitted to be located beneath the diagnostic equipment, such as an optometrist diopter. The proposed rule contained a different requirement for breast platforms on mammography equipment, that of the 48-inch depth minimum of the wheelchair space, the knee and toe clearance under a breast platform would be 25 inches deep (proposed M303.2.4).

Two commenters, one manufacturer and one disability rights organization, commented on the knee and toe clearance under breast platforms. The disability rights organization raised concerns that existing machines do not provide deep enough clearance and that during the examination the breast platform will hit the patient’s knees. The manufacturer also raised concerns with the size of the knee and toe clearance and recommended basing the requirements in relation to the height of the breast platform. Additionally, this commenter raised concerns that mammography equipment must have a stabilizing flange or foot at its base to prevent the equipment from tipping when the gantry is extended. This flange protrudes into the knee and toe clearance. Specifically, this commenter explained that the flange can be designed for optimal accessibility, but is necessary for the safety of the equipment.

The MDE Advisory Committee reviewed this provision and gave multiple recommendations regarding the necessary clearances for breast platforms. The Advisory Committee noted that mammography equipment presents a unique challenge for individuals seated in wheelchairs because the mammography exam requires the patient’s breasts to be placed on top of the breast platform thereby requiring the knees and toes to go deeper beneath the equipment. The MDE Advisory Committee recommended changes to the proposed requirements for knee and toe clearance to create a deeper knee space under breast platforms. The MDE Advisory Committee did not suggest revisions to the proposed knee and toe clearances for diagnostic equipment used by patients seated in wheelchairs, other than for mammography equipment.

The knee and toe clearance requirements were adopted from the 2004 ADA and ABA Accessibility Guidelines and typically will allow a person seated in a wheelchair to pull underneath a work surface or equipment component or permit forward access to a control located above equipment overhanging the knee and toe space. We are persuaded by the MDE Advisory Committee report that mammography equipment presents a unique use and requires different specifications for the knee and toe clearance to ensure that the patient’s breast can rest on top of the platform. The knee and toe clearance underneath mammography equipment must provide sufficient space to allow the patient to get close enough for their breast to be placed on the breast platform in order for the diagnostic procedure to be performed. Thus, the Access Board has reorganized the equipment clearances provision in the final rule into two separate requirements; breast platforms and other equipment. The requirements for breast platforms (M303.2.4.2 in the final rule) account for obstructions in the knee and toe clearance necessary to stabilize the mammography equipment and the location of the patient’s body within the depth of the wheelchair space, such that more of the overall space is allocated to knees and toes. As discussed above, these factors result in an exception to allow equipment components of a low profile to extend into the toe end of the wheelchair space. The requirements for other equipment (M303.2.4.2 in the final rule) are substantively unchanged from the NPRM, and are discussed below in the Section VI.C.10.d (Section-by-Section Analysis – M303.2.4).

a. Knee and Toe Clearance

The proposed rule recommended a knee and toe clearance depth for breast platforms of 25 inches. There were no comments received on this requirement. The MDE Advisory Committee recommended increasing the overall knee and toe space to a minimum 28 inches deep. MDE Advisory Committee Report, 115-116, available at https://www.access-board.gov/guidelines-and-standards/health-care/about-this-rulemaking/advisory-committee-final-report. The MDE Advisory Committee asserted that a minimum of 28 inches in overall knee and toe clearance would accommodate 95 percent of the population. Id.

The Access Board concurs with the MDE Advisory Committee’s conclusion that an increase in the overall knee and toe clearance under breast platforms is warranted. However, the Board is concerned that if the Advisory Committee’s recommendation is adopted without change, it would significantly impact the requirement in the final rule for a 48-inch deep wheelchair space. Because at least 25 inches of the space must accommodate knees and toes, only 23 inches remains to accommodate that portion of the occupied wheelchair not including knees and toes. If the Access Board were to require 28 inches minimum knee and toe clearance, only 20 inches would remain. After reviewing all the evidence before the MDE Advisory Committee, the Access Board has decided to make a number of changes to the requirements for the knee and toe clearances for breast platforms. These new requirements are described in the Section VI.C.10.d (Section-by-Section Analysis – M303.2.4). The requirements are intended to ensure that there is adequate space for a patient seated in a wheelchair to position underneath the equipment and align themselves against the breast platform so that the diagnostic procedures can be performed.

b. Exception for Base Support Allowance and Unobstructed Knee and Toe Space

In the proposed rule, obstructions were not permitted within the knee and toe clearance space. This is consistent with the requirement in the existing accessibility guidelines and standards. One manufacturer commented on this provision, asserting that mammography equipment poses unique challenges and requires separate consideration. The commenter explained that the gantry of a mammography machine includes a base lip which is required for structural and seismic stability, and protrudes into the knee and toe clearance. This commenter recommended revisions to allow for a base lip on mammography equipment.

The MDE Advisory Committee recommended allowing obstructions into the knee and toe clear space, up to a height and depth that still permits the footrests of wheelchairs to pass over it. Specifically, the Committee recommended allowing base supports to be a maximum of 1½ inches high and allowing an additional sloped region above the base support at a depth of 25 inches from the front edge of the breast platform at 1½ inches above the floor, which can extend to a height of 4 inches above the floor at a depth of 28 inches. The MDE Advisory Committee explained its recommendation, noting that:

• 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). 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. MDE Advisory Committee Report, 123-127, available at https://www.access-board.gov/guidelines-and-standards/health-care/about-this-rulemaking/advisory-committee-final-report.

The Access Board concurs with the need for permitting base components in the knee and toe clear space for mammography equipment. While the Access Board recognizes that this is a deviation from existing accessibility guidelines and standards, the Board believes that mammography equipment presents special challenges due to the diagnostic, structural, and seismic requirements of the diagnostic equipment. In the final rule, the Access Board has created an exception to the height requirement for breast platforms. This exception permits the profile of base components to extend into the wheelchair space at a height of 1½ inches maximum between 17 inches minimum and 25 inches maximum in depth measured from the leading edge of the breast platform. In addition, the Access Board has found that the profile of the base components should increase toward the rear of the clearance space where a patient’s foot and toes will be higher than the heel supporting portion of the footrest. Therefore, the final rule requires that from 25 inches to 28 inches measured from the leading edge of the breast platform, the height of the component above 1½ inches must be beveled at a rate of 2.5:3. This exception preserves a 17-inch minimum of unobstructed floor space measured from the leading edge of the breast platform.