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

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.