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

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.