1

MINORITY REPORT ON TRANSFER SURFACE HEIGHT RECOMMENDATIONS OF THE U.S.

ACCESS BOARD ADVISORY COMMITTEE

RE: NPRM: M301.2.1 AND M302.2.1 HEIGHT

I. Introduction

This Minority Report has been developed by the following medical diagnostic imaging equipment 

industry members of the Advisory Committee to the U.S. Access Board, including: GE Healthcare, 

Philips Healthcare, Siemens Healthcare, and Hologic, Inc.

The purpose of this Minority Report is to make a formal recommendation for a minimum transfer surface 

low height of 19 inches for diagnostic imaging medical equipment.

II. Recommendations of Diagnostic Imaging Equipment Manufacturers on Transfer Surface Low

Height

The aforementioned medical diagnostic imaging equipment manufacturers support a 19 inch minimum 

transfer surface low height for the following reasons:

1. A standard should set a minimum transfer surface low height requirement which is reasonable 

and achievable given the technical and engineering resource constraints upon the equipment 

manufacturer.

Diagnostic imaging equipment is comprised of both the image detectors/scanner, such as an x-ray

scanner, or nuclear medicine cameras, or imaging equipment using a bore, such as CT, PET and 

MRI, as well as the table supporting the patient. It should be recognized that the table, which 

supports the patient who is undergoing the diagnostic imaging procedure, is an integral part of

that equipment, and its precise alignment with the imaging scanner/bore itself is essential to 

achieving diagnostic quality images.

It is important to recognize, given the integrated nature of the table to the system and its imaging 

performance, that a change of even a few inches in minimum transfer surface low height 

constitutes a significant engineering change to the device. Any such change must ensure there are 

no adverse effects to image quality, system performance, and patient safety. Complete scanner

re-testing and re-certification under our formal FDA quality system and design controls are 

needed to verify overall system performance and safety.

Moreover, the most significant of these design changes can result in cascading alterations to the 

scanner, potentially leading to unacceptable heating in the case of MR, impacts on image 

signal/quality, and changes in dose levels to ensure the same, effective, high quality images and 

increased examination times, that is, additional workflow steps. It should be noted that future 

design projects are in the works many years before they become commercially available.

2. There was no compelling evidence presented of significant access improvement for diagnostic 

imaging devices at 17 inches that would warrant the additional efforts, timing and resources.
2

During the meetings of the Advisory Committee, there was no compelling evidence presented in 

support of a minimum transfer low height of 17 inches as the new standard for access. The 

original Notice of Proposed Rulemaking (NPRM) proposal was for a minimum height in the 

range of 17 to 19 inches. This would have allowed a table that lowers to a 19 inch minimum 

height to meet the standard. There did not appear to be sufficient, solid evidence presented that

19 inches minimum height was not adequate, and that 17 inches was necessitated to provide 

access. It should also be recognized, that due to the precision work which is required in the 

design of diagnostic imaging equipment, and the necessity of compliance with regulatory 

requirements, with each inch of decrease in minimum height from 19 inches, the time and costs 

which are required for equipment re-design go up exponentially.

However, the Committee did agree that an additional requirement, that of adjustability up to 25 

inches, was critical to ensure access, given the variety of mobility device seating heights. We 

believe the addition of the adjustability requirement delivers by far a larger increase in access 

than having a single minimum height of 17 inches. As a standard , we believe the increased 

access goal is well met by having a 19 inch minimum height and transfer height adjustability. 

Having an additional extension to the NPRM to require a fixed minimum of 17 inches would 

provide only a marginal increase in the population served (see Item 3 below for further details).

3. While it is ideal for transfer surfaces to be at the same height as the seat heights of mobility 

devices, there is evidence that non-level independent transfers are also feasible.

The original Notice of Proposed Rulemaking (NPRM) Preamble explains the motivation for a 

minimum transfer height of 17 inches with the following:

“Transfer surfaces that are adjustable to the same heights as the seat heights of mobility devices 

reduce the effort needed to transfer since patients do not have to lift their body weight to make up 

the difference between the two surfaces, in one direction or the other.” 1

The NPRM then goes on to discuss wheelchair seat heights, with the 5

th percentile lowest seat 

height being 17.3 inches, according to the IDeA study2.

While it is ideal for transfer surfaces to be at the same height as the seat heights of mobility 

devices, there is evidence that independent transfers are also feasible with a seat height 

discrepancy of up to two inches. As is discussed in Section 3.3.1 of the full Committee report, 

the Committee considered the findings from the University of Pittsburgh Human Engineering 

Research Laboratories (HERL) study that looked at transfers, and how different conditions affect 

the abilities of wheeled mobility devices (WMD) users to transfer from their WMD to another 

surface

3

. One of the goals of the study was to “determine acceptable ranges for non-level

transfers (e.g. vertical height differences)”. A portion of the study’s results are shown in Table 1

1

Notice of Proposed Rulemaking (NPRM). Preamble, page 18.

2

IDeA Center Study at the University of Buffalo, New York: The Wheeled Mobility Anthropometry Project, Final

Report, page 49, Figure 3-5, reference to “All Device Types*”.

3

“The Impact of Transfer Setup on the Performance of Independent Transfers: Final Report”; Human Engineering

Research Laboratories, VA Pittsburgh Healthcare System, University of Pittsburgh.
3

below. It should be noted that the addition of a 3-inch gap next to the transfer surface (permitted 

by the Committee’s recommendation) may impact the percentages shown here, but information 

was not presented that directly correlated step height, gap, and ability to transfer. Further 

information would be needed to quantify this directly.

Table 1. A portion of the results presented in the HERL study to determine acceptable 

ranges for non-level transfers.

Step Height

(No obstructions or gaps between the transfer 

surface and WMD intentionally introduced)

Percentage of Individuals Able To

Complete The Transfer

0” 96%

1” 94%

2” 86%

These findings suggest that those individuals with seat heights ≥18 inches high should be able to 

independently transfer to an adjustable-height transfer surface with a 19-inch minimum height, 

since the step in height will always be no more than one inch. For the small population of 

individuals with a seat height between 17.3 (5th percentile) and 18 inches, the maximum step 

height will be two inches. Based on this study, only about 14% of the individuals in this already 

very small population may need further assistance in transferring. In some instances, transfer or 

positioning supports may even be able to provide this assistance, thus maintaining independence 

of transfer. This study showed that adding a grab bar for patient support helped some wheelchair 

users to transfer at a height at which they could not transfer previously.

One of the Committee’s concerns regarding this particular study was that the study subjects did

not necessarily reflect the general population of persons who use WMD. Of the people studied,

88 were men and 24 were women. A large number of subjects in the study were veterans who 

participated in organized sports-related events. The study did find, though, that the subjects’ 

daily activity levels apart from the time of those sports events did not differ from adult WMD 

users who live in the community. We do acknowledge the concern about the population studied 

and understand that the findings and percentages above may not provide strict guidance on how 

many people will be able to transfer given a non-level transfer situation. However, we believe 

that the insights from this study are very important to take into consideration when setting a 

minimum low height for transfer surfaces, since there are in fact many individuals who will be 

able to independently transfer with a 1 or 2-inch step height. While setting the minimum low 

height, we also believe it is important to specifically consider the individuals who will be 

impacted by this low height requirement. Many of the wheelchairs with low seat heights 

(especially in the 17-18inch range) are manual wheelchairs. Many manual wheelchair users may 

use more upper body strength in moving around for day-to-day activities than power wheelchair 

and scooter users do, and so a non-level transfer may not be as difficult for those individuals.

4. Diagnostic imaging devices require a trained technician present to aid all patients in accessing 

the table in the proper imaging position.
4

Diagnostic imaging devices operate with a high level of precision. It is important to recognize 

that proper patient positioning on the table for diagnostic imaging devices, whether they are xray, nuclear medicine, PET or MRI devices, is essential to achieving diagnostic quality images. 

In order to achieve diagnostic quality images, trained technologists are required to position all

patients properly, regardless of the patient’s ability or disability to access the equipment.

III. Proposed alternative mechanisms to enhance patient access to diagnostic imaging equipment

Given the constraints on table redesign due to diagnostic needs, and physical and engineering limitations 

of many of the wide variety of imaging tables, there will be many types of imaging tables that will not be 

able to achieve even a 19 inch minimum if the table itself must be modified. For example, in a CT/PET 

system, the patient support surface is located on top of a transporter, which adds to the height of the 

transport surface.

DXA bone densitometry systems are currently at a fixed height of 25-28 inches because the imaging 

hardware is located beneath the patient and the precise position of the patient support surface relative to 

the x-ray equipment is critical to the clinical efficacy of the device. In the case of DXA systems, it may 

be most effective to specify a specific range of fixed heights that the table could be at to facilitate 

independent transfer, similar to the fixed height standards for everyday items like benches, bathing 

fixtures, and recreational structures.

For all other systems, the Committee was told that it needed to consider only modifications to the tables 

themselves. To the imaging industry this seems to be a rather arbitrary constraint, and one that is not 

reflective of the system nature of diagnostic imaging systems, their installations, nor an actual 

requirement in the law.

We believe that system accessibility configurations discussed in Section 7 of the Committee’s Report,

i.e., ancillary equipment that is not attached directly to the table, but rather that is part of the room layout, 

will need to play an essential role in enabling more imaging equipment to meet the scope of the proposed 

new standards. These alternative means can take many forms, and their specific designs would need to be 

worked out with appropriate stakeholders to maximize safety, patient handling, and of course, access.

Implementation of these alternatives, and others, will allow many more patients with disabilities to access 

the equipment, and can be implemented far more quickly and cost effectively than the significant time

and costs which would be required for equipment re-design. Many aspects of the system accessibility 

configuration concept would also be able to be applied to systems already in use, thereby increasing their 

accessibility.

The added benefits of implementation of these alternative means are the significant savings in healthcare 

costs, timelier implementation and broader system coverage which would be realized due to avoidance of 

costly, equipment re-design costs. Since our mutual goal is to enhance and improve access of patients to 

medical diagnostic equipment, we urge the Access Board to give serious consideration to these alternative 

means which will enable us to quickly accommodate many more patients with disabilities.
5

Conclusion

As diagnostic imaging equipment manufacturers, we are committed to achieving access of all patients to 

diagnostic imaging equipment. We stand ready to work with all stakeholders to accomplish this goal.

If you have any questions, or need further information, please do not hesitate to contact us. We would be 

pleased to further discuss these issues with you.

Sincerely,

John Jaeckle Elisabeth George Hans Beinke Michelle Lustrino

GE Healthcare Philips Healthcare Siemens Healthcare Hologic, Inc.