There are very specific spatial requirements for treatment chairs in areas where multiple treatment chairs are provided. Typically, each chair must be positioned within an imaginary zone such as 80 sq. ft. (for the patient chair & necessary equipment) exclusive of any cabinetry or fixed objects. There are also minimum clearances between the chair zone at the foot end or side wall for maneuvering by patient care technicians.
The requirements apply to new construction/remodeled projects only and are not retroactive to any existing facility. This does apply to not only stand alone facilities, but also dedicated units within a hospital.
If you are designing in an area that defers to the Guidelines for Design and Construction of Health Care Facilities, be sure to always check with each state as to how they are recognizing the footnotes. Some states mandate that the design requirements in the footnotes (which sometimes can be more stringent than the main body text) be followed, other states make them optional.
To learn more, visit http://www.fgiguidelines.org; check into the state health department guidelines for the state you are working as well as check the CMS.gov website for federal guidelines.