Section 280. Shielding plan review

A. Prior to construction, the floor plans, shielding specifications and equipment arrangement of all new installations, or modifications of existing installations, utilizing ionizing radiation machines shall be available to the agency for review. The required information is found in 12VAC5-481-280 E.

B. The agency may require the applicant to utilize the services of a private inspector to determine the shielding requirements prior to the plan review.

C. The review of such plans shall not preclude the requirement of additional modifications should a subsequent analysis of operating conditions indicate the possibility of an individual receiving a dose in excess of the limits prescribed in 12VAC5-481-640 and 12VAC5-481-680 through 12VAC5-481-730.

D. After installation of a radiation machine, the registrant shall maintain for inspection by the agency:

1. The maximum rated technique factors of each machine;

2. A scale drawing of the room in which a stationary radiation machine system is located with such drawing indicating the use of areas adjacent to the room and an estimation of the extent of occupancy by an individual in such areas. In addition, the drawing shall include:

a. The results of a survey for radiation levels present at the operator's position and at pertinent points outside the room at specified test conditions; or

b. The type and thickness of materials, or lead equivalency, of each protective barrier.

E. In order for the private inspector to provide an evaluation, technical advice, and approval on shielding requirements for a radiation installation, the following information shall be required.

1. The plans showing, as a minimum, the following:

a. The normal location of the system's radiation port; the port's travel and traverse limits; general direction(s) of the useful beam; locations of any windows and doors or other openings; the location of the operator's booth; and the location of the control panel;

b. The structural composition and thickness or lead equivalent of all walls, doors, partitions, floor, and ceiling of the room(s) concerned;

c. The dimensions of the room(s) concerned;

d. The type of occupancy of all adjacent areas inclusive of space above and below the room(s) concerned. If there is an exterior wall, show distance to the closest area(s) where it is likely that individuals may be present;

e. The make and model of the equipment, the maximum technique factors, and the energy waveform (single phase, three phase, etc.);

f. The type of examination(s) or treatment(s) that will be performed with the equipment.

2. Information on the anticipated workload of the system(s) in Ma-minutes per week.

3. A report showing all basic assumptions used in the development of the shielding specifications.

F. The following requirements shall be used in the design for an operator's booth:

1. Space requirements:

a. The operator shall be allotted not less than 0.70 square meter (7.5 square feet) of unobstructed floor space in the booth;

b. The operator's booth may be any geometric configuration with no dimension of less than 0.6 m (2 feet);

c. The space shall be allotted excluding any encumbrance by the X-ray control panel, such as overhang, cables, or other similar encroachments;

d. The booth shall be located or constructed such that unattenuated direct scatter radiation originating on the examination table or at the wall-mounted image receptor will not reach the operator's position in the booth.

2. Structural requirements:

a. The booth walls shall be permanently fixed barriers of at least 2 m (7 feet) high;

b. When a door or movable panel is used as an integral part of the booth structure, it must have an interlock which will prevent an exposure when the door or panel is not closed;

c. Shielding shall be provided to meet the requirements of Part IV (12VAC5-481-600 et seq.) of this chapter.

3. Radiation exposure control placement: The radiation exposure control for the system shall be fixed within the booth and:

a. Shall allow the operator to remain in the protected area and not be exposed to direct scatter, leakage or primary beam radiation;

b. Shall allow the operator to use the majority of the available viewing windows.

4. Viewing system requirements:

a. Each booth shall have at least one viewing device that will:

(1) Be so placed that the operator can view the patient during any exposure; and

(2) Be so placed that the operator can have full view of any occupant of the room and should be so placed that the operator can view any entry into the room. If any door that allows access to the room cannot be seen from the booth, then outside that door there shall be an "X-ray on" warning sign that will be lighted anytime the rotor of the X-ray tube is activated. Alternatively, an interlock shall be present such that exposures are prevented unless the door is closed.

b. When the viewing system is a window, the following requirements also apply:

(1) The window shall have a viewing area of at least 0.09 square meter (1 square foot); Regardless of size or shape, at least 0.09 square meter (1 square foot) of the window area must be centered no less than 0.6 meter (2 feet) from the open edge of the booth and no less than 1.5 meter (5.0 feet) from the floor;

(2) The window shall have at least the same lead equivalence as that required in the booth's wall in which it is mounted.

c. When the viewing system is by mirrors, the mirror(s) shall be so located as to accomplish the general requirements of subdivision 1 of this subsection.

d. When the viewing system is by electronic means:

(1) The camera shall be so located as to accomplish the general requirements of subdivision 1 of this subsection; and

(2) There shall be an alternate viewing system as a backup for the primary system.

Historical Notes

Derived from Volume 22, Issue 25, eff. September 20, 2006.

Statutory Authority

§ 32.1-229 of the Code of Virginia.