§ 17-30306. Definitions.

(a) “Automatic exposure control” means a device which automatically controls one or more technique factors in order to obtain at a preselected location(s) a required quantity of radiation.

(b) “Cineradiography” means the making of a motion picture record of the successive images appearing on a fluorescent screen.

(c) “Contact therapy” means irradiation of accessible lesions usually employing a very short source-skin distance and potentials of 40-50 KV.

(d) “Dead-man switch” means a switch so constructed that a circuit-closing contact can only be maintained by continuous pressure by the operator.

(e) “Diagnostic-type tube housing” means an X-ray tube housing so constructed that the leakage radiation measured at a distance of 1 meter from the source cannot exceed 100 milliroentgens in 1 hour when the tube is operated at its maximum continuous rate of current for the maximum rated tube potential.

(f) “Filter” means material placed in the useful beam to absorb preferentially the less penetrating radiations.

(g) “Interlock” means a device for precluding access to an area of radiation hazard either by preventing entry or by automatically removing the hazard.

(h) “Leakage radiation” means all radiation coming from within the tube housing except the useful beam.

(i) “Protective barrier” means a barrier of attenuating materials used to reduce radiation exposure.

(j) “Primary protective barrier” means a barrier sufficient to attenuate the useful beam to the required degree.

(k) “Scattered radiation” means radiation that, during passage through matter, has been deviated in direction.

( l “Secondary protective barrier” means a barrier sufficient to attenuate stray radiation to the required degree.

(m) “Shutter” means a device, generally of lead, fixed to an X-ray tube housing to intercept the useful beam.

(n) “Stray radiation” means radiation not serving any useful purpose. It includes leakage and scattered radiation.

(o) “Therapeutic-type tube housing” means,

(1) For X-ray therapy equipment not capable of operating at 500 kVp or above, an X-ray tube housing so constructed that the leakage radiation at a distance of 1 meter from the source does not exceed 1 roentgen in an hour when the tube is operated at its maximum rated continuous current for the maximum rated tube potential.

(2) For X-ray therapy equipment capable of operating at 500 kVp or above, an X-ray tube housing so constructed that the leakage radiation at a distance of 1 meter from the source does not exceed either 1 roentgen in an hour or 0.1 percent of the useful beam dose rate at 1 meter from the source, whichever is greater, when the machine is operated at its maximum rated continuous current for the maximum rated accelerating potential.

(3) In either case, small areas of reduced protection are acceptable provided the average reading over any 100 square centimeters area at 1 meter distance from the source does not exceed the values given above.

(p) “Useful beam” means that part of the radiation which passes through the window, aperture, cone, or other collimating device of the tube housing. (T17-30306-T24).

HISTORY

1. Renumbering and amendment filed 9-4-73 as an emergency; effective upon filing (Register 73, No. 36). Approved by State Building Standards Commission 11-30-73.

2. Certificate of Compliance filed 12-28-73 (Register 73, No. 52).

3. Amendment of subsection (e) filed 6-18-87; operative 7-18-87 (Register 87, No. 28).

Note

Note: Authority cited: Sections 208 and 25811, Health and Safety Code. Reference: Sections 25801, 25802, 25811 and 25815, Health and Safety Code.