### Radiation (Control of Irradiating Apparatus) Regulations 《輻射(管制輻照儀器)規例》

17. Material protection in case of static irradiating apparatus
(1) No person shall cause or permit any irradiating apparatus to be used continuously in any room unless the floors, ceilings, walls and observation windows thereof are so constructed that nowhere outside the room does the radiation dose rate exceed 3 micrograys per hour: (L.N. 410 of 1982; L.N. 225 of 1990; L.N. 154 of 1995)
Provided that the provisions of this subregulation shall not apply to any floor, ceiling, wall or observation window so sited that the space immediately outside thereof is not capable of habitual occupation by any human being.
(2) All protective material, other than sheet lead, shall be indelibly marked in such a way as to show readily its equivalent thickness of lead, and protective materials which depend upon substances other than lead for their protective properties shall in addition have marked thereon the constant electrical potential used for the generation of X-rays under the conditions at which the equivalence applies.
(3) All protective glass, including lead glass or lead barium glass, or protective liquid observation windows, shall be clearly and indelibly marked in such a way as to show readily its equivalent thickness of lead.
(4) No person shall use any protective material, other than sheet lead, which is not marked in accordance with the provisions of subregulation (2) or (3). (L.N. 225 of 1990)
(5) Nothing in this regulation shall be construed to prevent the temporary removal from the address stated in the licence relating thereto of any portable or mobile irradiating apparatus incidental to its operation as such.
(6) Any person who contravenes any of the provisions of subregulation (1) or (4) shall be guilty of an offence and be liable on conviction to a fine of $15,000. (L.N. 97 of 1970; L.N. 225 of 1990)

### Radiation (Control of Irradiating Apparatus) Regulations 《輻射(管制輻照儀器)規例》

18. Filtration of useful beam from irradiating apparatus
(1) No person shall use a dental irradiating apparatus or diagnostic irradiating apparatus on a live human body unless the total filtration of the useful beam from the apparatus is equivalent to not less than—
(a) 1.5 mm thickness of aluminium for an apparatus with a maximum voltage not exceeding 70 kV;
(b) 2.5 mm thickness of aluminium for an apparatus with a maximum voltage exceeding 70 kV;
(c) 0.5 mm thickness of aluminium or 0.03 mm thickness of molybdenum for an apparatus specially designed for soft-tissue procedures such as mammography.
(2) A person who contravenes subregulation (1) commits an offence and is liable to a fine of $15,000. (13 of 1995 s. 2)
(L.N. 225 of 1990)

19. X-ray tube housing
(1) The protective housing of an X-ray tube shall be so constructed that at every rating specified by the manufacturer for the tube in that housing the radiation leakage rate shall not exceed—
(a) 1 mGy in one hour at a focal distance of 1 m for an X-ray tube used in a diagnostic irradiating apparatus;
(b) 10 mGy in one hour at a focal distance of 1 m, and 300 mGy in one hour at 5 cm, from any surface of the housing accessible to the patient for an X-ray tube used in therapeutic irradiating apparatus capable of operating at voltages up to 500 kV;
(c) 0.1% of the dose rate of the useful beam at 1 m from the surface of an X-ray tube housing used in a therapeutic irradiating apparatus if the tube is capable of operating at voltages above 500 kV.
(2) For the purposes of subregulation (1) measurements may be averaged over an area of up to 100 cm2 at a focal distance of 1 m or 10 cm2 at a distance of 5 cm from the surface of the tube housing. (13 of 1995 s. 2)
(3) A person who operates or causes to be operated, an X-ray tube which is not enclosed in a protective housing in accordance with subregulation (1) or (2) commits an offence and is liable to a fine $15,000. (13 of 1995 s. 2)
(L.N. 225 of 1990)

### Radiation (Control of Irradiating Apparatus) Regulations 《輻射(管制輻照儀器)規例》

21. Determination of dose rate and quality of radiation
(1) No person shall use any irradiating apparatus for therapeutic purposes unless—
(a) the dose rate and the quality of the radiation emitted by the apparatus have been measured by a person approved by the Board for that purpose and using an ionometric or other method of measurement also approved by the Board;
(b) both the dose rate and the quality of the radiation from such apparatus are periodically so measured at such intervals as the Board may direct; and
(c) a record of all such measurements is kept by the licensee and is open to inspection by any person authorized by the Board for that purpose.
(2) No person shall use a radiation dosemeter or a radiation dose-rate meter for any determination made in accordance with subregulation (1), unless it is independent of, or corrected for, the quality of radiation within the range for which it is designed or used, and is provided with suitable arrangements for checking its ability to reproduce its readings.
(3) Any person who contravenes any of the provisions of subregulation (1) or (2) shall be guilty of an offence and be liable on conviction to a fine of $15,000. (L.N. 97 of 1970; L.N. 225 of 1990)

22. Testing of timers for use in connection with irradiating apparatus
(1) No person shall use any time switch, exposure timer or treatment time in connection with any irradiating apparatus used for therapeutic purposes unless such switch or timer is tested from time to time, as may be required by the Board, for accuracy by a person approved by the Board for such purpose and when last so tested was found to be accurate to within 1%.
(2) Any person who contravenes any of the provisions of subregulation (1) shall be guilty of an offence and be liable on conviction to a fine of $15,000. (L.N. 97 of 1970; L.N. 225 of 1990)

23. Supervision of persons undergoing treatment
(1) Any person administering any treatment involving the exposure of any patient to radiation from any irradiating apparatus shall, during exposure to such radiation, himself keep the patient under observation and also the apparatus by means of which the treatment is being administered and shall determine the duration of the treatment either by an automatic treatment timer or by an integrating dosemeter.
(2) Any person who fails to comply with any of the provisions of subregulation (1) shall be guilty of an offence and be liable on conviction to a fine of $15,000. (L.N. 97 of 1970; L.N. 225 of 1990)