Michigan Administrative Code › Department - Labor and Economic Opportunity › MIOSHA › X-Ray Machine Registration › Ionizing Radiation Rules Governing the Use of Radiation Machines › Part 7 - MEDICAL X-RAY INSTALLATIONS › THERAPEUTIC MACHINES OPERATED ABOVE 85 KVP › Section R. 333.5312 - X-ray equipment

Current through Vol. 24-12, July 15, 2024
Rule 312.
(1)
						The tube housing shall be of the therapeutic type.
(2) Permanent diaphragms or cones used for
						collimating the useful beam shall afford the same degree of attenuation as is
						required of the housing.
(3)
						Adjustable or removable beam-limiting devices shall transmit not more than 5%
						of the useful beam as determined at the maximum tube potential and with maximum
						treatment filter.
(4) Filters shall
						be so mounted as to prevent their movement during the treatment.
(5) The filter slot shall be so constructed
						that the radiation escaping through it does not produce an exposure rate
						exceeding 1 R/h at 1 meter, or if the patient is likely to be exposed to
						radiation escaping from the slot, 30 R/h at 5 centimeters (2 inches) from the
						external opening.
(6) A removable
						filter shall be permanently marked with its thickness and material.
(7) A filter indication system shall be used
						on therapy machines which use changeable filters. It shall indicate, from the
						control panel, the presence or absence of a filter and it shall be designed to
						permit easy recognition of the filter in place.
(8) The x-ray tube shall be so mounted that
						it cannot turn or slide with respect to the housing aperture. A reproducible
						means of measuring the focal spot to patient distance shall be
						provided.
(9) Means to immobilize
						the tube housing during stationary portal treatment shall be
						provided.
(10) An easily
						discernible indicator which shows whether or not x-rays are being produced
						shall be on the control panel.
(11)
						Beam monitoring devices shall be fixed in the useful beam to indicate an error
						due to incorrect filter, tube current, or tube potential, unless the device
						introduces more filtration than is clinically acceptable.
(12) A suitable exposure control device, such
						as an automatic timer, exposure meter, or dose meter, shall be provided to
						terminate the exposure after a preset time interval or preset exposure or dose
						limit. If a timer is used, it shall permit accurate presetting and
						determination of exposure times as short as 1 second. Means for the operator to
						terminate the exposure at any time shall be provided.
(13) Mechanical or electrical stops, or both
						shall be provided to insure that the useful beam is oriented only toward
						primary barriers.
(14) Interlocks
						shall be provided so that, when a door to the treatment room is opened, the
						machine turns off automatically or the radiation level within the room is
						reduced to an average of not more than 2 mR/h and a maximum of 10 mR/h at a
						distance of 1 meter in any direction from the source. After the shut-off or
						reduction in exposure rate, it shall be possible to restore the machine to full
						operation only from the control panel.
(15) The x-ray control circuit shall be so
						designed that it is not possible to energize the x-ray tube to produce x-rays
						without resetting the x-ray "ON-OFF" switch at the control panel.
(16) When the relationship between the beam
						interceptor (when present) and the useful beam is not permanently fixed,
						mechanical or electrical stops shall be provided to ensure that the beam is
						oriented only toward primary barriers.
(17) X-ray machines with electron beam
						extraction capability shall be provided with such additional safety devices as
						determined necessary and specified in writing by the department to prevent
						accidental electron beam exposure.
(18) To reduce the electron contamination of
						high energy treatment beams, shadow trays, or other accessories placed in the
						primary beam shall be placed at a sufficient distance from the patient that the
						electron contamination contribution to the skin dose is minimal.
An obvious
						  error in
						  R
						  325.5312 was corrected at the request of the
						  promulgating agency, pursuant to Section 56 of 1969 PA 306, as amended by 2000
						  PA 262, MCL 24.256. The rule containing the error was published in Michigan
						  Register, 2016 MR 10. The memorandum requesting the correction was published in
						  Michigan Register, 2016 MR 16