Section 325.5325. X-ray equipment.

Rule  325.  (1)  All  x-ray tube  housings  in  fixed   radiographic  installations  shall   be  of  the diagnostic type.

(2)   The aluminum equivalent of the total filtration in the useful beam shall not be less than the values shown in Table 1.

Table 1

Operating kVp                              Minimum Total Filter (Inherent plus added)

Below 50 kVp                              0.5 mm aluminum

50-70 kVp                                    1.5 mm aluminum

Above 70 kVp                             2.5 mm aluminum

(3)   If the filter in the machine is not accessible for examination and the total filtration is not known subrule (2) may be assumed to have been met if the half-value layer is not less than

0.6 mm aluminum at 49 kVp

1.6 mm aluminum at 70 kVp

2.6 mm aluminum at 90 kVp

(4)    Under conditions of subrule (3) for tube potentials above 90 kVp subrule (2) may be assumed to have been met if the half-value layer is not less than that specified in table 2.

(5)   The half-value layer (HVL) of the useful beam for a given x-ray tube potential shall not be less than the values shown in table 2.

Table 2

Design operating range (Kilovolts peak)

Measured potential (Kilovolts

peak)

Half-value layer (milli- meters of aluminum)

Below 50	30	0.3
	40	0.4
	49	0.5
50 to 70	50	1.2
	60	1.3
	70	1.5
Above 70	80	2.3
	90	2.5
	100	2.7
	110	3.0
	120	3.2
	130	3.5
	140	3.8
	150	4.1

(6)   If it is necessary to determine the half-value layer at an x-ray tube potential which is not listed in table 2, linear interpolation or extrapolation may be made.    Positive means shall be

provided to insure that at least the minimum filtration needed to achieve these beam quality requirements is in the useful beam during each exposure.

(7)   Machines equipped with beryllium window x-ray tubes with removable filters shall contain keyed filter interlock switches in the tube housing and suitable indication on the control panel of the added filter in the useful beam. The total filtration permanently in the useful beam shall not be less than 0.5 millimeter aluminum equivalent and shall be clearly indicated on the tube housing.

(8)   Beryllium window x-ray tubes shall not be used routinely for general purpose diagnostic examinations. Such a tube may comprise an x-ray subsystem if needed for special soft tissue technique in accord with subrule (7).

(9)   Beam-limiting devices (diaphragms, cones, adjustable collimators), capable of restricting the useful beam to the area radiographically recorded shall be provided to define the beam and shall provide the same degree of attenuation as that required of the tube housing.

(10)   Beam-limiting devices shall be calibrated in terms of the size of the projected useful beam at specified source-image distances (SID). This calibration shall be clearly and permanently recorded on the beam-limiting device. Calibration of adjustable beam-limiting devices shall permit reproducible settings.

(11)   X-ray systems designed for only 1 image receptor size at a fixed SID shall be provided with means to limit the field at the plane of the image receptor to dimensions no greater than those of the image receptor, and to align the center of the x-ray field with the center of the image receptor to within 2% of the SID. However, for mammography the x-ray field need not be aligned with the center of the image receptor if the x-ray field does not extend beyond the edge of the image receptor.

(12)    General purpose radiographic x-ray systems shall be equipped with adjustable beam- limiting devices containing light localizers that define the entire field. Rectangular beam- limiting devices are usually preferable.

(13)    The size of the x-ray beam projected by fixed aperture beam-limiting devices, except those used for stereoradiography, shall not exceed the dimensions of the image receptor by more than 2% of the SID when the axis of the x-ray beam is perpendicular to the plane of the image receptor.

(14)   The calibrated field size indicator on adjustable beam-limiting devices shall be accurate to within 2% of the SID. The light field shall be aligned with the x-ray field with the same degree of accuracy. The field size projected by automatic adjustable beam-limiting devices  shall provide the same precision.

(15)   For radiographic procedures resulting in multiple views on a single x-ray film the beam- limiting device shall limit the x-ray field size to the recorded radiographic image size within 2% of the SID. Covering a portion of the radiographic film with radio-opaque material is not a substitute for proper x-ray field limitation. This subrule does not apply to spotfilm devices manufactured before the effective date of these rules.

(16)  After the effective date of these rules radiographic x-ray machines used for purposes other than mammography or extremity radiography only shall be capable of operation at not less than an average current of 100 milliamperes (mA) during any radiographic technique used. A machine not capable of sustained operation at not less than an average of 100 mA for the duration of a given technique shall not be used for that technique.    As used in this subrule

"extremity radiography"  means  radiography of  the  hand  or  arm  excluding  the  shaft  of   the humerus or the foot or leg excluding the shaft of the femur.

(17)    A device shall be provided which terminates the exposure at a preset time interval or exposure limit. The operator shall be able to terminate the exposure at any time by discontinuing pressure upon the exposure switch except that during serial radiography means may be provided to permit completion of any single exposure in progress.

(18)    The exposure switch, except for those used in conjunction with spot film devices in fluoroscopy, shall be securely fixed so that the operator is required to be behind a fixed shield which will intercept the useful beam and any radiation which has been scattered only once.

(19)   When 2 or more x-ray tube heads are operated from a single exposure switch (multiple tube units), there shall be indication at the control panel showing which tube is connected and ready to be energized, and means to prevent energizing more than 1 tube head at the same time unintentionally. Machines designed for simultaneous multiple tube operation shall have positive means for selecting single tube or multiple tube operation.

(20)   The control panel shall provide positive visual identification of the production of x-rays whenever the x-ray tube is energized.  A milliammeter may comply with this subrule.

(21)   On radiographic machines manufactured after the effective date of these rules, a signal audible to the operator shall indicate that the exposure has ended.

(22)  The technique factors to be used during an exposure shall be indicated before the exposure begins, except when automatic exposure controls are used, in which case the technique factors which are set before the exposure shall be indicated. On equipment having fixed technique factors, this requirement may be met by permanent markings. Indication of technique factors shall be visible from the operator's position.

(23)   X-ray equipment installed after the effective date of these rules shall be installed and used in accord with the appropriate portions of the 1975 national electrical code (NFPA No. 70-1975) reproduced or referenced in rule 359. X-ray equipment installed before the effective date of these rules shall conform with the appropriate national electrical code in effect at the time of installation.

History: 1954 ACS 85, Eff. Dec. 3, 1975.