South Carolina Code of Regulations › Chapter 61 - DEPARTMENT OF HEALTH AND ENVIRONMENTAL CONTROL › Subchapter 61-64 - X-Rays (Title B) › Part V - QUALITY STANDARDS AND CERTIFICATION REQUIREMENTS FOR FACILITIES PERFORMING MAMMOGRAPHY › Appendix 61-64.V.A - Mammography Dose Measurement Protocol

Current through Register Vol. 48, No. 6, June 28, 2024
The technique factors used for performing a mammography
				  examination shall not permit the mean glandular absorbed dose to exceed the
				  limits specified in RHB 5.13.5.10. Radiation measurements shall be performed
				  with an integrating radiation measuring device that is appropriate to the high
				  beam intensity and mammographic kilovoltage peak (kVp) used, and sufficiently
				  sensitive to determine compliance with the criteria specified in
				  RHB 5.16. The instrument shall
				  have been calibrated as specified in RHB 5.16.
The mammography exam dose limits are based on an average
				  compressed breast value of 4.2 centimeters having an average density (i.e.,
				  fifty percent (50%) adipose and fifty percent (50%) glandular).
Perform the following steps to determine the mean glandular
				  dose to a nominal 4.2 centimeter compressed breast:
a) Measure and record the x-ray system's useful beam half
				  value layer (HVL). (See
				  RHB 5.13.5.8.) Any
				  compression device normally in the useful beam during mammography procedures
				  shall be required to be placed between the x-ray tube target and measuring
				  device when determining the HVL. The useful beam shall be collimated to a size
				  encompassing the detector.
NOTE: Filters used for the HVL evaluation should be placed as
				  close to the target as practical. The HVL for screen-film mammography should
				  not exceed the minimum acceptable HVL by more than 0.1 millimeter of aluminum
				  equivalent.
b) Determine the glandular dose to entrance exposure factor
				  from the Mammography Dose Evaluation Table (see Appendix C of this Part) using
				  the appropriate HVL, kVp, and x-ray tube target-filter material.
NOTE: The kVp of screen-film mammography systems with
				  molybdenum target-filter combinations should be accurately measured to
				  determine the appropriate glandular dose to entrance exposure factor from
				  Appendix C of this Part.
c) If the equipment has the capability for variable
				  source-to-image receptor distance (SID), set the craniocaudal SID for the image
				  receptor system used.
d) Position in the useful beam any compression apparatus
				  normally used.
NOTE: Some mammography systems have the capability of
				  providing automatic adjustment of technique factors through feedback from the
				  position of the compression device. On such systems, the compression device
				  should be lowered to a position 4.2 centimeters above the breast support
				  assembly (BSA). The device should then be removed, inverted, and replaced to
				  allow placement of the phantom and measuring device on the BSA below the
				  compression device. If the compression device cannot be replaced in an inverted
				  position, the device should be placed in the beam using auxiliary
				  support.
e) Placement of the Radiation Measuring Device
1) For systems equipped with automatic exposure control
				  (AEC):
A) Place a properly loaded film cassette in the cassette
				  holder.
NOTE: The loaded cassette is placed in the cassette holder to
				  simulate, as much as is possible, the conditions under which actual patient
				  exposures are made. Following radiation measurements, the film should be
				  discarded and the cassette reloaded with unexposed film.
B) Place a mammography phantom (see the definition for
				  "Phantom") on the breast support assembly (BSA). Align the phantom so that the
				  edge of the phantom is aligned with the chest wall side of the BSA and the
				  phantom is over the automatic exposure control device(s).
C) Place a radiation measuring device in the useful beam so
				  the center axis of the device is parallel to the breast support assembly (BSA).
				  The geometric center of the measuring device shall be positioned 4.5
				  centimeters above the BSA, 2.5 centimeters from the chest wall edge of the BSA,
				  and immediately adjacent to either side of the mammography phantom.
2) For systems not equipped with AEC, place a radiation
				  measuring device in the useful beam so that the center axis of the device is
				  parallel to the breast support assembly (BSA). The geometric center of the
				  measuring device shall be positioned so that it is centered 4.5 centimeters
				  above the BSA, 2.5 centimeters from the chest wall edge of the BSA, and at the
				  center line of the BSA. No part of the devices detector area shall be outside
				  of the useful beam.
f) Collimate the x-ray field to the size normally used and
				  assure that the area covered by the useful beam includes the detector area of
				  the radiation measuring device and the mammography phantom if the equipment is
				  equipped with automatic exposure.
g) Set the appropriate technique factors or automatic
				  exposure controls normally used for a nominal 4.2 centimeter compressed
				  breast.
h) Measure and record the exposure in air with the radiation
				  measuring device.
i) Calculate the mean glandular dose for a 4.2 centimeter
				  compressed breast by multiplying the measured exposure in millicoulombs per
				  kilogram or in roentgens by the glandular dose to entrance exposure factor,
				  which was determined using the procedure described in subsection (b) of this
				  Appendix.
EXAMPLE: A mammography system is provided with a molybdenum
				  target-filter combination, and the HVL and kVp are determined to be 0.3 and 30,
				  respectively. Therefore, for a 4.2 centimeter compressed breast, the glandular
				  dose to entrance exposure factor from the Mammography Dose Evaluation Table
				  (Appendix C of this Part) would be 159 mrad. The measured roentgen output
				  determined in subsection (h) of this Appendix is determined to be 1.8 R.
				  Therefore, the mean glandular dose would be 1.8 R multiplied by 159 mrad/R.
				  This results in a mean glandular dose measurement of 286 mrad. As such, the
				  system would be in compliance with RHB 5.13.5.10.