Improving Health Through Medical Physics


Dustin A. Gress, MS | Reston, VA

AAPM Newsletter — Volume 44 No.2 — March | April 2019

In each issue of this newsletter, I'll present frequently asked questions (FAQs) or other information of particular importance for medical physicists. You may also check out the ACR's accreditation web site portal for more FAQs, accreditation application information, and QC forms.

Before I present FAQs, I am proud to share that in January, the ACR Board of Chancellors approved the Richard L, Morin, PhD, Fellowship in Medical Physics. The Morin Fellowship is ACR's eighth fellowship and the only one exclusively for medical physics residents and fellows, recognizing the importance of our incoming generations of medical physicists and the value of mentoring them in the work of the ACR. The application period for our inaugural Morin Fellow(s) closed March 1. Dr. Morin is an ACR Gold Medalist and Fellow, and a Fellow of the AAPM, among many other accomplishments. The ACR is delighted to name this Fellowship in Dr. Morin's honor. Now, some FAQs.

The ACR recently released its 2018 Digital Mammography QC Manual with 2D and Digital Breast Tomosynthesis. The following are select FAQs pertaining to the new manual. These and more FAQs can be found on the ACR Digital Mammography QC Manual Resources web page, where you can also find updated Microsoft Excel forms for technologist and medical physicist QC (free to download), and recordings and slides from recent webinars pertaining to the manual. Please contact us if you have questions.

Q: Does the 2018 edition of the manual supersede the 2016 edition?
A: Yes.

Q: For a facility with multiple units whose annual test dates are spread throughout the year, is it acceptable to do the transition surveys when annual surveys come due?
A: Yes. Each unit (and display device) must be evaluated according to an FDA-approved QC manual at all times. Transitioning each unit on its own annual survey schedule is acceptable.

Q: Must all units within a facility follow the same QC manual?
A: No. All units within a facility are not required to use the same QC manual. Each unit within a facility must be evaluated according to a QC manual that has been approved by the FDA, but the QC manuals do not need to be the same.

Q: What if radiologists reading from remote workstations do not want to transition to the new ACR QC manual?
A: If your facility will be switching to the new QC manual and the images are going to be reviewed offsite, those offsite display devices must be evaluated according to the ACR DM QC Manual, including the Technologist's QC. This is why it is so important that the lead interpreting physician be involved with the facility's decision to transition (or not to transition) to the ACR manual. The ACR manual offers a streamlined and standardized QC program.

Q: Can the medical physicist, during an annual survey, conduct and report failed tests normally performed during MEEs (e.g. kVp, collimation, etc.), or is the facility allowed to ignore the failures because they are not required for an annual survey?
A: The MEE tests are also troubleshooting tests for medical physicists to use as they see fit. If a medical physicist performs a test and it fails, then the failure must be reported and corrective action initiated.

Q: MQSA requires that the AGD delivered during a single cranio-caudal view of an FDA-accepted phantom be less than 3.0 mGy. Are the 2D and DBT views of a clinical "combo mode" acquisition considered separate views?
A: Yes. The 2D and DBT views are considered separate, and therefore each view is individually subject to the 3.0 mGy limit, even in a “combo mode” acquisition.

Q: If we do not switch to the ACR phantom for QC and continue with the manufacturer QC, do we still need to do reject or repeat tests?
A: If your facility chooses to follow the manufacturer's QC manual, and the manual requires that a reject or repeat analysis be performed, you must perform it.

Q: How do I know which vendor "tests" are necessary calibrations that must be continued if we choose to use the ACR QC manual?
A: Equipment calibrations are procedures that are used to detect and automatically correct equipment problems. For example, digital detector manufacturers create calibration procedures that optimize detector performance by compensating for dead or over-responding pixels, structured or other noise, nonlinear response, and other technical performance parameters. QC tests are procedures that detect problems but the procedure itself does not correct the problem. Manufacturers should clearly identify the calibration procedures necessary to keep their detectors in optimal operating condition. If you have questions regarding which manufacturer tests are “calibrations” as opposed to QC tests, you should contact your equipment manufacturer.

Q: Should the medical physicist stop subtracting from the phantom image quality score due to artifacts for both the small ACR Mammography Phantom as well as the large ACR Digital Mammography Phantom used with the new ACR QC manual?
A: No. If the unit is using the manufacturer's QC manual with the small ACR Mammography Phantom, artifacts should be subtracted from the test object scores as described in these manuals. For units using the new ACR QC manual with the large ACR Digital Mammography Phantom, there is no subtraction from the phantom test object scores due to artifacts. However, note that artifacts can cause failure of the unit's phantom image quality test.

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