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Is a patient's cumulative dose measurement relevant when ordering a diagnostic radiology exam?

In response to the growing attention given to measurement of the cumulative radiation dose level for patients receiving diagnostic tests that utilize ionizing radiation, the leading national organizations of radiological/medical physics have issued a new joint statement that strives to push back against this trend. This month, August 2021, the American Association of Physicists in Medicine, the American College of Radiology, and the Health Physics Society (AAPM/ACR/HPS) jointly released a position statement advising against using information about a patient’s previous cumulative dose information from medical imaging exams to decide the appropriateness of future imaging exams.

The statement recommends that the decision to order medical imaging exams should be based on clinical grounds, including the information available from prior imaging results, and not on the dose from prior imaging-related radiation exposures. The organizations also released a set of frequently asked questions. Among the strongly-worded advice in the FAQs, the organizations advise:

  • Against the use of dose monitoring software to monitor dose metrics from imaging exams. The AAPM/ACR/HPS state that it is inappropriate to consider estimated cumulative risks from past exposures when evaluating the need for a new medical imaging exam. They believe that such factors could negatively influence the decision to order imaging studies and could be detrimental to a patient’s care.
  • That imaging providers contact the manufacturers of their dose monitoring software and ask if the functionality for a patient's individual cumulative dose measure can be turned off. The AAPM/ACR/HPS recommend that radiology information systems stop sending the DICOM modality worklist to the dose monitoring software because dose monitoring programs can trigger (presumably inappropriately in the eyes of AAPM/ACR/HPS) prospective alerts or cumulative dose alarms.
  • Against tracking an individual patient’s total organ doses, especially for parts of the body that are more sensitive to radiation, such as the thyroid. The statement contends that there is no scientific or medical consensus on what to do when a specific cumulative organ dose is reached. They concede, however, from a research perspective organ dose tracking in large populations of patients may be valuable for improving radiation risk models in the future.

The AAPM/ACR/HPS push back against the notion that there is a lifetime limit to the amount of radiation that a patient can receive from medical procedures. They note agreement with the International Commission on Radiological Protection that, unlike for occupational exposures, exposure limits for patients are not appropriate in medicine.

As for the use of ionizing radiation in interventional radiology procedures, the three organizations advise that radiation doses from interventional procedures should be tracked, but only for purposes of determining a patient’s risk of developing radiation-induced tissue reactions.

Finally, the AAPM/ACR/HPS statement draws a distinction between using tools to measure "stochastic" effects (i.e., the potential increased risk of developing cancer) versus the "deterministic" effects (i.e., damage to the skin, hair follicles, or lens of the eye.) They see the latter as appropriate to track.

The Radiological Society of North America (RSNA) and the Society of Nuclear Medicine and Molecular Imaging (SNMMI) have endorsed the new AAPM/ACR/HPS joint statement.

It will be fascinating to watch this debate over the use of cumulative radiation dose measurement tools. And it will be interesting to see if diagnostic imaging providers take affirmative steps to heed many of the strong, and arguably controversial, recommendations of AAPM/ACR/HPS, such as turning off functionality for a patient's cumulative dose measurements.

It is essential that the amount of radiation used for an imaging exam is optimized, not minimized. Achieving the image quality required for the clinical task should not be compromised, and the amount of radiation used should be dictated by the image quality needs. Optimization should include considerations of patient-specific factors that influence image quality, such as patient size.

Tags

health care & life sciences, diagnostic imaging, physics, radiation, dose measurement

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