Enhanced Dosimetry Systems for CT Scans

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Objective for A.13.0

  • Develop a coherent dosimetry system based upon NIST traceable dosimeters which can be used routinely in the administration of CT scans.

Background: The enhanced image quality of X-ray generated computerized tomography (CT scans) has lead to a growing use of this diagnostic method in the medical community. For the most part, radiologists conducting CT scans rely upon protocols established by the manufacturers of the CT scanning equipment to set exposure parameters. Supposed corrections are made for body weight and bulk. Because this diagnostic procedure can sometimes lead to the detection of undesired health issues, i.e. detection of cancers, patients can be prone to seek multiple CT-scans from different facilities, shopping around while in denial of an unfavorable result. Studies have shown that excessive, multiple CT scans can themselves be a source of radiation induced malignancies.

To ensure patient safety, industry standards for CT scanning equipment have to be established and then administered by appropriate authorities, such as the US Food and Drug Administration’s Center for Devices and Radiological Health. Reliance upon vendor generated protocols does not assure patient safety. In conjunction with this, a database has to be established within the Department of Health and Human Service which will catalog patient exposures with due respect to individual patient privacy rights. Radiologists need to be informed prior to administering a CT scan of how many times a given patient has had this procedure.

Action Items:

1 – In conjunction with the AAPM and the ACR, standards, such as those developed for equipment through the American National Standards Institute (ANSI), have to be established for CT equipment. Such standards should include the use of NIST traceable dosimeters and phantoms that have a high degree of dose sensitivity.

2 – Relying upon its existing database in the Medicare/Medicaid system, the Department of Health and Human Services can begin to establish a database annotating how often an individual is to have a CT-scan. Radiologists need to be informed as to how often a given patient has been subjected to this procedure.

3 - Interact with ACR to see to develop standards for organ dose to make good use of the data that they are already acculumating in their dose register.

Resource Requirements:

1 – A coordination team of representatives of the appropriate associations, of NIST, of FDA CDRH and of DHHS will take several years to implement this need.