A Children's Oncology Group Physics Committee Report on Imaging and Radiation Oncology Core Site Credentialing and...

The Imaging and Radiation Oncology Core works with the Children's Oncology Group (COG) to provide institutional credentialing and patient radiation therapy plan review for sites that enroll patients on COG clinical trials. COG protocols that include radiation therapy require specific site credentialing activities depending on the treatment technique that is allowed in the protocol. In addition, there are protocol-specific treatment planning guidelines for tumor coverage and normal tissue sparing that define not only protocol acceptable limits but also variations in limits if deemed clinically necessary, as well as protocol deviations. With many institutions participating in COG protocols, credentialing activities ensure standards for radiation therapy equipment and delivery are met and individual patient case reviews ensure consistency in target delineation, tumor coverage, and normal tissue avoidance for each protocol. The purpose of this work is to provide a descriptive analysis of retrospective credentialing and case review data for COG clinical trials.

This work was conducted by representatives of the COG Physics Committee and aimed to characterize protocol deviations of recently closed COG trials. This analysis included closed COG protocols from a 10-year period (2013-2023). Phantom credentialing performance of COG institutions was assessed and compared with case review deviations to determine trends. Credentialing phantom irradiation failures were collated and reviewed for common failure modes. From patient case reviews, protocol deviations were categorized, and patterns of protocol deviations are described.

This study found that credentialing and case reviews in clinical trial quality assurance were complementary, identifying unique failure modes, often before they affected enrolled patients. For example, phantom credentialing identified errors in beam modeling or patient setup processes, whereas case reviews identified errors in anatomical contouring, prescriptions, treatment planning techniques, and dose coverage.

Although the final rate of protocol deviations was low for COG protocols, many errors were identified through the case review and credentialing processes, highlighting the continued need for quality assurance checks of radiation therapy data in clinical trials.