Initial experience with quality assurance of multi-institutional 3D radiotherapy clinical trials. A brief report.

In 1992, a 3D Quality Assurance (3D QA) Center was established at the Mallinckrodt Institute of Radiology under the auspices of the Radiation Therapy Oncology Group (RTOG). The role of the 3D QA Center is to provide quality assurance reviews of external beam treatment planning and verification (TPV) information for patients enrolled in multi-institutional 3D radiotherapy treatment protocols. Computer hardware and software components have been implemented which allow participating institutions to submit (via either the Internet or magnetic tape) common format 3D TPV data for QA review including: volumetric CT image data, normal structure, tumor and target volume contours, digitally reconstructed radiographs or simulator (prescription) and portal radiographs, beam geometry, dose distributions, fractionation information, and dose-volume histograms. Prior to enrolling patients on a 3D radiotherapy treatment protocol, each participating institution is required to complete a 3D Facility Questionnaire documenting their 3D treatment planning capability. In addition, the successful completion of a protocol "dry run" test is required to demonstrate the participating institution's ability to submit a protocol complaint digital data set to the 3D QA Center prior to placing patients on the 3D CRT study. Two site specific (prostate and lung) phase I/II 3D dose escalation trials are currently accruing patients. The QA center reviews at a minimum the first 5 cases from each participating institution and spot checks subsequent submissions. For each case review the following parameters are evaluated: 1. data exchange compliance, 2. CT data quality, 3. target volume contours, 4. normal structure contours, 5. field placement, 6. field shape, 7. dose prescription, 8. dose uniformity, and 9. dose conformity. By April 1997, over 300 protocol patient TPV data sets have been submitted and reviewed by the 3D QA Center.