Documentation of ovoid cap size

The need for precise documentation in radiation oncology is paramount; assurance of the quality of therapy delivered is the responsibility of everyone engaged in the treatment of cancer patients. Although all aspects of quality assurance require meticulous attention to detail, the documentation of brachytherapy procedures, both written dose prescription and film verification, is particularly important as no single method of dose reporting is universally accepted and used. The size of ovoid caps used in brachytherapy applications for gynecologic malignancies cannot be verified on treatment planning films, as the caps are not radio-opaque. If the cap size is improperly reported by the physician, resulting surface dose calculations used to determine source loading and implant duration could cause over- or underdosing. In an effort to improve and refine gynecologic brachytherapy record-keeping, we have devised a method to verify and document cap size. Narrow stainless steel bands have been embedded into grooves cut circumferentially on the surface of the ovoid caps. These bands are readily visible on localization films, producing documentation of the cap diameter, reducing the risk of error in dose reporting, and providing a permanent record of ovoid size. We will review the nature of possible dose errors affecting clinical decisions.