Brachytherapy workflow for locally advanced cervical cancer: A survey of Canadian Medical Physicists

Abstract

To report on brachytherapy (BT) workflows for image-based treatments of locally advanced cervical cancer (CC) in Canada. Medical Physicists in every Canadian cancer center were contacted and those with a CC-BT program were emailed a 44-item electronic questionnaire surveying workflow patterns including: fractionation schedules, prescription, equipment, imaging, and treatment delivery. Of 47 centers contacted, all 34 who performed CC-BT participated in the survey. Brachytherapy boost, following external beam treatments, was delivered using high-dose-rate (HDR); one center also used pulsed-dose-rate. Intracavitary and/or interstitial treatments were done in 47% centers for 25-80% of their patients. All centers used image-based planning: CT (32%), CT planned with MRI for contouring (47%), MRI (18%), or cone beam CT (3%). For those performing volume-based planning (74%), the contours commonly included Clinical Target Volume (CTV)-High Risk (HR), CTV-Intermediate Risk, rectum, sigmoid, and bladder. The most common HDR dose-fractionation schedule was 7 [4.6 - 10] Gy in 4 [3 - 6] fractions with radiobiological dose prescriptions performed in 62% centers. Medical physics contribution was significant during most activities along the BT treatment pathway in all centers, especially in planning (88%), second checks (68%), and during treatment delivery (88%). Compared to previous surveys, there is an increasing trend in the use of image-based volumetric planning, interstitial procedures, and radiobiological dose prescription. Cervical cancer brachytherapy in Canada is becoming more streamlined with the use of international practice guidelines. Involvement of medical physicists is vital to all stages of CC-BT, including program implementation, routine quality control, dosimetry, and treatment delivery.