Cesium-131 permanent seed brachytherapy: Dosimetric evaluation and radiation exposure to surgeons, radiation oncologists, and staff

PURPOSE: Cesium-131 (Cs-131) radioactive seed is Food and Drug Administration approved for permanent seed implant for all cancers, including lung and head and neck (HN) cancers. We describe the first clinical report of Cs-131 dosimetry and exposure rates to treating physicians and staff. METHODS AND MATERIALS: Twenty-eight patients received Cs-131 implant for early stage lung and recurrent HN cancers. A nomogram was developed to calculate the number of seeds needed to cover the wedge line with the prescription dose (80 Gy). Final dosimetry was obtained after CT planning a few days following the surgical procedure. Radiation exposure to the treating physicians and staff was measured at the completion of the procedure. RESULTS: A nomogram was developed using the variseed software with source data from American Association of Physicists in Medicine TG-43 report. The total volume covered by the prescription isodose line of Cs-131 was measured and compared with I-125. The prescription volume was smaller for Cs-131. In addition, the exposure rate with Cs-131 was found to be acceptable. CONCLUSION: Our preliminary experience with Cs-131 lung and HN brachytherapy has been very encouraging with excellent dosimetric coverage and acceptable exposure to the treating physicians and staff. (C) 2011 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.