Dosimetric verification of dose calculation algorithm in the lung during total marrow irradiation using helical tomotherapy
Abstract
Treatment of proliferative diseases of the hematopoietic system involves, in most cases, chemotherapy combined with radiation therapy, which is intended to provide adequate immunosuppressant. Conventionally, total body irradiation (TBI) was used; however, total marrow irradiation (TMI) performed with helical tomotherapy (HT) has been proposed as an alternative, with the aim of delivering the highest dose in the target area (skeleton bone). The purpose of this study is to evaluate the accuracy of the dose calculation algorithm for the lung in TMI delivered with HT. Thermoluminescent detectors (TLD-100 Harshaw) were used to measure delivered doses. Doses were calculated for 95 selected points in the central lung (53 TLDs) and near the rib bones (42 TLDs) in the anthropomorphic phantom. A total of 12 Gy were delivered (6 fractions of 2 Gy/fraction). HT-TMI technique reduces the dose delivered to the lungs in a phantom model to levels that are much lower than those reported for TBI delivered by a conventional linear accelerator. The mean calculated lung dose was 5.6 Gy versus a mean measured dose of 5.7 ± 2.4 Gy. The maximum and minimum measured doses were, respectively, 11.3 Gy (chest wall) and 2.8 Gy (central lung). At most of th...Continue Reading
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