Abstract
We studied the usefulness of a new type of solid‐state detector, the OneDose single‐use MOSFET (metal oxide semiconductor field effect transistor) dosimeter, for entrance dose measurements for total body irradiation (TBI). The factory calibration factors supplied by the manufacturer are applicable to conventional radiotherapy beam arrangements and therefore may not be expected to be valid for TBI dosimetry because of the large field sizes and extended source‐to‐axis distances used. OneDose detectors were placed under a 1‐cm thick bolus at the head, neck, and umbilicus of 9 patients undergoing TBI procedures. Thermoluminescent dosimeters (TLDs) were placed beside the detectors. We found that the OneDose readings differed from the TLD readings by 4.6% at the head, 1.7% at the neck, and 3.9% at the umbilicus, with corresponding standard deviations of 3.9%, 2.2%, and 2.7%. For all patient measurements, 95% of the OneDose readings fell within 3.3%±6.0% of the TLD readings. Anthropomorphic phantom measurements showed differences of −0.1% at the neck and −1.2% midway between the phantom's carina and umbilicus. Our results suggest that these detectors could be used for TBI quality assurance monitoring, although TLDs should remain the standard when critical dose measurements are performed. If OneDose detectors are to be used for TBI, the use of more than one at each location is strongly recommended. Because the detectors are designed for single use, they cannot be individually calibrated. However, to obtain institution‐specific correction factors for better applicability to TBI dosimetry, measurements of several detectors taken from a particular lot could also be obtained in phantom with the TBI geometry configurations used for patient treatment.PACS numbers: 87.53.Bn, 85.30.Tv, 87.55.‐x
Highlights
201 Briere et al.: Patient dosimetry for total body irradiation...beams,(11) and patient dosimetry for total body irradiation (TBI) procedures.[6]
The results for the OneDose detectors placed on the abdominal phantom in the TBI geometry showed an average difference from the thermoluminescent dosimeters (TLDs) readings of –1.2% at the neck and –0.1% at the midline
The results for the OneDose detectors irradiated at conventional geometry show agreement with the TLD readings with an average difference of 0.7% and a maximum difference of 4.3%, well within manufacturer’s specifications (Fig. 2)
Summary
201 Briere et al.: Patient dosimetry for total body irradiation. Beams,(11) and patient dosimetry for total body irradiation (TBI) procedures.[6] For conventional geometries under full buildup conditions, the manufacturer states that the accuracy[12] for these detectors is. Two important characteristics of these detectors are that they are wireless, and they can be read immediately after completion of a treatment procedure. The latter characteristic would be advantageous for short treatment courses, including entrance dose measurements for TBI procedures and stereotactic treatments. The goal of the present work was to determine if the OneDose detector can be used clinically as an alternative to TLDs for monitoring and measuring TBI doses that are delivered at various anatomic sites
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