Ehrlich Marqarete, Welter Garv L
Institute for Basic Standards, National Bureau of Standards, Washington, D.C. 20234.
J Res Natl Bur Stand A Phys Chem. 1976 Jul-Aug;80A(4):663-668. doi: 10.6028/jres.080A.066. Epub 1976 Aug 1.
The National Bureau of Standards is performing a study of the ability of radiation-therapy departments to deliver prescribed absorbed doses of Co gamma radiation to a water phantom. Batches of thermoluminescence dosimeters are mailed to participating therapy departments for irradiation under prescribed conditions. Upon return of the dosimeters, the participants' computations are checked and the absorbed dose is evaluated from dosimeter response. The rugged dosimetry system was assembled mainly from commercial components adapted to the present requirements of relatively high flexibility of readout parameters and data-handling techniques, and of relatively high accuracy. The uncertainty in the dose interpretation inherent in the system is estimated to be about 4 percent. In order to illustrate the type of information that can be obtained from such a study, results of the first four mailings involving tests on 114 Co gamma-ray beams are discussed. They show about 75 percent of the dose interpretations to be within 5 percent of the prescribed absorbed dose, and about 20 percent to be within 5 to 10 percent of this dose. Four dose interpretations showed discrepancies larger than 20 percent. Differences in the computations larger than 1 percent were observed in over one-half of the cases.
美国国家标准局正在对放射治疗部门向水模体输送规定吸收剂量的钴伽马辐射的能力进行一项研究。将一批批热释光剂量计邮寄给参与的治疗部门，以便在规定条件下进行照射。剂量计返回后，会检查参与者的计算结果，并根据剂量计的响应评估吸收剂量。这种坚固的剂量测定系统主要由商业组件组装而成，这些组件适应了读出参数和数据处理技术具有较高灵活性以及较高准确性的当前要求。该系统中剂量解释所固有的不确定性估计约为4%。为了说明从这样一项研究中可以获得的信息类型，讨论了前四次邮寄的结果，这些邮寄涉及对114束钴伽马射线束的测试。结果显示，约75%的剂量解释在规定吸收剂量的5%以内，约20%在该剂量的5%至10%以内。有四次剂量解释显示差异大于20%。在超过一半的案例中观察到计算差异大于1%。
