Department of Medical Physics, Kermanshah University of Medical Sciences, Kermanshah, Iran.
Department of Medical Physics, Faculty of Medicine, Tarbiat Modares University, Tehran, Iran.
Radiat Environ Biophys. 2023 May;62(2):269-277. doi: 10.1007/s00411-023-01025-4. Epub 2023 May 2.
The objective of our study was to determine organ doses to estimate the lifetime attributable risk (LAR) of cancer incidence related to chest tomography simulations for Radiotherapy Treatment Planning (RTTP) using patient-specific information. Patient data were used to calculate organ doses and effective dose. The effective dose (E) was calculated by two methods. First, to calculate effective dose in a standard phantom, the collected dosimetric parameters were used with the ImPACT CT Patient Dosimetry Calculator and E was calculated by applying related correction factors. Second, using the scanner-derived Dose Length Product, LARs were computed using the US National Academy of Sciences (BEIR VII) model for age- and sex-specific risks at each exposure. DLP, CTDI, and scan length were 507 ± 143 mGy.cm, 11 ± 4 mGy, and 47 ± 7 cm, respectively. The effective dose was 10 ± 3 mSv using ImPACT patient dosimetry calculator software and 9 ± 2 mSv using the scanner-derived Dose Length Product. The LAR of cancer incidence for all cancers, all solid cancers and leukemia were 65 ± 29, 62 ± 27, 7 ± 2 cases per 100,000 individuals, respectively. Radiation exposure from the usage of CT for radiotherapy treatment planning (RTTP) causes non-negligible increases in lifetime attributable risk. The results of this study can be used as a guide by physicians to implement strategies based on the As Low As Reasonably Achievable (ALARA) principle that lead to a reduction dose without sacrificing diagnostic information.
本研究的目的是确定器官剂量，以估算与放射治疗计划（RTTP）的胸部断层扫描模拟相关的癌症发病率的终生归因风险（LAR），使用患者特定信息。使用患者数据计算器官剂量和有效剂量。有效剂量（E）通过两种方法计算。首先，为了在标准体模中计算有效剂量，使用收集的剂量学参数，结合 ImpACT CT 患者剂量计算器，通过应用相关修正因子来计算 E。其次，使用扫描仪衍生的剂量长度乘积，根据美国国家科学院（BEIR VII）模型，针对每个暴露的年龄和性别特异性风险计算 LAR。DLP、CTDI 和扫描长度分别为 507±143 mGy.cm、11±4 mGy 和 47±7 cm。使用 ImpACT 患者剂量计算软件计算有效剂量为 10±3 mSv，使用扫描仪衍生的剂量长度乘积计算有效剂量为 9±2 mSv。所有癌症、所有实体癌和白血病的癌症发病率终生归因风险分别为 65±29、62±27 和 7±2 例/100000 人。使用 CT 进行放射治疗计划（RTTP）会导致辐射暴露，从而不可忽视地增加终生归因风险。本研究的结果可作为医生的指南，实施基于合理可达到的最低水平（ALARA）原则的策略，在不牺牲诊断信息的情况下降低剂量。
