National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, United Kingdom. Author to whom any correspondence should be addressed.
Phys Med Biol. 2020 Apr 23;65(8):085016. doi: 10.1088/1361-6560/ab7b30.
Despite well-established dosimetry in clinical radiotherapy, dose measurements in pre-clinical and radiobiology studies are frequently inadequate, thus undermining the reliability and reproducibility of published findings. The lack of suitable dosimetry protocols, coupled with the increasing complexity of pre-clinical irradiation platforms, undermines confidence in preclinical studies and represents a serious obstacle in the translation to clinical practice. To accurately measure output of a pre-clinical radiotherapy unit, appropriate Codes of Practice (CoP) for medium energy x-rays needs to be employed. However, determination of absorbed dose to water (D) relies on application of backscatter factor (B) employing in-air method or carrying out in-phantom measurement at the reference depth of 2 cm in a full backscatter (i.e. 30 × 30 × 30 cm) condition. Both of these methods require thickness of at least 30 cm of underlying material, which are never fulfilled in typical pre-clinical irradiations. This work is focused on evaluation the effects of the lack of recommended reference conditions in dosimetry measurements for pre-clinical settings and is aimed at extending the recommendations of the current CoP to practical experimental conditions and highlighting the potential impact of the lack of correct backscatter considerations on radiobiological studies.
尽管临床放射治疗中的剂量学已经得到了很好的建立，但在临床前和放射生物学研究中，剂量测量常常不够充分，从而破坏了已发表研究结果的可靠性和可重复性。缺乏合适的剂量学协议，再加上临床前照射平台日益复杂，这削弱了人们对临床前研究的信心，成为向临床实践转化的一个严重障碍。为了准确测量临床前放射治疗设备的输出，需要采用中能 X 射线的适当实践准则 (CoP)。然而，水吸收剂量 (D) 的确定依赖于使用反散射因子 (B) 的空气比释动能测定法，或者在全反散射（即 30×30×30cm）条件下在参考深度 2cm 处进行体模内测量。这两种方法都需要至少 30cm 厚的底层材料，而这在典型的临床前照射中从未得到满足。这项工作集中于评估在临床前环境中剂量测量中缺乏推荐参考条件对剂量学测量的影响，并旨在将当前 CoP 的建议扩展到实际实验条件，并强调缺乏正确反散射考虑对放射生物学研究的潜在影响。
