Björk-Eriksson T, West C, Karlsson E, Mercke C
Department of Oncology, Sahlgrenska University Hospital, Gothenburg, Sweden.
Int J Radiat Oncol Biol Phys. 1998 Dec 1;42(5):1147-53. doi: 10.1016/s0360-3016(98)00287-9.
Evaluation of the theoretical and practical value of using low-dose rate (LDR) irradiation to increase the resolution of radiosensitivity testing of primary human tumors using clonogenic assays.
Fourteen human tumor cell lines were assessed for surviving fraction at 2-8 Gy (SF2-SF8) using low-dose rate irradiation and a clonogenic assay. Further data were collected from the literature for 64 low-dose rate irradiation survival curves from human tumor cell lines. The data were grouped into five different radioresponsiveness categories (A-E). An analysis was made of the ability of the graded survival levels to discriminate between the different radioresponse groups and compared with previous analyses for high-dose rate SF2. Fifteen human cervical carcinoma specimens were analysed for SF2 and SF3.5 following high- and low-dose rate irradiation.
Low-dose rate irradiation increased the spread of tumor cell line radiosensitivity data and the ability to discriminate between radioresponse groups was greater at low than at high-dose rates. Using low-dose rate irradiation on primary tumor specimens and a soft agar clonogenic assay decreased the success rate in obtaining data. The latter dropped from 70% for high-dose rate SF2 to 51% for low-dose rate SF3.5.
The work on cell lines illustrates that low-dose rate irradiation does improve the ability of clonogenic radiosensitivity measurements to discriminate between tumors of different radioresponsiveness groups. However, using low-dose rate irradiation on primary human tumors with a soft agar clonogenic assay was not practical because of reducing the success rate for obtaining data for radiosensitivity measurements.
评估使用低剂量率（LDR）照射提高原发性人类肿瘤放射敏感性测试分辨率的理论和实用价值，该测试采用克隆形成试验。
使用低剂量率照射和克隆形成试验评估14种人类肿瘤细胞系在2 - 8 Gy剂量下的存活分数（SF2 - SF8）。从文献中收集了64条来自人类肿瘤细胞系的低剂量率照射存活曲线的进一步数据。数据被分为五个不同的放射反应类别（A - E）。分析分级存活水平区分不同放射反应组的能力，并与之前对高剂量率SF2的分析进行比较。对15例人类宫颈癌标本进行高剂量率和低剂量率照射后的SF2和SF3.5分析。
低剂量率照射增加了肿瘤细胞系放射敏感性数据的离散度，且低剂量率下区分放射反应组的能力高于高剂量率。对原发性肿瘤标本使用低剂量率照射和软琼脂克隆形成试验会降低获取数据的成功率。后者从高剂量率SF2的70%降至低剂量率SF3.5的51%。
细胞系研究表明，低剂量率照射确实提高了克隆形成放射敏感性测量区分不同放射反应组肿瘤的能力。然而，对原发性人类肿瘤使用低剂量率照射和软琼脂克隆形成试验并不实用，因为这会降低放射敏感性测量数据获取的成功率。
