Nyman J, Turesson I
Department of Oncology, University of Gothenburg, Sahlgrenska Hospital, Sweden.
Acta Oncol. 1991;30(6):753-9. doi: 10.3109/02841869109092452.
Radiation-induced changes in the basal cell density (BCD) and the labelling index (LI) in the epidermis of pig skin were used to compare the effect of high and low dose rate irradiation. Single doses of 6, 12 and 24 Gy were applied at 1.5 and 0.02 Gy/min with two equal 137Cs sources. Punch biopsies were taken daily for 40 days. The linear BCD was calculated from histological sections. The LI was determined by an in vitro H3-thymidine labelling technique. We found a degenerative phase in the basal cell layer with a linear cell loss of 2% per day, independent of the dose and dose rate. The time and level of the minimum BCD were dose and dose rate dependent. The LI data indicated an increased proliferation rate after a 25% reduction in BCD, i.e. before the nadir was reached. From the BCD data an iso-effective dose factor of 1.8 was estimated for the two dose rates used, which was consistent with that determined from macroscopic scoring. The BCD can be used as an endpoint for comparison of different radiotherapy modalities and gives, together with the LI, further information on the time-course of the proliferation changes in the tissue.
利用猪皮肤表皮中辐射诱导的基底细胞密度（BCD）和标记指数（LI）的变化来比较高剂量率和低剂量率照射的效果。使用两个相同的铯 - 137源，分别以1.5 Gy/min和0.02 Gy/min的剂量率施加6、12和24 Gy的单剂量。在40天内每天进行打孔活检。从组织学切片计算线性BCD。通过体外H3 - 胸苷标记技术测定LI。我们发现基底细胞层存在一个退化阶段，每天细胞线性损失2%，与剂量和剂量率无关。最低BCD出现的时间和水平取决于剂量和剂量率。LI数据表明，在BCD降低25%后，即在达到最低点之前，增殖率增加。根据BCD数据，估计所使用的两种剂量率的等效剂量因子为1.8，这与通过宏观评分确定的结果一致。BCD可用作比较不同放疗方式的终点指标，并与LI一起提供有关组织中增殖变化时间进程的更多信息。
