Chougule A
Department of Radiotherapy, R.N.T. Medical College and Hospital, Udaipur, India.
Strahlenther Onkol. 1994 Jan;170(1):30-5.
Various types of fractionation schemes have been tried in recent year with the objective of improving tumor control rate because conventional fractionation schedules do not always produce optimum results. To compare the radiobiological effectiveness and the gain in the therapeutic ratio due to various fractionation schemes, empirical formulae such as NSD, TDF, CRE and TSD were introduced and used despite of many short comings. Recent linear quadratic (LQ) model is claimed to be able to predict the radiobiological responses of tumor as well as normal tissues more accurately. In the present study various empirical models are compared.
We treated malignancy of cervix uteri by twice daily fractionation schedules of 1.2 Gy/fraction, 1.4 Gy/fraction and 1.6 Gy/fraction with interfraction interval of four to six hours. The percentage tumor regression was estimated from weekly clinical observations and the TDFt, TSD and ERDt concepts were applied to the data and the predictions are compared.
It was observed that TDFt and TSD concepts predicts equally well (within +/- 3%) the probable tumor regression as predicted by LQ concept.
Till precise values of various parameters of LQ model are known, the TDF and TSD models can be used to predict probable tumor control rates within reasonable accuracy.
近年来，人们尝试了各种分割方案，目的是提高肿瘤控制率，因为传统的分割方案并不总能产生最佳效果。为了比较各种分割方案的放射生物学有效性和治疗增益比，尽管存在许多缺点，但还是引入并使用了诸如NSD、TDF、CRE和TSD等经验公式。最近的线性二次（LQ）模型据称能够更准确地预测肿瘤以及正常组织的放射生物学反应。在本研究中，对各种经验模型进行了比较。
我们采用每天两次的分割方案，每次分割剂量为1.2 Gy、1.4 Gy和1.6 Gy，分割间隔为4至6小时，治疗子宫颈恶性肿瘤。根据每周的临床观察估计肿瘤消退百分比，并将TDFt、TSD和ERDt概念应用于数据，并比较预测结果。
观察到TDFt和TSD概念对肿瘤消退可能性的预测与LQ概念预测的结果同样良好（在±3%以内）。
在LQ模型的各种参数的精确值已知之前，TDF和TSD模型可用于在合理的准确度内预测可能的肿瘤控制率。
