HIGH-DOSE RATE INTRACAVITARY BRACHYTHERAPY FOR CARCINOMA OF THE CERVIX - THE MADISON SYSTEM .1. CLINICAL AND RADIOBIOLOGICAL CONSIDERATIONS
HIGH-DOSE RATE INTRACAVITARY BRACHYTHERAPY FOR CARCINOMA OF THE CERVIX - THE MADISON SYSTEM .1. CLINICAL AND RADIOBIOLOGICAL CONSIDERATIONS
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DOI：
10.1016/0360-3016(92)90690-j
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发表时间：
1992-01-01
影响因子：
7
通讯作者：
KINSELLA, TJ
中科院分区：
文献类型：
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作者：
STITT, JA;FOWLER, JF;KINSELLA, TJ
在临床上，威斯康星州大学综合癌症中心（UWCCC）决定每周使用5次高剂量率腔内（HDR-ICR）插入治疗宫颈浸润癌。这是基于实际考虑和全球范围内的既往临床经验，这些经验表明使用了2至16次插入，结果明显可接受。尽管放射生物学考虑倾向于大量的小剂量，但如此大量的HDR-ICR插入在临床上是不实用的。我们的策略是保持体外射束和腔内插入的生物学效应的比例与在这里接受低剂量率（LDR）治疗的大量患者相同。这意味着保持相同的外部射束治疗方案，并尽可能找到与先前LDR治疗生物等效的高剂量率（HDR）剂量。详细介绍了麦迪逊系统治疗宫颈癌的外照射和HDR腔内剂量计划。由于在晚期反应的正常组织中存在更多的可修复损伤，因此当从LDR改变为HDR时，这些组织中的保留损失比肿瘤中的保留损失更大，因此对于相等的晚期并发症，总剂量应比对于相等的肿瘤控制减少更多。临床决策旨在实现同等肿瘤控制。晚期并发症的可能增加必须通过使用HDR源的极其小心的解剖定位来减少对关键正常组织的剂量来避免。重要的正常组织必须远离辐射源，使得它们的剂量比LDR几何结构低约20%。这需要额外分离几毫米，具体取决于单个插入的解剖结构和几何形状。该策略是，几个大部分的不利的放射生物学效应必须抵消更好的物理剂量分布与HDR-ICR比以前的LDR插入。这些良好的分布可以通过HDR下的短曝光来获得。
The decision to use five high dose rate intracavitary (HDR-ICR) insertions at weekly intervals for invasive carcinoma of the cervix treated at the University of Wisconsin Comprehensive Cancer Center (UWCCC) was made clinically. It was based on practical considerations and on previous clinical experience worldwide which showed that between 2 and 16 insertions have been used with apparently acceptable results. Although radiobiological considerations favor a large number of small doses, such a large number of HDR-ICR insertions is not clinically practical. Our strategy was to keep the biological effects of external beam and intracavitary insertions in the same ratio as used on a large series of patients treated here with low dose rate (LDR) therapy. This means keeping the same external beam treatment scheme and finding high dose rate (HDR) doses that are biologically equivalent to the previous LDR therapy, as far as possible. External beam and HDR intracavitary dose schedules for the Madison System of treating cervical carcinoma are described in detail. Because there is more repairable damage in late-reacting normal tissues, there is a bigger loss of sparing in these tissues than in tumors when changing from LDR to HDR, so total doses should be reduced more for equal late complications than for equal tumor control. The clinical decision was made to aim at equal tumor control. The possible increase in late complications has to be avoided by reducing the doses to critical normal tissues using extremely careful anatomic positioning of the HDR sources. Critical normal tissues must be kept further away from the radiation sources so that their doses are about 20% lower than with LDR geometry. This requires an extra separation of some millimeters depending on the anatomy and geometry of the individual insertion. The strategy is that the unfavorable radiobiological effects of a few large fractions must be counteracted by better physical dose distributions with HDR-ICR than with the previous LDR insertions. These good distributions are obtainable with the short exposures at HDR.