The usefulness of metal markers for CTV-based dose prescription in high-dose-rate interstitial brachytherapy
The usefulness of metal markers for CTV-based dose prescription in high-dose-rate interstitial brachytherapy
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金属标记物在高剂量率间质近距离放射治疗中基于 CTV 的剂量处方中的作用
DOI：
10.11182/jastro1989.14.253
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
K. Yoshida
中科院分区：
文献类型：
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作者：
K. Yoshida
(HDR)间质近距离放射治疗然而，通过X线片或CT扫描来确定CTV和危及器官（OAR）并不容易。为了解决这个问题，我们从1999年10月开始使用金属标记。此外，金属标记物可以帮助修改剂量处方。通过调节金属标记物的剂量，可以容易地实现细化剂量处方。在这项研究中，我们调查的有用性的metal markers.Methods和MaterialsBetween 1999年10月和2001年5月，51例患者植入金属标记在大坂医疗中心癌症和心血管疾病（OMCC），大坂国立医院（ONH）和山田市医院（SCH）。分析了49例使用金属标记的患者（头颈部：32例;骨盆：11例;软组织：3例;乳腺：3例）。术中CTV植入金属标记物49例（179枚），OAR植入金属标记物26例（151枚）。在治疗计划时，根据金属标记物、施源器位置和手术记录重建CTV。一般来说，我们将杀肿瘤剂量规定在覆盖CTV的等剂量表面。我们还计划将OAR的剂量限制在低于特定水平。直肠、尿道、下颌骨、皮肤和大血管的最大正常组织剂量分别为处方剂量的80%、150%、100%、50%和200%。使用基于CTV的剂量处方生成金属标记物的剂量。这些与巴黎系统理论计算的剂量进行了比较。结果42例CTV患者的158种金属标记物的剂量均高于“杀瘤剂量”。在7例患者中，由于剂量处方的影响，9种标志物低于杀肿瘤剂量。其他12个标记物（7%）被排除在剂量评价之外，因为它们被判定为植入错误。OAR的142个金属标记物（24例患者）的剂量低于最大正常组织剂量。OAR（尿道）的2种标记物（1例患者）的剂量高于最大正常组织剂量。由于金属冠，OAR（下颌骨）的7个标记不可见。如果使用了巴黎系统（参考剂量为基础剂量的85%的等剂量面），则16名患者”剂量不足”，4名患者（直肠+尿道：2名;尿道：1名;大血管：I名）”剂量过量”。剂量不均匀性比（DNR）为0.31 ± 0.08，最大剂量套筒直径为4-49 mm（中位数：7 mm）。在基于CTV的剂量处方和巴黎系统之间观察到统计学显著差异{0.28·} 0.08和3-99 mm（中值：6 mm））（p< 0.002，0.0002）。42例接受高于杀肿瘤剂量治疗的患者中有2例局部复发，而7例剂量不足的患者中有4例局部复发。结论金属标记物对CTV的治疗剂量和OAR的治疗剂量有一定的指导意义。局部控制率高于杀瘤剂量的患者治疗效果明显。金属标记的误植入是一个需要解决的问题。
(HDR) interstitial brachytherapy. However, it is not easy to define CTV and organs at risk (OAR) from X-ray film or CT scanning. To solve this problem, we have utilized metal markers since October 1999. Moreover, metal markers can help modify dose prescription. By regulating the doses to the metal markers, refining the dose prescription can easily be achieved. In this research, we investigated the usefulness of the metal markers.Methods and MaterialsBetween October 1999 and May 2001, 51 patients were implanted with metal markers at Osaka Medical Center for Cancer and Cardiovascular Diseases(OMCC), Osaka National Hospital (ONH) and Sanda City Hospital(SCH). Forty-nine patients(head and neck: 32; pelvis: 11; soft tissue: 3; breast: 3) using metal markers were analyzed. During operation, we implanted 179 metal markers(49 patients) to CTV and 151 markers(26 patients) to OAR. At treatment planning, CTV was reconstructed judging from the metal markers, applicator position and operation records. Generally, we prescribed the tumoricidal dose to an isodose surface that covers CTV. We also planned to limit the doses to OAR lower than certain levels. The maximum normal tissue doses were decided 80%, 150%, 100%, 50% and 200% of the prescribed doses for the rectum, the urethra, the mandible, the skin and the large vessel, respectively. The doses to the metal markers using CTV-based dose prescription were generated. These were compared with the doses theoretically calculated with the Paris system. Treatment results were also investigated.ResultsThe doses to the 158 metal markers(42 patients) for CTV were higher than" tumoricidal dose". In 7 patients, as a result of compromised dose prescription, 9 markers were lower than the tumoricidal dose. The other 12 markers(7%) were excluded from dose evaluation because they were judged as miss-implanted. The doses to the 142 metal markers(24 patients) for OAR were lower than the maximum normal tissue doses. The doses of 2 markers(1 patient) for OAR (the urethra) were higher than the maximum normal tissue dose. Seven markers for OAR (the mandible) were not visualized because of metal crowns. If the Paris system (reference dose is prescribed to an isodose surface of 85% of the basal dose) had been used, 16 patients had been" underdosed" and 4 patients(the rectum+ the urethra: 2; the urethra: 1; the large vessel: I)" overdosed". Dose non-uniformity ratio (DNR) and maximum diameter of hyperdose sleeve were 0.31•} 0.08 and 4-49 mm (median: 7 mm) in CTV-based dose prescription. A statistically significant difference was seen between CTV-based dose prescription and Paris system{0.28•} 0.08 and 3-99 mm (median: 6 mm))(p< 0.002, 0.0002). Two of 42 patients treated with higher than the tumoricidal dose had local recurrence, while 4 of 7 underdosed patients had local recurrence. A significant difference was found between them (p< 0.0001).ConclusionsMetal markers were useful to prescribe the tumoricidal dose to CTV and to regulate the doses for OAR. Local control rate of the patients treated with higher than the tumoricidal dose was significantly better. Miss-implantation of metal markers was a problem that should be resolved.