Preliminary estimation of minimum target dose in intracavitary radiotherapy for cervical cancer.
Preliminary estimation of minimum target dose in intracavitary radiotherapy for cervical cancer.
复制标题
宫颈癌腔内放疗最小靶剂量的初步估算。
作者：
K. Ohara;Y. Tanaka;S. Sugahara;Y. Itai
目的
在宫颈癌的腔内放射治疗(ICRT)中，最小靶区剂量(Dmin)将比参考点A剂量(D(A))更直接地与局部疾病控制有关。但是，由于未标识目标卷，因此传统上执行ICRT时不指定Dmin。我们通过使用磁共振(MR)图像识别肿瘤来回溯性地估计Dmin。
材料和方法
对31例接受高剂量率ICRT治疗的患者进行治疗前和治疗后的磁共振成像。ICRT每周进行一次，剂量为6.0GyDA，每例患者需插入2~5次，共119次。用肿瘤宽度(W(A))与D(A)比较，在A节段任意计算Dmin。通过对治疗前和治疗后W(A)进行回归分析，估计每个插入点的W(A)。
结果
每次植入的Dmin从3.0到46.0Gy不等，相差16倍。每例患者的总Dmin与总DA的比值在0.5~6.5之间。首次插入和最终插入之间的患者体内Dmin差值从1.1到3.4不等。
结论
初步估计显示，在通用剂量处方下，Dmin变化很大。当在磁共振成像下进行ICRT-敷贴器插入时，将实现完整的Dmin规范。
PURPOSE
In intracavitary radiotherapy (ICRT) for cervical cancer, minimum target dose (Dmin) will pertain to local disease control more directly than will reference point A dose (D(A)). However, ICRT has been performed traditionally without specifying Dmin since the target volume was not identified. We have estimated Dmin retrospectively by identifying tumors using magnetic resonance (MR) images.
MATERIALS AND METHODS
Pre- and posttreatment MR images of 31 patients treated with high-dose-rate ICRT were used. ICRT was performed once weekly at 6.0 Gy DA, and involved 2-5 insertions for each patient, 119 insertions in total. Dmin was calculated arbitrarily simply at the point A level using the tumor width (W(A)) to compare with D(A). W(A) at each insertion was estimated by regression analysis with pre- and posttreatment W(A).
RESULTS
Dmin for each insertion varied from 3.0 to 46.0 Gy, a 16-fold difference. The ratio of total Dmin to total DA for each patient varied from 0.5 to 6.5. Intrapatient Dmin difference between the initial insertion and final insertion varied from 1.1 to 3.4.
CONCLUSION
Preliminary estimation revealed that Dmin varies widely under generic dose prescription. Thorough Dmin specification will be realized when ICRT-applicator insertion is performed under MR imaging.