The accuracy of intracavitary applicator reconstruction for cervical cancer was assessed. A homemade phantom that mimics clinical applicator placement and reference points was used. Three stainless steel (15°, 30°, and 45°) tandems, x-ray markers, and three reference points were used to compare radiography- and CT-based systems. For CT reconstructions, two Fletcher CT compatible (15° and 30°) tandems, two ovoids, and two reference points, with and without inserted x-ray markers, were used. A 2.5-mm CT slice thickness was used. To check for inter- and intra-operator variations in CT, only a 30° tandem without x-ray markers and 1.25-mm CT slice thickness were used. Applicators were reconstructed three times for each image set to verify the operator reproducibility. A 6 Gy dose was prescribed and normalized at AL-point. Source dwell times were compared to check for dose variation at A-point. Maximum standard deviations SD (σ) for radiography and CT reconstructions were 0.35 and 0.83 mm, respectively. Analysis of variance for the means of 15° and 30° tandems showed no significant difference. Levene’s test proved insignificant difference for 15° tandem (p value = 0.131), whereas it showed a significant difference for 30° tandem (p value = 0.011). This phantom study showed that the variance of dwell times between the two methods for 30° tandem was statistically significant due to increased applicator curvature. CT proves superiority to radiography. X-ray marker method was more accurate but has less image quality. Inter- and intra-oncologist variations showed good agreement.

中文翻译：

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腔内涂药器重建术对宫颈癌近距离治疗的准确性

评估了腔内涂药器重建宫颈癌的准确性。使用模仿临床涂药器放置和参考点的自制模型。使用三个不锈钢（15°，30°和45°）的光斑，X射线标记和三个参考点来比较基于X射线和CT的系统。对于CT重建，使用了两个Fletcher CT兼容（15°和30°）的双色膜，两个卵形和两个参考点，带有和不带有插入的X射线标记。使用2.5毫米CT切片厚度。为了检查手术中和手术中CT的变化，仅使用了30°串联，没有X射线标记和1.25mm CT切片厚度。对于每个图像集，将施药器重建3次，以验证操作员的可重复性。开出6 Gy剂量，并在AL点标准化。比较源停留时间以检查A点的剂量变化。射线照相和CT重建的最大标准偏差SD（σ）分别为0.35和0.83 mm。对15°和30°色散平均值的方差分析显示无显着差异。列文（Levene）的测试证明15°串联时的差异不大（p值= 0.131），而在30°串联时显示出显着差异（p值= 0.011）。这项幻影研究表明，由于涂药器曲率的增加，两种方法在30°串联时的停留时间差异具有统计学意义。CT证明比射线照相更优越。X射线标记法更准确，但图像质量较差。肿瘤内和肿瘤内的差异显示出良好的一致性。