Factors affecting the geometry variations of surgical clips in radiotherapy after breast-conserving surgery / 中华放射医学与防护杂志

Objective:To investigate the variations and related influencing factors of the volumes, positions, and morphologies of geometries formed by surgical clips in intensity-modulated radiation therapy (IMRT) for whole breasts after breast-conserving surgery.Methods:A retrospective analysis was conducted on 18 patients treated with IMRT from October 2021 to September 2022 after breast-conserving surgery. Set-up errors were obtained by reading the coordinate information of tumor bed surgical clips according to the cone beam CT (CBCT) images at 0, 10, 20, 30, 40, and 50 Gy sequentially. Geometries were constructed using the convex hull program, and the volumes ( Vct and V0-5) of geometries were then calculated based on the localization CT images and the six CBCT images, respectively. The centroid displacements ( D0-5) and degrees of inclusion ( DI0-5) of these geometries were compared. The t-test or rank-sum test was used to analyze the effects of radiation doses on V0-5, D0-5, and DI0-5. The Pearson correlation analysis was conducted to analyze the correlations between D0-5 and corresponding set-up errors in three-dimensional directions, and the correlations of average V0-5 variation ( AV), average D0-5 ( AD), and average DI0-5 ( ADI) with the body mass index (BMI), the volume of a breast ( VB), the breast axial height ( H), and the time interval from surgery to radiotherapy ( T) each. The influences of quadrants ( Q) where geometries are located and states ( S) of geometries adhering to or away from the chest walls on AV, AD, and ADI were analyzed through one-way ANOVA. Results:The differences between D5 and D0, between D5 and D1, and between D5 and D2 were statistically significant ( t = -3.27, -4.52, -3.38, P < 0.05), respectively. The differences between DI5 and DI0, between DI5 and DI1, between DI5 and DI2 were statistically significant ( t = 2.53, 2.70, 2.64, P < 0.05), respectively. D1 and D4 correlated with the set-up errors in the superior-inferior dimension, and D3 correlated with the set-up errors in the left-right dimension ( r = 0.50, 0.56, 0.53, P < 0.05). The AD was related to BMI, VB, and H ( r = 0.54, 0.48, 0.50, P < 0.05). There were statistically significant differences in AV and ADI of geometries away from ( S3) and near ( S2) chest walls ( F = 2.66, 3.83, P < 0.05). The AD differences of geometries between S3 and the state adhering to chest walls ( S1) and between S3 and S2 were statistically significant ( F = 7.46, P < 0.05), respectively. Conclusions:The geometries are relatively constant volumes during whole-breast radiotherapy. However, their positions and morphologies vary greatly in the late course. The volume variation ratios, centroid displacements, and degrees of inclusion of geometries are all affected by the states of their attachments to the chest walls. The centroid displacements correlate with breast morphologies and BMI. The radiotherapy plan modification can be individualized.

Study on Automatic Plan Method for Radiotherapy after Breast-conserving Surgery Based on TiGRT System / 中国医疗器械杂志

To study an automatic plan(AP) method for radiotherapy after breast-conserving surgery based on TiGRT system and and compare with manual plan (MP). The dosimetry parameters of 10 patients and the evaluation of scoring table were analyzed, it was found that the targets dose of AP were better than that of MP, but there was no statistical difference except for CI, The V5, V20 and V30 of affected lungs and whole lungs in AP were lower than all that in MP, the Dmean of hearts was slightly higher than that of MP, but the difference was not statistically significant, the MU of AP was increase by 16.1% compared with MP, the score of AP evaluation was increase by 6.1% compared with MP. So the AP could be programmed and automated while ensuring the quality of the plan, and can be used to design the plans for radiotherapy after breast-conserving surgery.

Dosimetric comparison of TomoDirect and TomoHelical modalities in Tomotherapy system for left-breast cancer radiotherapy after breast-conserving surgery / 中华放射医学与防护杂志

Objective To compare the dosimetric difference among plans designed by 4-field,6-field TomoDirect and TomoHelical techniques in Tomotherapy system for left-breast cancer patients with radiotherapy after breast-conserving surgery.Method A total of 16 patients with left-breast cancer following breast-conserving surgery and intensity-modulated radiation therapy were enrolled in this retrospective study.The 4-field TomoDirect (TD4),6-field TomoDirect (TD6),and TomoHelical (TH) techniques were applied to design simulation plans in tomotherapy system for each patient,respectively.The differences of dose distribution and treatment parameters were analyzed in this study.Results Three plans all met the clinical requirement.Thereinto,TD4 was superior to TH in the dose limitation of organs at risk (OARs),especially the max dose of cord and right-breast,thc 5 Gy radiation volume of lung,and the mean dose of heart(F =595.60,129.24,60.44,65.37,P ＜ 0.05),but inferior to TH in dose homogeneity (HI) and conformity (CI) (F =2.78,60.93,P ＜ 0.05).However,TD6 improved TD4's HI and CI when delivered the lower OARs dose compared to TH.Meanwhile,the number of monitor units was less in TD technique and reduced the treatment times (F =24.89,3.75,P ＜ O.05).Conclusions For the radiotherapy of left-breast cancer patients after breast-conserving surgery,TD6 technique appeared to be superior,with the lower radiation dose of OARs compared to TH technique,and the better target's HI and CI in comparison with TD4 technique,especially in patients with early stage breast cancer.