Design of a drum-shaped applicator through Monte Carlo simulation for breast intraoperative radiotherapy / 中华放射肿瘤学杂志

Objective:To design a drum-shaped applicator through Monte Carlo simulation for breast intraoperative radiotherapy.Methods:Applicator designing process is as follows: first, determined the shape of the applicator based on the geometric characteristics of the breast tumor bed closed to the chest wall; second, calculated the scattering angle and dose rate of the electron beam after passing through a series of scattering foils of different thicknesses to determine the thickness of the scattering foil; thrid, modeled the layer according to the applicator′s geometric characteristics where modulator located, and designed the modulator through the relationship between the geometric characteristics of the layer and the surface dose of the applicator. EGSnrc/BEAMnrc and EGS4/DOSXYZ were employed to model the head of the Mobetron, the layer, the applicator, and to calculate the dose distributions.Results:The applicator has two components. The upper component is a 3cm-diametre cylindrical collimator with 0.5cm wall made of 0.3cm steel and 0.2cm water equivalent material (WEM), a 0.13cm-foil made of tansgen. The lower component is a 4cm-diametre drum made of 0.2cm WEM and a 0.14cm maximum thickness hill-shaped modulator made of steel. When the energy of electron beam was 12MeV, the dose rate was about 90.44 cGy/min, and the depth of the 50% isodose curve was 1cm.Conclusion:The applicator is successfully designed, and can obtain a drum-shaped dose distribution.

Research progress in intraoperative radiotherapy for tumor / 中华放射肿瘤学杂志

Intraoperative radiotherapy (IORT) is a radiotherapy method that uses a radiotherapy device to provide a brachytherapy with single high-dose radiation to a target tissue (primary tumor beds,residual tumors,and lymphatic drainage areas) during surgery,which includes intraoperative electron beam radiotherapy and high-dose-rate intraluminal brachytherapy.Nowadays,the implementation of precise radiation dose is an important part of multidisciplinary,individualized treatment of tumors.IORT achieves precise treatment by maximizing the radiation dose to the target volume and protecting surrounding normal tissues as much as possible.This article describes the recent research on IORT.

Clinical effect of intraoperative electron beam radiotherapy in treatment of unresectable locally advanced pancreatic cancer / 中华放射肿瘤学杂志

Objective To assess the prognostic benefits of intraoperative radiotherapy (IORT) with electron beam among patients with unresectable locally advanced pancreatic cancer.Methods Between January 2009 and December 2014,167 patients with unresectable locally advanced pancreatic cancer received IORT with electron beam (10-20 Gy) in our hospital.After surgery,12 patients were treated with external beam radiotherapy,56 patients with chemoradiotherapy (CRT),and 17 patients with chemotherapy.Overall survival (OS),local recurrence,and toxicities were retrospectively analyzed.The Kaplan-Meier method was used to calculate survival rates,the log-rank test was used for survival difference analysis and univariate prognostic analysis,and the Cox model was used for multivariate prognostic analysis.Results The follow-up rate was 100％.The median OS time was 10.3 months,and the 2-year OS rate was 22％.The median progression-fiee survival (PFS) time was 6.3 months,and the 2-year PFS rate was 9.9％.The cancer-specific survival (CSS) time was 11.2 months,and the 2-year CSS rate was 23.6％.In the patients treated with IORT alone at doses of＜15 Gy,15 Gy and＞15 Gy,the median OS times were 6.2 months vs.9.1 months vs.22.2 months,and the 1-year OS rates were 10.0％ vs.39.6％ vs.74.4％ (P=0.000).Among the patients receiving postoperative adjuvant therapy,those treated with IORT+CRT had the best survival,with a median OS time of 11.6 months (P=0.033).The univariate analysis showed that IORT dose (P =0.000),tumor size (P =0.006),and IORT applicator diameter (P =0.007) were prognostic factors.The multivariate analysis showed that IORT dose (P=0.000) and IORT combined with CRT (P=0.006) were independent prognostic factors.Conclusions IORT with electron beam is an effective and safe treatment strategy for unresectable locally advanced pancreatic cancer.After protecting surrounding organs,increasing the IORT dose can improve the survival.IORT combined with CRT should be recommended because it improves survival for unresectable locally advanced pancreatic cancer without increasing toxicities.

Safety and feasibility of low?energy X?ray radiotherapy in breast conserving surgery for early?stage breast cancer / 中华放射肿瘤学杂志

Objective To investigate the short?term complications and cosmetic outcomes of radiotherapy in breast conserving surgery for early?stage breast cancer. Methods A retrospective analysis was performed on clinical data from 30 patients with early?stage breast cancer from 2013 to 2015. All patients underwent breast conserving surgery combined with intraoperative low?energy X?ray radiotherapy. The prescribed dose was 20 Gy at the surface of the applicator. Local complications, radiation injury, and cosmetic outcomes were observed after surgery. Results No grade 3?4 adverse reactions were found in patients. In terms of short?term complications, four patients (13%) had seroma, two of whom needed suction treatment;three patients ( 10%) had grade 1?2 skin erythema. Half of the patients had excellent cosmetic outcomes. None of the patients had local recurrence or distant metastasis. Conclusions Intraoperative low?energy X?ray radiotherapy is safe and feasible in breast conserving surgery for breast cancer. It can be considered as an optional approach for tumor bed boost in some patients with early?stage low?risk breast cancer.