An Innovative Tool for Intraoperative Electron Beam Radiotherapy Simulation and Planning: Description and Initial Evaluation by Radiation Oncologists

Abstract

SummaryThe lack of specific treatment planning tools limits the spread of Intraoperative Electron Radiation Therapy. An innovative simulation and planning tool is presented. Applicator positioning, isodose curves, and dose volume histograms can be estimated for previously segmented regions to treat/protect. Evaluation by three radiation oncologists on 15 patients showed high parameter agreement in nine cases, demonstrating the possibilities in cases involving different anatomical locations, and Purpose: Intraoperative electron beam radiation therapy (IOERT) involves a modified strategy of conventional radiation therapy and surgery. The lack of specific planning tools limits the spread of this technique. The purpose of the present study is to describe a new simulation and planning tool and its initial evaluation by clinical users. Methods and Materials: The tool works on a preoperative computed tomography scan. A physi cian contours regions to be treated and protected and simulates applicator positioning, calcu lating isodoses and the corresponding doseevolume histograms depending on the selected electron energy. Three radiation oncologists evaluated data from 15 IOERT patients, including different tumor locations. Segmentation masks, applicator positions, and treatment parameters were compared. Results: High parameter agreement was found in the following cases: three breast and three rectal cancer, retroperitoneal sarcoma, and rectal and ovary monotopic recurrences. All radiation oncologists performed similar segmentations of tumors and high risk areas. The average appli cator position difference was 1.2 AE 0.95 cm. The remaining cancer sites showed higher devia tions because of differences in the criteria for segmenting high risk areas (one rectal, one pancreas) and different surgical access simulated (two rectal, one Ewing sarcoma). Conclusions:The results show that this new tool can be used to simulate IOERT cases involving different anatomic locations, and that preplanning has to be carried out with specialized surgical input.

In vivodosimetry using Gafchromic films during pelvic intraoperative electron radiation therapy (IOERT)

“…A dedicated treatment-planning software was developed for IOERT; however, its use requires a CT scan of the patient. 1 This is a limitation, because pre-operative CT scans do not take into account modifications of the patient anatomy during surgery. Furthermore, intraoperative CT scans of individual patients are unfeasible in most treatments.…”

Image-guided intraoperative radiation therapy: current developments and future perspectives

“…Therefore, IOERT planning needs to incorporate tools for both surgical simulation and radiation dose distribution estimation. The complexity of the required approach had limited the availability of such IOERT planning systems until recently [8].…”

“…Although all these developments have improved the protocols for IOERT, it is also clear that there is one important area that remains unsolved with the solution presented [8]: accurate reporting of both the real patient's anatomy and the final position details of all treatment elements. The physicians may have simulated the IOERT procedure in advance, but how do they know if the real treatment matches the preoperative simulation?…”

Towards a Guidance System to Aid in the Dosimetry Calculation of Intraoperative Electron Radiation Therapy

“…A multidisciplinary group of surgeons, anesthetists, medical physicists, radiation oncologists (ROs), and technical and nursing staff have to be involved. However, treatment planning has not been available in IOERT up to now [2]. In the current clinical practice, all necessary parameters, such as the applicator diameter, bevel angle, position, and electron beam energy, are decided by the RO in real-time, with high dependence on the accumulated expertise [3].…”