Dosimetric comparison of graphical optimization and inverse planning simulated annealing for brachytherapy of cervical cancer

Abstract

Purpose: Graphical optimization (GO) and inverse planning simulated annealing (IPSA) are the main treatment planning optimization techniques used in patients undergoing 3D brachytherapy treatment. This study aims to compare the dosimetric difference of plans optimized by GO and IPSA in cervical cancer brachytherapy. Material and methods: 21 cervical cancer patients data sets consisted of computed tomography (CT) and magnetic resonance imaging (MRI), acquired with the Fletcher applicator in situ were transferred to the Oncentra brachytherapy planning system. For each patient, the treatment plan was initially optimized with GO to reach a maximal D 90 tumor dose (6 Gy/fraction, 5 fractions), while keeping the dose to organs at risk (OARs) as low as possible. A second plan was then optimized with IPSA on the same CT images and data set (i.e., contours, catheters, and location of dwell points). Targets and OARs dose volume histograms and irradiation time were compared; data were analyzed with paired t-test; p value < 0.05 was considered statistically significant. Results: The plans with both optimizations meet the clinical requirements. The mean D 90 of the clinical target volume was comparable for GO and IPSA. Similar values (p > 0.05) of target V 100 , V 150 , V 200 , HI, and CI were registered for GO and IPSA optimizations. Bladder and rectum D 1cc and D 2cc obtained by GO resulted in larger values than those obtained by IPSA (p = 0.002). V 75 for bladder and rectum were slightly higher for IPSA, but without statistical difference (p > 0.05). The irradiation time was comparable (p > 0.05). Conclusions: In 3D brachytherapy of cervical cancer, GO and IPSA optimizations do not present a significant difference in target dose coverage; nevertheless, IPSA may reduce the maximum dose to normal tissue when compared with GO.

Evaluation of rectal volume correlation with dosimetric parameters during optimized intracavitary high-dose-rate brachytherapy in cervical cancer

“…Target values of D 90 , V 100 , V 150 , and V 200 were comparable in these two planning methods (p > 0.05). Although, D 2cc and D 1cc of rectum and bladder were significantly lower in the IPSA method [19].…”

Optimizing the IPSA Conditions to Improve the Treatment Plan Quality in Brachytherapy for Cervical Cancer

“…In the practical application of clinical IPSA, group three is most commonly used as the standard, which can meet the dosage requirements of most cases. e idea for this study began with an article reporting that the IPSA plan system was significantly superior to GO [10]. GO often requires more skilled physicists and even removed the especial dwell points of radioactive source to optimize the plan [19].…”

“…In general, IPSA significantly increased target coverage, reduced dose to OARs, and shortened planning time compared to GO. In clinical practice, the conditions of IPSA routinely used by different hospitals and physicists are not uniform and differ greatly [10,11]. In this study, we compared the influence of four IPSA conditions on 3D brachytherapy plan, promoting the more rational application of IPSA in clinics.…”

Dosimetric Comparison of Inverse Planning Simulated Annealing and Manual Optimization for Intracavitary Cervix Brachytherapy

“…In our current study, while a dose of 700 cGy was prescribed to the target volume, the superiority of the IPSA technique was found in the rectum and bladder doses. In addition, the IPSA technique was found to be superior in terms of active irradiation and treatment planning time (22).…”