Investigation of the dosimetric characteristics of intra-operative radiatherapy (iort) system with monte carlo simulation (mc) method

Intraoperatif radyoterapi (IORT), elektron ya da foton ışınları kullanılarak cerrahi prosedür sırasında tümör yatağına doğrudan radyasyon dozu verilmesi işlemidir. Monte Carlo benzetim yöntemi, deterministik hesaplamaların aksine, stokastik bir çözüm sunan ve rastgele üretilen sayılar sayesinde gerçeğe en uygun sonuçlar verebilen bir hesaplama yöntemidir. Radyasyonun doğası ile uyuşan bu yöntem, doz hesaplamalarında Dünya genelinde altın standart olarak kabul edilmektedir. Bu çalışmanın amacı IORT'nin dozimetrik performansını araştırmak, güvenirliğini doğrulamak ve klinik uygulamalardaki avantajlarını ve dezavantajlarını araştırmaktır. Bu çalışmada Carl Zeiss Meditec AG'den edinilen veriler ve cihaz kılavuzları kullanılarak MCNP5 (Monte Carlo N-Particle Ver.5) simülasyon kodu ile Intrabeam cihazının probunun ve farklı yarıçaplardaki küresel aplikatörlerin modellemesi yapılmıştır. Monte Carlo simülasyonu ile elde edilen sonuçlar, Carl Zeiss Meditec AG tarafından gönderilen iyon odası ile ölçülmüş sistem verileriyle karşılaştırılmıştır. Buna göre, simülasyon ve ölçümler arasındaki fark PDDprobe, PDD5cmAPP, PDD4cmAPP ve PDD3cmAPP için sırasıyla <%4, <%3.2, <%2.1 ve <%1.05 şeklindedir. Monte Carlo simülasyon sonuçları ile sisteme girilmiş dozimetrik datalar karşılaştırıldığında maksimum farkın %5'in altında olduğu görülmüş ve literatür ile uyum sağladığı saptanmıştır.Intraoperative Radiotherapy (IORT) is the process of directly irradiating the tumor bed during surgery using electron or photon beams. The Monte Carlo simulation method is a computational method, unlike deterministic calculations, provides a stochastic solution and gives the most accurate results using randomly generated numbers. This method, compatible with the nature of the radiation, is accepted as the gold standard in the world at dose calculations. The aim of this study is to investigate the dosimetric performance and reliability of IORT, to analyze its advantages and disadvantages in clinical practice. In this study, probes of the Intrabeam device and spherical applicators of different radii were modelled with MCNP5 (Monte Carlo NParticle Ver.5) simulation code using the data and device manuals obtained from Carl Zeiss Meditec AG. Monte Carlo simulation results were compared with ion chamber measurements. Accordingly, the difference between Monte Carlo simulation results and measurements are less than 4%, 3.2%, 2.1% and 1.05% for PDDprobe, PDD5cmAPP, PDD4cmAPP and PDD3cmAPP, respectively. Monte Carlo simulation results uncertainty was less than 5%. The results of this study are compatible with literature

The Effect of Dose Enhancement in Tumor With Silver Nanoparticles on Surrounding Healthy Tissues: A Monte Carlo Study

Objectives: Cancer-related death rates account for approximately one-third of all deaths, and this rate is increasing remarkably every year. In this study, we examined the dose enhancement factor (DEF) in the tumor and surrounding tissues by adding different concentrations of silver nanoparticles (AgNPs) to the brain tumor using the Monte Carlo (MC) technique. Methods: This study used MCNP6.2 simulation software. A Planning Target Volume (PTV) of 1 × 1 × 1 cm 3 was placed in the center of a cubic cranial model with dimensions of 5 × 5 × 5 cm 3 . Five different simulations were initially generated using the simple method. These simulations included pure PTV and PTV consisting of 4 different silver concentrations (5, 10, 20, and 30 mg/g). Additionally, a model was created using the nanolattice method, considering the size, position, and distribution of the AgNPs. Irradiation was performed using a source with a 6 MV linac photon spectrum. Measurements were performed using the *f8 tally, and DEF values were calculated. Results: In the simulation study using the simple method, the DEF value of PTV increased linearly with concentration, whereas the DEF values were lower than the simulation results with the nanolattice model (1.9 vs 1.4 for 30 mg/g NP concentration). Performing the simple method, we observed no remarkable dose increase in lateral OARs surrounding PTV. While a remarkable dose decrease was observed in distal OARs, a dose increase in the proximal OAR was observed, which was consistent with that of PTV. However, according to the results obtained by performing the nanolattice method, the dose increase was observed in both the proximal OAR and the distal OAR and was similar to that of PTV. Conclusion: While enhancing the dose in the tumor by adding NPs into the tumor, it is essential to consider whether it also increases the OAR dose. In addition, simulation studies on NPs showed that the dose increase varied significantly with particle size, position, and distribution. Hence, these factors should be considered carefully

Investigation of the accuracy of different lung SBRT plans created in multiplan treatment planning system

...American Association of Physicists in Medicin

Investigation of the accuracy of different lung SBRT plans created in eclipse treatment planning system

59th Annual Meeting and Exhibition of the American-Association-of-Physicists-in-Medicine (AAPM) -- JUL 30-AUG 03, 2017 -- Denver, COWOS: 000426452601254…American Association of Physicists in Medicin