Dosimetric and Radiobiological Evaluation of Combined Radiotherapy of Cervical Cancer Based on the VMAT Technique

A dosimetric and radiobiological investigation of the possibility to replace the traditional combined radiation therapy (3D-CRT + high-dose-rate brachytherapy (HDR-BT)) of cervical cancer with the following combinations, 60Co + VMAT, 3D-CRT + VMAT, and VMAT + VMAT, without change of total course dose and the number of fractions is described. For the investigation, the data of 11 patients with a diagnosis of cervical cancer (stages T2bNxM0 and T3NxM0) who received a course of combined radiotherapy was used. The 3D-CRT + high-dose-rate brachytherapy (HDR-BT) combination of dose delivery techniques was used as the basic one. The following fractionation regimes for combined radiotherapy were simulated: external beam radiation therapy (RT) (EBRT) of the first stage, total dose 50 Gy and fractional dose 2 Gy (25 fractions), and the second stage—total dose 28 Gy and fractional dose 7 Gy (4 fractions). Total combined RT course dose amounted to EQD2 = 89.7 Gy. Simulation results show that there is a technical possibility of replacing the second stage of combined RT of cervical cancer by EBRT based on the VMAT technique. Implementation of the VMAT technique allows increasing the uniformity of irradiated volume coverage compared with traditional high-dose rate. While using the VMAT technique, the tolerant levels of organs at risk are not exceeded

Исследование энергетических характеристик рентгеновской трубки

В настоящей работе приведены результаты исследования энергетических характеристикрентгеновской трубки Xstrahl300 путем моделирования процесса переноса тормозного излучения методом Монте-Карло, на котором основаны алгоритмы расчёта программы PC LAB. Показана возможность оценки распределения поглощенной дозы в различных точках координат водного фантома используя математическую модель. Таким образом, могут быть найдены оптимальные условия эксплуатации рентгеновской трубки в лучевой терапии при различных локализациях. Кроме того, математическая модель рентгеновского излучения способна моделировать ожидаемую эффективность проводимой терапии и относительную биологическую эффективность, используя теоретические модели

Simulation of Coherent Diffraction Radiation Generation by Pico-Second Electron Bunches in an Open Resonator

In this report we present new approach for calculation of processes of diffraction radiation generation, storage and decay in an open resonator based on generalized surface current method. The radiation characteristics calculated using the developed approach were compared with those calculated using Gaussian-Laguerre modes method. The comparison shows reasonable coincidence of the results that allows to use developed method for investigation of more complicated resonators

Study of HeLa Cells Clone Survival after X-ray Irradiation in the Presence of Cisplatin

Radiation therapy in the presence of heavy elements nuclei (Z>53) is widely developed these days. The presence of such nuclei in cancer cells results in the local increase of energy release from primary photon beam thus increasing relative biological efficiency. In this paper we present the preliminary results of the cell survival study while irradiating cells by X-Ray photon beam in the presence of cisplatin (Pt, Z=78). The preliminary results show the decrease of the cell survival in the presence of both radiation and cisplatin

Study of HeLa Cells Clone Survival after X-ray Irradiation in the Presence of Cisplatin

Radiation therapy in the presence of heavy elements nuclei (Z>53) is widely developed these days. The presence of such nuclei in cancer cells results in the local increase of energy release from primary photon beam thus increasing relative biological efficiency. In this paper we present the preliminary results of the cell survival study while irradiating cells by X-Ray photon beam in the presence of cisplatin (Pt, Z=78). The preliminary results show the decrease of the cell survival in the presence of both radiation and cisplatin

Simulation of transition radiation based beam imaging from tilted targets

Transverse beam profile diagnostics in linear electron accelerators is usually based on direct imaging of a beam spot via visible transition radiation. In this case the fundamental resolution limit is determined by radiation diffraction in the optical system. A method to measure beam sizes beyond the diffraction limit is to perform imaging dominated by a single-particle function (SPF), i.e. when the recorded image is dominated not by the transverse beam profile but by the image function of a point source (single electron). Knowledge of the SPF for an experimental setup allows one to extract the transverse beam size from an SPF dominated image. This paper presents an approach that allows one to calculate two-dimensional SPF dominated beam images, taking into account the target inclination angle and the depth-of-field effect. In conclusion, a simple fit function for beam size determination in the case under consideration is proposed and its applicability is tested under various conditions