One of the main factors affecting the effectiveness of radiation therapy is the constancy of the patient’s position on the treatment table created by immobilization devices of various designs and held throughout the entire irradiation procedure, which guarantees the accuracy of the delivery of the prescribed dose distribution. The purpose of the work was to establish the numerical values of the dominant components of a radiation therapy session for each of the irradiation techniques most commonly used in clinical practice of the radiation therapy.To determine the numerical values of the components of the radiation therapy session, the authors have measured each component for some clinical cases of patients’ irradiation placed. The patients had been diagnosed with the following malignant tumours: prostate cancer, breast cancer, lung cancer, head and neck tumours. More than 2000 individual measurements have been carried out with the help of such medical linear accelerators as "Clinac", "Unique", "Truebeam", and the gamma-therapeutic apparatus named "Theratron".The numerical values of the time spent on 3 groups of parameters of an irradiation session were established: the mechanical parameters of the radiation therapy equipment, the functional characteristics of the irradiation systems and the parameters that directly depend on the personnel involved in an irradiation procedure.According to the measurement results, the flow diagram for the procedures of verifying a patient’s position on the therapeutic table (2 different techniques), preceding their irradiation and the radiation therapy procedures themselves was proposed. It has been shown that a number of session components can run in parallel to each other thus optimizing the time spent by a patient in the treatment room.Using the obtained values of the time spent on the radiation session parameters it is possible to actualize the mathematical model that will allow the medical physicist to determine in advance the duration of the irradiation session at the stage of treatment planning and choose a radiation therapy technique taking into account the individual parameters of the irradiation session in each particular clinical case.
Ацетилирование araG 19 уксусным ангидридом в ацетонитриле, в присутствии триэтиламина и диметиламинопиридина в качестве катализаторов давало триацетат 20, который выделяли в кристаллическом состоянии с выходом 90%. Обработка триацетата 20 хлорокисью фосфора в ацетонитриле в присутствии бензилтриэтиламмоний хлористого при 100-110°С и последующая стандартная обработка реакционной смеси (нейтрализация и обработка смесью хлороформ-вода) приводили к 6-хлорпроизводному ( 21), которое без дополнительной очистки дезацетилировали действием раствора карбоната калия в метаноле при 50-60°С. Последующая обработка реакционной смеси ионообменной смолой Дауэкс 50х8 (Н + -форма) и активированным углём приводили к дезацетилированному 6-хлорпроизводному ( 22) в виде аморфного порошка. Действием раствора метилата натрия в метаноле на хлорпроизводное 22 получали неларабин 3, который выделяли колоночной хроматографией на силикагеле и последующей перекристаллизацией из воды с суммарным выходом 50% в расчёте на исходный araG.Структура синтезированного неларабина подтверждена данными УФ-и ЯМР-спектроскопии, массспектрометрии и сравнением с образцом неларабина.Разработанный химический метод синтеза получения неларабина не требует выделения промежуточных продуктов реакции в чистом виде, что упрощает процесс синтеза и позволяет получать продукт в препаративных количествах. ЛИТЕРАТУРА 1. 6-Methoxypurine arabinoside as a selective and potent inhibitors of varicella-zoster virus / D. V. Averett [et al.] // Antimicrob.
A typical process for verification of treatment plans in radiation therapy with intensity modulation is described. The simplest way to compare dose distributions, i.e., superposition of contours of dose distributions on top of each other, is considered, its advantages and disadvantages are given. The main measurement geometries used in clinical practice for dosimetric verification of irradiation plans are described. The term “gamma analysis” is defined, as well as the gamma analysis criteria - dose difference, distance criterion, degree of comparison by the gamma index. The values of the gamma analysis criteria used in domestic clinics and abroad are given.
The presented work reviews the methodology for calculating stationary radiation protection used in the Republic of Belarus. The calculation of stationary radiation protection from direct and scattered photon radiation, as well as, if necessary, from direct and scattered neutron radiation is described. The methodology is written in accordance with the Sanitary Rules and Regulations 2.6.12-34-2006.
For the correct application of high-tech methods of radiation therapy, it is necessary to use strict requirements for the technical and dosimetric parameters of radiotherapy equipment, the accuracy of adjustment and calibration of its geometric, mechanical and radiation parameters. To determine the values of possible errors in patient positioning during radiation treatment, the authors considered the design and characteristics of typical RTS, developed a model of the patient’s «average» body, which allows changing the load on the TP RTS with a step of 1 kg. The parameters of the TP position were determined for the main types of localizations of radiation therapy for malignant neoplasms. Numerical values of deviations of the radiation beam isocenter from the treatment couch prescribed horizontal position were experimentally established for a load on it from 40 to 180 kg for treatment couch used for patients’ treatments in N.N. Alexandrov National Cancer Centre of Belarus.
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