background: the artificial neural networks (anns) are useful in solving nonlinear processes, without the need for mathematical models of the parameters. since the relationship between the ct numbers and material compositions is not linear, ann can be used for obtaining tissue density and composition. objective: the aim of this study is to utilize ann for determination of the composition and mas...

introduction: in brachytherapy, radioactive sources are placed close to the tumor, therefore, small changes in their positions can cause large changes in the dose distribution. this emphasizes the need for computerized treatment planning. the usual method for treatment planning of cervix brachytherapy uses conventional radiographs in the manchester system. nowadays, because of their advantages ...

In radiotherapy a common method used to compensate for patient setup error and organ motion is to enlarge the clinical target volume (CTV) by a 'margin' to produce a 'planning target volume' (PTV). Using weighted power loss functions as a measure of performance for a treatment plan, a simple method can be developed to calculate the ideal spatial dose distribution (one that minimizes expected lo...

Opioid Substitution Treatment (OST) is a harm reduction strategy enabling opiate consumers to avoid withdrawal symptoms and maintain health and wellbeing. Some research shows that within a disaster context service disruptions and infrastructure damage affect OST services, including problems with accessibility, dosing, and scripts. Currently little is known about planning for OST in the reductio...

introduction: the selection of suitable beam angles and weights in external-beam radiotherapy is at present generally based upon the experience of the planner. therefore, automated selection of beam angles and weights in forward-planned radiotherapy will be beneficial. material and methods: in this work, an efficient method is presented within the matlab environment to investigate how to improv...

introduction radiotherapy with small fields is used widely in newly developed techniques. additionally, dose calculation accuracy of treatment planning systems in small fields plays a crucial role in treatment outcome. in the present study, dose calculation accuracy of two commercial treatment planning systems was evaluated against monte carlo method. materials and methods siemens once or linea...

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