الفهرس 
chapter 1Only 14 pages are availabe for public view
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Abstract
The Aim of radiotherapy is homogeneous dose in the target volume (Tumour)
and Optimal sparing of the surrounding normal tissues. The daily set-up errors
are the major problem that face the patient during the treatment. The uncertainties
in the daily set-up of the Prostate cancer patients during the treatment can give
rise to the complications the results of the treatment. Those Set-up errors
(uncertainties) can be reduced by repositioning of the patient according to the setup
verification. According to this, protocol for repositioning of the patients is
chosen. on which re positioning that yields the lowest radiation dose to the organs
at risk (OAR), and thereby less side effects to patients.
The purpose of this work was the determination of the set-up errors for Prostate
cancer patients and investigation of the dose distribution and dose-volume
variations of planning target volume (PTV) and organ at risks (OARs). The
electronic portal imaging device (EPID) is used as tool to verify the patient
treatment positioning. This could be done by the means of identifying and
correcting the field displacements in patient’s setups which requires accurate
patient positioning with reference to the initial three-dimension conformal
Abstract
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radiotherapy (3DCRT). Patient setup is controlled by comparing the Digitally
reconstructed radiographs (DRR) with portal images acquired immediately
before patient treatment.
It is generally accepted that two classes of set-up uncertainties identified by Σ setup
and Random setup errors σ setup. A study on 15th prostate cancer patients using
Varian Linear accelerator model DMX to treat and portal image device Si500
shall be used to evaluate the selected portal images taken for each patient.
In this study comparison has been made between previous publish work and new
approach. The margins which are calculated according to ICRU Report 62 that is
suggested as an optimum margin for target volume coverage which is <3 mm in
all three directions. And indicate the effect of set-up errors on the dose
distribution and dose volume histogram (DVH) has been determined by
calculating the dose distribution and dose volume histogram (DVH) of PTV and
OARs of actual treatment plan and treatment plan with setup errors correction.