Design Of Adaptive Control System For Real Time Collimator In Co -60 Radiation Therapy Machine

Abstract

Radiotherapy is concerned as important method for cancer tumor deices treatment ,using Cobalt -60 me chain . But respiration (Inhalation and Expiration) makes the abdomen or a chest expand and contract which cause the organ displace partially away from the field size boundary area , while the collimator diaphragm is fixed adjusted manually to the tumor volume, this results in two problems , one of them is critical healthy tosses that surrounding the tumor area will receive unwanted radiation dose which cause bad effect on this healthy tosses (will damage) .The other problem , represented on some tosses of the treated area displace away out of the radiation field which lead to un sufficient dose , thus the treat will not be totally completed to this part which displaced away from the field size, then cancer will recurring again . So , for solving the problem of organs motion , so many researchers attempts to overcome the problem of organ motion in radiotherapy , but not succeed totally , so in this thesis there is attempt ion to design an electronic control system to translate the mechanical abdomen and chest movement into an electrical signal , then supplied to the collimator diaphragm after the collimator been manually adjusted to the tumor volume to make it open and close partially according to the organ motion on real time . Some studies done in the electronic components , their specifications ,types ,manners ,behaviors and values , some of components selected carefully to represent the constructed designed an adaptive control system , then connected using a certain design and then simulation design has been run which gives accepted results linearly ,such as pressure against voltage , also voltage against displacement and also the motor direction of rotation clockwise or anti clockwise in really time .