In radiotherapy applications, limiting the rays to the target area is very decisive in reducing the side effects. For this reason, the tissues around the target are protected from the rays or are exposed to radiation at permissible tolerance doses. Care must be taken not to miss the target during planning and implementation. Changes in patient position, possible changes in therapy devices, or daily differences such as respiratory circulation or full-empty organs can lead to changes in the treated volume. Therefore, variable factors are tried to be limited. It also adds a safety margin around it to accurately teleport the target every day.
During the treatment, special fixation devices and some fixation materials are used in order to keep the body stable and to provide accurate treatment in the same position every day. Generally, masks are used in the brain, head and neck region, and special fixation beds and materials are used in breast, lung, breast, abdomen and limb tumors. These materials are applied to the patient in each treatment and the patient’s position is kept in the same condition throughout the treatment.
The cooperation of the patient is very important and necessary in the correct treatment. In some abdominal tumors such as prostate cancer, treatment every day when the large intestine is empty and the bladder is close to fullness reduces set-up errors and helps organ protection. In lung and breast cancers, sometimes respiratory-controlled therapy can provide better organ protection. Compliance of the patients facilitates the treatment process and reduces the development of long-term side effects.
Medical imaging procedures such as positron emission tomography and magnetic resonance imaging help to identify the target accurately and precisely. During treatment planning, computed tomography images are taken for planning purposes, together with the fixation materials used, in the treatment set-up position. Then, target definition is made by overlaying these images with positron emission tomography and/or magnetic resonance images. The target to be irradiated on each cross-section of the images for planning purposes and the organs to be protected are determined by the physician. Then, Medical Radiation Physics Specialists prepare the plans that obtain the sufficient dose at the target by placing the beam fields, making alternative plans, preserving the healthy tissues in the best way. Among these plans, the best plan is chosen for treatment.
Radiotherapy process is applied by Radiotherapy Technicians who are experts in their fields who have received higher education. In each treatment, it is ensured that the patient’s position is as it was done during planning. For this purpose, pre-treatment radiological imaging is performed, set-up verification is performed within millimeters and treatment is applied. During the treatment, the patient’s body weight increase, decrease, tissue and organ changes can be closely monitored and changes can be made when necessary. For this reason, it is necessary to closely monitor the patient by his physician and technicians. Special reference marks can be placed on the patient’s skin to facilitate daily set-up verification.