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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-23 18:06 |
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Conference: Bucharest University Faculty of Physics 2022 Meeting
Section: Biophysics; Medical Physics
Title:
External radiotherapy and afterloading brachytherapy in genital cancers
Authors:
Bianca-Alexandra IORDAN(1), Claudia CHILOM(1), Raducu POPA(2)
Affiliation:
1) Department of Biophysics, Faculty of Physics, University of Bucharest, 405 Atomistilor, Magurele-Ilfov, Romania
2) MedEuropa Bucuresti, Soseaua Dobroiesti, 20A
E-mail
biancaalexandraiordan@gmail.com
Keywords:
external radiotherapy, brahihterapy, treatment plan
Abstract:
There are two types of radiotherapy according to the position of radiation source in relation to the patient body: external radiotherapy, when the radiation source is located outside the patient and internal radiotherapy or brachytherapy, when the radiation source is placed inside the tumor or in direct contact with it. A female patient with a cervix tumor was chosen to underwent the two types of treatment.
In the case of external radiotherapy, the first step is a CT scan to create the treatment plan. The female patient is positioned by restraint systems, armrest, knee bracket and leg brace with bar bracket, mattress for back and sitting. The second step is to center and scan the patient, and the last step is to mark the tattoo spots on her skin. After completing the CT scans, the data are inserted into the Monaco system where the physician outlines the risk organs and the tumor. After contouring the tumor, the physician prescribes the dose, and the medical physicist will prepare the plan according to the indications of the radiotherapist. The CBCT system (CONEBEAM CT) is used which makes a complete rotation around the patient and acquires the CT scan with the actual position of the patient and the treatment position. After this stage, one can start irradiation of the patient with the prescribed treatment.
In the case of afterloading brachytherapy, two or three brachytherapy sessions are performed depending on the doses received by the primary critical organs (rectum, bladder and intestines) in external radiation therapy, but also on the stage of the disease. The cylindrical applicator is mounted to the patient and, for a better view of the bladder, a contrast substance is introduced by means of a urinary catheter. The next step is to move the patient to the CT scanner, in order to scan her and record the images needed to perform the treatment plan. The patient is scanned in the pelvic area so that the vaginal applicator can be fully visualized. The images are transmitted to the Monaco treatment plan system, in order to delimit the target volume and the critical organs. The set of images with the completed contours are sent further to the Oncenta treatment plan system, specially designed for the development of a treatment plan in brachytherapy. After the treatment plan is performed the patient's irradiation can begin.
References:
Radiation Oncology Physics: A Handbook for Teachers and Students E.B. Podgorsak,Technical Editor
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