Kotno občutljiva kamera gama s scintilacijskim detektorjem za lokalizacijo vira v brahiterapiji

Črnič, Boštjan (author), Lipoglavšek, Matej (mentor), Vencelj, Matjaž (comentor)

V sodobni medicini uporabljamo za zdravljenje rakastih obolenj vire ionizirajočega sevanja. S skupnim imenom pravimo takšnim medicinskim terapevtskim metodam radioterapija. Brahiradioterapija ali krajše brahiterapija je vrsta radioterapije, pri kateri enega ali več radioaktivnih virov (običajno virov žarkov gama) namestimo v neposredno bližino rakastega tkiva ali v samo rakasto tkivo. Zaradi visokih hitrosti doze na mestu, kjer se nahaja vir, je pomembno, da je položaj vira čim bolj pravilen, saj že majhen odmik vira od pravilne lege lahko pomeni veliko prejeto dozo v zdravem tkivu v bližini rakastega tkiva, po drugi strani pa premajhno prejeto dozo v rakastem tkivu. Vprašanje, ki ga je v klinični praksi potrebno rešiti, je, kako pri brahiterapiji neinvazivno slediti viru v pacientu in s tem preveriti pravilnost obsevanja pacienta oziroma izboljšati zagotavljanje kakovosti obsevanja. Če bi zdravniki med obsevanjem lahko sledili viru, bi lažje odkrili morebitne nepravilnosti pri legi vira in bi zdravljenje prilagodili, s tem pa zmanjšali neželene posledice nepravilnosti med obsevanjem. V okviru magistrskega dela sem najprej pregledal različne vrste kamer gama in njihovo uporabo, podrobneje pa sem opisal kotno občutljive kamere gama. Nato sem opisal idejno zasnovo sistema za sledenje viru med brahiterapijo ter pot do izdelave prototipa takšne kamere gama s scintilacijskim detektorjem in preprosto svinčeno zaslonko, s katero lahko na preprost in neinvaziven način med obsevanjem sledimo radioaktivnemu viru. Vpeljal sem tudi parameter kakovosti kamere gama ^, s katerim opišemo kotno ločljivost kamere gama.

• Language: Slovenian
• Keywords: kamera gama, vpadni kot, brahiterapija
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FMF - Faculty of Mathematics and Physics
• Year: 2021
• PID: 20.500.12556/RUL-124830
• COBISS.SI-ID: 52202499
• Publication date in RUL: 21.02.2021

Secondary language

• Language: English
• Title: An Angle-Sensitive Gamma Camera with Scintillation Detector for Source Localization in Brachytherapy

Abstract

In contemporary medicine, sources of ionizing radiation are applied in therapeutic use for cancer treatment. The common name for different therapies utilizing ionizing radiation is radiation therapy or radiotherapy. Brachyradiotherapy, also brachytherapy, is a type of radiotherapy where one or more radiation sources (usually gamma ray sources) are placed inside or next to the cancerous tissue. Due to the high dose rates at the point where the source is located, a safe and accurate implantation of the source into the affected tissue is required. Even a small deviation of the source from the planned position can cause a large dose received in a healthy tissue or organ near the cancerous tissue or the effect of the radiation dose on the target cancerous tissue is diminished. The question that needs to be answered in a clinical practice is how to track the source movement during the implantation into the patient's tissue in a non-invasive way. If the position of the source in the body is determined precisely enough, we can estimate the radiation dose more accurately and consequently improve the quality of radiation treatment of the patients. If doctors could track the position of the source during the procedure, it would be easier for them to detect possible errors in the position of the source and they could adjust the treatment of the patient in a way to reduce the radiation side effect. In the introduction of my master’s thesis I reviewed different types of gamma cameras used in brachytherapy. I paid special attention to the angle-sensitive gamma cameras. In the next chapter I described the conceptual design of a source tracking system for brachytherapy procedure and a stepwise roadmap to construct a prototype. The source tracking system is based on a gamma camera with a scintillation detector and a simple lead aperture that can easily and non-invasively track a radioactive source during implantation. To assess the measurement results using the prototype I devised a gamma camera quality parameter K, which describes the angular resolution of the gamma camera.

• Keywords: gamma camera, angle of incidence, brachytherapy