Analiza ponovnih priprav pri raku glave in vratu na obsevalnem aparatu Halcyon 3.0 (Varian) : diplomsko delo

Pogorevčnik, Lea (author), Robida, Anja (author), Žager Marciuš, Valerija (mentor), Majger, Martina (co-mentor), Mekiš, Nejc (reviewer)

Uvod: Radioterapija predstavlja pomembno vlogo pri zdravljenju bolnikov z rakom glave in vratu. Med obsevanjem se lahko pri bolnikih pojavijo anatomske spremembe, ki lahko privedejo do premajhnega odmerka doze na tarčni volumen in prevelikega odmerka doze na kritične organe. V primeru prevelikih odstopanj je pomembno, da se naredi ponovna priprava bolnika na obsevanje na računalniško tomografskem (CT) simulatorju. Namen: Z raziskavo smo želeli ugotoviti, koliko je bilo ponovnih priprav pri bolnikih z rakom glave in vratu na aparatu Halcyon 3.0 (Varian), zakaj je do njih prišlo in pri kateri frakciji so se pojavile. Prav tako je namen preveriti, ali z uporabo geometrične verifikacije s kilovoltno (kV) računalniško tomografijo s stožčastim snopom (CBCT) odkrijemo več primerov za ponovno pripravo kot na Unique Performance Edition (Varian), kjer se uporablja MV slikovna verifikacija z uporabo sistema za elektronsko portalno slikanje (EPID). Metode dela: Retrospektivno raziskavo smo izvedli na Onkološkem Inštitutu v Ljubljani na oddelku za teleradioterapijo. Pregledali smo podatke bolnikov z rakom glave in vratu, ki so bili od novembra 2020 do marca 2022 obsevani na obsevalnem aparatu Halcyon 3.0 (Varian). Na podlagi podatkov smo raziskali, koliko je bilo ponovnih priprav na obsevanje, pri kateri frakciji so se pojavile in zakaj je do njih prišlo ter izvedli primerjavo med dvema različnima geometričnima verifikacijama na obeh aparatih. Rezultati: Od 203 bolnikov na Halcyon 3.0 (Varian) je bila pri 30 bolnikih (15%) izvedena ponovna priprava na obsevanje na CT simulatorju. Rezultati so pokazali, da je najpogostejši vzrok za to izguba telesne teže med obsevanjem (30 %). Ponovna priprava je bila najpogosteje izvedena že pred/po 1. frakciji in pri 2.-5. frakciji zaradi neujemanja položaja hrbtenice, zmanjšanja tumorja ali pa bolnik ni mogel zdržati pod fiksacijsko masko. Razprava in zaključek: Anatomske spremembe, ki se pojavijo med obsevanjem bolnikov z rakom glave in vratu, so najpogosteje posledica izgube telesne teže. Za prepoznavo anatomskih sprememb in zagotavljanja natančnega obsevanja se je geometrična verifikacija kV CBCT izkazala za bolj učinkovito v primerjavi z MV EPID sistemom. Za nadaljnjo raziskovanje bi bilo priporočljivo izvesti še primerjavo med obema geometričnima verifikacijama za različne vrste rakov

• Language: Slovenian
• Keywords: diplomska dela, radiološka tehnologija, radioterapija, verifikacija, obsevalne tehnike, rak glave in vratu, ponovna priprava, anatomske spremembe
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: ZF - Faculty of Health Sciences
• Place of publishing: Ljubljana
• Publisher: [L. Pogorevčnik ; A. Robida]
• Year: 2022
• Number of pages: 32 str., [3] str. pril.
• PID: 20.500.12556/RUL-139394
• UDC: 616-07
• COBISS.SI-ID: 120487171
• Publication date in RUL: 02.09.2022

Secondary language

• Language: English
• Title: Analysis of repeated patient CT simulations for head and neck cancer on linear accelerator Halcyon 3.0 (Varian) : diploma work

Abstract

Introduction: Radiotherapy plays an important role in the treatment of patients with head and neck cancer. During irradiation, some anatomical changes can occur leading to underdose on the target and overdose on critical organs. In case of excessive deviations, it is important to make repeated patient computed tomography (CT) simulations. Purpose: The purpose of the diploma work was to analyze, how many repeated patient CT simulations for head and neck cancer on linear accelerator Halcyon 3.0 (Varian) there were, why they occurred, and in which fraction they appeared. We also wanted to research, whether we can discover more repeated patient CT simulations using geometric verification with kilovolt (kV) cone beam CT (CBCT) or with MV imaging verification using electronic portal imaging (EPID) on Unique Performance Edition (Varian). Methods: Retrospective research was conducted at the Institute of Oncology Ljubljana at the Department of Teleradiotherapy. We reviewed the data of patients with head and neck cancer from November 2020 till March 2022, who were irradiated on Halcyon 3.0 (Varian). Based on the data, we performed an analysis of how many repeated patient CT simulations there were, why they occurred, and in which fraction they appeared and made a comparison between two different geometric verifications on each of the linear accelerators. Results: Of the 203 patients on Halcyon 3.0 (Varian), 30 patients (15%) underwent repeated patient CT simulations. The results showed that the most common reason for that was weight loss during irradiation (30%). Repeated patient CT simulations were most often performed before / after the 1st fraction and in the 2nd-5th fraction due to mismatch of the spine position, tumor reduction or the patient could not stand the fixation mask. Discussion and conclusion: Anatomical changes, that occur during irradiation of patients with head and neck cancer, most often happen due to weight loss. To identify anatomical changes and ensure accurate irradiation, geometric verification of kV CBCT has proven to be more effective compared to the MV EPID system. For further research, it would be recommended to make a comparison between the two geometric verifications for different types of cancers.

• Keywords: diploma theses, radiologic technology, radiotherapy, verification, radiation techniques, head and neck cancer, repeated patient CT simulations, anatomical changes