Ustreznost roba planiranega tarčnega volumna pri stereotaktični radioterapiji telesa pri oligometastatski bolezni : magistrsko delo

Rožič, Katja (author), But-Hadžić, Jasna (mentor), Žager Marciuš, Valerija (comentor), Ratoša, Ivica (reviewer)

Uvod: Ena izmed metod zdravljenja oligometastatske bolezni je stereotaktična radioterapija telesa, ki se izvaja na Onkološkem inštitutu v Ljubljani. Pri stereotaktični radioterapiji telesa je za uspešno zdravljenje ključna določitev ustreznih varnostnih robov, saj zdravljenje poteka z natančno aplikacijo visoke doze na tarčni volumen ob katerem lahko ležijo tudi kritični organi. Natančnost zagotavljamo z vsakodnevno slikovno vodeno radioterapijo z računalniško tomografijo s konusnim snopom, doslednim izvajanjem postopkov za kontrolo kvalitete in z upoštevanjem smernic in protokolov. Namen: Želeli smo ugotoviti ustreznost varnostnega roba 0,5 cm za obsevanje zasevkov s stereotaktično radioterapijo telesa na treh obsevalnih aparatih na Onkološem inštitutu v Ljubljani. Zanimalo nas je ali uporaba različnih fiksacijskih pripomočkov vpliva na premike tarčnega volumna. Zanimalo nas je tudi, ali je mogoče varno skrajšati postopek slikovno vodene radioterapije z manjšo uporabo slikanja. Metode dela: Raziskavo smo zasnovali kot retrospektivno neintervencijsko klinično raziskavo. Uporabili smo deskriptivno raziskovalno metodo s pregledom domače in tuje strokovne literature. V raziskavo smo vključili 190 bolnikov (204 tarčni volumni). Beležili smo spremenljivke (translacijske premike v treh smereh: levo/desno, anteriorno/posteriorno, kranialno/kavdalno ter uporabljene fiksacijske podlage) pri obsevanju vseh bolnikov z oligometastatsko boleznijo, obsevanih s SBRT tehniko od 1. 1. 2016 do 9. 10. 2024. Rezultati: Glavna ugotovitev raziskave je, da so bili intrafrakcijski premiki v analizirani populaciji majhni. Premiki, večji od 4 mm, so se v posameznih smereh pojavili pri največ približno 1 % analiziranih frakcij, delež dvodimenzionalnih vektorskih premikov nad 4 mm pa je bil manjši od 2 %. Povprečne vrednosti premikov so bile nizke, kar kaže na dobro ponovljivost namestitve in ustrezno intrafrakcijsko stabilnost pri uporabi različnih fiksacijskih pripomočkov, slikovno vodene radioterapije in izvedbe obsevanja. Razprava in zaključek: Rezultati potrjujejo ustreznost enotnega 5 mm varnostnega roba ne glede na uporabljen fiksacijski pripomoček, anatomsko regijo in obsevalni aparat. Rutinsko izvajanje zaključnega slikanja pri stabilnem poteku zdravljenja verjetno ni potrebno. Smiselno bi bilo ohraniti izvedbo zaključenga slikanja, kadar obstaja klinični razlog.

• Language: Slovenian
• Keywords: magistrska dela, radiološka tehnologija, stereotaktična radioterapija telesa, oligometastatska bolezen, tarčni volumen, fiksacijski pripomočki
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: ZF - Faculty of Health Sciences
• Place of publishing: Ljubljana
• Publisher: [K. Rožič]
• Year: 2026
• Number of pages: IX, 43 str., [5] str. pril.
• PID: 20.500.12556/RUL-188655
• UDC: 616-07
• COBISS.SI-ID: 292448003
• Publication date in RUL: 25.09.2026

Secondary language

• Language: English
• Title: Planning target volume margin accuracy in oligometastatic stereotactic body radiotherapy : master thesis

Abstract

Introduction: One of the treatment methods for oligometastatic disease is stereotactic body radiotherapy, which is performed at the Institute of Oncology Ljubljana. In stereotactic body radiotherapy accurate determination of appropriate safety margins is crucial for successful treatment, as therapy involves the precise delivery of a high dose to the target volume. Accuracy is ensured by daily image-guided radiotherapy using cone-beam computed tomography, consistent implementation of qualiy assurance procedures and following the clinical guidelines and protocols. Purpose: The aim of the study was to evaluate the adequacy of a 5 mm planning target volume margin for stereotactic body radiotherapy treatment on three radiotherapy machines at the Institute of Oncology in Ljubljana, with respect to the immobilisation devices used. We were also interested in whether it was possible to safely shorten the image guidance procedure by reducing the use imaging. Methods: This retrospective non-interventional clinical study was complemented by a review of the national and international scientific literature. The study included 190 patients (204 target volumes) treated with stereotactic body radiotherapy from 1.1.2016 to 9.10.2024. Variables were recorded (translational shifts in three directions - left/right, anterior/posterior, cranial/caudal and immobilisation devices) during the treatment of all oligometastatic patients treated with the stereoctic body radiotherapy technique. Results: The main finding of this study is that intrafractional motion in the analyzed population was minimal. Displacements greater than 4 mm in individual directions occurred in approximately 1% of the analyzed fractions, while the proportion of vector displacements that exceeded 4 mm was less then 2%. The mean displacement values were low, indicating good setup reproducibility with the immobilization devices used, image guidance and treatment delivery. Discussion and conclusion: The results support the use of a uniform PTV margin of 5 mm regardless of the immobilization device, anatomical region or treatment machine. Based on these findings, routine acquisition of post-treatment imging scan in patients with stable positioning is probably not necessary. Post-treatment imaging should be retained when clinically indicated.

• Keywords: master's theses, radiologic technology, stereotactic body radiotherapy, oligometastatic disease, planning target volume, immobilisation devices