Vpliv postavitve izhodišča na sistematične in naključne nastavitvene napake pri obsevanju raka glave in vratu : magistrsko delo

Lenko, Helena (author), Peterlin, Primož (mentor), Strojan, Primož (reviewer)

Namen: Namen raziskave je bil ugotoviti morebiten vpliv izbire izhodišča (na bolnikovi glavi ali vratu) na sistematične in naključne nastavitvene napake pri obsevanju raka glave in vratu in posledično izboljšanje kakovosti obsevanja. Metoda: Popravki nastavitve položajev so bili pridobljeni z uporabo verifikacije kilovoltnega sistema OBI, poravnave 2D/2D in so bili avtomatsko zabeleženi pred vsakim obsevanjem. Na Onkološkem inštitutu Ljubljana je bilo v letih 2013 in 2014 zabeleženih 3413 takšnih zapisov za 117 bolnikov z rakom glave in vratu, obsevanih z volumetrično modulirano ločno terapijo VMAT na obsevalnem aparatu 8. Pri 75 bolnikih je bilo izhodišče postavljeno v področju glave, pri 42 bolnikih pa v področju vratu. Rezultati: Standardni odkloni skupinske sistematične napake v vertikalni, longitudinalni in lateralni smeri in rotacije mize so bili 2,5 mm, 2,1 mm, 1,9 mm in 0,43° za izhodišče na bolnikovi glavi in 2,6 mm, 1,8 mm, 1,7 mm in 0,48° za izhodišče na bolnikovem vratu. Naključna napaka vertikalnega, longitudinalnega, lateralnega in rotacijskega popravka položaja je bila 1,8 mm, 1,5 mm, 1,6 mm in 0,62° (glava) ter 2,0 mm, 1,6 mm, 1,5 mm in 0,61° (vrat). Za obe nastavitvi izhodišča je distribucija rotacijskih popravkov pokazala izrazito odstopanje od normalne distribucije. Wilcoxonov test vsote rangov je pokazal statistično pomembno razliko (p < 0,05) med obema nastavitvama izhodišča le pri distribuciji popravkovi položaja v longitudinalni smeri. Izkazalo se je, da so bili položaji premikov v različnih smereh večinoma nepovezani. V primeru rotacijskih popravkov ta nepovezanost izvira iz dejstva, da v 75 % primerov ni bil uporabljen nikakršen popravek. Če upoštevamo samo zapise, pri katerih je bil uporabljen rotacijski popravek, je bilo zaznati šibko povezavo (?B 0,37 za glavo in 0,33 za vrat) med rotacijskim popravkom in lateralnim premikom. Zaključki: Glede na rezultate nobena nastavitev bolnikovega izhodišča ne kaže jasne prednosti pred drugo.

• Language: Slovenian
• Keywords: magistrska dela, radiološka tehnologija, radioterapija glave in vratu, bolnikovo izhodišče, nastavitvene napake
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: ZF - Faculty of Health Sciences
• Place of publishing: Ljubljana
• Publisher: [H. Lenko]
• Year: 2020
• Number of pages: 53 str., [14] str. pril.
• PID: 20.500.12556/RUL-121671
• UDC: 616-07
• COBISS.SI-ID: 33659395
• Publication date in RUL: 22.10.2020

Secondary language

• Language: English
• Title: The impact of patient origin position on systematic and random setup position errors in head-and-neck radiotherapy : master's thesis

Abstract

Purpose: The purpose of the study was to examine and quantify set-up errors in patient positioning at head-and-neck radiotherapy and to investigate the impact of the choice of patient origin (patient neck or patient skull) on the magnitude of set-up errors. Method: Set-up position corrections obtained using On-Board Imaging OBI 2D/2D matching were recorded automatically for every treatment fraction. 3413 such treatment records for 117 patients with head-and-neck cancer treated with volumetric modulated arc therapy VMAT in the years 2013 and 2014 on a single treatment machine in our clinic were analysed. In 75 of them, patient origin was set on the patient skull, and in 42 of them, they were set on the patient neck. Results: Standard deviation of group systematic error in the vertical, longitudinal and lateral direction, as well as in the couch rotation were found to be 2.5 mm, 2.1 mm, 1.9 mm and 0.43䃦 for the patient origin on patient skull and 2.6 mm, 1.8 mm, 1.7 mm and 0.48䃦 were found to be for the patient origin on patient neck. Random error of the vertical, longitudinal, lateral and rotational position correction was 1.8 mm, 1.5 mm, 1.6 mm and 0.62䃦 (skull) and 2.0 mm, 1.6 mm, 1.5 mm and 0.61䃦 (neck). For both origin set-ups, the distribution of rotational corections was showing a pronounced deviation from a normal distribution, indicating that radiation therapists were reluctant to apply very small rotational corrections. Wilcoxon rank-sum test was showing a significant (p<0.05) difference between two patient origin set-ups only in correction distributions in the longitudinal direction. Positional shifts in different directions were found to be mostly uncorelated; however, in the case of rotational correction, this effect was dominated by the fact that in 75 % of the cases, no rotation correction was applied. When only considering the records where rotational correction was applied, a weak corelation (τB, 0.37 for skull and 0.33 for neck) between the rotational correction and lateral shift was found. Conclusions: Based on the results, neither patient origin set-up showed a clear advantage over the other in terms.

• Keywords: master's theses, radiologic technology, head-and-neck radiotherapy, patient origin, set-up error