Author/Editor		Kragelj, Borut
Title		Setup and its effect on safety margin in conformal radiotherapy of the prostate
Translated title		Napaka nastavitve bolnika in njen vpliv na varnostni rob pri konformnem obsevanju prostate
Type		članek
Source		Radiol Oncol
Vol. and No.		Letnik 39, št. 3
Publication year		2005
Volume		str. 211-7
Language		eng
Abstract		Background. In radiotherapy, setup errors in positioning the patients influence the size of safety margin and thereby also the size of irradiation field and toxicity of radiotherapy. Methods. The setup errors were calculated by evaluating the deviations from the measured distance between the irradiation field margin and the bony pelvis. Results. The research was performed on 23 patients. With respect to lateral, craniocaudal and anteroposterior axis, the observed systemic error ranged from -5 to + 9 mm, -4 to +5 mm, and from -4 to +4 mm, respectively, whereas the observed random error ranged from 0 to 7.5 mm, 0 to 3.6 mm, and from 0 to 4.2 mm, respectively. The safety margin, with the 90% probability to cover clinical target volume (CTV) and allowing for the prostate position variability, measured 9 mm, 9.5 mm, 7 mm, and 10 mm in the respective lateral, craniocaudal, anterior and dorsal direction. Conclusions. Irradiation of the prostate with a 7 mm dorsal safety margin, allowing for 90% coverage probability of CTV, was feasible in 22/23 patients on condition that the gross systemic error (>3mm) was eliminated.
Summary		Izhodišča. Napake pri nastavitvi položaja bolnikov med obsevanjem določajo velikost varnostnega roba in s tem tudi velikost obsevalnih polj. Metode. Napako pri nastavitvi bolnikov smo ugotavljali z merjenjem odmikov robov obsevalnega polja od kosti medeničnega obroča. Rezultati. V raziskavo je bilo vključenih 23 bolnikov, pri katerih je bila glede na lateralno, kraniokaudalno in anteroposteriorno os ugotovljena sistematska napaka od -5 do +9 mm, -4 do +5 mm in -4 do +4 mm ter naključna napaka od 0 do7,5 mm, 0-3,6 mm ter 0-4,2 mm. Varnostni rob za 90% verjetnost zajetja kliničnega tarčnega volumna (CTV) z upoštevanjem tudi gibanje prostate je bil 9 mm v lateralni, 9,5 mm v kraniokaudalni, 7 mm v anteriorni in 10 mm v dorzalni smeri. Zaključek. Obsevanje prostate s 7 mm dorzalnim varnostnim robom je možno z odpravo izrazite sistematske napake(>3 mm), pri čemer je dosežena 90% verjetnost zajetja CTV pri 22/23 bolnikov.
Descriptors		PROSTATIC NEOPLASMS RADIOTHERAPY DOSAGE RADIOTHERAPY PLANNING, COMPUTER-ASSISTED