title: Utilization of cone beam CT for reconstruction of dose distribution delivered in image-guided radiotherapy of prostate carcinoma - bony landmark setup compared to fiducial markers setup.
abstract: The purpose of this study was to compare two different styles of prostate IGRT: bony landmark (BL) setup vs. fiducial markers (FM) setup. Twenty-nine prostate patients were treated with daily BL setup and 30 patients with daily FM setup. Delivered dose distribution was reconstructed on cone-beam CT (CBCT) acquired once a week immediately after the alignment. Target dose coverage was evaluated by the proportion of the CTV encompassed by the 95% isodose. Original plans employed 1 cm safety margin. Alternative plans assuming smaller 7 mm margin between CTV and PTV were evaluated in the same way. Rectal and bladder volumes were compared with initial ones. While the margin reduction in case of BL setup makes the prostate coverage significantly worse (p = 0.0003, McNemar's test), in case of FM setup with the reduced 7 mm margin, the prostate coverage is even better compared to BL setup with 10 mm margin (p = 0.049, Fisher's exact test). Moreover, partial volumes of organs at risk irradiated with a specific dose can be significantly lowered (p &lt; 0.0001, unpaired t-test). Reducing of safety margin is not acceptable in case of BL setup, while the margin can be lowered from 10 mm to 7 mm in case of FM setup.
authors: Department of Medical Biophysics, Faculty of Medicine in Hradec Kralove, Charles University in Prague, Czech Republic. paluska@fnhk.cz
authors: Petr
authors: P
authors: Paluska
authors: Josef
authors: J
authors: Hanus
authors: Jana
authors: J
authors: Sefrova
authors: Lucie
authors: L
authors: Rouskova
authors: Jakub
authors: J
authors: Grepl
authors: Jan
authors: J
authors: Jansa
authors: Linda
authors: L
authors: Kasaova
authors: Miroslav
authors: M
authors: Hodek
authors: Milan
authors: M
authors: Zouhar
authors: Milan
authors: M
authors: Vosmik
authors: Jiri
authors: J
authors: Petera
mesh_terms: D000230:Adenocarcinoma / Q000532:radiotherapy*; D000368:Aged; D054893:Cone-Beam Computed Tomography / Q000706:statistics & numerical data*; D057918:Fiducial Markers; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D061089:Radiotherapy, Image-Guided
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