[Dosimetric evaluation of an automatic segmentation tool of pelvic structures from MRI images for prostate cancer radiotherapy].
OBJECTIVE
An automatic segmentation tool of pelvic structures from MRI images for prostate cancer radiotherapy was developed and dosimetric evaluation of differences of delineation (automatic versus human) is presented here.


METHODS
CTV, rectum and bladder were defined automatically and by a physician in 20 patients. Treatment plans based on "automatic" volumes were transferred on "manual" volumes and reciprocally. Dosimetric characteristics of PTV (V(95), minimal, maximal and mean doses), rectum (V(50), V(70), maximal and mean doses) and bladder (V(70), maximal and mean doses) were compared.


RESULTS
Automatic delineation of CTV did not significantly influence dosimetric characteristics of "manual" PTV. Rectal V(50) and V(70) were not significantly different; mean rectal dose is slightly superior (43.2 versus 44.4Gy, p=0.02, Student test). Bladder V(70) was significantly superior too (19.3 versus 21.6, p=0.004). Organ-at-risk (OAR) automatic delineation had little influence on their dosimetric characteristics; rectal V(70) was slightly underestimated (20 versus 18.5Gy, p=0.001).


CONCLUSIONS
CTV and OAR automatic delineation had little influence on dosimetric characteristics. Software developments are ongoing to enable routine use and interobserver evaluation is needed.
Pasquier
D
D
Département universitaire de radiothérapie, centre Oscar-Lambret, 3, rue Frédéric-Combemale, 59020 Lille, France. d-pasquier@o-lambret.fr
Lacornerie
T
T
Betrouni
N
N
Vermandel
M
M
Rousseau
J
J
Lartigau
E
E
D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D010388:Pelvis / Q000033:anatomy & histology*; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011879:Radiotherapy Dosage