[Quantification of the volumetric benefit of image-guided radiotherapy (IGRT) in prostate cancer: margins and presence probability map]. / Bénéfice volumétrique de la radiothérapie guidée par l'image dans les cancers prostatiques : marges et cartographies de probabilité de présence.
Cancer Radiother
; 13(5): 365-74, 2009 Sep.
Article
en Fr
| MEDLINE
| ID: mdl-19643650
ABSTRACT
PURPOSE:
To quantify the prostate and seminal vesicles (SV) anatomic variations in order to choose appropriate margins including intrapelvic anatomic variations. To quantify volumetric benefit of image-guided radiotherapy (IGRT). PATIENTS ANDMETHODS:
Twenty patients, receiving a total dose of 70 Gy in the prostate, had a planning CT scan and eight weekly CT scans during treatment. Prostate and SV were manually contoured. Each weekly CT scan was registered to the planning CT scan according to three modalities radiopaque skin marks, pelvis bone or prostate. For each patient, prostate and SV displacements were quantified. 3D maps of prostate and SV presence probability were established. Volumes including minimal presence probabilities were compared between the three modalities of registration.RESULTS:
For the prostate intrapelvic displacements, systematic and random variations and maximal displacements for the entire population were 5mm, 2.7 mm and 16.5mm in anteroposterior axis; 2.7 mm, 2.4mm and 11.4mm in superoinferior axis and 0.5mm, 0.8mm and 3.3mm laterally. Margins according to van Herk recipe (to cover the prostate for 90% of the patients with the 95% isodose) were 8mm, 8.3mm and 1.9 mm, respectively. The 100% prostate presence probability volumes correspond to 37%, 50% and 61% according to the registration modality. For the SV, these volumes correspond to 8%, 14% and 18% of the SV volume.CONCLUSIONS:
Without IGRT, 5mm prostate posterior margins are insufficient and should be at least 8mm, to account for intrapelvic anatomic variations. Prostate registration almost doubles the 100% presence probability volume compared to skin registration. Deformation of SV will require either to increase dramatically margins (simple) or new planning (not realistic).
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Próstata
/
Neoplasias de la Próstata
/
Vesículas Seminales
/
Planificación de la Radioterapia Asistida por Computador
Tipo de estudio:
Diagnostic_studies
Límite:
Humans
/
Male
Idioma:
Fr
Revista:
Cancer Radiother
Asunto de la revista:
NEOPLASIAS
/
RADIOTERAPIA
Año:
2009
Tipo del documento:
Article
País de afiliación:
Francia