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Titolo:
Patient positioning in prostate radiotherapy: Is prone better than supine?
Autore:
Weber, DC; Nouet, P; Rouzaud, M; Miralbell, R;
Indirizzi:
Hop Cantonal Univ Geneva, Div Radiol, Dept Radiat Oncol, CH-1211 Geneva 14, Switzerland Hop Cantonal Univ Geneva Geneva Switzerland 14 11 Geneva 14, Switzerland
Titolo Testata:
INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS
fascicolo: 2, volume: 47, anno: 2000,
pagine: 365 - 371
SICI:
0360-3016(20000501)47:2<365:PPIPRI>2.0.ZU;2-O
Fonte:
ISI
Lingua:
ENG
Soggetto:
3-DIMENSIONAL CONFORMAL RADIOTHERAPY; RIGID IMMOBILIZATION; RADIATION-THERAPY; TARGET VOLUME; CANCER; REPRODUCIBILITY; QUANTIFICATION; IRRADIATION; CARCINOMA;
Keywords:
prone position; conformal radiotherapy; reproducibility; prostate cancer;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Clinical Medicine
Life Sciences
Citazioni:
20
Recensione:
Indirizzi per estratti:
Indirizzo: Weber, DC Hop Cantonal Univ Geneva, Div Radiol, Dept Radiat Oncol, 24 Rue Micheli duCrest, CH-1211 Geneva 14, Switzerland Hop Cantonal Univ Geneva 24Rue Micheli du Crest Geneva Switzerland 14
Citazione:
D.C. Weber et al., "Patient positioning in prostate radiotherapy: Is prone better than supine?", INT J RAD O, 47(2), 2000, pp. 365-371

Abstract

Purpose: To assess potential dose reductions to the rectum and to the bladder with three-dimensional conformal radiotherapy (3D-CRT) to the prostate in the prone as compared with the supine position; and to retrospectively evaluate treatment position reproducibility without immobilization devices. Methods and Materials: Eighteen patients with localized prostate cancer underwent pelvic CT scans and 3D treatment planning in prone and supine positions. Dose-volume histograms (DVHs) were constructed for the clinical target volume, the rectum and the bladder for every patient in both treatment positions. "Comparative DVHs" (cDVHs) were defined for the rectum and for thebladder: cDVH was obtained by subtracting the organ volume receiving a given dose increment in the prone position from the corresponding value in thesupine position. These values were then integrated over the entire dose range. The prescribed dose to the planning target volume (PTV) was 74 Gy using a 6-field technique; To evaluate reproducibility, portal films were subsequently reviewed in 12 patients treated prone and 10 contemporary patients treated supine (controls). No immobilization devices were used. Deviations in the anterio-posterior (X) and cranio-caudal (Y) axes were measured. Meantreatment position variation, total setup variation, systematic setup variation, and random setup variation were obtained. Results: Prone position was associated with a higher dose to the rectum orto the bladder in 6 (33%) and 7 (39%) patients, respectively. A simultaneously higher dose to rectum and bladder was noted in 2 (11%) patients in prone and in 7 (39%) patients in supine. Rectal and bladder volumes were frequently larger in prone than in supine: mean prone/supine volume ratios were 1.21 (SD, 0.68) and 1.03 (SD, 1.32), respectively. In these cases cDVH analysis more often favored the prone position. Mean treatment position variation and total setup variation were similar for both prone and supine plans. A higher systematic setup variation was observed in prone positioning: 2.7 mm vs. 1.9 mm (X axis) and 4.1 mm vs. 2.2 mm (Y axis). The random variationwas similar for both prone and supine: 4.0 mm vs. 3.6 mm (X axis) and 3.7 mm vs. 3.6 mm (Y axis). Conclusions: Prone position 3D-CRT is frequently, but not always, associated with an apparent dose reduction to the rectum and/or to the bladder for prostate cancer patients. As suggested by the increased mean prone/supine rectal volume ratio, the advantage of prone positioning for the rectum may be artifactual, at least partly reflecting a position-dependent rectal air volume, which may significantly vary from treatment to treatment. In the absence of immobilization devices, daily setup reproducibility appears less accurate for the prone position, primarily due to systematic setup variations. (C) 2000 Elsevier Science Inc.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 01/04/20 alle ore 18:42:36