Preliminary results on setup precision of prone-lateral patient positioning for whole breast irradiation.
OBJECTIVE
The aim of this study was to develop a rapid and reproducible technique for prone positioning and to compare dose-volume indices in prone and supine positions.


METHODS
Eighteen patients underwent computed tomography imaging for radiotherapy planning in prone and supine position. Experience was gained in the first eight patients, which lead to modifications of the Horizon prone breast board (Civco Medical Solutions, Orange City, Iowa, USA) and the patient setup technique. A unilateral breast holder (U-BH) was developed (Van de Velde, Schellebelle, Belgium) to retract the contralateral breast away from the treated breast. The technique was then applied to an additional 10 patients. The setup precision was evaluated using daily cone-beam CT.


RESULTS
Modifications to the breast board were made to secure a prone-lateral rather then a pure prone position. We evolved from a classical setup using laser marks on the patients' body to a direct breast setup using marks on the breast only. The setup precision of the direct positioning procedure with the modified breast board and the U-BH is comparable to supine setup data in the literature. Dose-volume indices for heart and lung show significantly better results for prone than for supine position, and dose homogeneity within the treated breast did not differ according to the treatment position.


CONCLUSIONS
The setup precision of our prone-lateral positioning technique is comparable to supine data in literature. Our data show the advantage of prone radiotherapy to spare the lung and heart. Further research is necessary to reduce the duration of prone setup.
Department of Radiotherapy, Ghent University Hospital, Ghent, Belgium. Liv.Veldeman@uzgent.be
Liv
L
Veldeman
Bruno
B
Speleers
Marlies
M
Bakker
Filip
F
Jacobs
Marc
M
Coghe
Werner
W
De Gersem
Aline
A
Impens
Sarah
S
Nechelput
Carlos
C
De Wagter
Rudy
R
Van den Broecke
Geert
G
Villeirs
Wilfried
W
De Neve
D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D003020:Clothing; D054893:Cone-Beam Computed Tomography / Q000379:methods; D004867:Equipment Design; D005260:Female; D006321:Heart / Q000528:radiation effects; D006801:Humans; D008168:Lung / Q000528:radiation effects; D008488:Medical Illustration; D008875:Middle Aged; D056888:Patient Positioning / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D016684:Prone Position; D011832:Radiation Injuries / Q000517:prevention & control; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D016896:Treatment Outcome