Treatment planning of tangential breast irradiation using a simulator with CT-option compared to a conventional CT.
OBJECTIVE
Treatment planning for breast cancer is often performed using a conventional computed tomography (CT), which does not allow patient positioning in the treatment set-up. Using a simulator with CT option the scanning procedure can be performed in an identical position as the treatment. Aim of the present study was to investigate feasibility and accuracy of a simulator with CT option compared to treatment planning with a conventional CT for breast irradiation.


METHODS
Twenty patients submitted for radiotherapy after breast conserving surgery underwent simulation with the SLS-CT (Elekta Oncology Systems, EOS). Additionally, a planning CT with a diagnostic CT scanner (Somatom Plus, Siemens,) was performed. All the patients were scanned with both modalities and had 3 to 5 slices. For Somatom-CT patients lay flat, for SLS-CT they rested on a breast angle board. The target volume was delineated in the CT scans obtained with both modalities, the planning procedure was carried out using the 3-D planning system Helax-TMS.


RESULTS
The median values for SLS-CT (1) and Somatom (2) were: Target volume: 679 cm3 (1) and 670 cm3 (2) for all patients and 1,025 cm3 (1) and 1,100 cm3 (2) for large breasts. Maximal dose in the dose-volume histogram (DVH): 109.3% (1) and 109.7% (2). Lung volume in the 20% isodose: 119 cm3 (1) and 123 cm3 (2). The distance between entrance and exit point in the central axis: 13.8 (1) and 14.6 cm (2).


CONCLUSIONS
Treatment planning with a CT option is feasible, the simulation procedure can be performed with 1 single device and under identical set-up conditions as the treatment itself. Our data show a tendency towards sparing of irradiated volume with SLS-CT, the clinical relevance cannot yet be determined.
Sautter-Bihl
M L
ML
Department of Radiooncology, Städtisches Klinikum Karlsruhe, Germany. sb2s@rz.uni-karlsruhe.de
Hültenschmidt
B
B
Scheurig
H
H
D000368:Aged; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D003131:Combined Modality Therapy; D003198:Computer Simulation; D005260:Female; D006801:Humans; D008327:Mammography / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data; D008875:Middle Aged; D011182:Postoperative Care; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods* / Q000706:statistics & numerical data; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data