Experimental evaluation of the accuracy of skin dose calculation for a commercial treatment planning system.
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ABSTRACT:
SUBMITTER: Court LE
PROVIDER: S-EPMC5721536 | biostudies-other | 2008 Jan
REPOSITORIES: biostudies-other
Publications
Experimental evaluation of the accuracy of skin dose calculation for a commercial treatment planning system.
Court Laurence E LE Tishler Roy B RB Allen Aaron M AM Xiang Hong H Makrigiorgos Mike M Chin Lee L
Journal of applied clinical medical physics 20080128 1
This work investigates the accuracy of skin dose calculations using the Eclipse treatment planning system. Skin dose was measured using micro-MOSFETs for a range of irradiation conditions (open fields, physical wedges, dynamic wedges, different SSDs) for 6MV and 10MV beams, and compared with the mean dose calculated to a 2mm thick "skin" structure for semi-cylindrical phantoms (representative of a neck or breast). Agreement between the calculated and measured skin dose values was better than +/- ...[more]
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Project description:Background and purposeHead-Neck (HN) patients may experience severe acute skin complications that can cause treatment interruption and increase the risk of late fibrosis. This study assessed a method for accurately monitoring skin dose changes during helical tomotherapy for HN cancer based on deformable image registration of planning computed tomography (CT) and mega-voltage CT (MVCT).Materials and methodsPlanning CTs of nine patients were deformably registered to mid-treatment MVCT (MV15) images resulting in CTdef images. The original plans were recalculated on both CTdef and mid-treatment kilo-voltage CT (CT15) taken as ground truth. Superficial layers (SL) of the body with thicknesses of 2, 3 and 5 mm (SL2, SL3, SL5) were considered as derma surrogates. SL V95%, V97%, V98%, V100%, V102%, V105% and V107% of the prescribed PTV dose were extracted for CT15/CTdef and compared (considering patients with skin dose > 95%). For comparison, doses were calculated directly on the calibrated MVCT and analyzed in the same way.ResultsDifferences between SL2/SL3/SL5 V95%-V107% in CT15/CTdef were very small: for eight of nine patients the difference between the considered SL2 Vd% computed on CTdef and CT15 was less than 1.4 cm3 for all d%. A larger value was found when using MVCT for skin dose calculation (4.8 cm3 for SL2), although CTdef body contour matched CT15 body with accuracy similar to that of MV15.ConclusionsDeforming the planning CT-to-MVCT was shown to be accurate considering external body contours and skin DVHs. The method was able to accurately identify superficial overdosing.
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