Medical Dosimetry
Volume 22, Issue 3 , Pages 231-236, Autumn 1997

Commissioning of enhanced dynamic wedge on a ROCS RTP system☆

Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL, USA

Abstract 

The enhanced dynamic wedge (EDW) is clinically commissioned on a ROCS RTPS (Version 5.03) in a manner similar to that used for any standard physical wedge. The required data set for implementation includes central axis depth dose, and open and wedge beam profiles at several depths and output factors. The features distinguishing the EDW from the physical wedge are a sharp change in output with field size in the wedge plane and a primary intensity difference at the end of the wedge field because the moving jaw stops 0.5 cm short of the fixed jaw position for all field sizes, for safety reasons. The monitor unit (MU) calculation for an EDW field in ROCS is based on scaling factors that are derived from a normalized golden STT (NGSTT). This approach requires no change in the data file structure of ROCS. It was found that the output for EDW is very sensitive to the value of final moving jaw position. Every 0.5 cm difference between planned and set value can cause 3.5% error.

Keywords:  Enhanced dynamic wedge, Golden segmented treatment table, Treatment planning

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PII: S0958-3947(97)00024-1

Medical Dosimetry
Volume 22, Issue 3 , Pages 231-236, Autumn 1997

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