Authors (including presenting author) :
Wong PW(1), Lee CH(1)
Affiliation :
Department of Medical Physics, Pamela Youde Nethersole Eastern Hospital
Introduction :
Immobilization devices are used in radiation therapy for reducing patient movement and reproducing treatment positions. As most of the immobilization devices are made of low density materials such as hollow carbon fiber tubes and the dosimetric effect was considered negligible, they are usually not included for dose calculation in treatment planning. In fact, high density materials are often added to reinforce some regions like edges or joints of an immobilization device.
Objectives :
The dosimetric effect from Type S overlay boards, used as an immobilization device in head and neck cases, was examined.
Methodology :
This study examine the effect of such device by comparing the differences in point doses and dose volume histograms (DVH) with and without a Type S overlay board using Eclipse treatment planning system.
Result & Outcome :
Some regions of the board showed significant attenuation of photon beams, the effect was minor on the dose volume histograms of a head and neck IMRT case but it might not be clinically negligible. In this study, we would also demonstrate a simple and fast procedure in Eclipse treatment planning system to include the immobilization device for dose calculation to compensate for the majority of the dosimetric effects.
Co-location with:
