Document Type: Conference Proceedings
Department of Medical Physics, Kerman University of Medical Sciences, Kerman, Iran. Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
Department of Medical Physics, Isfahan University of Medical Sciences, Isfahan, Iran.
.Medical Physics Department, Royal Adelaide Hospital. Adelaide, SA 5000, Australia
Department of Radiation Oncology, Isfahan Milad Hospital, Isfahan, Iran.
Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
Introduction: The use of electronic portal imaging devices (EPIDs) is a method for the dosimetric verification of radiotherapy plans both pretreatment and in-vivo. The aim of this study was to test a 2D EPID-based dosimetry algorithm for dose verification of some plans inside a homogenous and anthropomorphic phantom and in-vivo, as well.
Materials and Methods: Dose distributions were reconstructed from EPID images using a 2D EPID dosimetry algorithm inside a homogenous slab phantom for a simple 10×10 cm2 box technique, the 3D conformal (prostate, head-and-neck and lung) and an IMRT prostate plans inside an anthropomorphic (Alderson) phantom and the patients (one fraction in-vivo) for the 3D conformal plans (prostate, head-and-neck and lung).
Results: The Planned and EPID dose difference at isocenter, on average, was 1.7% for the pretreatment verification and was less than 3% for all in vivo plans except a head-and-neck which was 3.6%. The mean γ values for a 7-field prostate IMRT plan delivered to the Alderson phantom varied from 0.28 to 0.65. For 3D conformal plans applied for the Alderson phantom, all γ1% values were within the tolerance level for all plans and in both AP-PA beams.
Conclusion: The 2D EPID-based dosimetry algorithm provides an accurate method to verify the dose of a simple 10×10 cm2 fields in two dimensions inside a homogenous slab phantom as well as for IMRT prostate plan and 3D conformal plans (prostate, head-and-neck and lung plans) applied using an anthropomorphic phantom and in-vivo.