Evaluation of Mid-Plane Dose by Flat Panel Transit Dosimetry Method and by EBT2 Film Incident Dosimetry

• 作者: Christina Armpilia Christos Antypas Ioannis Floros Kalliopi Mandourari Panagiotis Sandilos Pantelis Karaiskos
• 来源期刊: 医学物理学、临床工程、放射肿瘤学(英文)
• 学科: 医学
• 关键词: EPID EBT2 Films In VIVO DOSIMETRY Calibration Model
• 年，卷（期）: 2015,（3）
• 页码范围: 243-254
• 页数: 12页
• 分类号: R73

摘要

Purpose: The aim of this study is to validate an easily applicable flat panel dosimetry method based on the back projection approach and to compare this method with the incident dosimetry by EBT2 film method for mid-plane dose calculations. Methods: The dosimetric characteristics of the flat panel were determined for 6 MV photon energy. Then, the methodology to calculate the dose on the central axis of the photon beam was described. While, the flat panel dosimetry method was validated with phantom measurements using an ionization chamber. Once the method was validated, in vivo measurements of ten prostate patients treated with 6 MV photon energy 3D conformal plans were also performed both with the flat panel and the EBT2 films. Results: The phantom measurements revealed a mean dispersion of 1.7% between flat panel and ionization chamber doses and 2.2% between flat panel and EBT2 film doses. While, the in vivo measurements in prostate patients revealed a mean dispersion of 0.8% between flat panel doses and treatment planning calculated doses and 1% between flat panel and EBT2 film doses. Conclusions: The presented flat panel dosimetry method is accurate, easily applicable to all types of flat panels without the use of any sophisticated software and is not time consuming.