Evaluation and Commissioning of Commercial Monte Carlo Dose Algorithm for Air Cavity

• 作者: Hideharu Miura Hiroya Shiomi Junichi Sasaki Kouichi Yamada Muhammad Nauman Usmani Norihisa Masai Ryoong-Jin Oh Toshihiko Inoue
• 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: MONTE Carlo PENCIL BEAM Air CAVITY Treatment Planning
• 年，卷（期）: 2014,（1）
• 页码范围: 9-13
• 页数: 5页
• 分类号: R73

摘要

The purpose of this study was to compare the Pencil Beam (PB) with Monte Carlo (MC) calculated dosimetric results using phantoms for air cavity region. Measurements in Tough water phantom with air gaps were used to verify the calculated dose. The plane-parallel ionization chamber was moved from 2 mm to 20 mm behind air gap. Calculations were performed for various air gaps (1.0, 2.0, 3.0 and 4.0 cm) and field sizes (4.2 × 4.2, 6.0 × 6.0 and 9.8 × 9.8 cm2). The lateral missing tissue measurement was performed using the radiochromic RT-QA film. Dose difference between PB and chamber measurement near an air gap was greater for smaller field size, larger air gap thickness, and shallower depth behind air gap. As the distance from the phantom edge became shorter, the dose differences of the PB calculation and film measurement became larger. MC calculations were found within 3% agreement to the measured dose distributions. Our results demonstrate an excellent agreement between ionization chamber and radiochromic RT-QA film measurements and MC calculations.