pmp Progress in Medical Physics Progress in Medical Physics 2508-4445 2508-4453 Korean Society of Medical Physics 10.14316/pmp.2017.28.3.129 pmp-28-129 Original Article A Pilot Study of the Scanning Beam Quality Assurance Using Machine Log Files in Proton Beam Therapy ChungKwangzoo Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea Corresponding author Kwangzoo Chung (kchung@skku.edu) Tel: 82-2-3410-1353 Fax: 82-2-3410-2619 92017 1792017 283 129133 25092017 29092017 30092017 Copyright © 2017 Korean Society of Medical Physics 2017 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract

The machine log files recorded by a scanning control unit in proton beam therapy system have been studied to be used as a quality assurance method of scanning beam deliveries. The accuracy of the data in the log files have been evaluated with a standard calibration beam scan pattern. The proton beam scan pattern has been delivered on a gafchromic film located at the isocenter plane of the proton beam treatment nozzle and found to agree within ±1.0 mm. The machine data accumulated for the scanning beam proton therapy of five different cases have been analyzed using a statistical method to estimate any systematic error in the data. The high-precision scanning beam log files in line scanning proton therapy system have been validated to be used for off-line scanning beam monitoring and thus as a patient-specific quality assurance method. The use of the machine log files for patient-specific quality assurance would simplify the quality assurance procedure with accurate scanning beam data.

 Proton beam therapy Scanning beam Quality assurance Machine log file REFERENCES RR Wilson Radiological use of fast protons Radiology. 194647 48791 Kang JK MS Kim WI Jang, et. al. The clinical utilization of radiation therapy in Korea between 2009 and 2013 Radiat Oncol J. 201634 8895 M Jermann Particle therapy statistics in 2014 Int J Particle Ther. 20152 504 H Li, N Sahoo, F Poenisch et al. Use of treatment log files in spot scanning proton therapy as part of patient-specific quality assurance Med Phys. 201340 0217031-11. Scandurra D Albertini F Meer R Assessing the quality of proton PBS treatment delivery using machine log files: comprehensive analysis of clinical treatments delivered at PSI Gantry 2 Phys Med Biol. 201661 117181 K Chung, Y Han, J Kim et al. The first private-hospital based proton therapy center in Korea: Status of the Proton Therapy Center at Samsung Medical Center Radiat Oncol J. 201533 33743 K Chung, J Kim, DH Kim, S Ahn, Y Han The proton therapy nozzles at Samsung Medical Center: A Monte Carlo simulation study using TOPAS J Korean Phys Soc. 201567 1704 K Chung, Y Han, SH Ahn, JS Kim, H Nonaka Commissioning and Validation of a Dedicated Scanning Nozzle at Samsung Proton Therapy Center Prog Med Phys. 201627 26771 GAFChromicTM EBT3 film specifications Available at www.gafchromic.com G Moliere Theorie der Streuung schneller geladener Teilchen II. Mehrfach-und Vielfachstreuung Z Naturforsch A: Phys Sci. 19483a 7897 Figures and Tables

A scanned EBT3 film irradiated with the standard scan pattern composed of 5x5 points (230 MeV).

An example of scanning beam information recorded in the scanning control unit (Top left: x-position in time, top right: y-position in time, bottom left: monitor count in time, bottom right: x-position vs. y-position. Raw data without pedestal/noise reduction).

A scanning beam information recorded in the scanning control unit (one sample layer of a patient beam delivery plan).

The summary of pre-treatment QA log file analysis. The “ds” stands for the displacement of the recorded position from the planned position. For a given field (case), the entire energy layers (number of layers) have been analyzed.

Cases Number of layers Average of ds Standard deviation
[mm] of ds [mm]
Case 1 15 0.09 0.09
Case 2 17 0.11 0.10
Case 3 23 0.15 0.07
Case 4 18 0.10 0.11
Case 5 11 0.06 0.14