Sohyun Ahn

Statistical Process Control Analysis for Patient Quality Assurance of Intensity Modulated Radiation Therapy

This study applied statistical process control to set and verify the quality assurances (QA) tolerance standard for our hospital’s characteristics with the criteria standards that are applied to all the treatment sites with this analysis. Gamma test factor of delivery quality assurances (DQA) was based on 3%/3 mm. Head and neck, breast, prostate cases of intensity modulated radiation therapy (IMRT) or volumetric arc radiation therapy (VMAT) were selected for the analysis of the QA treatment sites. The numbers of data used in the analysis were 73 and 68 for head and neck patients. Prostate and breast were 49 and 152 by MapCHECK and ArcCHECK respectively. Cp value of head and neck and prostate QA were above 1.0, Cpml is 1.53 and 1.71 respectively, which is close to the target value of 100%. Cpml value of breast (IMRT) was 1.67, data values are close to the target value of 95%. But value of was 0.90, which means that the data values are widely distributed. Cp and Cpml of breast VMAT QA were respectively 1.07 and 2.10. This suggests that the VMAT QA has better process capability than the IMRT QA. Consequently, we should pay more attention to planning and QA before treatment for breast Radiotherapy.

Erratum to: Branch length similarity entropy-based descriptors for shape representation (Journal of the Korean Physical Society, (2017), 71, 10, (727-732), 10.3938/jkps.71.593)

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Status and Perception of Risk Management in Radiation Therapy: Survey Among Korean Medical Physicists

Abstract This study was conducted as part of an endeavor to improve the risk management system of radiation therapy departments in the Republic of Korea. An online survey on the status and perception of Korea’s medical physicists on risk management in radiation therapy was carried out. A total of 40 domestic radiation oncology departments participated. This survey is divided into three categories: (1) work environment; (2) risk management status; and (3) opinions on how to improve risk management. Based on the results of the survey, the conclusions that can be derived are (1) the majority of respondents have a high interest in the risk management of radiation therapy; (2) the lack of staffing is one cause of risk management difficulties; (3) a risk-related terminology and classification system at the national or professional association level are required; (4) each hospital should create a voluntary reporting system for the handling of incidents; (5) medical physicists should establish incident reporting, analysis and countermeasures; and (6) government should develop education and training programs. It was confirmed that the current risk management system should be changed by education in the hospital and at the national level in order to improve risk management related to radiation therapy. In addition, it was recognized that a dedicated staff and a risk management certification system and organization for patient safety in radiotherapy are needed.

SU-F-I-06: Evaluation of Imaging Dose for Modulation Layer Based Dual Energy Cone-Beam CT

PURPOSE Dual energy cone beam CT system is finding a variety of promising applications in diagnostic CT, both in imaging of endogenous materials and exogenous materials across a range of body sites. Dual energy cone beam CT system to suggest in this study acquire image by rotating 360 degree with half of the X-ray window covered using copper modulation layer. In the region that covered by modulation layer absorb the low energy X-ray by modulation layer. Relative high energy X-ray passes through the layer and contributes to image reconstruction. Dose evaluation should be carried out in order to utilize such an imaging acquirement technology for clinical use. METHODS For evaluating imaging dose of modulation layer based dual energy cone beam CT system, Prototype cone beam CT that configured X-ray tube (D054SB, Toshiba, Japan) and detector (PaxScan 2520V, Varian Medical Systems, Palo Alto, CA) is used. A range of 0.5-2.0 mm thickness of modulation layer is implemented in Monte Carlo simulation (MCNPX, ver. 2.6.0, Los Alamos National Laboratory, USA) with half of X-ray window covered. In-house phantom using in this study that has 3 cylindrical phantoms configured water, Teflon air with PMMA covered for verifying the comparability the various material in human body and is implemented in Monte Carlo simulation. The actual dose with 2.0 mm copper covered half of X-ray window is measured using Gafchromic EBT3 film with 5.0 mm bolus for compared with simulative dose. RESULTS Dose in phantom reduced 33% by copper modulation layer of 2.0 mm. Scattering dose occurred in modulation layer by Compton scattering effect is 0.04% of overall dose. CONCLUSION Modulation layer of that based dual energy cone beam CT has not influence on unnecessary scatter dose. This study was supported by the Radiation Safety Research Programs (1305033) through the Nuclear Safety and Security Commission.