Journal of Korean Neurosurgical Society

The Korean Neurosurgical Society (대한신경외과학회)
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Validation of Gamma Knife Perfexion Dose Profile Distribution by a Modified Variable Ellipsoid Modeling Technique

  • Hur, Beong Ik (Department of Neurosurgery, Pusan National University Hospital) ;
  • Jin, Seong Jin (Gamma-knife Center, Haeundae Paik Hospital, Inje University) ;
  • Kim, Gyeong Rip (Gamma-knife Center, Pusan National University Yangsan Hospital) ;
  • Kwak, Jong Hyeok (Department of Radiology, Pusan National University Yangsan Hospital) ;
  • Kim, Young Ha (Department of Neurosurgery, Pusan National University Yangsan Hospital) ;
  • Lee, Sang Weon (Gamma-knife Center, Pusan National University Yangsan Hospital) ;
  • Sung, Soon Ki (Gamma-knife Center, Pusan National University Yangsan Hospital)
  • Received : 2020.06.26
  • Accepted : 2020.12.15
  • Published : 2021.01.01
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Abstract

Objective : High precision and accuracy are expected in gamma knife radiosurgery treatment. Because of the requirement of clinically applying complex radiation and dose gradients together with a rapid radiation decline, a dedicated quality assurance program is required to maintain the radiation dosimetry and geometric accuracy and to reduce all associated risk factors. This study investigates the validity of Leksell Gamma plan (LGP)10.1.1 system of 5th generation Gamma Knife Perfexion as modified variable ellipsoid modeling technique (VEMT) method. Methods : To verify LGP10.1.1 system, we compare the treatment plan program system of the Gamma Knife Perfexion, that is, the LGP, with the calculated value of the proposed modified VEMT program. To verify a modified VEMT method, we compare the distributions of the dose of Gamma Knife Perfexion measured by Gafchromic EBT3 and EBT-XD films. For verification, the center of an 80 mm radius solid water phantom is placed in the center of all sectors positioned at 16 mm, 4 mm and 8 mm; that is, the dose distribution is similar to the method used in the x, y, and z directions by the VEMT. The dose distribution in the axial direction is compared and analyzed based on Full-Width-of-Half-Maximum (FWHM) evaluation. Results : The dose profile distribution was evaluated by FWHM, and it showed an average difference of 0.104 mm for the LGP value and 0.130 mm for the EBT-XD film. Conclusion : The modified VEMT yielded consistent results in the two processes. The use of the modified VEMT as a verification tool can enable the system to stably test and operate the Gamma Knife Perfexion treatment planning system.

Keywords

Acknowledgement

This research was supported by the Korea Research Foundation (NRF) funded by the government (Ministry of Science, Technology and Information) in 2017 (NRF-2017R1C1B5077022).

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