Iranian Journal of Medical Physics

Iranian Journal of Medical Physics

The Effect of Total Fields' Area and Dose Distribution in Step and Shoot IMRT on Gamma Passing Rate Using OCTAVIUS 4D-1500 Detector Phantom

Document Type : Original Paper

Authors
Abdulrahman Mohammed Abdulbaqi 1
Siham Sabah Abdullah 2
Haydar Hamza Alabedi 3
nabaa alazawy 4
Mustafa Jabbar Al-Musawi 5
Ahmed faris Heydar 5
1 Alamal National Hospital for Cancer Treatment, Baghdad, Iraq
2 Department of phsiology and medical physics, college of medicine, Alnahrain university, Iraq
3 Oncology Department, Baghdad University, Diwaniya, Iraq
4 Al-Mansour University College, Medical Instrumentation Engineering Department, Baghdad, Iraq
5 Physicist, Ministry of Health and Environment/Medical City, Baghdad Center for Radiotherapy and Nuclear Medicine, Baghdad, Iraq
10.22038/ijmp.2020.44712.1690
Abstract
Introduction: Quality assurance is necessary for every IMRT plan.‎Octavius 4D-1500 detector phantom is ‎one of the new phantoms for ‎determining the treatment plan quality‎.‎ This study aimed to examine the IMRT plans using the ‎Octavius 4D-1500‎‏ ‏‎to determine if ‎it is a reliable, ‎dependable, and durable. 
Material and Methods: IMRT QA conducted for 30 cases: HN and pelvis. The Monaco TPS used for treatment planning. The treatment plans ‎were then applied ‎to the Octavius 4D-1500 phantom (virtually and actually), ‎‎the γ-index was calculated in VeriSoft program to evaluate the IMRT plans.
Results: Significant differences were observed between the ‎‎‎measured and calculated dose distributions for HN and pelvic plans, while the treatment ‎sites did not affect the GP rate. The results of the global Gp ‎ were higher than the local GP, ‎regardless of the study criteria. The ‎HN plans ‎showed a more significant difference ‎than the pelvic plans. The HN plans, ‎a ‎strong significant correlation was found between the total ‎fields’area and %GP in both global ‎‎and local analyses, while in the pelvic plans, there was only a significant association with the ‎local %GP.
Conclusion: The measured dose distributions significantly different from calculated distributions. The relationship between the ‎‎fields’ ‏‎ area ‎and ‎‎‎%GP was inverse. In the HN plans, a ‎significant correlation found between the total ‎‎fields’ ‎area ‎and %GP in both global and ‎local, while only local %GP in the pelvic plans was significant correlation. Overall, the Octavius 4D-1500 detector phantom ‎might be applicable for ‎assessing the QA of IMRT plans.
Keywords
Gamma Passing Rate
Dose Distribution
Intensity Modulated Radiotherapy
Quality Assurance
Subjects

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Iranian Journal of Medical Physics
Volume 18, Issue 4
July and August 2021
Pages 226-231

  • Receive Date 29 November 2019
  • Revise Date 16 April 2020
  • Accept Date 26 April 2020