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

1 Ibn-Alhaitham Teaching Hospital

2 Department of phsiology and medical physics, college of medicine, Alnahrain university, Iraq

3 University of Baghdad /Ministry of Health and Environment, Baghdad Center for Radiation Therapy and Nuclear Medicine

4 Physiology department , college of medicine , Al-Mustansiriyah University

5 Physics Unit , Baghdad Center for Radiotherapy and Nuclear Medicine , Ministry of Health and Environment , Baghdad, Iraq

6 Physicist unit, medical ‎city,Baghdad Center ‎for radiotherapy and ‎nuclear medicine , Ministry of health and ‎environment.

Abstract

Introduction:more complicated ‎techniques are emerging with rapid ‎‎involvement in technology for accurate coverage of tumors by prescribed ‎‎‎radiation dose with excellent sparing of normal organs from scattered ‎‎‎radiation dose.SS-‎IMRT technique are one of those newly ‎used techniques.QA of ‎the treatment plan used for every treatment plan.‎OCTAVIUS4D-1500 detector phantom is ‎one of the new devices for ‎getting the plan quality‎.‎This study aimed at test SS-IMRT planning with ‎OCTAVIUS4D-1500 detector phantom‎‏ ‏‎to see if ‎the device is reliable, ‎dependable and sturdy.Materials and Method:Thirty cases had QA for IMRT in Baghdad center for radiotherapy and nuclear ‎medicine. ‎Treatment plans were done for two regions: HN,‎and ‎pelvis ‎carcinoma by using the SS-IMRT technique. They prepared ‎with ‎‎the energy of 6 MV in the MONACO 5.1 TPS.These treatment plans ‎were applied ‎to OCTAVIUS 4D-1500 and were ‎‎compared with an actual QA of it under LINAC, and ‎‎calculating γ-index by “Verisoft 7.1” program of OCTAVIUS‎‎4D-‎‎1500 to evaluate IMRT plan which is ‎being administered ‎‎by 80-leaf MLC ELEKTA‏’‏s LINAC.Results:a major difference between the calculated and ‎‎‎measured dose distribution for HN and pelvic plans and also the treated ‎site is not ‎affecting the gamma passing rate results.Global ‎γ-analysis ‎is higher than local γ-analysis ‎regardless of study criteria.The ‎HN plans ‎had a better significant difference ‎than the pelvic plans. HN plans show ‎a ‎strong significant correlation for total ‎fields' area with%GP for both global ‎‎and local,while they were significant in ‎local%GP for the pelvic plans only.Conclusion: the measured dose distribution is significantly different from ‎‎calculated once. the overall fields‏’‏‎ area ‎relationship results are inverse with ‎‎‎%GP.HN plans showed a powerful ‎significant correlation for total fields' ‎area ‎with%GP for both global and ‎local, while the pelvic plans showed a ‎‎correlation in local%GP only.The OCTAVIUS 4D-1500 detector phantom ‎might be enthusiastic about ‎checking the QA of LINAC for ‎the SS-IMRT ‎technique

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Articles in Press, Accepted Manuscript
Available Online from 26 April 2020
  • Receive Date: 29 November 2019
  • Revise Date: 16 April 2020
  • Accept Date: 26 April 2020