Design, fabrication, and validation of a polymethyl methacrylate head phantom for dosimetric verification of cranial radiotherapy treatment plans

V. Shaiju, Rajesh Kumar, Debjani Phani, K. Rajasekhar, George Zacharia, Saju Bhasi, Raghuram Nair

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Purpose: The present study aims to design and fabricate a novel, versatile, and cost-effective Polymethyl Methacrylate (PMMA) head phantom for the dosimetric pretreatment verification of radiotherapy (RT) treatment plans. Materials and Methods: The head phantom designing involves slice-wise modeling of an adult head using PMMA. The phantom has provisions to hold detectors such as ionization chambers of different sizes, Gafchromic films, gel dosimeter, and optically stimulated luminescence dosimeter. For the point dose verification purpose, 15 volumetric modulated arc therapy patient plans were selected, and doses were measured using a CC13 ionization chamber. The percentage gamma passing rate was calculated for acceptance criteria 3%/3 mm and 2%/2 mm using OmniPro I'mRT film QA software, and Gafchromic EBT3 films were used for 2D planar dose verification. Results: Treatment planning system calculated, and the measured point doses showed a percentage deviation ranged from 0.26 to 1.92. The planar dose fluence measurements, for set acceptance criteria of 3%/3 mm and 2%/2 mm, percentages of points having gamma value <1 were in the range of 99.17 ± 0.25 to 99.88 ± 0.15 and 93.16 ± 0.38 to 98.89 ± 0.23, respectively. Measured dose verification indices were within the acceptable limit. Conclusions: The dosimetric study reveals that head phantom can be used for routine pretreatment verification for the cranial RT, especially for stereotactic radiosurgery/RT as a part of patient-specific quality assurance. The presently fabricated and validated phantom is novel, versatile, and cost-effective, and many institutes can afford it.

Original languageEnglish
Pages (from-to)66-70
Number of pages5
JournalJournal of Medical Physics
Volume45
Issue number2
DOIs
StatePublished - 1 Apr 2020
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2020 Wolters Kluwer Medknow Publications. All rights reserved.

Funding

We extend our sincere thanks to Dr. Thayal Singh Elias, Head, Radiation Physics Division, Regional Cancer Centre, Thiruvananthapuram, India, for his valuable support. This research work has been funded by Kerala State Council for Science, Technology, and Environment (KSCSTE), Kerala, India.

FundersFunder number
Kerala State Council for Science, Technology and Environment

    Keywords

    • Gamma analysis
    • head phantom
    • point dose

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