Abstract
Introduction: The use of radionuclides in telecobalt and brachytherapy machines demands safe handling of the equipment and accurate measurement of source activity to ensure safety of the patients, workers and public. This paper reports dosimetric consistency of few Quality Assurance parameters of Theratron Phoenix Telecobalt and micro Selectron HDR Brachytherapy machines performed for a period of thirteen years from 2007 to 2019.
Materials and Method: The output of the telecobalt unit for both SSD and SAD techniques and the source strength of the HDR Brachytherapy unit in terms of RAKR were measured as per national and international guidelines. The percentage variations between measured and theoretically calculated values were obtained for the thirteen years period. Timer error, error in Timer linearity and variations in TPS vs. manually calculated treatment times were calculated for the HDR unit after each source replacements.
Results: The results obtained from the measurements done all over the thirteen years period were found to be well within the stipulated values specified by competent authority. The results were shown in graphical and tabulated form.
Conclusion: The results show that the parameters measured were well within tolerance limits for a long period of thirteen years. Hence, this study establishes the consistency and accuracy in the dosimetric parameters of the Theratron Phoenix and micro Selectron HDR Brachytherapy machines.
Keywords: Telecobalt, Brachytherapy, Reference Air Kerma Rate, Timer Error and Linearity, Dosimetric Consistency, TPS.
References
- Zubizarreta EV, Van Dyk J, Lievens Y. Analysis of global radiotherapy needs and costs by geographic region and income level. Clinical Oncology. 2017 Feb 1;29(2):84-92.
- Grover S, Xu MJ, Yeager A, Rosman L, Groen RS, Chackungal S, Rodin D, Mangaali M, Nurkic S, Fernandes A, Lin LL. A systematic review of radiotherapy capacity in low-and middle-income countries. Frontiers in oncology. 2015 Jan 22;4:380.
- Kutcher GJ, Coia L, Gillin M, Hanson WF, Leibel S, Morton RJ, Palta JR, Purdy JA, Reinstein LE, Svensson GK. Comprehensive QA for radiation oncology: Report of AAPM Radiation Therapy Committee Task Group 40. Medical Physics. 1994;21(4):581-618.
- Biggs PJ, Ling CC, Purdy JA, van de Geijn J. AAPM code of practice for radiotherapy accelerators: report of AAPM Radiation Therapy Task Group No. 45. Medical Physics. 1994 Jul;21:1093.
- Klein EE, Hanley J, Bayouth J, Yin FF, Simon W, Dresser S, Serago C, Aguirre F, Ma L, Arjomandy B, Liu C. Task Group 142 report: Quality assurance of medical accelerators. Medical physics. 2009 Sep 1;36(9Part1):4197-212.
- Radiological Physics & Advisory Division, Bhabha Atomic Research Centre. Acceptance/Quality Assurance tests for telegamma (teletherapy) therapy unit. RP&AD/telegamma/QA/01. Mumbai, India: BARC, 2001.
- Nath R, Anderson LL, Meli JA, Olch AJ, Stitt JA, Williamson JF. Code of practice for brachytherapy physics: report of the AAPM Radiation Therapy Committee Task Group No. 56. Medical physics. 1997 Oct 1;24(10):1557-98.
- International Atomic Energy Agency. Absorbed dose determination in external beam radiotherapy: An International Code of Practice for Dosimetry based on standards of absorbed dose to water. TRS 398. International Atomic Energy Agency, Vienna. 2000.
- Radiological Physics & Advisory Division, Bhabha Atomic Research Centre. Performa for acceptance/quality assurance tests on remote after loading brachytherapy unit, RP&AD Remote QA/01. Mumbai, India: BARC, 2001.
- International Atomic Energy Agency. Calibration of Brachytherapy Sources, IAEA‑TECDOC‑1079. Guidelines on Standardized Procedures for Calibration of Brachytherapy Sources at Secondary Standards Dosimetry Laboratories and Hospitals. Vienna: IAEA; 1999.
- Saminathan S, Godson HF, Ponmalar R, Manickam R, Mazarello J. Dosimetric evaluation of newly developed well-type ionization chamber for use in the calibration of brachytherapy sources. Journal of medical physics. 2016 Oct;41(4):234.
- American Association of Physicists in Medicine. Specification of brachytherapy source strength. AAPM Report No. 21. AAPM,1987.
- International Commission on Radiation Units and Measurements. Dose and volume specifications for reporting intracavitary therapy in gynaecology. ICRU Report 38. International Commission on Radiation Units and Measurements, Bethesda, Maryland, 1985.
- International Atomic Energy Agency. Measurement uncertainty: A practical guide for secondary standards dosimetry laboratories. IAEA‑TECDOC International Atomic Energy Agency, Vienna. 2008.
Corresponding Author
Pranjal Goswami, MSc., DRP
Medical Physicist, Dept. of Radiation Oncology, Dr. B. Borooah Cancer Institute, Guwahati, Assam
DOI: https://dx.doi.org/10.18535/jmscr/v8i8.41
