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Variation in patient dose due to differences in calibration and dosimetry protocols

  • Wazir Muhammad
  • Asad Ullah
  • Gulzar Khan
  • Tahir Zeb Khan
  • Tauseef Jamaal
  • Fawad Ullah
  • Matiullah Khan
  • Amjad Hussain
Article

Abstract

For precise and accurate patient dose delivery, the dosimetry system must be calibrated properly according to the recommendations of standard dosimetry protocols such as TG-51 and TRS-398. However, the dosimetry protocol followed by a calibration laboratory is usually different from the protocols that are followed by different clinics, which may result in variations in the patient dose. Our prime objective in this study was to investigate the effect of the two protocols on dosimetry measurements. Dose measurements were performed for a Co-60 teletherapy unit and a high-energy Varian linear accelerator with 6 and 15 MV photon and 6, 9, 12, and 15 MeV electron beams, following the recommendations and procedures of the AAPM TG-51 and IAEA TRS-398 dosimetry protocols. The dosimetry systems used for this study were calibrated in a Co-60 radiation beam at the Secondary Standard Dosimetry Laboratory (SSDL) PINSTECH, Pakistan, following the IAEA TRS-398 protocol. The ratio of the measured absorbed doses to water in clinical setting, Dw (TG-51/TRS-398), was 0.999 and 0.997 for 6 and 15 MV photon beams, whereas these ratios were 1.013, 1.009, 1.003, and 1.000 for 6, 9, 12, and 15 MeV electron beams, respectively. This difference in the absorbed doses-to-water Dw ratio may be attributed mainly due to beam quality (KQ) and ion recombination correction factor.

Keywords

Radiation dosimetry Dosimetry systems calibrations Patient dose Absorbed dose-to-water ratio AAPM TG-51 IAEA TRS-398 

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Copyright information

© Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Chinese Nuclear Society, Science Press China and Springer Nature Singapore Pte Ltd. 2018

Authors and Affiliations

  • Wazir Muhammad
    • 1
    • 2
  • Asad Ullah
    • 2
  • Gulzar Khan
    • 3
  • Tahir Zeb Khan
    • 3
  • Tauseef Jamaal
    • 4
  • Fawad Ullah
    • 5
  • Matiullah Khan
    • 5
  • Amjad Hussain
    • 6
  1. 1.Department of Therapeutic Radiology, Yale-School of MedicineYale UniversityNew HavenUSA
  2. 2.Heath Physics Division (HPD)Pakistan Institute of Nuclear Science and Technology (PINSTECH)IslamabadPakistan
  3. 3.Department of PhysicsAbul Wali Khan UniversityMardanPakistan
  4. 4.Pakistan Institute Nuclear Science & Technology (PIEAS)IslamabadPakistan
  5. 5.Department of PhysicsKohat University of Science and TechnologyKohatPakistan
  6. 6.Department of Medical PhysicsCancerCare ManitobaBrandonCanada

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