Iranian Journal of Medical Physics

Iranian Journal of Medical Physics

Diagnostic Reference Levels for Computed Tomography Examinations in Iran: A Nationwide Radiation Dose Survey

Document Type : Original Paper

Authors
Mohsen Asadinezhad 1
Mohammad Taghi Bahreyni Toossi 2
Mina Nouri 1
1 Department of Radiology Technology, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
2 Medical Physics Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
10.22038/ijmp.2018.33100.1402
Abstract
Introduction: International Commission on Radiological Protection introduced three basic principles of radiation protection, namely justification, optimization, and dose limit. Medical exposure has no dose limits, and generally, diagnostic reference levels are used as a tool for optimization of patient protection.
Material and Methods: Dosimetry was performed on 20 CT scanners located in 14 cities in 12 provinces of Iran. A calibrated pencil-shaped ionization chamber, standard head and body CT dosimetry phantoms and a radiation monitor were used to determine and calculate Computed Tomography Dose Index (CTDI) and Dose Length Product (DLP). The DLP-based estimates of effective dose were derived using effective dose conversion coefficients.
Results: The nCTDIw values for head phantoms fell within the range of 22.05-168.38 and 43.77-426.69 µGy/mAs for 5 and 10mm slice thicknesses, respectively. These values for body phantom were 4.65-146.39 and 9.43-308.92 µGy/mAs for 5 and 10mm slice thicknesses, respectively. The third quartile of CTDIvol and DLP values for head CT examinations were 49.85 mGy and 1161.00 mGy-cm, respectively. The body CT examinations had the values of 8.89 mGy and 370.97 mGy-cm, respectively. The findings of this study revealed that the above-mentioned values can be considered as national diagnostic reference levels for head and body CT examinations in Iran.
Conclusion: The results of the current study suggested that there is a need to re-assess DRLs for CT examinations at regular time intervals by the appropriate regulatory authority which can improve the continuous performance of CT scanners in Iran.
Keywords
Computed Tomography
Iran
Radiation Dosimetry
Subjects

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Iranian Journal of Medical Physics
Volume 16, Issue 1 - Serial Number 1
January and February 2019
Pages 19-26

  • Receive Date 30 June 2018
  • Revise Date 11 September 2018
  • Accept Date 11 September 2018