Estimation of Absorbed and Effective Doses in Organs through Computed Tomography Examinations Using Automatic Exposure Control and Fixed Tube Current Techniques: A Phantom Case Study

Document Type : Original Paper

Authors

1 Department of Medical Physics, Graduate School of Nuclear and Allied Sciences, University of Ghana, Accra, Ghana

2 Radiation Protection Institute, Ghana Atomic Energy Commission, Accra, Ghana

Abstract

Introduction: The study aimed to assess absorbed and effective doses in organs through computed tomography (CT) examinations using automatic exposure control (AEC) and fixed tube current (FTC) techniques.
Material and Methods: Scanning parameters were obtained for routine adult CT examinations and used to estimate the organ absorbed and effective doses using CT-Expo software. The estimated effective doses were based on International Commission on Radiological Protection publication 103 recommendations.
Results: Regarding the scans performed with AEC, doses to head, chest, abdomen and pelvic organs were within the range of 19.7-41.8, 6.4-17.4, 19.2-20.9, and 10.5-24.9 mGy respectively. Moreover, the effective doses for the mentioned organs were 1.6, 6.1, 6.4 and 5.4 mSv respectively. Considering FTC technique, doses to organs ranged 16.7-75.5, 4.1-52.2, 10.6-33.2 and 5.2-38.7 mGy respectively. Moreover, the mean effective doses of FTC were 2.1, 6.9, 9.4 and 6.1 mSv, respectively. Examinations performed with AEC technique induced a dose reduction of 9% and 34% for head organs, 52, 62 and 25% for chest organs, 16% and 14% for abdomen organs, and 11% and 10% for pelvic organs, compared to the FTC. A dose increase of 3% was observed for testes. The mean effective doses for scans with AEC were 13-46% lower than those obtained by FTC.
Conclusion:According to the obtained results of the current study, the estimated doses for scans with AEC technique were in a lower level compared to FTC technique. Accordingly, it is recommended to utilize this technique for CT examinations to ensure optimal dose reduction to radiosensitive organs.

Keywords

Main Subjects

References

  1.  

     

    1. Brenner,D.J, Hall, E. J. Computed tomography-An increasing source of radiation exposure. The New England Journal of Medicine. 2007; 357:          2277–84.
    2. United Nations Scientific Committee on   the effects of Atomic Radiation. UNSEAR Report to the General Assembly on Medical Radiation Exposures. New York, NY: United Nations, 2010; available from http://www.un scear.org. P. 2011.z.
    3. Schauer D. Ionizing Radiation Exposure of the Population of the United States. The National Council on Radiation Protection and Measurements (NCRP), Report. 2009(160).
    4. Chaparian A, Zarchi HK. Assessment of radiation induced cancer risk to patients undergoing computed tomography angiography scans. International Journal of Radiation Research. 2018;16(1): 107–15.
    5. ICRP Publication 60. 1990 recommendations of the International Commission on Radiological Protection. Ann.ICRP 1991;21(1-3):1-201.
    6. Brenner DJ, Elliston CD, Hall EJ, Berdon WE. Estimated risks of radiation fatal cancer from paediatric CT. Am J Roentgenol. 2001; 176:289–96.
    7. Deak PD, Smal Y, Kalender WA. Multisection CT Proto-cols: sex and age-specific conversion factors used to determine effective dose from dose-Length Product. Radiology. 2010 Oct: 257(1): 158 – 66
    8. Brix G, Nagel HD, Stamm G, Veit R, Lechel U, Griebel J, Galanski M. Radiation exposure in multi-slice versus single-slice spiral CT: results of a nationwide survey. European Radiology. 2003 Aug 1; 13(8):1979–91.
    9. Muhogora WE, Nyanda AM, Ngoye WM, Shao D. Radiation doses to patients during selected CT procedures at four hospitals in Tanzania. European Journal of Radiology. 2006 Mar 1; 57(3): 461-7.
    10. Hidajat, N., Mäurer, J., Schröder, R. J., Nunnemann, A., Wolf, M., Pauli, K., et al. Relationships between physical dose quantities and patient dose in CT. British Journal of Radiology 1999; 72(858):556– 61.
    11. Geleijns J, Van Unnik JG, Zoetelief J, Zweers D, Broerse JJ. Comparison of two methods for assessing patient dose from computed tomography. The British Journal of Radilogy.1994 Apr; 67(796):360–65.
    12. Kalra MK, Naz N, Rizzo SM, Blake MA. Computed tomography radiation dose optimization: Scanning protocols and clinical applications of automatic exposure control. Current Problems in Diagnostic Radiology. 2005 Sep 1; 34(5): 171–81.
    13. Siemens. Computed Tomography; Its History and Technology. Siemens Medical, 2010; 1–36.
    14. Söderberg M. Automatic exposure control in CT: An investigation between different manufacturers con-sidering radiation dose and image quality. Acta Radiol. 2010: 626-37
    15. Keat N. Report 05016 CT scanner automatic exposure control systems. Medicines and Healthcare Products Regulatory Agency. London, England: ImPACT, 2005.
    16. Stamm G, Nagel H. CT-Expo: A novel program for dose evaluation in CT. Rofo. 2002;174:1570-6.
    17. Shope TB, Gagne RM, Johnson GC. A method for describing the doses delivered by transmission X-rays computed tomography.Medical Physics. 1981 Jul;8(4): 488-95.
    18. Shrimpton PC Hart D, Hillier MC, Wall BF Faulkner F. Survey of CT practice in the UK. Part 2: Dosimetric as-pects, NRPB-R249. Chilton: National Radiological Pro-tection Board. 1991.
    19. Acquah GF, Schiestl B, Cofie AY, Nkansah JO, Gustavsson M. Radiation dose reduction without degrading image quality during computed tomography examinations: Dosimetry and quality control study. Int J Cancer Ther Oncol 2014; 2: 02039.
    20. Nishizawa K, Maruyama T, Takayama M, Okada M, Hachiya J, Furuya Y. Determination of organ doses and effective dose equivalents from computed tomographic examination. The British Journal of Radiology 1991 Jan; 64(757): 20–28.
    21. Ngaile JE, Msaki PK. Estimation of patient organ doses from CT examinations in Tanzania. Journal of Applied Clinical Med Phys. 2006; 7(3): 80–94.
    22. Breiki G, Abbas Y, El-Ashry M, Diyab H. Evaluation of Radiation Dose and Image Quality for Patients Undergoing Computed Tomography Examinations. In IX Radiation Physics & Protection Conference, 15-19 November Nasr City - Cairo, Egypt. 2008; 141- 56.
    23. Goddard CC, Al-Farsi A. Radiation doses from CT in the Sultanate of Oman. British Journal of Radiology 1999. 72(863):1073–77.
    24. Inkoom S, Schandorf C, Boadu M, Emi-Reynolds G, Nkansah A. Adult medical X-ray dose assessments for computed tomography procedures in Ghana – a review paper. Journal of Agricultural Science and Technology. 2014; 19(1-2): 1–9.
    25. United Nations Scientific Committee on the Effects of Atomic Radiation, (UNSCEAR): Report of the United Nations Scientific Committee on the effects of atomic radiation, 2008.
    26. Clarke J, Cranley K, Robinson J, Smith S, Workman A. Application of draft European commission reference levels to a regional CT dose survey. The British journal of radiology. 2000; 73(856): 43-50.
Iranian Journal of Medical Physics
Volume 17, Issue 1 - Serial Number 1
January and February 2020
Pages 58-65

Files

History

  • Receive Date: 24 January 2019
  • Revise Date: 13 March 2019
  • Accept Date: 15 March 2019

Share

How to cite

Statistics