Assessment of Radiation Dose to the Lens of the Eye and Thyroid of Patients Undergoing Head and Neck Computed Tomography at Five Hospitals in Mashhad, Iran

Document Type: Original Paper

Authors

1 Medical Physics Department, Medical Physics Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.

2 Mashhad University of Medical Sciences

3 M.Sc. Student of Medical Physics, Medical Physics Dept., Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran

4 Medical Physics Department, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran

5 M.Sc. Student of Medical Imaging Technology, Medical Physics Dept., Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran

6 B.Sc. of Radiology, Department of Radiology Technology, Faculty of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran

7 M.Sc. of Medical Engineering, Medical Physics Dept., Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran

8 M.Sc. of Medical Physic, Medical Physics Dept., Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran

9 Medical Physics Research Center, Mashhad University of Medical Sciences, Mashahd, Iran.

10 Reza Radiotherapy Oncology Center, Mashhad, Iran

Abstract

Introduction: In recent years, the number of computed tomography (CT) scans, which is a high-dose technique, has increased significantly. Head and neck CT is performed frequently and thyroid, particularly in children, has always been considered a sensitive organ. In recent years, radiobiologists and health physicists have been more concerned about the safety of lenses of the eyes, as cataract is no longer considered a deterministic effect.
Material and Methods: In the present study, incurred doses to the thyroid and lens of the eye of 140 patients who underwent common head and neck CT at five hospitals were measured by thermoluminescent dosimeters (TLD-100). The patients were divided into two age groups of pediatrics and adults. TLD chips were placed on the patient’s skin surface. For each patient, scan parameters, sex and age were recorded. Exposed TLDs were read by a manual TLD reader.
Results: The verage absorbed dose of the thyroid, as well as the lenses of the left and right eyes were 5.89±1.74, 15.84±2.81 and 16.25±2.57, respectively, for the pediatric patients and 5.00±1.17, 17.64±1.69 and 24.41±1.89 for adults. Patient-specific organ doses were influenced by the scanned region, scan protocol and patient's age.
Conclusion: In the present study, the mean eye dose was much lower than the 500 mGy threshold recommended by International Commission on Radiological Protection (ICRP) for lens of the eye damage, thus, it appears to be clinically safe. While CT scan remains a crucial tool, further dose reduction can be achieved by controlling different factors affecting patient doses.

Keywords

Main Subjects


References

 

  1. Schauer DA, Linton OW. NCRP report No. 160, ionizing radiation exposure of the population of the United States, medical exposure—are we doing less with more, and is there a role for health physicists? Health physics. 2009;97(1):1-5.
  2. Seyedatashi S, Athari M, Bitarafan-Rajabi A, Hasanzadeh H, Rafati M, Pouraliakbar H, et al. Dosimetric evaluation of multislice ct using anthropomorphichead phantom. Frontiers in Biomedical Technologies. 2015;2(1):31-5.
  3. Jibiri N, Adewale A. Estimation of radiation dose to the lens of eyes of patients undergoing cranial computed tomography in a teaching Hospital in Osun state, Nigeria. International Journal of Radiation Research. 2014;12(1):53.
  4. Mazonakis M, Tzedakis A, Damilakis J, Gourtsoyiannis N. Thyroid dose from common head and neck CT examinations in children: is there an excess risk for thyroid cancer induction? European radiology. 2007;17(5):1352-7.
  5. Lee YH, Park E-t, Cho PK, Seo HS, Je B-K, Suh S-i, et al. Comparative analysis of radiation dose and image quality between thyroid shielding and unshielding during CT examination of the neck. American Journal of Roentgenology. 2011;196(3):611-5.
  6. Dougeni E, Faulkner K, Panayiotakis G. A review of patient dose and optimisation methods in adult and paediatric CT scanning. European journal of radiology. 2012;81(4):e665-e83.
  7. Wiest PW, Locken JA, Heintz PH, Mettler FA, editors. CT scanning: a major source of radiation exposure. Seminars in Ultrasound, CT and MRI; 2002: Elsevier.
  8. Abuzaid MM EW, Haneef C, Alyafei S. Thyroid shield during brain CT scan: dose reduction and image quality evaluation. Imaging Med. 2017;9(3):4.
  9. Niu Y, Wang Z, Liu Y, Liu Z, Yao V. Radiation dose to the lens using different temporal bone CT scanning protocols. American Journal of Neuroradiology. 2010;31(2):226-9.
  10. Beaconsfield T, Nicholson R, Thornton A, Al-Kutoubi A. Would thyroid and breast shielding be beneficial in CT of the head? European radiology. 1998;8(4):664-7.
  11. Bassim MK, Ebert CS, Sit RC, Senior BA. Radiation dose to the eyes and parotids during CT of the sinuses. Otolaryngology-Head and Neck Surgery. 2005;133(4):531-3.
  12. Ploussi A, Stathopoulos I, Syrgiamiotis V, Makri T, Hatzigiorgi C, Platoni K, et al. Direct Measurements Of Skin, Eye Lens And Thyroid Dose During Pediatric Brain Ct Examinations. Radiation protection dosimetry. 2017;179(3):199-205.
  13. Mahdavi M, Hosseinnezhad M, Vahabi Moghaddam M. Determination of radiosensitive organs in head CT for the head area. Iranian Journal of Science and Technology (Sciences). 2015;39(3.1):441-4.
  14. Cohnen M, Fischer H, Hamacher J, Lins E, Kötter R, Mödder U. CT of the head by use of reduced current and kilovoltage: relationship between image quality and dose reduction. American journal of neuroradiology. 2000;21(9):1654-60.
  15. Asgari A, Parach A, Sharafi A, Nazarparvar B, Parvizi S. Thyroid, Parathyroid and Eye Dose Evaluation in Head and Neck Computed Tomography Examinations, Phantom and Clinical Study. West Indian Medical Journal. 2016;65(3).
  16. Jaffe TA, Hoang JK, Yoshizumi TT, Toncheva G, Lowry C, Ravin C. Radiation dose for routine clinical adult brain CT: variability on different scanners at one institution. American Journal of Roentgenology. 2010;195(2):433-8.
  17. Lam SY, Bux SI, Kumar G, Ng KH, Hussain AF. A comparison between low-dose and standard-dose non-contrasted multidetector CT scanning of the paranasal sinuses. Biomedical imaging and intervention journal. 2009;5(3):e13.
  18. Ngaile JE, Msaki PK. Estimation of patient organ doses from CT examinations in Tanzania. Journal of Applied Clinical Medical Physics. 2006;7(3):80-94.
  19. Suzuki S, Furui S, Ishitake T, Abe T, Machida H, Takei R, et al. Lens exposure during brain scans using multidetector row CT scanners: methods for estimation of lens dose. American Journal of Neuroradiology. 2010;31(5):822-6.
  20. Tan J, Tan K-L, Lee J, Wan C-M, Leong J-L, Chan L-L. Comparison of eye lens dose on neuroimaging protocols between 16-and 64-section multidetector CT: achieving the lowest possible dose. American Journal of Neuroradiology. 2009;30(2):373-7.
  21. Zammit-Maempel I, Chadwick C, Willis S. Radiation dose to the lens of eye and thyroid gland in paranasal sinus multislice CT. The British journal of radiology. 2003;76(906):418-20.
  22. AKPOCHAFOR M. ABDOMEN-PELVIS. Radiation protection of patients and staff in diagnostic radiography, fluoroscopy and CT.27(6.6):29.8-7.1.