Determination of Absorbed Radiation Dose Levels of Lenses Thyroid and Oral Mucosa in Computed Tomography Imagining: Phantom Study

Öz

Objective: Head-neck computed tomography (CT) imaging is one of the most common tomography examinations in medical imaging. Lenses and thyroid are among the most sensitive organs to radiation. The aim of this study was to determine the radiation dose levels to which the patient's lens, oral mucosa, and thyroid were during head and neck CT imaging.

Methods: Thyroid, oral mucosa and lens areas of human equivalent Alderson rando phantom were placed in thermoluminescence dosimeter (TLD) dosimeters and computerized tomography imaging of head-neck of phantom was performed in this study. A total of 18 TLD dosimetry was used in this study. Firstly, dosimeters were calibrated. 6 of these dosimeters were placed on the thyroid of the phantom and 4 of them were placed in the mouth and 4 of them were in the lens. 4 dosimeters were used for background measurements

Results: The radiation dose in TLDs placed at the center of the lens was between 15.03 and 23.71 mSv (mean 19.83±3.93 mSv), the oral mucosa was 10.36 to 19.47 mSv (mean 15.15±2.96 mSv), and the thyroid gland was between 11.21 and 16.73 mSv (mean 13.97±3.90 mSv).

Conclusion: The permissible radiation dose for whole body and eye lenses in ICRP reports is 20 mSv/year for radiation officers. Likewise, there is no definite limit for patients, it is aimed to keep the dose level to a minimum. Therefore, knowing the reference dose is important for imaging planning.

Anahtar Kelimeler

• radiation dose,thyroid,lens,computed tomography,Thermoluminescence dosimeter

Bilgisayarlı Tomografi Çekimlerinde Lens Tiroid ve Oral Mukoza Absorbe Radyasyon Doz Düzeylerinin Belirlenmesi: Fantom Çalışması

Öz

Amaç: Baş ve boyun bilgisayarlı tomografi (BT) görüntülemesi, en sık kullanılan radyolojik incelemelerinden biridir. Birçok hastalığın tanısında önemli rol oynar. Lens ve tiroid bezi radyasyona karşı en duyarlı organlardandır. Bu çalışmanın amacı, BT görüntülemesi yapılan hastaların, lens, oral mukoza ve tiroid dokusunun maruz kaldığı radyasyon dozunun belirlenmesidir.

Yöntem: Çalışmada, insan eşdeğeri olan Alderson Rando fantomunun tiroid, oral mukoza, lens bölgelerine termolüminesans dozimetreleri (TLD) yerleştirilmiş ve fantomun baş-boyun bölgesinin BT görüntülemesi yapılmıştır. Toplam 18 adet TLD kullanılmıştır. Öncelikle dozimetrelerin kalibrasyon işlemleri yapılmıştır. Bu dozimetrelerden 6 tanesi fantomun tiroid bölgesine, 4 tanesi oral mukozaya, 4 tanesi de lens bölgesine yerleştirilmiştir. 4 tane dozimetre ise arkaplan (background) ölçümleri için kullanılmıştır.

Bulgular: Lens merkezine yerleştirilen TLD’lerdeki radyasyon dozu 15,03 ile 23,71 mSv arasında (ortalama 19,83±3,93 mSv), oral mukozada 10,36 ile 19,47 mSv arasında (ortalama 15,15±2,96 mSv), tiroid bezinde ise 11,21 ile 16,73 mSv arasında (ortalama 13,97±3,90 mSv) bulunmuştur.

Sonuç: Uluslararası Radyolojik Koruma Komisyonu (ICRP)raporlarında tüm vücut ve lensler için müsaade edilen radyasyon dozu, radyasyon görevlilerinde 20 mSv/yıl’dır. Hastalar için kesin bir limit olmamakla beraber, doz düzeyinin minimum tutulması amaçlanır. Bu nedenle referans dozunun bilinmesi çekim planlaması için önemlidir.

Anahtar Kelimeler

• radyasyon dozu,göz,tiroid,bilgisayarlı tomografi,Termolüminesans dozimetreleri

Kaynakça

1. Sodickson A, Baeyens PF, Andriole KP, et al. Recurrent CT, cumulative radiation exposure and associated radiation-induced cancer risks from CT of adults. Radio. 2009;251(1):175-84.
2. McNitt-Gray MF. AAPM/RSNA physics tutorial for residents: topics in CT: radiation dose in CT. Radiograph. 2002;22(6):1541-1553.
3. Işık Z, Selçuk H, Albayram S. Bilgisayarlı tomografi ve radyasyon. Kln Gelşm. 2010;23:16-18.
4. Tomar SS, Bhargava A, Reddy N. Significance of computed tomography scans in head injury. Open J Clinic Diagn. 2013;3(03):109-114.
5. Sharif-Alhoseini M, Khodadadi H, Chardoli M, Rahimi-Movaghar V. Indications for brain computed tomography scan after minor head injury. J Emerg Trau Shoc. 2011;4(4):472-476.
6. Wang X, You JJ. Head CT for nontrauma patients in the emergency department: clinical predictors of abnormal findings. Radio. 2013;266(3):783-790.
7. Berrington de Gonzalez A, Darby S. Risk of cancer from diagnostic x-rays: estimates for the UK and 14 other countries. The Lancet. 2004;363(9406):345-351.
8. Ron E. Cancer risks from medical radiation. Health Phys. 2003;85(1):47-59.

9. Takamura N, Orita M, Saenko V, Yamashita S, Nagataki S, Demidchik Y. Radiation and risk of thyroid cancer: Fukushima and Chernobyl. Lancet Diabet Endoc. 2016;4(8):647.
10. Hall EJ, Brenner DJ. Cancer risks from diagnostic radiology. British J Radio. 2008;81(965):362-378.
11. Brenner DJ, Hall EJ. Computed tomography-an increasing source of radiation exposure. N Eng J Medic. 2007;357(22):2277-2284.
12. Amis ES Jr, Butler PF, Applegate KE, et al. American College of Radiology white paper on radiation dose in medicine. J Amerc Col Radio. 2007;4(5):272-284.
13. Hamada N, Fujimichi Y. Role of carcinogenesis related mechanisms in cataractogenesis and its implications for ionizing radiation cataractogenesis. Canc Letter. 2015;368(2):262-274.
14. Shore RE. Radiation and cataract risk: Impact of recent epidemiologic studies on ICRP judgments. Mutation Resc Rev Mutation Resrc. 2016;770:231-237.
15. Boal TJ, Pinak M. Dose limits to the lens of the eye: International Basic Safety Standards and related guidance. Ann ICRP. 2015;44(Suppl. 1):112-117.
16. Stewart FA, Akleyev AV, Hauer-Jensen M, et al. ICRP publication 118: ICRP statement on tissue reactions and early and late effects of radiation in normal tissues and organs-threshold doses for tissue reactions in a radiation protection context. Ann ICRP. 2012;41(1-2):1-322.
17. Lee GS, Ki JS, Seo YS, Kim JD. Effective dose from direct and indirect digital panoramic units. Imag Sci Dentis. 2013;43(2):77-84.
18. Günay O, Demir M. Bilgisayarlı tomografi çekimlerinde hastanın yakın çevresinde radyasyon dozu ölçümleri. SDÜ Fen Bilim Enst Derg. 2019;23(3):792-796.
19. Jibiri NN, Adewale AA. Estimation of radiation dose to the lens of eyes of patients undergoing cranial computed tomography in a teaching Hospital in Osun state, Nigeria. I J Radia Res. 2014;12(1):53-60.
20. Perisinakis K, Raissaki M, Tzedakis A, Theocharopoulos N, Damilakis J, Gourtsoyiannis N. Reduction of eye lens radiation dose by orbital bismuth shielding in pediatric patients undergoing CT of the head: a Monte Carlo study. Med Phys. 2005;32(4):1024-1030.
21. Kleiman NJ. Radiation cataract. Annals ICRP. 2012;41(3-4):80-97.
22. Chodick G, Bekiroglu N, Hauptmann M, et al. Risk of cataract after exposure to low doses of ionizing radiation: a 20-year prospective cohort study among US radiologic technologists. Am J Epidem. 2008;168(6):620-631.
23. Wang J, Duan X, Christner JA, Leng S, Grant KL, McCollough CH. Bismuth shielding, organ-based tube current modulation, and global reduction of tube current for dose reduction to the eye at head CT. Radio. 2012;262(1):191-198.
24. Lund E, Halaburt H. Irradiation dose to the lens of the eye during CT of the head. Neuroradio. 1982;22(4):181-184.
25. Akhilesh P, Kulkarni AR, Jamhale SH, Sharma SD, Kumar R, Datta D. Estimation of eye lens dose during brain scans using Gafchromic Xr-QA2 film in various multidetector CT scanners. Rad protect dosm. 2017;174(2):236-241.
26. Bahreyni Toossi MT, Zare H, Eslami Z, et al. 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. I J Med Phys. 2018;15(4):226-230.
27. Abuzaid MM, Elshami W, Haneef C, Alyafei S. Thyroid shield during brain CT scan: dose reduction and image quality evaluation. Imag Med. 2017;9(3):45-48.
28. Santos FS, Gomez AML, da Silva CAM, do Carmo Santana P, Mourao AP. Analysis of thyroid absorbed dose in cervical CT scan with the use of bismuth shielding. Brazil J Rad Scienc. 2019;7(2A):1-8.
29. Aytugar E, Kose TE, Gumru B, et al. Are bismuth shields useful in dentomaxillofacial radiology practice for the protection of eyes and thyroid glands from ionizing radiation? Iran J Radio. 2018;15(3):e40723. doi:10.5812/iranjradiol.40723
30. Iwai K, Hashimoto K, Nishizawa K, Sawada K, Honda K. Evaluation of effective dose from a RANDO phantom in video fluorography diagnostic procedures for diagnosing dysphagia. Dentomaxil Radio. 2011;40(2):96-101. doi:10.1259/dmfr/51307488