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The Study of Radiation Exposure Reduction by Developing Corpus Striatum Phantom

두개골-선조체 팬텀을 이용한 선량 저감화 방안 연구

  • Kim, Jung-Soo (Department of Radiological Technology, Dongnam Health University) ;
  • Park, Chan-Rok (Department of Nuclear Medicine, Seoul National University Hospital)
  • 김정수 (동남보건대학교 방사선과) ;
  • 박찬록 (서울대학교병원 핵의학과)
  • Received : 2017.09.18
  • Accepted : 2017.11.21
  • Published : 2017.12.31

Abstract

The study is to produced a brain phantom simulating corpus striatum, which can evaluate the progression of parkinson's disease, to investigate possibility of reducing the brain exposure dose to CT while maintaining optimal image quality during PET-CT examinations. CT scans were performed by varying tube voltage (100, 120 kVp) and tube current (80, 140, 200 mAs) with $^{18}F$ FP-CIT injected into the phantom's hot sphere and background (radioactivity ratio 3:1)(reference condition; 120 kVp, 140 mAs). Estimated effective dose was calculated by using conversion factor according to each condition, and image quality was evaluated by setting SNR and CRChot image evaluation factors. Experimental results showed that the predicted effective dose below the CT imaging reference condition was reduced by at least 10% and by up to 60%, and the predicted effective dose beyond the reference condition was increased by 40%. In addition, there was no significant difference between SNR and CRChot of PET images, and it was confirmed that brain dose decreased with decrease of tube voltage and tube current. At the same time, there was no significant change in the quality of the image in terms of SNR and CRChot despite the change in scan conditions. This fact suggests that the quality of the images acquired under the existing dose conditions can be obtained even at low dose conditions and it is expected that it will be possible to use the brain PET-CT scan as a basic data for the research on reduction of dose and improvement of image quality.

본 연구는 파킨슨질환의 진행 정도를 평가할 수 있는 선조체를 모사한 brain 팬텀을 직접 제작하여, PET-CT검사 시 최적의 영상의 질을 유지하면서 CT 스캔에 의한 brain 선량 저감을 위한 가능성을 평가하였다. 팬텀의 hot sphere와 background (radi oacti vi ty rati o 3:1)에 $^{18}F$ FP-CIT를 주입하고, 관전압(100, 120 kVp)과 관전류(80, 140, 200 mAs)의 조건을 변화시키며 CT 스캔을 실험하였다(기준조건; 120 kVp, 140 mAs). 각 조건에 따라 예상유효선량을 conversion factor를 적용해 계산하였고, SNR과 CRChot의 영상평가 인자를 설정하여 영상의 질을 평가하였다. 실험결과 CT 촬영 기준조건 이하에서의 예상유효선량은 최소 10%에서 최고 60% 정도 감소하였고, 기준조건 이상에서의 예상유효선량은 40% 증가하였다. 또한 PET 영상의 SNR과 CRChot의 유의한 차이는 없었으므로, 관전압과 관전류의 감소에 따라 brain 선량이 감소함을 확인하였다. 이와 동시에 스캔 조건의 변화에도 불구하고 SNR과 CRChot 측면에서의 영상의 질에는 유의한 변화가 없었다. 이러한 사실은 낮은 선량 조건으로도 기존의 선량 조건으로 획득한 영상의 질 수준을 얻을 수 있었으므로, 추후 brain PET-CT 스캔의 선량감소와 동시에 영상의 질 향상에 관한 연구의 기초자료로 활용이 가능할 것으로 사료된다.

Keywords

References

  1. Robeson W, Dhawan V, Belakhlef A, Ma Y, Pillai V, Chaly T, et al. Dosimetry of the dopamine transporter radioligand 18F FP-CIT in human subjects. J Nucl Med. 2003;44(6):961-966.
  2. Hong SK, Park KW, Cha JK, Kim SH, Chun DY, Yang CK, et al. Quality of life in patients with parkinson’s disease. J Korean Neurol Assoc. 2002;20(3):227-233.
  3. Chun HJ, Kim YS, Yi HJ, Ko Y, Oh SH, Choi YY. Clinical significance of 123I-IPT SPECT for the diagnosis of the parkinson’s disease. J Korean Neurosurg Soc. 2003;34:104-109.
  4. Kathleen R. Fink, James R, Fink. Imaging of brain metastases. Surg Neurol Int. 2013;4(4):209-219. https://doi.org/10.4103/2152-7806.111298
  5. Marc C Mabray, Ramon F Barajas, Cha SM. Modern brain tumor imaging. Brain Tumor Res Treat. 2015;3(1):8-23. https://doi.org/10.14791/btrt.2015.3.1.8
  6. Lee WY, Kim JY, Kim ST. Transcranial sonography in parkinsons’s disease and parkinsonism. Journal of Movement Disorders. 2008;1(1):6-12. https://doi.org/10.14802/jmd.08002
  7. Lee WH, Chung YA. Clinical application of $^{18}F$-FDG PET in parkinson's disease. Nucl Med Mol Imaging. 2008;42:177-180.
  8. Lee SG. Policy synchronization for high-tech medical devices in korea. J korean Med Assoc. 2012;55(10): 950-958. https://doi.org/10.5124/jkma.2012.55.10.950
  9. Pasha Razifar, Mattias Sandstrom, Harald Schnieder, Bengt Langstrom, Enn Maripuu, Ewert Bengtsson, et al. Noise correlation in PET, CT, SPECT and PET/CT data evaluated using autocorrelation function: a phantom study on data, reconstructed using FBP and OSEM. BMC Med Imaging. 2005;5(5):148-152.
  10. Marcus Soderberg, Mikael Gunnarsson. The effect of different adaptation strengths on image quality and radiation dose using siemens care dose 4D. Radiation Protection Dosimetry. 2010;139(1-3): 173-179. https://doi.org/10.1093/rpd/ncq098
  11. W Mazrani, K McHugh, PJ Marsden. The radiation burden of radiological investigations. Arch Dis Child. 2007;92(12):1127-1131. https://doi.org/10.1136/adc.2006.101782
  12. Vigh Teichmann I, Vigh B. The system of cerebrospinal fluid-contacting neurons. Arch Histol Jpn.1983;46(4):427-468. https://doi.org/10.1679/aohc.46.427
  13. Balajiranganathan Anupreethi, Shivaramu. Effective atomic numbers for photon energy absorption and energy dependence of some thermoluminescent dosimetric materials. IARP. 2016;39(2):62-67.
  14. Hidehiro Iida, Yuki Hori, Kenji Ishida, Etsuko Imabayashi, Hiroshi Matsuda, Masaaki Takahashi. Three-dimensional brain phantom containing bone and grey matter structures with a realistic head contour. Ann Nucl Med. 2013;27(1):25-36. https://doi.org/10.1007/s12149-012-0655-7
  15. Abraham T, Feng J. Evolution of brain imaging instrumentation. Semin Nucl Med. 2011;41(3): 202-219. https://doi.org/10.1053/j.semnuclmed.2010.12.001
  16. Qinan Bao, Arion F. Chatziioannou. Estimation of the minimum detectable activity of preclinical PET imaging systems with an analytical method. Med Phys. 2010;31(11):6070-6083.
  17. Daube-Witherspoon ME, Karp JS, Casey ME, DiFilippo FP, Hines H, Muehllehner G. PET performance measurements using the NEMA NU 2-2201 standard. J Nucl Med, 2002;43(10):1398-1409.
  18. Charles C. Watson, Michael E. Casey, Lars Eriksson, Tim Mulnix, Doug Adams, Bernard Bendriem. NEMA NU 2 performance tests for scanners with intrinsic radioactivity. J Nucl Med. 2004;45(5):822-826.
  19. AAPM Report 96, The measurement, reporting and management of radiation dose in CT. American Association of Physicists in Medicine. 2007.
  20. Ting Xia, Adam M. Alessio, Bruno De Man, Ravindra Manjeshwar, Evren Asma, Paul E. Kinahan. Ultra-low dose CT attenuation correction for PET/CT. Phys Med Biol. 2012;57(2):309-328. https://doi.org/10.1088/0031-9155/57/2/309
  21. Xia T, Alessio AM, Kinahan PE. Dual energy CT for attenuation correction with PET/CT. Med Phys. 2014;41(1):012501 https://doi.org/10.1118/1.4828838
  22. Joshi A, Koeppe RA, Fessler JA. Reducing between scanner differences in multi-center PET studies. NeuroImage. 2009;46(1):154-159. https://doi.org/10.1016/j.neuroimage.2009.01.057
  23. Calvini P, Rodriguez G, Inguglia F, Mignone A, Guerra UP, Nobili F. The basal ganglia matching tools package for striatal uptake semi-quantification : description and validation. Eur J Nucl Med Mol Imaging. 2007;34(8):1240-1253. https://doi.org/10.1007/s00259-006-0357-2