Journal of the Korean Society of Radiology (한국방사선학회논문지)

The Korean Society of Radiology (한국방사선학회)
권호 표지
DOI QR코드

DOI QR Code

Evaluation of Radiation Dose and Image Quality according to CT Table Height

CT 테이블 높이에 따른 방사선 선량 및 화질 평가

  • Lee, Jongwoong (Department of Radiology Kyung Hee University Hospital) ;
  • Jung, Hongmoon (Department of Radiological Science Daegu Health College)
  • Received : 2017.10.10
  • Accepted : 20171131
  • Published : 2017.11.30
Download PDF
⟨ Previous Next ⟩

Abstract

Computed Tomography (CT) provides information on the Diagnostic Reference Level Computed Tomography Dose Index (CTDI) and Dose Length Product (DLP) for accurate diagnosis of patients. However, it does not provide a dose change according to the table height for the diagnostic reference level provided by the CT equipment. The purpose of this study was to evaluate the image and dose according to the table height change using phantom (PMMA: Polymethyl Methacrylate) in order to find the optimal image and the minimum dose during computed tomography examination. When examining using a 32 cm PMMA phantom with the same thickness as the abdomen of an adult, there was little change in dose with table height. However, the noise evaluation of the image caused a high fluctuation of noise depending on the table height. and in the case of the 16 cm PMMA phantom, the change of the noise was small, but the dose change was about 30%. In conclusion, the location of the patient and the center of the detector are important during computed tomography (CT) examinations. In addition, table height setting is considered to be important for examinations with optimized image and minimum dose.

컴퓨터단층촬영 (CT:Computed Tomography)은 환자의 정확한 진단을 위해 진단참고준위인 전산화 단층촬영 선량지표 (CTDI: Computed Tomography Dose Index)와 (DLP:Dose Length Product)의 정보를 제공한다. 그러나 CT 장비가 제공하는 진단참고준위는 테이블 높이에 따른 선량의 변화를 제공하지 않는다. 이번 연구는 컴퓨터단층촬영 검사 시 최적화된 이미지와 최소선량을 찾기 위하여 컴퓨터단층촬영 테이블 높이 변화에 따른 이미지와 선량을 팬텀(PMMA: Polymethyl Methacrylate)을 사용하여 비교 평가하였다. 성인의 복부와 같은 두께인 32 cm PMMA 팬텀을 촬영할 경우 테이블 높이에 따른 선량 변화는 거의 없었다. 그러나 이미지의 노이즈(Noise) 평가에서는 테이블 높이에 따라 노이즈 변동 폭이 크게 발생되었다. 그리고 16 cm PMMA 팬텀인 경우는 노이즈의 변화는 작지만 선량변화는 약 30 % 발생하였다. 결론적으로 컴퓨터단층촬영 (CT:Computed Tomography)의 검사 시에는 환자의 두께에 중심에 정확하게 일치시켜야 한다. 또한 최적화된 이미지와 최소선량으로 검사하기 위해서는 테이블 높이 설정이 중요할 것으로 사료된다.

Keywords

References

  1. D.J. Brenner, "Estimating cancer risks from pediatric CT: going from thequalitative to the quantitative." Pediatr Radiol. Vol. 32, pp. 449-455, 2002.
  2. X.O. Shu, J.D. Potter, M.S, Linet, et al. "Diagnostic x-rays and ultrasound exposure and risk of childhood acute lymphoblastic leukemia by immuophenotype." Cancer Epidemiol Biomarkers Prev, Vol. 11, pp. 177-185, 2002.
  3. W. Huda, "Assessment of the problem: pediatric doses in screen-film and digital radiography." Pediatr Radiol, Vol. 33, No. 3, pp. 177-185, 2004. https://doi.org/10.1007/s00247-002-0840-2
  4. D. Hart , D. G. Jones, B.F Wall. "Coefficients for estimating effective dose from pediatric x-ray examinations.", National Radiological Protection Board Report, R279, NRPB, Oxon, 1996.
  5. M. Galanski, H.D.Nagel , G. Stamm, "Paediatric CT exposure practice in the federal republic of Germany: results of a nationwide survey in 2005-2006. Medizinische Hochschule." Hannover. 2007.
  6. J. Clarke ,K. Cranley, J Robinson , P.H. Smith, A. Workman,"Application of draft European Commission reference levels to a regional CT dose survey." Br J Radiol, Vol. 73, No. 865, pp. 43-50, 2000. https://doi.org/10.1259/bjr.73.865.10721319
  7. V. Tsapaki , J.E. Aldrich , R. Sharma , et al, "Dosereduction in CT while maintaining diagnostic confidence: diagnostic referecne levels at routine head, chest, and abdoinal CT-IAEA coordinated research project." Radiology, Vol. 240, No. 3, pp. 828-834, 2006. https://doi.org/10.1148/radiol.2403050993
  8. D. Hart ,B. F. Wall , P.C. Shrimpton ,et al, " Reference doses and patient size in pediatric radiology." National Radiological Protection Board Report, R318, NRPB, Oxon, 2000.
  9. "Radiation Safety Management Series No.31 Guideline for patient dose recommendation of CT CT Medical Imaging." KFDA, 2012.
  10. J.S. Lee, H. J. Kim, I.C. Im, "Analyzed the Computed Tomography Dose Index (CTDI) to the Pediatric Brain CT by Reason of the Observation for the Exposure Dose : Base on a Hospital." The Korea Contents Society, Vol. 15, No. 6, pp. 290-296, 2015.
  11. "Managing Patient Dose in Computed Tomography." International Radiation Protection Committee publication 87 , 2000.
  12. J. K. Lee, S. J. Jang, Y.I. Jang, "Medical Radiation Exposure in Children CT and Dose Reduction." The Journal of the Korea Contents Association, Vol. 14, No. 1, pp. 356-363, 2014. https://doi.org/10.5392/JKCA.2014.14.01.356