Journal of Radiation Protection and Research

The Korean Association for Radiation Protection (대한방사선방어학회)
권호 표지

Measurement of Patient Dose from Computed Tomography Using Physical Anthropomorphic Phantom

물리적 팬텀을 이용한 CT 촬영 환자의 피폭 선량 측정 및 평가

  • 장기원 (방사선 안전 신기술 연구센터) ;
  • 이춘식 (방사선 안전 신기술 연구센터) ;
  • 권정완 (한양대학교 원자력공학과) ;
  • 이재기 (한양대학교 원자력공학과)
  • Published : 2005.09.30
Download PDF
⟨ Previous Next ⟩

Abstract

The computed tomogrpahy(CT) provides a high quality in images of human body but contributes to the relatively high patient dose. The frequency of CT examination is increasing and, therefore, the concerns about the patient dose are also increasing. In this study the experimental determination of patient dose was performed by using a physical anthropomorphic phantom and thermoluminescent dosimeter(TLD). The measurements were done for the both axial and spiral scan mode. As a result the effective doses for each scan mode were 17.78mSv and 10.01 mSv respectively and the fact that the degree of the reduction in the patient dose depends on the pitch scan parameter was confirmed. The measurement methods suggested in this study can be applied for the reassessment of the patient dose when the technique in CT equipment is developed or the protocol for CT scanning is changed.

전산화단층촬영(Computed Tomography, CT)은 높은 품질의 인체 단층 영상을 제공하지만 기존의 진단 X선 촬영에 비해 상당히 높은 선량을 환자에게 부여한다. 더욱이 CT 촬영의 수요는 계속적인 증가추세를 보이고 있어 CT 촬영 환자의 선량에 대한 관심이 높아지고 있다. 이에 본 연구에서는 물리적 실측 팬텀과 열형광 선량계를 이용하여 CT 촬영으로 인한 환자의 피폭 선량을 측정을 통해 평가해 보았다. 촬영방식을 기존의 축방향 스캔과 현재 주류를 이루고 있는 나선형 스캔으로 구분하여 선량 측정을 수행하였으며 그 결과 환자의 유효선량이 각각 17.78mSv, 10.01mSv으로 평가되었다. 또한 나선형 스캔 시 환자 선량의 감축 정도는 pitch에 의존한다는 기존의 연구결과를 재확인할 수 있었다. 본 연구에서 사용한 실측 기법은 CT 기술 발전에 기인한 촬영 프로토콜의 변화가 있는 경우 환자 선량 재평가에 응용할 수 있다.

Keywords

References

  1. ICRP, Managing Patient Dose in Computed Tomography, International Commission on Radiological Protection, ICRP Publication 87 (2001)
  2. NRPB, Survey of CT Practice in the UK Part 3: Normalised Organ Doses Calculated using Monte Carlo Techniques, National Radiological Protection Board, NRPB-R250(1991)
  3. GSF, The calculation of dose from external photon exposures using reference human phantoms and Monte Carlo methods, Part VI: Organ doses from tomographic examinations, Gesellschaft Fur Strahlen-und Umweltforschung mbH, GSF Rep 30/91(1991)
  4. K.K.L. Fung, W. B. Gilboy, 'Anode heel effect on patient dose in lumbar spine radiography,' Br. J. Radiol, 73, 531-536 (2000) https://doi.org/10.1259/bjr.73.869.10884750
  5. J. Geleijns, J. G. Van Unnik, J. Zoeteliff, D. Zweers, J. J. Broerse, 'Comparison of two methods for assessing patient dose from computed tomography,' Br. J. Radiol, 67, 360-365(1994) https://doi.org/10.1259/0007-1285-67-796-360
  6. A. Calzado, S. Ruiz Sanz, M. Melochor, E. Vano, 'A comparison of measured and calculated organ doses from CT examinations,' Radial Prot. Dosim, 57 (1-4), 381-385(1995) https://doi.org/10.1093/oxfordjournals.rpd.a082565
  7. ICRU, Tissue Substitutes in Radiation Dosimetry and Measurement, International Commission on Radiation Units and Measurements, ICRU Publication 44(1989)
  8. ICRP, Recommendations of the InternatCommission on Radiological Protectionional , International Commission on Radiological Protection, ICRP Publication 60(1991)
  9. W. S. Snyder, M. R. Ford, G. G. Warner, 'Estimates of Specific Absorbed Fraction for Photon Sources Uniformly Distributed in Various Organs of a Heterogeneous Phantom,' Society of Nuclear Medicine, New York, MIRD Pamphlet No. 5. Revised (1978)
  10. J. L. Muniz et al, 'A study of LiF GR-200 for radiotherapy mailed dosimetry,' Phys. Med. Biol, 42, 2569-2576(1997) https://doi.org/10.1088/0031-9155/42/12/020
  11. J. L. Ioppolo, R. I. Price, T. Tuchyna, C. E. Buckley, ' Diagnostic x-ray dosimetry using Monte Carlo simulation,' Phys. Med Biol., 47, 1707-1720(2002) https://doi.org/10.1088/0031-9155/47/10/307
  12. K. Cranley, B. J. Gilmore, G. W. A. Fogarty, L. Desponds, Catalogue of Diagnostic X-ray Spectra and Other Data, The Institute of Physics and Engineering in Medicine Report No.78(1997)
  13. J. H. Hubbell, S. M. Seltzer, 'Tables of X-Ray Mass Attenuation Coefficients and Mass Energy-Absorption Coefficients,' National Institute of Standards and Technology, Gaithersburg (at http://phvsics.nist.gov/PhvsRefData/XravMassCoef /cover.html)(1996)
  14. G. Drexler, 'Verlauf der lonendosis an Grenzschichten, In Microdosimetry', Proc. Symp. Microdosimetry, Ispra, 13-15, EIR3747 d-f-e, European Communities, Brussels(1968)
  15. Rosenstein M., 'Organ Doses in Diagnostic Radiology,' US Department of Health, Education and Welfare, Bureau of Radiological Health BRH Tech. Publ., DA 76-8030(1976)
  16. Michael F. McNitt-Gray, Christopher H. Cagnon, 'Radiation dose in Sprial CT: The relative effects of collimation and pitch,' Med. Phys., 26(3), 409-414(1999) https://doi.org/10.1118/1.598532