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SPECT scatter correction in non-homogeneous media

  • S R Meikle
  • B F Hutton
  • D L Bailey
  • R R Fulton
  • K Schindhelm
1. Image Formation And Reconstruction
Part of the Lecture Notes in Computer Science book series (LNCS, volume 511)

Abstract

Single photon emission computed tomography (SPECT) has the potential for quantitation of absolute activity concentration in vivo. The accuracy of activity estimates depends to a large extent on the accuracy of the attenuation and scatter corrections performed. This is particularly so in the thorax, where assumptions about regular object shape and constant density are inappropriate. We have developed a method of scatter correction based on convolution subtraction (CS) which takes account of variable tissue density. Rather than assuming the scatter fraction to be constant, the scatter fraction is determined at each point in the image based on measured photon transmission through the object. For comparison, a modified lower window subtraction (LWS) technique has also been developed, involving convolution of lower window data with a theoretically derived kernel, which more accurately relates lower window scatter to photopeak scatter compared with conventional LWS.

Both methods have been assessed in a phantom study using a non-uniform medium and distributed activity. The methods described were compared with the two conventional methods on which they are based. The accuracy for determining activity concentration was calculated for a 5cm diameter "hot" cylinder, the "warm" background and a 10cm diameter "cold" air cylinder. Quantitative accuracy of >95% was achieved in the "hot" cylinder and in the "warm" background for both the TDCS and MLWS methods, whilst all 4 methods yielded no significant reconstructed counts in the region of the "cold" air cylinder, indicating very good cold contrast.

Keywords

Quantitation attenuation transmission tomography convolution subtraction lower window subtraction 

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References

  1. Axelsson B, Msaki P and Israelsson A (1984): Subtraction of compton-scattered photons in single-photon emission computerized tomography. J Nucl Med 25:490–494.Google Scholar
  2. Bailey DL, Hutton BF, Walker PJ (1987). Improved SPECT using simultaneous emission and transmission tomography. J Nucl Med 28:844–851.Google Scholar
  3. Bailey DL, Hutton BF, Meikle SR, Fulton RR and Jackson CB (1989): Iterative scatter correction incorporating attenuation data (abstract). Eur J Nucl Med 15:452.Google Scholar
  4. Chang LT (1978). A method for attenuation correction in radionuclide computed tomography. IEEE Trans Nucl Sci NS-25:638–643.Google Scholar
  5. Hubbell JH (1963). A power series buildup factor formulation. Application to rectangular and off-axis disk source problems. J Res NBS 67C:291–306.Google Scholar
  6. Hutton BF, Bailey DL, Fulton RR and Meikle SR (1988). Use of a patient derived computer simulation for assessment of SPECT attenuation correction algorithms (abstract). Aust NZ J Med 18:508.Google Scholar
  7. Ivanovich M and Weber DA (1990). Monte Carlo study of compton scattering in SPECT (abstract). Eur J Nucl Med 16:404.Google Scholar
  8. Jaszczak RJ, Greer KL, Floyd CE Jr, Harris CC and Coleman RE (1984). Improved SPECT quantitation using compensation for scattered photons. J Nucl Med 25:893–900.Google Scholar
  9. Ljungberg M and Strand S (1990). Accurate scatter and attenuation correction of SPECT projections for extended sources in a non-homogeneous object: a Monte Carlo study. In: Development and evaluation of attenuation and scatter correction techniques for SPECT using the Monte Carlo method. Ljunberg M (thesis). University of Lund press, Lund, pp. 151–167.Google Scholar
  10. Moore SC (1982). Attenuation compensation. In: Computed emission tomography. Ell PJ and Holman BL (eds), Oxford University Press, London, pp. 339–360.Google Scholar
  11. Morozumi T, Nakajima M, Ogawa K and Yuta S (1988). Attenuation correction methods using the information of attenuation distribution for single photon emission CT. Med Imag Tech 2:20–28.Google Scholar
  12. Murase K, Itoh H, Mogami H, Ishine M, Kawamura M, Lio A, Hamamoto K (1987). A comparative study of attenuation correction algorithms in single photon emission computed tomography (SPECT). Eur J Nucl Med 13:55–62.Google Scholar
  13. Tan P, Bailey DL, Hutton BF, Fulton RR, Meikle SR, Keyser R and Barbagallo S (1989). A moving line source for simultaneous transmission/emission tomography (abstract). J Nucl Med 30:964.Google Scholar
  14. Todd-Pokropek A, Clarke G and Marsh R (1984). Preprocessing of SPECT data as a precursor for attenuation correction. In: Information processing in medical imaging. Deconninck F (ed), Martinus Nijhoff, Boston, pp 130–150.Google Scholar
  15. Wu RK and Siegal JA (1984). Absolute quantitation of radioactivity using the buildup factor. Med Phys 11:189–192.Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1991

Authors and Affiliations

  • S R Meikle
    • 1
  • B F Hutton
    • 1
  • D L Bailey
    • 1
  • R R Fulton
    • 1
  • K Schindhelm
    • 2
  1. 1.Department of Nuclear MedicineRoyal Prince Alfred HospitalSydney
  2. 2.Centre for Biomedical EngineeringUniversity of New South WalesSydneyAustralia

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