Optimizing Compton camera geometries.

Compton cameras promise to improve the characteristics of nuclear medicine imaging, wherein mechanical collimation is replaced with electronic collimation. This leads to huge gains in sensitivity and, consequently, a reduction in the radiation dosage that needs to be administered to the patient. Design modifications that improve the sensitivity invariably compromise resolution. The scope of the current project was to determine an optimal design and configuration of a Compton camera that strikes a balance between these two properties. Transport of the photon flux from the source to the detectors was simulated with the camera geometry serving as the parameter to be optimized. Two variations of the Boltzmann photon transport equation, with and without photon polarization, were employed to model the flux. Doppler broadening of the energy spectra was also included. The simulation was done in a Monte Carlo framework using GEANT4. Two clinically relevant energies, 140 keV and 511 keV, corresponding to 99mTc and 18F were simulated. The gain in the sensitivity for the Compton camera over the conventional camera was 100 fold. Neither Doppler broadening nor polarization had any significant effect on the sensitivity of the camera. However, the spatial resolution of the camera was affected by these processes. Doppler broadening had a deleterious effect on the spatial resolution, but polarization improved the resolution when accounted for in the reconstruction algorithm.

[1]  A Compton camera for nuclear medicine applications using 113mIn1 , 1999 .

[2]  K. Koral,et al.  SPRINT II: a second generation single photon ring tomograph. , 1988, IEEE transactions on medical imaging.

[3]  T. Tomitani,et al.  An analytical image reconstruction algorithm to compensate for scattering angle broadening in Compton cameras. , 2003, Physics in medicine and biology.

[4]  Jorge Eduardo Fernandez.  Polarization effects in x‐ray photon diffusion , 1993 .

[5]  T. Tomitani,et al.  Image reconstruction from limited angle Compton camera data , 2002, Physics in medicine and biology.

[6]  Neal H. Clinthorne,et al.  Experimental results from the C-SPRINT prototype Compton camera , 1998 .

[7]  L. Parra,et al.  Reconstruction of cone-beam projections from Compton scattered data , 1999, 1999 IEEE Nuclear Science Symposium. Conference Record. 1999 Nuclear Science Symposium and Medical Imaging Conference (Cat. No.99CH37019).

[8]  J. Leblanc,et al.  A Compton camera for low energy gamma ray imaging in nuclear medicine applications. , 1999 .

[9]  J. F. Butler,et al.  Feasibility of using cadmium-zinc-telluride detectors in electronically collimated SPECT , 1995 .

[10]  John D. Valentine,et al.  The spatially-variant back-projection point kernel function of an energy-subtraction Compton scatter camera for medical imaging , 1996 .

[11]  W. Heitler,et al.  The quantum theory of radiation , 1936 .

[12]  Maria Grazia Pia,et al.  GEANT4 low energy electromagnetic models for electrons and photons , 1999 .

[13]  Tumay O. Tumer,et al.  A high sensitivity, electronically collimated gamma camera , 1996 .

[14]  J. D. Valentine,et al.  An energy-subtraction Compton scatter camera design for in vivo medical imaging of radiopharmaceuticals , 1996 .

[15]  J. M. Nightingale,et al.  A proposed γ camera , 1974, Nature.

[16]  C. E. Ordonez,et al.  A concept of cylindrical Compton camera for SPECT , 1997, 1997 IEEE Nuclear Science Symposium Conference Record.

[17]  Manbir Singh,et al.  An electronically collimated gamma camera for single photon emission computed tomography. Part I: Theoretical considerations and design criteria , 1983 .

[18]  Jorge E. Fernandez.  Polarisation effects in multiple scattering photon calculations using the Boltzmann vector equation , 1999 .

[19]  Alfred O. Hero,et al.  3D image reconstruction for a Compton SPECT camera model , 1999 .

[20]  Richard M. Leahy,et al.  Noise propagation in electronically collimated single photon imaging , 1988 .

[21]  M. Singh,et al.  Experimental test-object study of electronically collimated SPECT. , 1990, Journal of nuclear medicine : official publication, Society of Nuclear Medicine.

[22]  G. Knoll.  Radiation detection and measurement , 1979 .

[23]  High pressure xenon electronically collimated camera for low energy gamma ray imaging , 1996, 1996 IEEE Nuclear Science Symposium. Conference Record.

[24]  Neal H. Clinthorne,et al.  C-SPRINT: a prototype Compton camera system for low energy gamma ray imaging , 1997 .

[25]  Roland Ribberfors,et al.  Relationship of the relativistic Compton cross section to the momentum distribution of bound electron states , 1975 .

[26]  Manbir Singh,et al.  An electronically collimated gamma camera for single photon emission computed tomography. Part II: Image reconstruction and preliminary experimental measurements , 1983 .

[27]  D. Wehe,et al.  A source reconstruction method for multiple scatter Compton cameras , 1991, Conference Record of the 1991 IEEE Nuclear Science Symposium and Medical Imaging Conference.

[29]  Robert J. Ott,et al.  Gamma ray imaging with silicon detectors — A Compton camera for radionuclide imaging in medicine , 1988 .

[30]  J. D. Valentine,et al.  A novel Compton scatter camera design for in-vivo medical imaging of radiopharmaceuticals , 1995, 1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record.

[31]  Wei Chang,et al.  Dependence of angular uncertainties on the energy resolution of Compton cameras , 1997, 1997 IEEE Nuclear Science Symposium Conference Record.

[32]  Elena Aprile,et al.  The Polarization Sensitivity of the Liquid Xenon Imaging Telescope , 1993 .