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Optimizing Compton camera performance
No full textAmore realistic simulation approach is used to study the behavior of the Compton camera in
this thesis than previous studies to date. The Compton camera differs from gamma cameras
in that the collimator is replaced by a detector known as the ‘scatterer’. Gamma rays may be
Compton scattered in the scatterer and subsequently detected by an ‘absorber’ which is the
equivalent of the detector in a gamma camera. By measuring the energies and the positions
of the points on the scatterer and the absorber where the incident and scattered gamma rays
interacted with the detectors, an image of the source can be reconstructed. Because there is
no collimator present, the potential sensitivity of the Compton camera is much higher than
the gamma camera, resulting in reduced acquisition times.
Most of the work described in this thesis was done with the GEANT4 Monte Carlo
simulation software. GEANT4 has been proven to be very robust and efficient in modelling
physics problems of radiation transport and interactions with matter in complex geometries.
Four major studies are carried out to estimate and optimize the performance of this
novel equipment. The first study takes a look at the scatterer’s imaging parameters with
the aim of prescribing an optimal scatterer material and geometry. In the second study,
the contribution of the absorber to the overall Compton camera performance is evaluated,
considering detector material, interaction type and geometry. The third study explores the
limitations imposed by the detector energy threshold and dead time on the Compton camera
performance, using a simplified model of the general electronic architecture. An evaluation
of Compton camera for scintimammography was performed in the fourth study. For
this study, three dual-head Compton camera models (Si/CZT, Si/LaBr₃:Ce and Si/NaI(Tl)
Compton cameras) were simulated, and the effect of scintillation photons’ interactions with
the photomultipliers was implemented.
The results show that silicon of about 1 cm thickness would be adequate as the Compton
camera scatterer. Analyses suggest however, that the choice of silicon is not completely
flawless. Doppler broadening for this detector material contributes as much as 7.3 mm
and 2.4 mm to full-width-at-half-maximum (FWHM) image resolution at 140.5 keV and
511 keV respectively. On the other hand, detector spatial resolution which accounts for
the least image degradation at 140.5 keV is found to be the dominant degrading factor
at 511 keV, suggesting that the absorber parameters play major roles in image resolution
at higher diagnostic energies. Findings further suggest that cadmium zinc telluride (CZT)
would be themost suitable detector as the absorber since thematerial demonstrated the highest efficiency and least positioning error due to multiple interactions as well as good spatial
resolution. The inclusion of the energy threshold and detector dead time at 140.5 keV, reduced
the Compton camera detection efficiency by 48% and 17% respectively, but improved
the image resolution from 10.7 mm to 9.5 mm at the source-to-scatterer distance of 5 cm.
At 511 keV, the inclusion of these parameters reduced the efficiency by 6% and 13% respectively,
but made no significant difference on the camera resolution. For a challenging
detection case in scintimammography, 5 mm breast tumours of tumour/background uptakes
of 10:1 and 6:1 at 511 keV were used. The best signal-to-noise ratio (SNR) was attained
for the Si/CZT Compton camera model, with the SNR values of 12.2 and 5.3.
It is therefore envisioned that with an optimal camera geometry, improved reconstruction
technique and adequate filter algorithm, the combination of Si and CZT as the scatterer
and the absorber of the Compton camera would make a very promising imaging system for
nuclear medicine studies at higher gamma ray energies where the collimated SPECT systems
perform very poorly due to increased septal penetration. It is equally evident from the
studies that with improved technology, new detectors such as LaBr₃:Ce could replace the
traditional NaI(Tl) detector as imaging detectors
Compton Union High School and Junior College
No full textPostcard drawing of Compton Union High School and Junior College. View is looking south on Acacia Street
Compton Union High School and Junior College
No full textPostcard drawing of Compton Union High School and Junior College. View is looking west on Myrrh Street
D. H. Burden Home, Compton, CA.
No full textPostcard drawing of home of D. H. Burden, President of D. H. Burden Building Materials, Inc., Compton, CA
Susan LaNell Compton papers, 1829-2002
No full textThe Susan LaNell Compton papers contain correspondence, photographs, family history papers, and subject files. Her papers also document her education, career in librarianship, and writings on the history of Arkansas and her Christadelphian religious beliefs.; Incoming correspondence details the daily activities of women living in Arkansas, Missouri, and other states, from the 1920s through the 1990s. Compton grew up as an only child, and she formed close bonds with her mother, Susan Whitlow Compton, and five aunts, Mary Compton Calaway, Lois Compton Shaw, Agnes Compton, Willie Compton Glenn, and Helen Compton. Kathleen B. Hennessee, a fellow Christadelphian, wrote to Compton about family life and her interpretations of Christadelphian beliefs.; There are also drafts of her manuscripts for; The subject files contain newspaper clippings, magazine articles, newsletters, correspondence, and programs. Topics include the Bible, the American Association of University Women Arkansas Branch, adult education, Arkansas Library Commission, and Arkansas Symphony Orchestra. There are also Horace Mann Junior High School student records and diplomas, though the connection of these items to Compton is unclear.Susan LaNell Compton papers, 1829-200
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Correspondence with Mrs. S. M. Compton
No full textLetter written by Carl Compton to his mother, Mary, about his travels, by boat, to France
Correspondence with Mrs. S. M. Compton
No full textLetter and envelope written by Carl Compton to his mother, Mary, about his travels in Switzerland
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Correspondence with Mrs. S. M. Compton
No full textLetter written by Carl Compton to his parents, Mary and Silas, about hist travels in Italy
Correspondence with Mrs. S. M. Compton
No full textLetter and envelope written by Carl Compton to his mother, Mary, about his travels in France
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