A backprojection kernel (KRNL3D) for very-wide-aperture 3D tomography applied to PET with multigrid for precise use of time-of-flight data

Author(s):  
Keith Miller
2018 ◽  
Vol 123 (8) ◽  
pp. 6494-6513 ◽  
Author(s):  
M. Felici ◽  
C. S. Arridge ◽  
R. J. Wilson ◽  
A. J. Coates ◽  
M. Thomsen ◽  
...  

2019 ◽  
Author(s):  
Cornelius Pieterse ◽  
Michiel B. De Kock ◽  
Wesley D. Robertson ◽  
Hans C. Eggers ◽  
R. J. Dwayne Miller

Deconvolution of low-resolution time-of-flight data has numerous advantages including the ability to extract additional information from the experimental data. We augment the well-known Lucy-Richardson deconvolution algorithm by various Bayesian prior distributions and show that a prior of second-differences of the signal outperforms the standard Lucy-Richardson algorithm, accelerating the rate of convergence by more than a factor of four, while preserving the peak amplitude ratios of a similar fraction of the total peaks. A novel stopping criterion and boosting mechanism is implemented to ensure these methods converge to a similar entropy, and that local minima are avoided, respectively. Improvement by a factor of two in mass resolution allows more accurate quantification of the spectra. The general method is demonstrated in this paper by the deconvolution of fragmentation peaks of the DHB matrix, as well as the BTP thermometer ion, following femtosecond ultraviolet laser desorption.


1996 ◽  
Vol 50 (2) ◽  
pp. 161-166 ◽  
Author(s):  
David C. Muddiman ◽  
Anthony J. Nicola ◽  
Andrew Proctor ◽  
David M. Hercules

Fundamental aspects regarding the use of time-of-flight secondary-ion mass spectrometry (TOF-SIMS) as a quantitative tool for the analysis of organic compounds are reported. The following factors are discussed: (1) the use of Poisson's law to correct for dead-time in single-ion data collection; (2) practical considerations concerning the analysis of “real world” samples; and (3) the effect of the etching process on the reproducibility of the intensity ratio (analyte/internal standard) of Ag-cationized species. To evaluate the importance of these factors, we used cocaine and cyclosporin A (CsA) as analytes because they show protonated and Ag-cationized species, respectively, in their SIMS spectra. Correction for detector dead-time using Poisson's law of single-ion counting expanded the dynamic range for cocaine by ∼2 orders of magnitude. For analyses requiring only a small dynamic range (i.e., CsA), the correction improved the % RSD of the slope from 2.43 to 0.87%. The maximum secondary-ion (SI) yield of CsA (Ag-cationized species) occurs at a CsA concentration ∼3 orders of magnitude higher than the therapeutic levels in blood (25–2000 ng/mL). It is discussed how this problem should be addressed. Analysis of variance (ANOVA) indicates that Ag substrates must be etched under identical conditions to obtain quantitative results when species requiring cationization are being analyzed.


Author(s):  
Malcolm Reynolds ◽  
Jozef Dobos ◽  
Leto Peel ◽  
Tim Weyrich ◽  
Gabriel J Brostow
Keyword(s):  

2019 ◽  
Vol 151 (24) ◽  
pp. 244307
Author(s):  
Cornelius L. Pieterse ◽  
Michiel B. de Kock ◽  
Wesley D. Robertson ◽  
Hans C. Eggers ◽  
R. J. Dwayne Miller

Sign in / Sign up

Export Citation Format

Share Document