Resolution and sensitivity improvement in positron emission tomography by the first interaction point determination

Cho, Z.H.; Juh, S.C.

doi:10.1109/nssmic.1991.259189

Cited by 7 publications

(4 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Because the inter-detector scatter degrades crystal identification and DOI accuracy, it can be expected that the inter-detector scatter leads the spatial resolution loss of the detector module. To eliminate the artifact due to the detector scatter, algorithms to find the first interaction position in multiple interactions (detector scatter) were investigated [72,73]. However, the study based on Monte Carlo simulation indicated that detector scatter may have a small effect (6%~8%) on the image resolution (FWHM) of a reconstructed point source for the DOI capable detector systems [74][75][76].…”

Section: Discussionmentioning

confidence: 99%

Positron emission tomography (PET) detectors with depth-of- interaction (DOI) capability

2011

View full text Add to dashboard Cite

Because positron emission tomography (PET) provides biochemical information in vivo with the sensitivity at the sub-pico-molar level, pre-clinical research using PET plays an important role in biological and pharmaceutical sciences. However, small animal imaging by PET has been challenging with respect to spatial resolution and sensitivity due to the small volume of the imaging objects. A DOI-encoding technique allows for pre-clinical PET to simultaneously achieve high spatial resolution and high sensitivity. Thus many DOI-encoding methods have been proposed. In this paper we describe why DOI measurements are important, what is required in DOI-encoding designs, and how to extract DOI information in scintillator-based DOI detectors. Recently, there has been a growing interest in DOI measurements for TOF PET detectors to correct time walk as a function of DOI position. Thus, the DOI-encoding method with a high time performance suitable for TOF detectors is now required. The requirements to improve the time resolution in DOI detectors are discussed as well.Keywords Positron emission tomography (PET), Depth of interaction (DOI), Multi-layer detector, Dual-ended readout, Single-ended readout THE IMPORTANCE OF DOI MEASUREMENT Simultaneous improvement in spatial resolution and sensitivityThe PET is an important pre-clinical imaging technique because PET provides biochemical information down to the sub-pico-molar level in vivo [1]. Thus, the development of pre-clinical PET scanners has been actively promoted. The major focus of the development is to obtain a similar quality in small animal images as human images, while the size of the imaging subject decreases and the amount of radiopharmaceutical injected into the small animals is limitedTo obtain a similar level of detail and SNR in mouse images as human images, spatial resolution and sensitivity should be increased. That is why many PET instrument researchers have been attempting for the pre-clinical PET to simultaneously achieve high spatial resolution and high sensitivity. The pre-clinical PET systems therefore have been designed by using very long and narrow crystals with small diameter ring geometry. However, such system structures cause the parallax error to become lager when providing no depth-of-interaction (DOI) information within crystals (general PETs can measure no DOI information), and bring the degradation of the radial resolution in the peripheral field of view (FOV). That is because the reconstruction algorithm, when drawing a line of response (LOR) without DOI information, usually assigns the interaction positions over all depths within a crystal to a single position (i.e. the center position on the front of the interacted crystals).

show abstract

Section: Discussionmentioning

confidence: 99%

Positron emission tomography (PET) detectors with depth-of- interaction (DOI) capability

2011

View full text Add to dashboard Cite

show abstract

“…Through simulations, previous work explored various algorithms to determine the position of initial interaction to eliminate effect of inter-crystal Compton scatter [1], as well as the impact of Compton scatter event recovery on system resolution and sensitivity improvements of a non-ToF-PET scanner [2].…”

Section: Introductionmentioning

confidence: 99%

Sensitivity improvement of time-of-flight (ToF)-PET detector through recovery of Compton scattered annihilation photons

Wagadarikar

Iván

Dolinsky

et al. 2012

2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)

View full text Add to dashboard Cite

In PET detector designs, the scintillator material can be partitioned such that a block of crystals share timin g /ener g y readout electronics. A fraction of the incident 511 keY photons produce simultaneous events in two adjacent block readouts due to Compton scatterin g followed by escape from the primary block. These inter-block Compton scatter events are typically not processed in current PET scanners. We have used radiation transport simulations to determine the fraction of inter-block Compton events for different block sizes usin g LYSO scintillator.The simulations showed the statistical distribution of the ener g y si g nals and time stamps in the two blocks and guided the selection of ener g y and time criteria for an event recovery al g orithm. With a particular block size, we experimentally demonstrated that inter-block Compton events may be recovered as valid events with a corrected time stamp and estimated position of initial interaction. The results showed a si g nificant improvement in detector sensitivity at the expense of a small de g radation in the timin g resolution of the detector block.

show abstract

“…If ICS happens, position decoding using the center of gravity method will provide incorrect gamma ray interaction positions, which affects both the spatial (transversal-axial direction) and DOI (radial direction) resolution. This blur in detector resolution causes degradation of the reconstructed image [11,12]. Rejection of ICS events has been used to improve spatial resolution [13], however, this method also reduces system sensitivity.…”

Section: Introductionmentioning

confidence: 99%

Compton PET: a simulation study for a PET module with novel geometry and machine learning for position decoding

Peng

Judenhofer

Jones

et al. 2018

Biomed. Phys. Eng. Express

View full text Add to dashboard Cite

This paper describes a simulation study of a positron emission tomography (PET) detector module that can reconstruct the kinematics of Compton scattering within the scintillator. We used a layer structure, with which we could recover the positions and energies for the multiple interactions of a gamma ray in the different layers. Using the Compton scattering formalism, the sequence of interactions can be estimated. The true first interaction position extracted in the Compton scattering will help minimize the degradation of the reconstructed image resolution caused by intercrystal scatter events. Because of the layer structure, this module also has readily available user-defined resolution for the depth of interaction. The semi-monolithic crystals enable high light collection efficiency and an energy resolution of ∼10% has been achieved in the simulation. We used machine learning to decode the gamma ray interaction locations, achieving an average spatial resolution of 0.40 mm. Our proposed detector design provides a pathway to increase the sensitivity of a system without affecting other key performance features.

show abstract

Resolution and sensitivity improvement in positron emission tomography by the first interaction point determination

Cited by 7 publications

References 10 publications

Positron emission tomography (PET) detectors with depth-of- interaction (DOI) capability

Positron emission tomography (PET) detectors with depth-of- interaction (DOI) capability

Sensitivity improvement of time-of-flight (ToF)-PET detector through recovery of Compton scattered annihilation photons

Compton PET: a simulation study for a PET module with novel geometry and machine learning for position decoding

Contact Info

Product

Resources

About