Volume 35, Issue 12 p. 5829-5840
Nuclear medicine physics

A novel method to calibrate DOI function of a PET detector with a dual-ended-scintillator readout

Yiping Shao

Yiping Shao

Department of Imaging Physics, University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 600, Houston, Texas 77030

Address for correspondence: Department of Imaging Physics, University of Texas M.D. Anderson Cancer Center, 8014A El Rio, Houston, Texas 77054. Electronic mail: [email protected]

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Rutao Yao

Rutao Yao

Department of Nuclear Medicine, State University of New York at Buffalo, 105 Parker Hall, 3435 Main Street, Buffalo, New York 14214

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Tianyu Ma

Tianyu Ma

Department of Nuclear Medicine, State University of New York at Buffalo, 105 Parker Hall, 3435 Main Street, Buffalo, New York 14214 and Department of Engineering Physics, Tsinghua University, Beijing, 100084, People's Republic of China

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First published: 20 November 2008
Citations: 24

Abstract

The detection of depth-of-interaction (DOI) is a critical detector capability to improve the PET spatial resolution uniformity across the field-of-view and will significantly enhance, in particular, small bore system performance for brain, breast, and small animal imaging. One promising technique of DOI detection is to use dual-ended-scintillator readout that uses two photon sensors to detect scintillation light from both ends of a scintillator array and estimate DOI based on the ratio of signals (similar to Anger logic). This approach needs a careful DOI function calibration to establish accurate relationship between DOI and signal ratios, and to recalibrate if the detection condition is shifted due to the drift of sensor gain, bias variations, or degraded optical coupling, etc. However, the current calibration method that uses coincident events to locate interaction positions inside a single scintillator crystal has severe drawbacks, such as complicated setup, long and repetitive measurements, and being prone to errors from various possible misalignments among the source and detector components. This method is also not practically suitable to calibrate multiple DOI functions of a crystal array. To solve these problems, a new method has been developed that requires only a uniform flood source to irradiate a crystal array without the need to locate the interaction positions, and calculates DOI functions based solely on the uniform probability distribution of interactions over DOI positions without knowledge or assumption of detector responses. Simulation and experiment have been studied to validate the new method, and the results show that the new method, with a simple setup and one single measurement, can provide consistent and accurate DOI functions for the entire array of multiple scintillator crystals. This will enable an accurate, simple, and practical DOI function calibration for the PET detectors based on the design of dual-ended-scintillator readout. In addition, the new method can be generally applied to calibrating other types of detectors that use the similar dual-ended readout to acquire the radiation interaction position.