The recent introduction of high-resolution molecular imaging technology is considered by many experts as a major breakthrough that will potentially lead to a revolutionary paradigm shift in health care and revolutionize clinical practice. This paper intends to balance the capabilities of the two major molecular imaging modalities used in nuclear medicine, namely positron emission tomography (PET) and single photon emission computed tomography (SPECT). The motivations are many-fold: (1) to gain a better understanding of the strengths and limitations of the two imaging modalities in the context of recent and ongoing developments in hardware and software design; (2) to emphasize that certain issues, historically and commonly thought as limitations of one technology, may now instead be viewed as challenges that can be addressed; (3) to point out that current state of the art PET and SPECT scanners can (greatly) benefit from improvements in innovative image reconstruction algorithms; and (4) to identify important areas of research in PET and SPECT imaging that will be instrumental to further improvements in the two modalities. Both technologies are poised to advance molecular imaging and have a direct impact on clinical and research practice to influence the future of molecular medicine.

PET versus SPECT: strengths, limitations and challenges

Geiger-mode avalanche photodiodes (G-APDs) have been developed during recent years and promise to be an alternative to photomultiplier tubes. They have many advantages like single photon response, high detection efficiency, high gain at low bias voltage and very good timing properties but some of their properties, the dark count rate for example, can be a problem. Several types of G-APDs are on the market and should be selected carefully for a given application.

Geiger-mode avalanche photodiodes, history, properties and problems

Semiconductor photodiodes were developed in the early `Forties approximately at the time when the photomultiplier tube became a commercial product (RCA 1939) Only in recent years, with the invention of the Geiger-mode avalanche photodiodes, have the semiconductor photo detectors reached sensitivity comparable to that of photomultiplier tubes The evolution started in the `Sixties with the p-i-n (PIN) photodiode, a very successful device, which is still used in many detectors for high energy physics and a large number of other applications like radiation detection and medical imaging The next step was the development of the avalanche photodiode (APD) leading to a substantial reduction of noise but not yet achieving single photon response The weakest light flashes that can be detected by the PIN diode need to contain several hundreds of photons An improvement of the sensitivity by 2 orders of magnitude was achieved by the development of the avalanche photodiode, a device with internal gain At the end of the millennium, the semiconductor detectors evolved with the Geiger-mode avalanche photodiode into highly sensitive devices, which have an internal gain comparable to the gain of photomultiplier tubes and a response to single photons A review of the semiconductor photo detector design and development, the properties and problems, some applications and a speculative outlook on the future evolution will be presented

https://iopscience.iop.org/article/10.1088/1748-0221/4/04/P04004/pdf

Advances in solid state photon detectors

The detection and generation of single photons has seen an upsurge in interest in recent years as new scientific fields of research, for example quantum information processing, have been established. This review serves to provide an overview of progress in these areas, describing some of the main candidates for single-photon components for use in emerging fields of research.

https://iopscience.iop.org/article/10.1088/0957-0233/21/1/012002/pdf

Single-photon generation and detection

The state of art of the Silicon Photomultipliers (SiPM’s)—their features, possibilities and applications—is given. The significant progress of this novel technique of photo detection is described and discussed. r 2006 Elsevier B.V. All rights reserved.

/pdf/status-report-on-silicon-photomultiplier-development-and-its-4jpsmj6kzz.pdf

Status report on silicon photomultiplier development and its applications

The Silicon Photomultiplier (SiPM) is a semiconductor device consisting of many photon microcounters (10 3 mm 2 ) positioned on a common Si substrate. SiPM operates in a limited Geiger mode and has single photoelectron gain (10 6 ) and photon detection efficiency (20%) similar to vacuum PMT. Main SiPM features are described and a number of examples of its possible applications are demonstrated, such as scintillator fiber readout, scintillator tiles+WLS readout, imaging Cherenkov counter timing. These SiPM applications are based on experimental test data and SiPM performance is compared with other photodetectors (PMT, APD, HPD, VLPC). r 2003 Elsevier Science B.V. All rights reserved.

/pdf/silicon-photomultiplier-and-its-possible-applications-57h4ky7twh.pdf

Silicon photomultiplier and its possible applications

The advanced study of new photo detector Silicon Photomultiplier (SiPM) is presented. SiPM consists of many (∼103 mm−2) silicon micro pixels, which are independent photon micro counters working in limited Geiger mode with a gain of 106. The SiPM output signal is a sum of the signals from a number of pixels fired by photons. The main features of SiPM are: low excess noise factor, the photon detection efficiency at the level of vacuum PMT, low bias voltage (∼24V). The timing of the SiPM is about 30 ps for 10 photoelectrons. The possibilities of SiPM applications based on experimental tests are demonstrated: sci fiber readout, scintillator-shifter system readout, possible application for hadron calorimeters.

http://statistics.roma2.infn.it/~elettronica/SiPM/Cartella2/other/smirnov.pdf

The Advanced Study of Silicon Photomultiplier

/pdf/scintillation-fiber-detector-of-relativistic-particles-38u5oh81d8.pdf

F. Kayumov

Papers

Silicon photomultiplier and its possible applications

Status report on silicon photomultiplier development and its applications

The Advanced Study of Silicon Photomultiplier

Scintillation fiber detector of relativistic particles