Requirements of Scintillation Crystals with the Development of PET Scanners

Abstract

Positron emission tomography (PET) is widely used in the diagnosis of tumors, cardiovascular system diseases, and neurological diseases. Scintillation crystals are an important part of PET scanners; they can convert γ photons into fluorescent photons to obtain their energy, time, and position information. Currently, an important research goal in PET is to find scintillation crystals with better performance. In this work, the principle of scintillation crystals is introduced, and the properties and requirements of scintillation crystals in different PET scanners are analyzed. At present, Lu2(1−x)Y2xSiO5 (LYSO) is the scintillation crystal with the best comprehensive properties. LaBr3 performs even better regarding the timing characteristics and light output; however, LaBr3 has not been used in any PET scanner because of its deliquescence. Detectors made of Gd3(Ga, Al)5O12 (GAGG) exhibit a high depth of interaction (DOI) resolution and have considerable application potential. The application fields of PET are constantly expanding, and its future development aims to achieve high spatial resolution and high sensitivity, which require scintillation crystals with better performance.

Recent advances in combined Positron Emission Tomography and Magnetic Resonance Imaging

“…Currently, there are different types of scintillation crystals (organic and inorganic in solid, liquid, and gaseous forms) [26]. In PET scanners, we commonly find solid inorganic crystals because of their high stopping power (defined as the energy lost per unit length) and high light response [27,28].…”

“…Lutetium-based scintillators LSO (Lu 2 SiO 5 ) [33] and LYSO (Lu 2(1-x) Y 2x SiO 5 ) have become the trend in modern PET scanners because of their high stopping power, high light yield, and fast time response [28]. Other proposed materials are GSO (Gd 2 SiO 5 ) [34,35], since it has a low price and acceptable performance, making it suitable for long axial field-of-view (FOV) scanners, and GAGG (Gd 3 (Ga, Al) 5 O 12 ) or LaBr 3 [28], because of their superior performance. NaI(Tl) was the first scintillation crystal used in PET [36], but it was soon substituted by other materials with higher stopping power, such as BGO (Bi 4 Ge 3 O 12 ).…”

“…Spatially sensitive photosensors are also required to provide the gamma interaction point in the detector [19]. Another quality [28] and Lewellen et al [19]. The refractive index for GAGG was taken from [41].…”

The detection instrumentation and geometric design of clinical PET scanner: towards better performance and broader clinical applications

“…Gadolinium Aluminium Gallium Garnet (GAGG) has good detection efficiency, a high atomic number; good energy resolution, a high light yield, and a slightly longer decay time (see table 1). In addition, this material has a high DOI and considerable potential for medical applications [96]. For Gadolinium-lutetium-gallium aluminium garnet (GLuGAG) has a relatively high density and atomic number, excellent light yield, good energy resolution, and is not hygroscopic (see table 1) [122], which makes it particularly interesting for positron emission tomography (PET).…”

State-of-the-art challenges and emerging technologies in radiation detection for nuclear medicine imaging: A review

“…Thallium strontium iodide (TlSr 2 I 5 ) is a new scintillator detector material that has shown promise with an energy resolution of less than 3% at 662 keV due to the high light yield of 54,000 photons/ MeV [34]. Lanthanum bromide (LaBr 3 ) scintillators have a high light output of 61,000 ph/MeV resulting in an energy resolution of 2.8% at 662 keV, but have found limited use in PET and SPECT due to stability issues in ambient conditions [35,36].…”