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In recent years, silicon photomultipliers (SiPMs) have emerged as preferred photoelectric conversion devices in positron emission tomography (PET) due to their outstanding performance. SiPMs possess single-photon resolution capability and time resolution below 100 ps, enabling precise photon arrival time measurements. These advances paved the way for emerging applications such as time-of-flight PET (TOF-PET), photon counting CT, and positron emission lifetime imaging, presenting new challenges to SiPM performance, the advancing of which to their physical limits has become a key focus area in next-generation SiPM research. In traditional SiPM architectures, signal processing and analog-to-digital conversion introduce noise and degrade time performance, thereby limiting the full SiPM potential. With the recent and rapid development of semiconductor manufacturing processes, SiPMs could be manufactured on standard CMOS process nodes, which marks a significant breakthrough in the SiPM field, allowing for the integration of digital logic within SiPM devices. This advancement opens the possibility of achieving more precise time, energy, and position information within a single SiPM, thereby providing potential possibilities to push SiPMs to their performance limits. In this study, we reviewed the development history, working principles, and performance parameters of SiPMs. We analyzed the limitations of traditional SiPMs, outlined key aspects of digital SiPM research, and introduced various current digital SiPM architectures. Finally, we summarized and anticipated key technologies in digital SiPMs.

The digital positron emission tomography (PET) innovation technology system, which gradually evolved from the Multi-Voltage Threshold (MVT) sampling method, has driven the development of many fields, including key materials, core devices, electronics, intelligent algorithms, and industry standards, forming a new PET industry ecology characterized by modular hardware and intelligent software. In 2010, the world's first All-Digital PET scientific instrument, based on the MVT method, was successfully developed and showed an obvious spatial resolution advantage. With the modular characteristics of the All-Digital PET’s detector, it has successively developed digital PET scientific instruments with different apertures, different fields of view (FOV), and different geometric structures for small animals, large animals, primates, and plants, and has been put into various scientific research applications. In 2015, the world's first All-Digital PET medical device prototype for human scanning was successfully developed. In the following 7 years, several clinical All-Digital PET products have been developed and put into the market. These All-Digital PET products break the fixed architecture of conventional whole body scanning in the past and use modular digital detectors to build various medical devices, such as site-dedicated PET systems, PET-insert system, wearable PET, and proton PET. It has helped promote the rapid expansion of PET applications from tumor diagnosis to new application fields such as nervous system diseases, unexplained fever, and proton precision treatment. The vigorous development of All-Digital PET ecology has also brought innovation to the industrial division of labor. The new scintillation crystal materials, the new silicon photomultiplier (SiPM), and the modular PET detector are developing independently and rapidly, forming their own standardized component or interface. The synchronous progress of upstream and downstream technologies has promoted the development of the entire PET industry chain and innovation chain. With the rapid development of All-Digital PET, the proposal of a variety of PET digital technology routes has also put forward new challenges to industry technical standards and regulatory systems, such as technical requirements for the digitization of PET medical devices and the registration guidelines that have been updated and developed simultaneously. This paper reviewed the dynamic progress of All-Digital PET in scientific instruments, medical devices, the industrial chain, and regulatory science in the past 20 years and looked forward to the future ecological development of All-Digital PET.

Utilizing the Multi-Voltage Threshold method, All-Digital PET technology, characterized by "All-Digital" and "accurate sampling," facilitates hardware and software decoupling and modular "LEGO-like" system construction. This innovation addresses the limitations of traditional PET system architectures, enabling a broader range of innovative applications. This paper reviews recent advancements in application-specific All-Digital PET systems, highlighting their applications and advantages in proton therapy monitoring, clinical and basic brain science research, and plant metabolism studies. Furthermore, we explore the development trends of All-Digital PET technology to meet the increasing demands of PET imaging applications.

Lutetium yttrium silicate (LYSO) has become the most prominent scintillation crystal material in positron emission tomography (PET) because of its outstanding comprehensive performance. In recent years, the emerging All-Digital PET technology based on the Multi-Voltage Threshold (MVT) method has digitized the origin of scintillation pulses, thereby improving key metrics such as spatial resolution and system sensitivity; this advancement has also given rise to new applications like proton therapy monitoring and positron lifetime spectroscopy. Unlike traditional time interval sampling methods, MVT represents a longitudinal sampling technique based on voltage-time, offering inherent advantages in rapidly varying pulse signal sampling domains. Consequently, tailoring the scintillation luminescence properties of LYSO crystals to adapt to the MVT sampling method becomes a new development direction for LYSO scintillation crystals under the demand of digital PET applications. This paper reviews the scintillation principles, performance modulation, and growth techniques of LYSO crystals. It outlines strategies for adjusting key properties of LYSO crystals, such as light output, decay time, and uniformity to align with the sampling characteristics of All-Digital PET. Furthermore, the paper presents the research progress of fast-decaying and highly uniform digitally modified LYSO crystals developed by the research team to meet the demands of All-Digital PET. Finally, based on the current research status of LYSO and the new demand for digital PET, the future development direction of LYSO scintillation crystals is discussed.

Traditional positron emission tomography (PET) systems apply analog circuits for signal processing and achieve coincidence event detection through coincident circuitry. However, these systems suffer from a significant loss of information during projection and image data processing, leading to poor algorithm scalability. In contrast, All-Digital PET systems leverage precise sampling and comprehensive digital processing to simplify hardware design while maximizing software capabilities. These advanced systems rely on software algorithms to handle more operations, thereby providing complete process data, abundant algorithms, and convenient optimization for replacement. By treating detectors and algorithms as fundamental “building blocks,” the plug and imaging (PnI) platform constructs imaging protocols, algorithms, and equipment layers to define the imaging process, extend algorithmic capabilities, and support the construction of diverse animal or clinical PET system types. Moreover, integrating PnI into All-Digital PET systems allows for early information mining from scintillation pulse data levels rather than at the image level, facilitating flexible additional algorithm integration. Based on the aforementioned background, in this study, we critically investigated PnI software-related research advancements, precisely elucidating the comprehensive structure of All-Digital PET systems, architectural flowcharting of the imaging process, and exemplary application cases. Our primary objective was to enhance flexibility for scientists involved in constructing All-Digital PET research instruments while providing valuable references for the expeditious and efficient development of diverse PET systems alongside software algorithmic enhancements.

Analog-to-digital converters (ADCs) transform the analog signals of time-variant physical quantity into digital signals for storing and processing. As the bridge between natural science and information science, ADCs are indispensable in modern industry and scientific research. Since the 1920s, uniform time-domain sampling has become the basic principle in the field of ADCs with the establishment of its electronic implementation and mathematical theory. In the following decades, applications such as positron emission tomography (PET), nuclear fusion neutron spectrum, neutrino detection, etc., which require sampling of many high-speed signals, have emerged one after another. In these applications, ADCs based on uniform time-domain sampling show disadvantages of high power consumption and high cost, so the signal has to be pre-processed before digitalization with losing the original information of the signal. Based on value-domain sampling, the Multi-Voltage Threshold (MVT) method digitizes the signal through several voltage thresholds and then reconstructs the signal with a computer using prior information. The MVT method makes it possible to accurately digitize a large number of high-speed signals. At present, the MVT method has been applied in PET, X-ray security inspection, neutron logging, proton therapy monitoring, etc. This paper outlines the principle of the MVT method, introduces the research progress of MVT electronics in recent years, and further provides an outlook of the MVT research trend.

The development of media technology, the display of different personalities and the stimulation of utilitarian, which make nowadays the best time for communication, but also the worst of time for communication. Helpless in communication troubles modern humans and Laotzu's converse thinking about interpersonal communication might help people out. Upon self-positioning, Laotzu suggested "tenderness and downwards as water" in order to avoid interpersonal conflict; upon the alienation motivation of interpersonal communication, Laotzu proposed "embrace your original nature" in order to purify people's soul which is skewed by fame and wealth; upon the people's high expectation for interpersonal relationship, Laotzu's focused on only getting ride of too much desiring and too high expectation can one "have enduring contentment". [ABSTRACT FROM AUTHOR]