Plenary Lectures and VIP Guests

Dr. Qiyu Peng

Abstract:

Positron emission tomography (PET) is one of the most sensitive tools for in vivo molecular imaging, but access to PET remains highly unequal worldwide. High equipment cost, specialized infrastructure, radiopharmaceutical supply, radiation dose, and the physical footprint of conventional scanners all limit wider use, particularly in resource-constrained settings [1]. Affordable PET should not mean low-end PET. Our view is that PET should be designed around the 5A principles—Affordable, Available, Accessible, Appropriate, and Acceptable—so that high-end molecular imaging can be delivered with less cost, dose, space, power, and infrastructure.

Our experience in building wearable, organ-dedicated, preclinical, and total-body PET systems suggests that affordability is fundamentally a system-design problem. PET does not need one universal architecture for every application. Detector coverage, scintillator materials, electronics, and system complexity should be matched to the clinical or scientific question. Depth-of-interaction (DOI) information helps mitigate parallax error and preserve spatial resolution in compact PET geometries. Improved time-of-flight (TOF) performance can be traded for better image quality or lower injected activity [2].

Our SmartBrain wearable brain PET is one example. Its published performance evaluation demonstrated 234-ps TOF resolution and visualization of 1.7-mm rods [3]. Ongoing engineering and clinical studies have since extended the platform to seated and freely moving human imaging. The system requires approximately 4 m² of space, and more than 20 human imaging examinations have been completed. A dedicated brain PET/CT follows the same principle from a different direction: concentrating detector coverage around the brain improves local sensitivity and spatial resolution while reducing system size. A dedicated low-cost brain CT can provide anatomical localization and attenuation correction at a substantially lower radiation dose than conventional whole-body CT.

Cost can also be addressed at the detector and electronics level. In a BGO-based DOI PET prototype, we achieved a central spatial resolution of 1.43 mm FWHM and clear separation of 1.5-mm rods. Unlike LYSO, BGO has no intrinsic ¹⁷⁶Lu background, which is advantageous for low-activity imaging. Our miniaturized readout electronics reduced module-level power consumption by approximately 80% while greatly reducing size and weight. Sparse detector designs are also being explored as a further way to reduce detector material and system cost.

For PET, sustainability has very practical consequences. Lower system and infrastructure costs determine whether scanners can be deployed. Lower material and power requirements reduce the engineering and environmental burden. Wider access determines whether technical advances ultimately benefit more patients. Total-body PET will remain essential where its exceptional sensitivity is needed [4], but many clinical and scientific questions can be addressed more appropriately with dedicated, wearable, or lower-cost systems.

Our long-term goal is simple: bring high-end PET to more people, in more places, at a cost and complexity that healthcare systems can realistically sustain.