Nationwide Survey of Postmortem CT Imaging Protocols among Facilities in Japan

Postmortem computed tomography (PMCT) is increasingly used in Japan for forensic imaging. Unlike countries with standardized protocols and dedicated PMCT units, Japan lacks a unified imaging framework. This study aimed to investigate the current status of PMCT protocols and equipment use nationwide, focusing on differences between hospitals and non-hospital facilities. A nationwide questionnaire was distributed to medical and forensic facilities performing PMCT between March and April 2024. Survey items included equipment specifications (e.g., CT detector rows), availability and use of advanced reconstruction technologies [e.g., iterative reconstruction (IR), automatic exposure control (AEC)], and protocol practices. Responses from 119 hospital-based and 13 non-hospital-based facilities were analyzed. Hospitals predominantly used ≥ 64-detector-row CT scanners, with high utilization of AEC and IR, reflecting integration with clinical imaging systems. Non-hospital facilities mainly relied on older 16-detector-row scanners, often lacking AEC and IR, and frequently reported overheating due to limited X-ray tube heat capacity. These disparities affected image quality and operational efficiency. Radiological technologists played a central role in adapting clinical protocols for postmortem applications, underscoring both their expertise and the absence of national standardization. PMCT practices in Japan vary significantly depending on facility type and scanner capability. These findings highlight the need for updated national guidelines tailored to modern imaging technologies and protocol stratification based on equipment performance. The flexible protocol adjustments made by technologists in Japan may be a unique strength, compensating for system heterogeneity.