The Application of Paewinsky et al.'s Age Estimation Method to Periapical Radiographs / 대한법의학회지

There have been many radiographic studies on age estimation that evaluate reduction in size of dental pulp cavity with secondary dentin formation. The Paewinsky method reported high accuracy in estimating ages by measuring the width of the pulp cavity in panoramic radiographs. The aim of this study was to evaluate the application of the Paewinsky method to digital periapical radiographs. This study was conducted on 103 cases that reported to the Section of Human Identification of the National Forensic Service. The age was calculated by applying the Paewinsky method that measures the root and pulp canal width at three points in a tooth. The estimation results were compared with those calculated by the Johanson method. When the Paewinsky models were applied to digital periapical radiographs, the errors were significantly greater as compared to the original study. The errors of the maxillary second premolar and mandibular lateral incisor were greater than those of the maxillary central incisor, lateral incisor, mandibular canine, and first premolar. Furthermore, errors of the age estimation models in level C were greater than those in levels A and B. This study could be a reference for the application of the Paewinsky method to digital periapical radiographs.

Radiocarbon Dating of Skeletal Remains: Case Report / 대한법의학회지

While radioactive isotope analysis has proved to be a useful method in disciplines such as archaeology and forensic anthropology, more recently, radiocarbon dating has allowed for a more nuanced biological profile of human skeletal remains. Radiocarbon dating has been made possible by the above ground nuclear bomb test conducted in 1963, which raised the level of atmospheric radiocarbon concentration to almost twice the natural level. Because the annually measured tropospheric ¹⁴C concentrations are integrated into the bomb peak curve, the time of birth and death of an individual can be estimated by comparing the radiocarbon content of a skeletal sample to the bomb-curve value. In July 2017, about 1,000 skeletal remains were excavated at the construction site of Sokcho. For medico-legal purposes, we conducted anthropological and odontological examinations of all the human remains. We then conducted the radiocarbon analysis on seven femora (head and body portions), five mandibular teeth, and soil from the site through a request to the Korea Institute of Geoscience and Mineral Resources. The results demonstrated that the estimated year of birth or death was prior to the 1950s. Due to the diverse distribution of results, we deduced that the human remains were from the local mass grave. This study supports and suggests the use of radiocarbon dating more frequently in the analysis of human skeletal remains.

The Application of Paewinsky et al.'s Age Estimation Method to Periapical Radiographs / 대한법의학회지

There have been many radiographic studies on age estimation that evaluate reduction in size of dental pulp cavity with secondary dentin formation. The Paewinsky method reported high accuracy in estimating ages by measuring the width of the pulp cavity in panoramic radiographs. The aim of this study was to evaluate the application of the Paewinsky method to digital periapical radiographs. This study was conducted on 103 cases that reported to the Section of Human Identification of the National Forensic Service. The age was calculated by applying the Paewinsky method that measures the root and pulp canal width at three points in a tooth. The estimation results were compared with those calculated by the Johanson method. When the Paewinsky models were applied to digital periapical radiographs, the errors were significantly greater as compared to the original study. The errors of the maxillary second premolar and mandibular lateral incisor were greater than those of the maxillary central incisor, lateral incisor, mandibular canine, and first premolar. Furthermore, errors of the age estimation models in level C were greater than those in levels A and B. This study could be a reference for the application of the Paewinsky method to digital periapical radiographs.

Radiocarbon Dating of Skeletal Remains: Case Report / 대한법의학회지

While radioactive isotope analysis has proved to be a useful method in disciplines such as archaeology and forensic anthropology, more recently, radiocarbon dating has allowed for a more nuanced biological profile of human skeletal remains. Radiocarbon dating has been made possible by the above ground nuclear bomb test conducted in 1963, which raised the level of atmospheric radiocarbon concentration to almost twice the natural level. Because the annually measured tropospheric ¹⁴C concentrations are integrated into the bomb peak curve, the time of birth and death of an individual can be estimated by comparing the radiocarbon content of a skeletal sample to the bomb-curve value. In July 2017, about 1,000 skeletal remains were excavated at the construction site of Sokcho. For medico-legal purposes, we conducted anthropological and odontological examinations of all the human remains. We then conducted the radiocarbon analysis on seven femora (head and body portions), five mandibular teeth, and soil from the site through a request to the Korea Institute of Geoscience and Mineral Resources. The results demonstrated that the estimated year of birth or death was prior to the 1950s. Due to the diverse distribution of results, we deduced that the human remains were from the local mass grave. This study supports and suggests the use of radiocarbon dating more frequently in the analysis of human skeletal remains.

Performance Characteristics of MicroPET R4 Scanner for Small Animal Imaging / 대한핵의학회잡지

PURPOSE: Dedicated animal PET is useful equipment for the study of new PET tracer. Recently, microPET R4 was installed in the Korea institute of radiology and medical science. In this study, we measured the characteristics of scanner. MATERIALS AND METHODS: Resolution was measured using a line source (F-18: 65 micro Ci, inner diameter: 0.5 mm). The line source was put in the axial direction and was moved from the center of field of view to outside with 1 mm interval. PET images were reconstructed using a filtered back-projection and ordered subset expectation maximization. Line source (16.5 micro Ci, 78 mm) was put on the center of axial direction to measure the sensitivity when the deadtime was under 1%. Images were acquired during 4 minutes respectively from center to 39 mm outward. Delayed count was subtracted from total count and then decay was corrected for the calculation of sensitivity. Noise equivalent count ratio and scatter fraction were calculated using cylindrical phantom. RESULTS: Spatial resolution of reconstructed image using filtered back-projection was 1.86 mm (radial), 1.95 mm (tangential), 1.95 mm (axial) in the center of field of view, and 2.54 mm, 2.8 mm, 1.61 mm in 2 cm away from the center respectively. Sensitivity was 2.36% at the center of transaxial field of view. Scatter fraction was 20%. Maximal noise equivalent count ratio was 66.4 kcps at 242 kBq/mL. Small animal images were acquired for confirmation of performance. CONCLUSION: Performance characteristics of microPET R4 were similar with reported value. So this will be a useful tool for small animal imaging.