Development of Respiratory Tract Organs for ICRP Pediatric Mesh-type Reference Computational Phantoms

ABSTRACT

As part of the activities of the International Commission on Radiological Protection (ICRP) Task Group 103, the present study developed a new set of respiratory tract organs consisting of the extrathoracic, bronchial, bronchiolar, and alveolar-interstitial regions for newborn, 1-, 5-, 10-, and 15-y-old males and females for use in pediatric mesh-type reference computational phantoms. The developed respiratory tract organs, while preserving the original topologies of those of the pediatric voxel-type reference computational phantoms of ICRP Publication 143, have improved anatomy and detailed structure and also include μm-thick target and source regions prescribed in ICRP Publication 66. The dosimetric impact of the developed respiratory tract organs was investigated by calculating the specific absorbed fraction for internal electron exposures, which were then compared with the ICRP Task Group 96 values. The results showed that except for the alveolar-interstitial region as a source region, the pediatric mesh phantoms showed larger specific absorbed fractions than the Task Group 96 values. The maximum difference was a factor of ~3.5 for the extrathoracic-2 basal cell and surface as target and source regions, respectively. These results reflect the differences in the target masses and geometry caused by the anatomical enhancement of the pediatric mesh phantoms. For the alveolar-interstitial region as a source region, the pediatric mesh phantoms showed larger values for low energy ranges and lower values with increasing energies, owing to the differences in the size and shape of the alveolar-interstitial region.

Defecation alleviates hangover by terminating intestinal drinking

Introduction

The concept of "intestinal drinking" in this study refers to the continued absorption of alcohol in the gastrointestinal tract until adequate defecation occurs.

Methods

A longitudinal observation of hangover symptoms and alcohol metabolites in healthy humans following binge drinking was conducted.

Results

The hangover symptoms resulting from binge alcohol consumption were relieved by defecation. Following the defecation process, not only the blood ethanol levels, but also the concentrations of blood acetaldehyde, methanol, and iso-propanol, exhibited significant reductions.

Conclusions

This pilot study provides a different perspective for addressing hangovers and potentially mitigating the risks of alcoholic liver diseases.

A Meta-Analysis of Preclinical Studies to Investigate the Effect of Panax ginseng on Alcohol-Associated Liver Disease

Alcohol-associated liver disease (ALD) has become a major global concern, but the development of effective drugs remains a challenge despite numerous preclinical and clinical pieces of research on the effects of natural compounds. To address this, a meta-analysis was conducted on the efficacy of Panax ginseng for ALD based on preclinical studies. We identified 18 relevant studies from PubMed, Web of Science, and Cochrane Library database and evaluated their methodological quality using the Systematic Review Centre for Laboratory animal Experimentation tool. We analyzed the data using I2, p-values, and fixed effects models to assess overall efficacy and heterogeneity. The results of the meta-analysis suggested that Panax ginseng treatment is effective in reducing the levels of inflammatory markers associated with hepatic injury caused by ALD in animal experiments. Additionally, the administration of Panax ginseng was found to down-regulate inflammatory cytokines and attenuate lipid metabolism in ALD. Moreover, Panax ginseng markedly improved the antioxidant systems in ALD. Therefore, we concluded that Panax ginseng has the potential to be a promising therapeutic agent for ALD. Further research is needed to confirm these findings and to determine the optimal dosage and duration of treatment for patients with ALD.

Development of alimentary tract organs for ICRP pediatric mesh-type reference computational phantoms

In line with the activities of Task Group 103 under the International Commission on Radiological Protection (ICRP), the present study was conducted to develop a new set of alimentary tract organs consisting of the oral cavity, oesophagus, stomach, small intestine, and colon for the newborn, 1 year-old, 5 year-old, 10 year-old, and 15 year-old males and females for use in the pediatric mesh-type reference computational phantoms (MRCPs). The developed alimentary tract organs of the pediatric MRCPs, while nearly preserving the original topology and shape of those of the pediatric voxel-type reference computational phantoms (VRCPs) of ICRPPublication 143, present considerable anatomical improvement and include all micrometre-scale target and source regions as prescribed in ICRPPublication 100. To investigate the dosimetric impact of the developed alimentary tract organs, organ doses and specific absorbed fractions were computed for certain external exposures to photons and electrons and internal exposures to electrons, respectively, which were then compared with the values computed using the current ICRP models (i.e. pediatric VRCPs and ICRP-100 stylised models). The results showed that for external exposures to penetrating radiations (i.e. photons >0.04 MeV), there was generally good agreement between the compared values, within a 10% difference, except for the oral mucosa. For external exposures to weakly penetrating radiations (i.e. low-energy photons and electrons), there were significant differences, up to a factor of ∼8300, owing to the geometric difference caused by the anatomical enhancement in the MRCPs. For internal exposures of electrons, there were significant differences, the maximum of which reached a factor of ∼73 000. This was attributed not only to the geometric difference but also to the target mass difference caused by the different luminal content mass and organ shape.

Identification of cranial nerve ganglia using sectioned images and three-dimensional models of a cadaver

Background

Cranial nerve ganglia, which are prone to viral infections and tumors, are located deep in the head, so their detailed anatomy is difficult to understand using conventional cadaver dissection. For locating the small ganglia in medical images, their sectional anatomy should be learned by medical students and doctors. The purpose of this study is to elucidate cranial ganglia anatomy using sectioned images and three-dimensional (3D) models of a cadaver.

Methods

One thousand two hundred and forty-six sectioned images of a male cadaver were examined to identify the cranial nerve ganglia. Using the real color sectioned images, real color volume model having a voxel size of 0.4 × 0.4 × 0.4 mm was produced.

Results

The sectioned images and 3D models can be downloaded for free from a webpage, anatomy.dongguk.ac.kr/ganglia. On the images and model, all the cranial nerve ganglia and their whole course were identified. In case of the facial nerve, the geniculate, pterygopalatine, and submandibular ganglia were clearly identified. In case of the glossopharyngeal nerve, the superior, inferior, and otic ganglia were found. Thanks to the high resolution and real color of the sectioned images and volume models, detailed observation of the ganglia was possible. Since the volume models can be cut both in orthogonal planes and oblique planes, advanced sectional anatomy of the ganglia can be explained concretely.

Conclusions

The sectioned images and 3D models will be helpful resources for understanding cranial nerve ganglia anatomy, for performing related surgical procedures.

Advanced-sectioned images obtained by microsectioning of the entire male body

Realistic two-dimensional (2D) and three-dimensional (3D) applications for anatomical studies are being developed from true-colored sectioned images. We generated advanced-sectioned images of the entire male body and verified that anatomical structures of both normal and abnormal shapes could be visualized in them. The cadaver was serially sectioned at constant intervals using a cryomacrotome. The sectioned surfaces were photographed using a digital camera to generate horizontal advanced-sectioned images in which normal and abnormal structures were classified. Advanced-sectioned images of the entire male body were generated. The image resolution was 3.3 × 3.3 fold better than that of the first sectioned images obtained in 2002. In the advanced-sectioned images, normal and abnormal structures ranging from microscopic (≥0.06 mm × 0.06 mm; pixel size) to macroscopic (≤473.1 mm × 202 mm; body size) could be identified. Furthermore, the real shapes and actual sites of lung cancer and lymph node enlargement were ascertained in them. Such images will be useful because of their true color and high resolution in digital 2D and 3D applications for gross anatomy and clinical anatomy. In future, we plan to generate new advanced-sectioned images of abnormal cadavers with different diseases for clinical anatomy studies.

Detailed tooth models for ICRP mesh-type reference computational phantoms

For use in electron paramagnetic resonance dosimetry with tooth enamel, in the present study, very detailed mesh-type tooth models composed of 198 individual tooth models (i.e. newborn: 20; 1 year: 28; 5 years: 48; 10 years: 38; 15 years: 32; and adult: 32) were developed for each sex. The developed tooth models were then implanted in the International Commission on Radiological Protection pediatric and adult mesh-type reference computational phantoms and used to calculate tooth enamel doses, by Monte Carlo simulations with Geant4, for external photon exposures in several idealized irradiation geometries. The calculated dose values were then compared to investigate the dependency of the enamel dose on the age and sex of the phantom and the sites of the teeth. The results of the present study generally show that, if the photon energy is low (i.e. <0.1 MeV), the enamel dose is significantly affected by the age and sex of the phantom and also the sites of the teeth used for dose calculation; the differences are frequently greater than a few times or even orders of magnitude. However, with a few exceptions, the enamel dose was hardly affected by these parameters for energies between 0.1 and 3 MeV. For energies >3 MeV, moderate differences were observed (i.e., up to a factor of two), due to the existence of dose build-up in the head of the phantom for high-energy photons. The calculated dose values were also compared with those of the previous studies where voxel and mathematical models were used to calculate the enamel doses. The results again show significant differences at low energies, e.g., up to ∼3500 times at 0.015 MeV, which are mainly due to the differences in the level of tooth-modeling detailedness.

Development of paediatric mesh-type reference computational phantom series of International Commission on Radiological Protection

Very recently, Task Group 103 of the International Commission on Radiological Protection (ICRP) completed the development of the paediatric mesh-type reference computational phantoms (MRCPs) comprising ten phantoms (newborn, one year-old, five year-old, ten year-old, and fifteen year-old males and females). The paediatric MRCPs address the limitations of ICRPPublication 143's paediatric reference computational phantoms, which are in voxel format, stemming from the nature of the voxel geometry and the limited voxel resolutions. The paediatric MRCPs were constructed by converting the voxel-type reference phantoms to a high-quality mesh format with substantial enhancements in the detailed anatomy of the small and complex organs and tissues (e.g. bones, lymphatic nodes, and extra-thoracic region). Besides, the paediatric MRCPs were developed in consideration of the intra-organ blood contents and by modelling the micron-thick target and source regions of the skin, lens, urinary bladder, alimentary tract organs, and respiratory tract organs prescribed by the ICRP. For external idealised exposures, the paediatric MRCPs provide very similar effective dose coefficients (DC_Es) to those from the ICRP-143 phantoms but significantly different values for weakly penetrating radiations (e.g. the difference of ∼20 000 times for 10 keV electron beams). This paper introduces the developed paediatric MRCPs with a brief explanation of the construction process. Then, it discusses their computational performance in Geant4, PHITS, and MCNP6 in terms of memory usage and computation speed and their impact on dose calculations by comparing their calculated values of DC_Es for external exposures with those of the voxel-type reference phantoms.

Development of skeletal systems for ICRP pediatric mesh-type reference computational phantoms

In 2016, the International Commission on Radiological Protection (ICRP) launched Task Group 103 (TG 103) for the explicit purpose of developing a new generation of adult and pediatric reference computational phantoms, named 'mesh-type reference computational phantoms (MRCPs)', that can overcome the limitations of voxel-type reference computational phantoms (VRCPs) of ICRPPublications 110and143due to their finite voxel resolutions and the nature of voxel geometry. After completing the development of the adult MRCPs, TG 103 has started the development of pediatric MRCPs comprising 10 phantoms (male and female versions of the reference newborn, 1-year-old, 5-year-old, 10-year-old, and 15-year-old). As part of the TG 103 project, within the present study, the skeletal systems, one of the most important and complex organ systems of the body, were developed for each phantom age and sex. The developed skeletal systems, while closely preserving the original bone topology of the pediatric VRCPs, present substantial improvements in the anatomy of complex and/or small bones. In order to investigate the dosimetric impact of the developed skeletons, the average absorbed doses and the specific absorbed fractions for radiosensitive skeletal tissues (i.e. active marrow and bone endosteum) were computed for some selected external and internal exposure cases, which were then compared with those calculated with the skeletons of pediatric VRCPs. The comparison result showed that the dose values of the pediatric MRCPs were generally similar to those of the pediatric VRCPs for highly penetrating radiations (e.g. photons >200 keV); however, for weakly penetrating radiations (e.g. photons ⩽200 keV and electrons), significant differences up to a factor of 140 were observed.

Real color volume model of cadaver for learning cardiac computed tomographs and echocardiographs

PURPOSE

It is difficult for medical students and novice clinicians to interpret cardiac computed tomographs and echocardiographs. This study was intended to help familiarize them with the clinical images of the heart by providing software to browse the various planes of a heart's volume model with real color and high resolution.

METHODS

On the sectioned images of a male cadaver, the heart and adjacent structures were segmented to obtain color-filled images. Volume models of the sectioned images and color-filled images were reconstructed and sectioned to obtain three orthogonal planes and five standard oblique planes. The planes were inputted into lab-made browsing software, which was then distributed free of charge.

RESULTS

Users of the software would hopefully progress as follows. After experiencing the real color and high resolution, they would become familiar with the grayscale and low resolution. After experiencing the automatic annotation of the basic heart structures, they would become familiar with the detailed structures. After experiencing the designated planes, they would become familiar with the arbitrary planes. After experiencing the still heart, they would become familiar with the moving heart during echocardiography.

CONCLUSION

The software, with a user-friendly interface and realistic features, is expected to properly orient medical novices to cardiac computed tomography and echocardiography images.

Automatic segmentation of true color sectioned images using FMRIB Software Library: First trial in brain, gray matter, and white matter

Three-dimensional (3D) models of the brain made from magnetic resonance images (MRI) are used in various medical fields. 3D models assembled from grayscale color and low-resolution can be complemented with true color sectioned images of the Visible Korean. The purpose of this study is to apply the MRI automatic segmentation technique to the sectioned images. 3D models of the sectioned images, which have true color and high resolution, can be produced without manual segmentation. The Brain Extraction Tool and the Automated Segmentation Tool of the FMRIB Software Library (FSL) were chosen for automatic segmentation. Using those tools, true color sectioned images were reconstructed from gray 3D models of brain, gray matter, and white matter. Color 3D models of those structures were generated from the gray 3D models using MRIcroGL. The color 3D models made from the sectioned images revealed details of brain anatomy that could not be observed on the 3D models from MRI. This trial suggests that convergence of the MRI segmentation technique with color sectioned images is a time-efficient method for producing color 3D models of various structures. In future, the method of this study will be used for various sectioned images of cadavers. The resulting color sectioned images and 3D models will be made available to other researchers.

Sectioned and segmented images of the male whole body, female whole body, male head, and female pelvis from the Visible Korean

In the Visible Korean, serially sectioned images with real color and high resolution have been prepared from four cadaveric subjects: male whole body, female whole body, male head, and female pelvis. Recently, segmented images of the female whole body were manufactured, permitting the distribution of the complete four data sets. The purpose of this report was to promote the applications of sectioned and segmented images from the Visible Korean by announcing them. Reduced image data were loaded to self-developed browsing software; using the browsing software, the contents could be quickly grasped and evaluated by other investigators. The four data sets were compared to disclose the individual merits and demerits. The sectioned and segmented images showed the possibility to be used to reconstruct the stereoscopic volume and surface models of body structures. The Visible Korean is expected to contribute to the interactive simulation of medical learning and clinical practice.

Portable Document Format File Containing the Schematics and Operable Surface Models of the Head Structures

BACKGROUND

A book entitled "Visually Memorable Regional Anatomy (VMRA)" consists of extremely schematic figures as well as concise anatomic knowledge. On the other hand, in the Visible Korean (VK) project, three-dimensional surface models of 297 head structures have been reconstructed. The study's objective was to verify how the coexistence of the schematic figures and realistic surface models affected anatomy learning.

METHODS

In the portable document format (PDF) file of VMRA, 19 pages of the surface models of the head from the PDF file of VK were embedded. The resultant PDF file was utilized as a learning tool of the medical students in two universities.

RESULTS

The PDF file could be downloaded free of charge from anatomy.co.kr. The PDF file has been accessed by users from multiple countries including Korea, United States, and Hungary. In the PDF file, the surface models could be selected in any combinations, magnified, freely rotated, and compared to the corresponding schematics. The number of hours that the PDF file was used by medical students and the scores of written examination on the PDF file showed a low positive correlation in a university. The students replied that the combined PDF file was helpful for understanding anatomy and for doing cadaver dissection. They were also satisfied with the convenience of comparing the surface models and schematics.

CONCLUSION

The freely obtainable PDF file would be a beneficial tool to help students learn anatomy easily, interactively, and accurately.

Effects of Reading a Free Electronic Book on Regional Anatomy with Schematics and Mnemonics on Student Learning

BACKGROUND

To help medical students learn anatomy effectively in limited hours, a regional anatomy book enhancing students' memorization was developed.

METHODS

Only anatomical terms essential for basic cadaver dissection are included along with schematic figures which enable memorization of complicated anatomical structures. Learning comics and comic strips that depict anatomy mnemonics and jokes were appended and sentences were written to be comfortably readable. The electronic book titled "Visually Memorable Regional Anatomy" has been distributed without payment or registration. With the help of 246 volunteer students from three Korean medical schools, the book's learning effects were evaluated.

RESULTS

These students' book reading led to increase in their anatomy scores, including written examination scores and tag examination scores. It was an encouraging result that almost 20% of students spontaneously read the book no matter who presented their lecture or examination. A webpage version of the book was visited by thousands of users.

CONCLUSION

The book with unique features may suggest a new perspective in the field of anatomy learning. After having acquaintance with essential structures from reading the book, students are able to and willing to study more from other resources.

The myodural bridge complex defined as a new functional structure

PURPOSE

The connective tissue between suboccipital muscles and the cervical spinal dura mater (SDM) is known as the myodural bridge (MDB). However, the adjacent relationship of the different connective tissue fibers that form the MDB remains unclear. This information will be highly useful in exploring the function of the MDB.

METHODS

The adjacent relationship of different connective tissue fibers of MDB was demonstrated based upon three-dimensional visualization model, P45 plastinated slices and histological sections of human MDB.

RESULTS

We found that the MDB originating from the rectus capitis posterior minor muscle (RCPmi), rectus capitis posterior major muscle (RCPma) and obliquus capitis inferior muscle (OCI) in the suboccipital region coexists. Part of the MDB fibers originate from the ventral aspect of the RCPmi and, together with that from the cranial segment of the RCPma, pass through the posterior atlanto-occipital interspace (PAOiS) and enter into the posterior aspect of the upper cervical SDM. Also, part of the MDB fibers originate from the dorsal aspect of the RCPmi, the ventral aspect of the caudal segment of the RCPma, and the ventral aspect of the medial segment of the OCI, enter the central part of the posterior atlanto-axial interspace (PAAiS) and fuse with the vertebral dura ligament (VDL), which connects with the cervical SDM.

CONCLUSIONS

Our findings prove that the MDB exists as a complex structure which we termed the 'myodural bridge complex' (MDBC). In the process of head movement, tensile forces could be transferred possibly and effectively by means of the MDBC. The concept of MDBC will be beneficial in the overall exploration of the function of the MDB.

Advanced Sectioned Images of a Cadaver Head with Voxel Size of 0.04 mm

BACKGROUND

The sectioned images of a cadaver head made from the Visible Korean project have been used for research and educational purposes. However, the image resolution is insufficient to observe detailed structures suitable for experts. In this study, advanced sectioned images with higher resolution were produced for the identification of more detailed structures.

METHODS

The head of a donated female cadaver was scanned for 3 Tesla magnetic resonance images and diffusion tensor images (DTIs). After the head was frozen, the head was sectioned serially at 0.04-mm intervals and photographed repeatedly using a digital camera.

RESULTS

On the resulting 4,000 sectioned images (intervals and pixel size, 0.04 mm³; color depth, 48 bits color; a file size, 288 Mbytes), minute brain structures, which can be observed not on previous sectioned images but on microscopic slides, were observed. The voxel size of this study (0.04 mm³) was very minute compared to our previous study (0.1 mm³; resolution, 4,368 × 2,912) and Visible Human Project of the USA (0.33 mm³; resolution, 2,048 × 2,048). Furthermore, the sectioned images were combined with tractography of the DTIs to elucidate the white matter with high resolution and the actual color of the tissue.

CONCLUSION

The sectioned images will be used for diverse research, including the applications for the cross sectional anatomy and three-dimensional models for virtual experiments.

Mesh-type reference Korean phantoms (MRKPs) for adult male and female for use in radiation protection dosimetry

In the present study, to overcome the dosimetric limitations of the previous voxel-type reference Korean computational phantoms due to their limited voxel resolutions (i.e. on the order of millimeters) and the nature of voxel geometry, a pair of new reference Korean phantoms, called mesh-type reference Korean phantoms (MRKPs), were developed for the adult male and female in a high-quality/fidelity mesh format. The developed phantoms include all target and source regions required for effective dose calculation, even micrometer-scale target and source regions of the respiratory and alimentary tract organs, skin, urinary bladder, and eye lens. The developed phantoms, which are in either the polygon-mesh (PM) format or the tetrahedral-mesh (TM) format as necessary, can be directly used in several general-purpose Monte Carlo codes (e.g. Geant4, MCNP6, and PHITS) without voxelization. In order to understand the dosimetric impact of the new phantoms, the dose coefficients (=fluence-to-effective dose conversion coefficients) were calculated for photons and electrons with energies ranging from 10 keV to 10 GeV for the anterior-posterior (AP) irradiation geometry and compared with those of the previous voxel-type reference Korean phantoms. The results demonstrate that the effective dose coefficients of the MRKPs were generally similar to those of the previous voxel-type reference phantoms for photons; however, for electrons, significant differences were observed at energies lower than 1 MeV that were mainly due to the explicit definition of the 50 µm-thick radiosensitive target layer in the skin of the new mesh phantoms.

Real-Color Volume Models Made from Real-Color Sectioned Images of Visible Korean

BACKGROUND

Volume models made from magnetic resonance images on computed tomographs can produce horizontal, coronal, sagittal, and oblique planes that are used widely in clinics, although detailed structures cannot be identified. Existing real color volume models are mostly commercial and their production methods have not been released. The aim of this study was to distribute free of charge, real-color volume models produced from sectioned images with the production method.

METHODS

The original voxel size of sectioned images was increased appropriately so that the volume model could be handled by typical personal computers. By using Dicom Browser and MRIcroGL, the sectioned images were processed to become the volume models.

RESULTS

On the MRIcroGL, the resultant volume model with the voxel size of 0.5 × 0.5 × 0.5 mm³ could be displayed and freely rotated. By adjusting variables of the software, desired oblique planes could be produced instantly. With overlay function, a model of segmented structure can be overlapped to the entire volume models. The sectioned images with high quality and the segmentation data of Visible Korean enabled the identification of detailed anatomical structures on the planes.

CONCLUSION

The volume models can be used by medical students and doctors for learning sectional anatomy. Other researchers can utilize the method of this study to produce volume models from their own sectioned images.

Peeled volume models of a whole body to enhance comprehension of anthropological bone landmarks

BACKGROUND

In physical anthropology, bone landmarks are palpated in living humans for the identification of corresponding skin landmarks and exact biometry. The purpose of this study is to help comprehend the locations and depths of representative bone landmarks all over the body.

MATERIALS AND METHODS

The sectioned images of a male cadaver's whole body were used to build a volume model, which was continuously peeled at 1 mm thicknesses to disclose 27 selected landmarks in the anterior, lateral, or posterior views.

RESULTS

The captured views of peeled volume models along with the labels of the bone landmarks were loaded to browsing software that was distributed for free. The browsing software containing the peeled volume models will enhance convenient studying of the bone landmarks.

CONCLUSIONS

With the knowledge of bone landmarks, investigators would be able to attain more accurate measurements between skin landmarks.

Rise of the Visible Monkey: Sectioned Images of Rhesus Monkey

BACKGROUND

Gross anatomy and sectional anatomy of a monkey should be known by students and researchers of veterinary medicine and medical research. However, materials to learn the anatomy of a monkey are scarce. Thus, the objective of this study was to produce a Visible Monkey data set containing cross sectional images, computed tomographs (CTs), and magnetic resonance images (MRIs) of a monkey whole body.

METHODS

Before and after sacrifice, a female rhesus monkey was used for 3 Tesla MRI and CT scanning. The monkey was frozen and sectioned at 0.05 mm intervals for the head region and at 0.5 mm intervals for the rest of the body using a cryomacrotome. Each sectioned surface was photographed using a digital camera to obtain horizontal sectioned images. Segmentation of sectioned images was performed to elaborate three-dimensional (3D) models of the skin and brain.

RESULTS

A total of 1,612 horizontal sectioned images of the head and 1,355 images of the remaining region were obtained. The small pixel size (0.024 mm × 0.024 mm) and real color (48 bits color) of these images enabled observations of minute structures.

CONCLUSION

Due to small intervals of these images, continuous structures could be traced completely. Moreover, 3D models of the skin and brain could be used for virtual dissections. Sectioned images of this study will enhance the understanding of monkey anatomy and foster further studies. These images will be provided to any requesting researcher free of charge.

Percentile-specific computational phantoms constructed from ICRP mesh-type reference computational phantoms (MRCPs)

Recently, the Task Group 103 of the International Commission on Radiological Protection (ICRP) has developed new mesh-type reference computational phantoms (MRCPs) for adult male and female. When compared to the current voxel-type reference computational phantoms in ICRP Publication 110, the MRCPs have several advantages, including deformability which makes it possible to create phantoms in different body sizes or postures. In the present study, the MRCPs were deformed to produce a set of percentile-specific phantoms representing the 10th, 50th and 90th percentiles of standing height and body weight in Caucasian population. For this, anthropometric parameters for the percentile-specific phantoms were first derived from the anthropometric software and survey data. Then, the MRCPs were modified to match the derived anthropometric parameters. For this, first, the MRCPs were scaled in the axial direction to match the head height, torso length, and leg length. Then, the head, torso, and legs were scaled in the transversal directions to match the lean body mass for the percentile-specific phantoms. Finally, the scaled phantoms were manually adjusted to match the body weight and the remaining anthropometric parameters (upper arm, waist, buttock, thigh, and calf circumferences and sagittal abdominal diameter). The constructed percentile-specific phantoms and the MRCPs were implemented into the Geant4 Monte Carlo code to calculate organ doses for a cesium-137 contaminated floor. The results showed that organ doses of the 50th percentile (both standing height and body weight) phantoms are very close to those of the MRCPs. There were noticeable differences in organ doses, however, for the 10th and 90th percentile phantoms when compared with those of the MRCPs. The results of the present study confirm the general intuition that a small person receives higher doses than a large person when exposed to a static radiation field, and organs closer to the source receive higher doses.

New Viewpoint of Surface Anatomy Using the Curved Sectional Planes of a Male Cadaver

BACKGROUND

The curved sectional planes of the human body can provide a new approach of surface anatomy that the classical horizontal, coronal, and sagittal planes cannot do. The purpose of this study was to verify whether the curved sectional planes contribute to the morphological comprehension of anatomical structures.

METHODS

By stacking the sectioned images of a male cadaver, a volume model of the right half body was produced (voxel size 1 mm). The sectioned images with the segmentation data were also used to build another volume model. The volume models were peeled and rotated to be screen captured. The captured images were loaded on user-friendly browsing software that had been made in the laboratory.

RESULTS

The browsing software was downloadable from the authors' homepage (anatomy.co.kr). On the software, the volume model was peeled at 1 mm thicknesses and rotated at 30 degrees. Since the volume models were made from the cadaveric images, actual colors of the structures were displayed in high resolution. Thanks to the segmentation data, the structures on the volume model could be automatically annotated. Using the software, the sternocleidomastoid muscle and the internal jugular vein in the neck region, the cubital fossa in the upper limb region, and the femoral triangle in the lower limb region were observed to be described.

CONCLUSION

For the students learning various medical procedures, the software presents the needed graphic information of the human body. The curved sectional planes are expected to be a tool for disciplinary convergence of the sectional anatomy and surface anatomy.

New mesh-type phantoms and their dosimetric applications, including emergencies

Committee 2 of the International Commission on Radiological Protection (ICRP) has constructed mesh-type adult reference computational phantoms by converting the voxel-type ICRP Publication 110 adult reference computational phantoms to a high-quality mesh format, and adding those tissues that were below the image resolution of the voxel phantoms and therefore not included in the Publication 110 phantoms. The new mesh phantoms include all the necessary source and target tissues for effective dose calculations, including the 8-40-µm-thick target layers of the alimentary and respiratory tract organs, thereby obviating the need for supplemental organ-specific stylised models (e.g. respiratory airways, alimentary tract organ walls and stem cell layers, lens of the eye, and skin basal layer). To see the impact of the new mesh-type reference phantoms, dose coefficients for some selected external and internal exposures were calculated and compared with the current reference values in ICRP Publications 116 and 133, which were calculated by employing the Publication 110 phantoms and the supplemental stylised models. The new mesh phantoms were also used to calculate dose coefficients for industrial radiography sources near the body, which can be used to estimate the organ doses of the worker who is accidentally exposed by an industrial radiography source; in these calculations, the mesh phantoms were deformed to reflect the size of the worker, and also to evaluate the effect of posture on dose coefficients.