Cylindrical Volume Research Articles

BREAKDOWN VOLTAGE OF MICRON RANGE AIR INCLUSIONS IN CAPACITOR PAPER

Purpose. To substantiate the breakdown mechanism of capacitor paper on the basis of numerical-field models with segmented cross-sections of cylindrical volumes of air and water, and also use the proposed models to determine the breakdown strength of air in micron-sized gaps under normal conditions. Methodology. The model bases on a finite element solution to an electrostatic problem in a volume of capacitor paper consisting of cellulose and pores with air and water. First, the possible scenarios for the growth of breakdown in capacitor paper are analyzed and to the conclusion is made, that complete breakdown developed from a partial breakdown in the air cavity. A brand of capacitor paper is chosen in such a way that when its thickness changed, the breakdown strength of the electric field changed over a wide range. Then, for the paper with the lowest average electric field intensity the possibility of explaining the complete breakdown by the breakdown of air segments on the basis of the Paschen dependence is checked. Further points of the obtained dependence by constructing models of papers of the same brand and a different thickness under the assumption of the similarity of electrostatic fields are determined. As such a criterion, the constancy of the equivalent effective permittivity are taken. Results. The dependence of the breakdown strength of the air in the range of 1.36...5.54 μm under normal conditions is determined. The obtained relationship is between the Peschot and Taev curves. Originality. For the first time, the possibility of indirectly estimation the breakdown strength of an insulating material using an electrostatic field model is indicated. Practical value. The proposed method for the numerical calculation of the breakdown voltage of air inclusions in the presence of water inclusions in the thickness of solid insulation can be applied to other types of solid thin-layer insulation.

A Computer Modeling Study of Water Radiolysis at High Dose Rates. Relevance to FLASH Radiotherapy.

"FLASH radiotherapy" is a new method of radiation treatment by which large doses of radiation are delivered at high dose rates to tumors almost instantaneously (a few milliseconds), paradoxically sparing healthy tissue while preserving anti-tumor activity. To date, no definitive mechanism has been proposed to explain the different responses of the tumor and normal tissue to radiation. As a first step, and given that living cells and tissues consist mainly of water, we studied the effects of high dose rates on the transient yields (G values) of the radical and molecular species formed in the radiolysis of deaerated/aerated water by irradiating protons, using Monte Carlo simulations. Our simulation model consisted of two steps: 1. The random irradiation of a right circular cylindrical volume of water, embedded in nonirradiated bulk water, with single and instantaneous pulses of N 300-MeV incident protons ("linear energy transfer" or LET ∼ 0.3 keV/µm) traveling along the axis of the cylinder; and 2. The development of these N proton tracks, which were initially contained in the irradiated cylinder, throughout the solution over time. The effect of dose rate was studied by varying N, which was calibrated in terms of dose rate. For this, experimental data on the yield G(Fe3+) of the super-Fricke dosimeter as a function of dose rate up to ∼1010 Gy/s were used. Confirming previous experimental and theoretical studies, significant changes in product yields were found to occur with increasing dose rate, with lower radical and higher molecular yields, which result from an increase in the radical density in the bulk of the solution. Using the kinetics of the decay of hydrated electrons, a critical time (τc), which corresponds to the "onset" of dose-rate effects, was determined for each value of N. For the cylindrical irradiation model, τc was inversely proportional to the dose rate. Moreover, the comparison with experiments with pulsed electrons underlined the importance of the geometry of the irradiation volume for the estimation of τc. Finally, in the case of aerated water radiolysis, we calculated the yield of oxygen consumption and estimated the corresponding concentration of consumed (depleted) oxygen as a function of time and dose rate. It was shown that this concentration increases substantially with increasing dose rate in the time window ∼1 ns-10 µs, with a very pronounced maximum around 0.2 µs. For high-dose-rate irradiations (>109 Gy/s), a large part of the available oxygen (∼0.25 mM for an air-saturated solution) was found to be consumed. This result, which was obtained on a purely water radiation chemistry basis, strongly supports the hypothesis that the normal tissue-sparing effect of FLASH stems from temporary hypoxia due to oxygen depletion induced by high-dose-rate irradiation.

Evaluation of radiation treatment planning by computed tomography metal artifact reduction algorithm

Introduction: The objective of this study was to evaluate the usefulness of Computed Tomography(CT) images acquired through repeated subtraction reconstruction algorithms to reduce metal artifacts in CT Treatment Planning System(TPS).Materials and methods: Origin images of Gammex phantom and Rando phantom and non orthopedic metal artifact reduction(O-MAR) images were obtained after high density implantation. O-MAR applied images were also obtained. For evaluation of images, regions of interest(ROI) were set at five tissue rods and three points directly affected by artifacts in Gammex phantom. CT number and noise were compared and analyzed. To investigate dose change according to CT number change of the surrounding artifact, a three virtual cylindrical target volume was formed on Rando phantom CT images. The average dose was then compared and analyzed.Results: CT number difference according to the application of O-MAR showed significant difference among lung and bone rod and 3 ROI directly affected. Noise difference according to O-MAR application was significantly different in rod except for bone rod. In the treatment plan using Rando phantom, non-O-MAR and O-MAR images showed -4.3 ~ 1.9% and -0.4 ~ 2.3% dose differences, respectively.Conclusion: Applying a metal artifact reduction reconstruction algorithm can reduce image distortion due to high density implantation, improve image quality, and correct CT number.

Cosmic-Ray Tracks in Astrophysical Ices: Modeling with the Geant4-DNA Monte Carlo Toolkit

Abstract Cosmic rays are ubiquitous in interstellar environments, and their bombardment of dust-grain ice mantles is a possible driver for the formation of complex, even prebiotic molecules. Yet, critical data that are essential for accurate modeling of this phenomenon, such as the average radii of cosmic-ray tracks in amorphous solid water (ASW) remain unconstrained. It is shown that cosmic-ray tracks in ASW can be approximated as a cylindrical volume with an average radius that is mostly independent of the initial particle energy. Interactions between energetic ions and both low-density amorphous (LDA) and high-density amorphous (HDA) ice targets are simulated using the Geant4-DNA Monte Carlo toolkit, which allows for tracking secondary electrons down to subexcitation energies in the material. We find the peak track-core radii, r cyl, for LDA and HDA ices to be 9.9 nm and 8.4 nm, respectively—somewhat less than double the value of 5 nm often assumed in astrochemical models.

True Coincidence Summing Correction for Cylindrical Volume Samples in γ-ray Spectrometry

True Coincidence Summing Correction for Cylindrical Volume Samples in γ-ray Spectrometry

Economic Loss of Timber Caused by Over Stumps and Defects in Community Forests Terai Nepal

The economic loss of timber caused by over stumps and defects is an essential issue in forest science but study regarding this is very limited in Nepal. Thus, this research was objectively conducted to assess the volume of timber loss and associated monetary loss caused by over stumps and defects in logs and reason behind this. Three community forests namely Deurali, Jay Durga and Raniphanta community forests were selected for this research. Total enumeration was done so 375 stumps and 224 defected logs were measured from15 March to 15 April, 2019. The height and diameter at the butt end were measured using simple tape and D-tape respectively. Additionally, the length and diameter of defects in log was recorded. Total thirty key informant interviews and three focus group discussions were organized to assess the major causes of over stumps and defects. The timber volume loss caused by over stumps was calculated using cylindrical volume formula and volume loss caused by defect was calculated using formula, i.e. gross volume - net volume. The price of wood was collected from community forest to calculate the monetary value of timber loss. The principal component analysis was applied to assess the major causes of over stumps and defect in log. The highest total volume loss was recorded around 15.217 m3 (28.49%) caused by over stumps and out of this, it was 53.41 m3 timber loss in Deurali community forest. The loss due to defects in tree was ranged from 128.57 to 284.21 m3 in the community forests. The monetary value of loss caused by over stump was US$ 6971.14 of Shorea robusta in Deurali community forest and it was US$ 8100.52 because of defect. The principal component analysis showed that use of saw and axe for felling the trees in the community forests was considered as highest factor of over stump and diseases and over mature trees were key factors of wood defect. The research will be useful for policy makers and scientific community to monitor the timber loss.

ECAL MPD: geometry and simulation

New features of the MPD electromagnetic calorimeter of “shashlyk”-type are emphasized. Projective geometry of modules in cylindrical volume and complicated carbon fiber support structure are briefly described. Geant4 based simulation programm and main characteristics of the calorimeter are discussed.

Dual-Wavelength Interferometric Measurement of Electrically Exploded Aluminum and Copper Wires in Low-Pressure Air for Electron and Ion Density Calculation

Electron and atomic densities of Cu and Al plasmas in low-pressure air are studied using the recently reported dual-wavelength (1064 and 532 nm) interferometric diagnostic. The electrical explosion of a 99.999% pure, straight wire forms cylindrical plasma volumes within a low-pressure air chamber, and the probing lasers' interferometry patterns are simultaneously recorded at prescribed times after wire explosion. The measurements are performed repeatedly from 50 to 1200 ns in 50-ns increments allowing the calculation of electron and ion densities and the observation of the plasma's expansion and dissipation. The densities are calculated from fringe line analysis using a signal-processing-based algorithm that automatically extracts the fringe ratio. Finally, the maximum average volumetric electron and ion densities are calculated. The results of atomic density agree with past reports but are two orders greater than electron density, which suggests that full ionization is unattained.

Objective assessment of the combined effect of exomass-related- and motion artefacts in cone beam CT.

To assess quantitatively the combined effect of exomass-related- and motion artefacts on voxel value parameters in cone beam CT (CBCT). A cylindrical phantom was manufactured, containing 21 tubes filled with a radiopaque solution, allowing the inclusion of three titanium implants in the periphery to induce exomass-related artefacts. The phantom was mounted on a robot simulating 0.75-, 1.5-, and 3 mm movements (nodding/lateral rotation/tremor). CBCT images with/without exomass and with/without movements were acquired in duplicate in three units: Cranex 3Dx, Orthophos SL-3D, and X1 (with motion-artefact correction). A cylindrical volume of interest was defined in each tube and voxel value mean and standard deviation were assessed. For each CBCT volume, the 21 mean voxel values were averaged providing the overall mean voxel value (MVV), and the standard deviation (among the 21 values) was calculated providing overall voxel value inhomogeneity (VVI). The standard deviation from each of the 21 volumes-of-interest were averaged, providing overall image noise (IN). The effect of the diverse tested situations was inferred from a repeated-measures analysis of variance, followed by Sidak's test (α = 0.05). Overall, images acquired with exomass showed significantly (p ≤ 0.05) lower MVV, and higher VVI and IN. Motion artefacts aggravated exomass-related alterations. MVV and VVI were mostly affected by 3 mm nodding movements. Motion-artefact correction eliminated the deleterious effect of movement. CBCT voxel-value parameters are altered by exomass-related artefacts, and this finding is aggravated in the presence of motion artefacts. Motion-artefact correction effectively eliminated the deleterious impact of movement.

Monte Carlo track-structure for the radionuclide Copper-64: characterization of S-values, nanodosimetry and quantification of direct damage to DNA

TOPAS-nBio was used to simulate, collision-to-collision, the complete trajectories of electrons in water generated during the explicit simulation of 64Cu decay. S-values and direct damage to the DNA were calculated representing the cell (C) and the cell nucleus (N) with concentric spheres of 5 μm and 4 μm in radius, respectively. The considered ‘target’←‘source’ configurations, including the cell surface (Cs) and cytoplasm (Cy), were: C←C, C←Cs, N←N, N←Cy and N←Cs. Ionization cluster size distributions were also calculated in a cylinder immersed in water corresponding to a DNA segment of 10 base-pairs in length (diameter 2.3 nm, length 3.4 nm), modeling a radioactive point source moving from the central axis to the edge of the cylinder. For that, the first moment (M1) and cumulative probability of having a cluster size of 2 or more ionizations in the cylindrical volume (F2) were obtained. Finally, the direct damage to the DNA was estimated by quantifying double-strand breaks (DSBs) using the clustering algorithm DBSCAN.The S-values obtained with TOPAS-nBio for 64Cu were 7.879 × 10−4 ± 5 × 10−7, 4.351 × 10−4 ± 6 × 10−7, 1.442 × 10−3 ± 1 × 10−6, 2.596 × 10−4 ± 8 × 10−7, 1.127 × 10−4 ± 4 × 10−7 Gy Bq-s−1 for the configurations C←C, C←Cs, N←N, N←Cy and N←Cs, respectively. The difference of these values, compared with previously reported S-values for 64Cu with the code MNCP and software MIRDCell, ranged from −4% to −25% for the configurations N←N and N←Cs, respectively. On the other hand, F2 was maximum with the source at the center of the cylinder 0.373 ± 0.001, and monotonically decreased until reaching a value of 0.058 ± 0.001 at 2.3 nm. The same behavior was observed for M1 with values ranging from 2.188 ± 0.004 to 0.242 ± 0.002. Finally, the DBSCAN algorithm showed that the mean number of DNA DSBs per decay were 0.187 ± 0.001, 0.0317 ± 0.0005, and 0.0125 ± 0.0002 DSB-(Bq-s)−1 for the configurations N←N, N←Cs, and N←Cy, respectively.In conclusion, the results of the S-values show that the absorbed dose strongly depends on the distribution of the radionuclide in the cell, the dose being higher when 64Cu is internalized in the cell nucleus, which is reinforced by the nanodosimetric study by the presence of DNA DSBs attributable to the Auger electrons emitted during the decay of 64Cu.

Theoretical model of a finite force at the moving contact line

In theoretical analyses of the moving contact line, an infinite force along the solid wall has been reported based off the non-integrable stress along a single interface. In this investigation we demonstrate that the stress singularity is integrable and results in a finite force at the moving contact line if the contact line is treated as a one-dimensional manifold and all three interfaces that make up the moving contact line are taken into consideration. This is due to the dipole nature of the vorticity and pressure distribution around the moving contact line. Mathematically, this finite force is determined by summing all the forces that act over an infinitesimally small cylindrical control volume that encloses the entire moving contact line. With this finite force, we propose a new dynamic Young’s equation for microscopic dynamic contact angle that is a function of known parameters only, specifically the interface velocity, surface tension, and fluid viscosity. We combine our model with Cox’s model for apparent dynamic contact angle and find good agreement with published dynamic contact angle measurements.

Linking the spatiotemporal variation of litterfall to standing vegetation biomass in Brazilian savannas

Abstract Aims Litterfall at a global scale is affected by climate, edaphic features and vegetation structure, with litter production increasing from grasslands to forests following the rise in standing biomass. However, at landscape scales, the same relationship between litter production and vegetation structure has rarely been studied and comparisons of litterfall patterns between adjacent, structurally distinct communities are lacking. Here, we use a standardized methodology to describe the structural differences among four savanna physiognomies and analyze their relationship with changes in litterfall across the Cerrado. Methods We evaluated the woody vegetation structure and composition in 48 sites, equally distributed across four physiognomies and monitored the monthly litter production from April 2014 to March 2015. Important Findings Results showed that the density, basal area, cylindrical volume and aboveground biomass of woody vegetation differ among physiognomies, increasing consistently from cerrado ralo, cerrado típico, cerrado denso and cerradão. Indeed, we found a strong and positive relationship between aboveground biomass and annual litter production, with litter yield increasing from 0.9 to 8.4 Mg ha−1 across different physiognomies, following the increment in vegetation structure. Monthly production was seasonal and similar among vegetation types, increasing during the dry season. Leaves comprised the dominant fraction (approx. 85%) and litterfall seasonality primarily resulted from the concentration of leaf shedding during dry months. However, the temporal pattern of litterfall throughout the year showed a gradual reduction in the seasonality from open to closed vegetation types, likely following the decrease of deciduous species abundance in the plant community. Our results showed that changes in vegetation structure may affect spatial and temporal litterfall patterns in different physiognomies, which co-occur across the Cerrado landscape, with potential implications for the overall functioning of this ecosystem. Moreover, these findings highlight the use of standardized methods as essential to correctly compare litterfall patterns among different environments.

Single-Sided Magnetic Particle Imaging Device with Field-Free-Line Geometry for in-vivo Imaging Applications.

Magnetic Particle Imaging (MPI) has shown great promise to surpass existing in vivo imaging modalities in some clinical applications. However, one of the challenges to MPI being translated into clinical practice has been the ability to scale up the selection field coils to surround a human body while being able to generate and drive a sufficiently strong magnetic field gradient. These requirements impose safety concerns as well as prohibitively high-power consumption in devices with large cylindrical volume. Therefore, we consider an alternative approach such as a single-sided topology, in which all the hardware is located on one side of the imaging volume accommodating larger subjects. Moreover, different from the previously implemented field-free point single-sided scanners, we realized a field-free line geometry providing, in principle, factor of ten higher signal and benefiting from a more robust back-projection image reconstruction technique. In this work, we present and characterize a first prototype of a single-sided MPI device with field-free-line geometry suited for in-vivo imaging of small animals as well as regions of interest in humans.

Large-Eddy Simulation of ECN Spray A: Sensitivity Study on Modeling Assumptions

In this study, various mixing and evaporation modeling assumptions typically considered for large-eddy simulation (LES) of the well-established Engine Combustion Network (ECN) Spray A are explored. A coupling between LES and Lagrangian particle tracking (LPT) is employed to simulate liquid n-dodecane spray injection into hot inert gaseous environment, wherein Lagrangian droplets are introduced from a small cylindrical injection volume while larger length scales within the nozzle diameter are resolved. This LES/LPT approach involves various modeling assumptions concerning the unresolved near-nozzle region, droplet breakup, and LES subgrid scales (SGS) in which their impact on common spray metrics is usually left unexplored despite frequent utilization. Here, multi-parametric analysis is performed on the effects of (i) cylindrical injection volume dimensions, (ii) secondary breakup model, particularly Kelvin–Helmholtz Rayleigh–Taylor (KHRT) against a no-breakup model approach, and (iii) LES SGS models, particularly Smagorinsky and one-equation models against implicit LES. The analysis indicates the following findings: (i) global spray characteristics are sensitive to radial dimension of the cylindrical injection volume, (ii) the no-breakup model approach performs equally well, in terms of spray penetration and mixture formation, compared with KHRT, and (iii) the no-breakup model is generally insensitive to the chosen SGS model for the utilized grid resolution.

Parameters of Air Cylindrical Shock Waves

In this paper, we perform a numerical analysis of the parameters of shock waves (SWs) generated during the expansion of cylindrical volumes of compressed methane. A single dimensionless approximation of the overpressure dependence on the distance is obtained using precise numerical solutions. The overpressure values ​​in the SW are estimated for both the near and far zones. Comparison with previously developed similar dependences shows a higher accuracy of the proposed approximation, which allows predicting the consequences of accidents during the rupture of pipelines.

Subject-Specific EMG Modeling with Multiple Muscles: A Preliminary Study.

Modeling of surface electromyographic (EMG) signal has been proven valuable for signal interpretation and algorithm validation. However, most EMG models are currently limited to single muscle, either with numerical or analytical approaches. Here, we present a preliminary study of a subject-specific EMG model with multiple muscles. Magnetic resonance (MR) technique is used to acquire accurate cross section of the upper limb and contours of five muscle heads (biceps brachii, brachialis, lateral head, medial head, and long head of triceps brachii). The MR image is adjusted to an idealized cylindrical volume conductor model by image registration. High-density surface EMG signals are generated for two movements - elbow flexion and elbow extension. The simulated and experimental potentials were compared using activation maps. Similar activation zones were observed for each movement. These preliminary results indicate the feasibility of the multi-muscle model to generate EMG signals for complex movements, thus providing reliable data for algorithm validation.

The fracture process zone in mode I fracture emanating from notch and plastic zone size

In the linear mechanics of fracture from notch, the volumetric approach assumes that the rupture occurs in a cylindrical physical volume. This article highlights the hypothesis of this approach from the experimental results. According to this approach, the area of development of the fracture is characterized by its diameter called the effective distance and the average stress called effective stress. The determination of the effective distance is necessary to delimit this area. On the one hand, this article proposes a new method to determine this distance from the triaxiality parameter instead of the relative stress gradient, and on the other hand, it establishes a comparison between the plastic zone and the fracture process zone. The results show that the effective distance can be determined from the triaxiality parameter as well as the plastic zone including the zone of elaboration of the fracture.

Spectral and spatial shaping of laser-driven proton beams using a pulsed high-field magnet beamline

Intense laser-driven proton pulses, inherently broadband and highly divergent, pose a challenge to established beamline concepts on the path to application-adapted irradiation field formation, particularly for 3D. Here we experimentally show the successful implementation of a highly efficient (50% transmission) and tuneable dual pulsed solenoid setup to generate a homogeneous (laterally and in depth) volumetric dose distribution (cylindrical volume of 5 mm diameter and depth) at a single pulse dose of 0.7 Gy via multi-energy slice selection from the broad input spectrum. The experiments were conducted at the Petawatt beam of the Dresden Laser Acceleration Source Draco and were aided by a predictive simulation model verified by proton transport studies. With the characterised beamline we investigated manipulation and matching of lateral and depth dose profiles to various desired applications and targets. Using an adapted dose profile, we performed a first proof-of-technical-concept laser-driven proton irradiation of volumetric in-vitro tumour tissue (SAS spheroids) to demonstrate concurrent operation of laser accelerator, beam shaping, dosimetry and irradiation procedure of volumetric biological samples.

Image-guided core needle biopsy for relapsed and refractory neuroblastoma: A focus on sample adequacy for genetic sequencing.

e22521 Background: Relapsed and refractory neuroblastoma (NBL) is a prime target for novel therapies targeting specific mutations. The genomic landscape of NBL can change between time of initial diagnosis and relapse, necessitating subsequent biopsy and next generation sequencing (NGS) to detect mutations within the relapsed neoplasm. Tissue of insufficient quality and quantity leads to specimen failure during NGS. Thus the goal of this study is to review core needle biopsy for relapsed and refractory NBL in a pediatric interventional radiology department and explore factors that enhance biopsy adequacy. Methods: Retrospective review of clinical records and images for 66 patients (36M, 30F) with median age 8.7 years (range 0.9 – 49.3 y) who underwent 95 biopsies (55 bone, 40 soft tissue) over a 12-year period. Results: Biopsy yield for neuroblastic tissue from 123I mIBG-avid masses was 89.7% overall, 84.9% in bone, and 91.6% in soft tissue. 87/95 masses were mIBG-avid; 2 non-avid masses were NBL-positive (but also 18F-FDG avid). 48/59 samples sent for NGS were adequate for analysis (81.4%); bone and soft tissue biopsies did not differ in adequacy (77.1% vs 87.5%, p = 0.32). Tumor cell percent (TC%) for adequate samples was 49.9% vs 11.1% for NGS failures (p = 0.0003). Number of needle passes performed in bone and soft tissue lesions was positively correlated with NGS adequacy (Bone: r2= 0.68, Soft: r2= 0.33). In bone and soft tissue, adequate biopsies tended towards higher mean needle passes than inadequate ones (Bone: 5.1 vs 3.4, p = 0.0582) (Soft: 10.5 vs 4.7, p = 0.0428). Total needle volume passed into a soft tissue mass (calculated as inner needle cylindrical volume * # of passes) was higher in the “adequate” vs “inadequate” group (0.20 cm3 vs 0.05 cm3, p = 0.0004). Lesion mIBG avidity was quantified with a ratio of lesion:liver SUV; this mIBG SUV ratio was positively correlated with TC% (R2 = 0.55, N = 14). Using a linear regression line, a TC% of 50% (the mean value for samples adequate for NGS) corresponded to an SUV ratio of 2.89. The rate of minor complications (requiring only nominal therapy) was 7/95 (7.4%). The rate of major complications (requiring longer hospital stay) was 1/95 (1.5%). Conclusions: Image-guided core needle biopsy for relapsed and refractory NBL has a moderately high yield for procuring tumor samples adequate for NGS with a low rate of major complications. Adequate bone and soft tissue biopsies averaged >5 and >10 needle passes, respectively. An approximate lesion:liver mIBG SUV ratio of >3 may maximize specimen quality for NGS.

Differences in fetal fractional limb volume changes in normal and gestational diabetic pregnancies: an exploratory observational study.

Fetal fractional limb volume has been proposed as a useful measure for quantifying fetal soft tissue development. The aim of this study was to investigate the growth of fractional arm volume (AVol) and fractional thigh volume (TVol) of fetuses with maternal gestational diabetes (GDM) compared with those of fetuses with normal glucose tolerance (NGT). We hypothesised fetal fractional limb volume would be larger in the GDM group than in the NGT group in late gestation. Exploratory observational study. Saitama Municipal Hospital. A total of 165 (125 NGT and 40 GDM) singleton Japanese pregnant women. AVol and TVol were assessed between 20 and 37weeks' gestation as cylindrical limb volumes based on 50% of the fetal humeral or femoral diaphysis length. Women were diagnosed as GDM based on the criteria of the Japan Society of Obstetrics and Gynecology. AVol and TVol were compared between women with NGT and those with GDM at each gestational age period (2-week intervals from 20 to 37weeks' gestation). Overall, 287 ultrasound scans were performed (NGT group, 205 scans; GDM group, 82 scans). There was no significant difference of AVol between the groups before 32weeks' gestation. AVol was significantly larger in the GDM group than in the NGT group after 32weeks' gestation (P<0.05). TVol was not statistically different between the groups across gestation. Detection of variations in fetal AVol may provide greater insight into understanding the origins of altered fetal body proportion in GDM. AVol, but not TVol, is significantly larger in fetuses with GDM than in those with NGT after 32weeks' gestation.