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Radiological Physics and Technology

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https://www.readbyqxmd.com/read/29159536/physics-of-epi-thermal-boron-neutron-capture-therapy-epi-thermal-bnct
#1
REVIEW
Ryoichi Seki, Yushi Wakisaka, Nami Morimoto, Masaaki Takashina, Masahiko Koizumi, Hiroshi Toki, Mitsuhiro Fukuda
The physics of epi-thermal neutrons in the human body is discussed in the effort to clarify the nature of the unique radiologic properties of boron neutron capture therapy (BNCT). This discussion leads to the computational method of Monte Carlo simulation in BNCT. The method is discussed through two examples based on model phantoms. The physics is kept at an introductory level in the discussion in this tutorial review.
November 20, 2017: Radiological Physics and Technology
https://www.readbyqxmd.com/read/29159535/acknowledgment
#2
(no author information available yet)
No abstract text is available yet for this article.
November 20, 2017: Radiological Physics and Technology
https://www.readbyqxmd.com/read/29134542/influence-of-the-menstrual-cycle-on-compression-induced-pain-during-mammography-correlation-with-the-thickness-and-volume-of-the-mammary-gland
#3
Hitomi Kitaoka, Hiroko Kawashima
In mammography, breast compression is necessary and an important factor influencing image quality. The purpose of this study was to determine the influence of the menstrual cycle on compression-induced pain during mammography and to evaluate the association between the thickness and volume of the mammary gland and pain. We examined basal body temperature and categorized the menstrual cycle into five phases. We executed breast compression in the craniocaudal view using a customized compression plate, to which we introduced an opening...
November 13, 2017: Radiological Physics and Technology
https://www.readbyqxmd.com/read/29128934/radiobiological-analysis-of-stereotactic-body-radiation-therapy-for-an-evidence-based-planning-target-volume-of-the-lung-using-multiphase-ct-images-obtained-with-a-pneumatic-abdominal-compression-apparatus-a-case-study
#4
Arun Chairmadurai, Harish Chandra Goel, Sandeep Kumar Jain, Pawan Kumar
This study evaluated the efficiency of stereotactic body radiation therapy of lung (SBRT-Lung) in generating a treatment volume using conventional multiple-phase three-dimensional computed tomography (3D-CT) of a patient immobilized with pneumatic abdominal compression. The institutional protocol for SBRT-Lung using the RapidArc technique relied on a planning target volume (PTV) delineated using 3D-CT and accounted for linear and angular displacement of the tumor during respiratory movements. The efficiency of the institutional protocol was compared with that of a conventional method for PTV delineation based on radiobiological estimates, such as tumor control probability (TCP) and normal tissue complication probability (NTCP), evaluated using dose-volume parameters...
November 11, 2017: Radiological Physics and Technology
https://www.readbyqxmd.com/read/29058267/robert-r-wilson-1914-2000-the-first-scientist-to-propose-particle-therapy-use-of-particle-beam-for-cancer-treatment
#5
EDITORIAL
Masahiro Endo
No abstract text is available yet for this article.
October 20, 2017: Radiological Physics and Technology
https://www.readbyqxmd.com/read/29039068/the-effect-of-scan-interval-and-bolus-length-on-the-quantitative-accuracy-of-cerebral-computed-tomography-perfusion-analysis-using-a-hollow-fiber-phantom
#6
Hiroyuki Hashimoto, Kazufumi Suzuki, Eiji Okaniwa, Hiroshi Iimura, Kayoko Abe, Shuji Sakai
The shuttle scan technique is expected to extend scan range in cerebral computed tomography (CT) perfusion by 16- or 64-row multidetector CT (MDCT), but it may affect quantitative accuracy. This study aims to evaluate the effect of long scan interval and bolus length on the quantitative accuracy of perfusion indices using an innovative hollow-fiber phantom.We used an originally developed hollow-fiber hemodialyzer covered with polyurethane resin as a perfusion phantom. We scanned the phantom during various scan intervals (1-13 s) and bolus injection lengths (5, 10, 15, and 20 s), and evaluated cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and time-to-peak (TTP)...
October 16, 2017: Radiological Physics and Technology
https://www.readbyqxmd.com/read/28988344/how-should-we-manage-internal-margins-in-four-dimensional-dose-assessments
#7
LETTER
Shinichiro Mori, Christian Graeff, Nobuyuki Kanematsu
No abstract text is available yet for this article.
October 7, 2017: Radiological Physics and Technology
https://www.readbyqxmd.com/read/28986818/investigation-of-spatial-resolution-improvement-by-use-of-a-mouth-insert-detector-in-the-helmet-pet-scanner
#8
Abdella M Ahmed, Hideaki Tashima, Taiga Yamaya
The dominant factor limiting the intrinsic spatial resolution of a positron emission tomography (PET) system is the size of the crystal elements in the detector. To increase sensitivity and achieve high spatial resolution, it is essential to use advanced depth-of-interaction (DOI) detectors and arrange them close to the subject. The DOI detectors help maintain high spatial resolution by mitigating the parallax error caused by the thickness of the scintillator near the peripheral regions of the field-of-view...
October 6, 2017: Radiological Physics and Technology
https://www.readbyqxmd.com/read/28983807/relationship-between-tumor-volume-and-quantitative-values-calculated-using-two-dimensional-bone-scan-images
#9
Shota Hosokawa, Kazumasa Inoue, Yasuyuki Takahashi, Kazunori Kawakami, Daisuke Kano, Yoshihiro Nakagami, Masahiro Fukushi
The bone scan index (BSI) is calculated from a whole-body bone scan image; it shows the tumor burden in bone as a percentage of total skeletal mass. It has been used to determine the prognosis and to assess treatment effects; however, little has been reported on whether the BSI calculated using a two-dimensional image can accurately evaluate the three-dimensional spread in tumor volume. We investigated the relationship between tumor volume and BSI using Monte Carlo simulation (MCS). We simulated a gamma camera and constructed a voxel phantom based on an anthropomorphic phantom computed tomography (CT) image and gamma rays emitted from each part according to technetium-99m-labeled methylene diphosphonate ((99m)Tc-MDP) uptake (bone 1, soft tissue 0...
October 5, 2017: Radiological Physics and Technology
https://www.readbyqxmd.com/read/28975537/mis-segmentation-in-voxel-based-morphometry-due-to-a-signal-intensity-change-in-the-putamen
#10
Masami Goto, Osamu Abe, Tosiaki Miyati, Shigeki Aoki, Tsutomu Gomi, Tohoru Takeda
The aims of this study were to demonstrate an association between changes in the signal intensity of the putamen on three-dimensional T1-weighted magnetic resonance images (3D-T1WI) and mis-segmentation, using the voxel-based morphometry (VBM) 8 toolbox. The sagittal 3D-T1WIs of 22 healthy volunteers were obtained for VBM analysis using the 1.5-T MR scanner. We prepared five levels of 3D-T1WI signal intensity (baseline, same level, background level, low level, and high level) in regions of interest containing the putamen...
October 3, 2017: Radiological Physics and Technology
https://www.readbyqxmd.com/read/28921448/assessment-of-dose-uniformity-around-high-dose-rate-192-ir-and-60-co-stepping-sources
#11
Bagher Farhood, Mahdi Ghorbani
This study aimed to evaluate dose uniformity for (192)Ir and (60)Co stepping sources. High dose rate (192)Ir and (60)Co stepping sources were simulated by the MCNPX Monte Carlo code. To investigate dose uniformity, treatment lengths of 30, 50, 100, and 150 mm with stepping distances of 3, 5, 7, and 10 mm were considered. Finally, dose uniformity for the (192)Ir and (60)Co stepping sources with increasing distances from the source were assessed at these treatment lengths and steps. The findings showed that the dose distribution was non-uniform for regions in close vicinity of the source, especially in the high source steps, but for most points at distances >10 mm from the center of the source, the dose distribution was uniform...
September 18, 2017: Radiological Physics and Technology
https://www.readbyqxmd.com/read/28895045/influence-of-gd-eob-dtpa-on-proton-density-fat-fraction-using-the-six-echo-dixon-method-in-3-tesla-magnetic-resonance-imaging
#12
Tatsuya Hayashi, Kei Fukuzawa, Hiroshi Kondo, Hiroshi Onodera, Shuji Toyotaka, Rie Tojo, Shimpei Yano, Masakatsu Tano, Tosiaki Miyati, Jun'ichi Kotoku, Takahide Okamoto, Keiko Toyoda, Hiroshi Oba
The purpose of this study was to evaluate whether disodium gadoxetate (Gd-EOB-DTPA) affects proton density fat fractions (PDFFs) during use of the multiecho Dixon (meDixon) method in phantom and simulation magnetic resonance imaging (MRI) studies at 3 T. Fat-water phantoms comprising vegetable fat-water emulsions with varying fat volume percentages (0, 5, 10, 15, 20, 30, 40, and 50) and Gd-EOB-DTPA concentrations (0 and 0.4 mM) were prepared. Phantoms without Gd-EOB-DTPA were defined as precontrast, and those with Gd-EOB-DTPA were defined as postcontrast...
September 11, 2017: Radiological Physics and Technology
https://www.readbyqxmd.com/read/28895040/clinical-utility-of-ultra-low-dose-pre-test-exposure-to-avoid-unnecessary-patient-exposure-due-to-positioning-errors-a-simulation-study
#13
Hideo Nose, Junji Shiraishi
The use of digital radiographic systems has decreased the frequency of image retakes due to over/underexposure in general radiography. However, image retakes owing to patient positioning errors are likely to increase because of the convenience of a real-time image check on a console table. The purpose of the present study is to propose a novel radiographic examination procedure with an ultra-low-dose pre-test exposure that may be utilized to check patient positioning prior to taking an actual image, thereby reducing unnecessary patient exposure owing to image retakes...
September 11, 2017: Radiological Physics and Technology
https://www.readbyqxmd.com/read/28895034/whole-body-biodistribution-and-the-influence-of-body-activity-on-brain-kinetic-analysis-of-the-11-c-pib-pet-scan
#14
Go Akamatsu, Tomoyuki Nishio, Kazuhiko Adachi, Yasuhiko Ikari, Michio Senda
Dynamic (11)C-PiB PET imaging with kinetic analysis has been performed for accurate quantification of amyloid binding in patients with Alzheimer's disease (AD). In this study, we measured the whole-body biodistribution of (11)C-PiB in nine subjects. We then evaluated the effect of body activity on quantitative accuracy of brain (11)C-PiB three-dimensional (3D) dynamic PET. Based on clinical biodistribution data, we conducted phantom experiments to estimate the effect of body activity on quantification of the brain 3D dynamic (11)C-PiB PET data and the error introduced by body activity using six different PET camera models...
September 11, 2017: Radiological Physics and Technology
https://www.readbyqxmd.com/read/28887805/quantitative-analysis-of-effects-of-hemodynamic-stress-on-temporal-variations-of-cardiac-phases-in-models-of-human-carotid-bulbs
#15
Tatsunori Saho, Hideo Onishi
In this study, we evaluated the hemodynamics of carotid artery models with carotid bulbs of various sizes using computational fluid dynamics (CFD) and the Fluent CFD software. The oscillatory shear index (OSI) and flow velocity distribution were evaluated in carotid models without a carotid bulb and with carotid bulbs of known geometry (major axis of 10, 11, 12, 13, and 14 mm; carotid bifurcation angle of 50°). Furthermore, the diameters of the common carotid artery, the external carotid artery, and the internal carotid artery were defined as 7...
September 8, 2017: Radiological Physics and Technology
https://www.readbyqxmd.com/read/28879578/improved-wedge-method-for-the-measurement-of-sub-millimeter-slice-thicknesses-in-magnetic-resonance-imaging
#16
Tsutomu Kanazawa, Masaki Ohkubo, Tatsuya Kondo, Takayuki Miyazawa, Shoichi Inagawa
The standard method for measuring the slice thickness of magnetic resonance images uses the inclined surface of a wedge (wedge method); it is sensitive to small increases in noise because of the differentiation of the edge response function (ERF) required. The purpose of this study was to improve the wedge method by fitting a curve to the ERF. The curve-fit function was obtained by convolving an ideal ERF (a ramp function) with a Gaussian function to represent ERF blurring. Measurements of 5- and 3-mm slice thicknesses were performed on a 3T scanner using the conventional wedge method, the improved wedge method, and another standard method using an inclined slab (slab method)...
September 6, 2017: Radiological Physics and Technology
https://www.readbyqxmd.com/read/28823084/effects-of-a-novel-tungsten-impregnated-rubber-neck-shield-on-the-quality-of-cerebral-images-acquired-using-15-o-labeled-gas
#17
Kei Wagatsuma, Keiichi Oda, Kenta Miwa, Motoki Inaji, Muneyuki Sakata, Jun Toyohara, Kiichi Ishiwata, Masayuki Sasaki, Kenji Ishii
The present study aimed to validate the effects of a novel tungsten-impregnated rubber neck shield on the quality of phantom and clinical (15)O-labeled gas positron emission tomography (PET) images. Images were acquired in the presence or absence of a neck shield from a cylindrical phantom containing [(15)O]H2O (phantom study) and from three individuals using [(15)O]CO2, [(15)O]O2 and [(15)O]CO gas (clinical study). Data were acquired in three-dimensional (3D) mode using a Discovery PET/CT 710. Values for cerebral blood flow, cerebral blood volume, oxygen extraction fraction, and cerebral metabolic rate of oxygen with and without the neck shield were calculated from (15)O-labeled gas images...
August 19, 2017: Radiological Physics and Technology
https://www.readbyqxmd.com/read/28822095/validation-of-a-calibration-method-using-the-cross-calibration-factor-and-system-planar-sensitivity-in-quantitative-single-photon-emission-computed-tomography-imaging
#18
Norikazu Matsutomo, Saki Matsumoto, Tomoaki Yamamoto, Eisuke Sato
The present study aimed to validate the absolute quantitative accuracy of a calibration method for single-photon emission computed tomography (SPECT) using cross-calibration factor (CCF)- and system sensitivity-based calibration methods. The CCF obtained with different reconstruction parameters was evaluated using a cylindrical phantom (diameter 20 cm, height 20 cm). SPECT images were acquired with a positron emission tomography/computed tomography (CT) phantom. Subsequently, they were reconstructed by using ordered subset expectation maximization with resolution recovery, scatter, and CT-based attenuation correction...
August 18, 2017: Radiological Physics and Technology
https://www.readbyqxmd.com/read/28822094/quantitative-knee-cartilage-measurement-at-mr-imaging-of-patients-with-anterior-cruciate-ligament-tear
#19
Kazuki Kato, Tamotsu Kamishima, Eiji Kondo, Tomohiro Onodera, Shota Ichikawa
In previous studies, numerous approaches were proposed that assess knee cartilage volume quantitatively using 3D magnetic resonance (MR) imaging. However, the clinical use of these approaches is limited because 3D MR is prone to metal artifacts in postoperative cases. Our purpose in this study was to validate a method for knee cartilage volume quantification using conventional MR imaging in patients who underwent anterior cruciate ligament (ACL) reconstruction surgery. The study included 16 patients who underwent MR imaging before and 1 year after ACL reconstruction surgery...
August 18, 2017: Radiological Physics and Technology
https://www.readbyqxmd.com/read/28822074/general-equations-for-optimal-selection-of-diagnostic-image-acquisition-parameters-in-clinical-x-ray-imaging
#20
Xiaoming Zheng
The purpose of this work was to examine the effects of relationship functions between diagnostic image quality and radiation dose on the governing equations for image acquisition parameter variations in X-ray imaging. Various equations were derived for the optimal selection of peak kilovoltage (kVp) and exposure parameter (milliAmpere second, mAs) in computed tomography (CT), computed radiography (CR), and direct digital radiography. Logistic, logarithmic, and linear functions were employed to establish the relationship between radiation dose and diagnostic image quality...
August 18, 2017: Radiological Physics and Technology
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