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Radiological Physics and Technology

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https://www.readbyqxmd.com/read/27910001/the-effect-of-influence-quantities-and-detector-orientation-on-small-field-patient-specific-imrt-qa-comparison-of-measurements-with-various-ionization-chambers
#1
Henry Finlay Godson, Ravikumar Manickam, Sathiyan Saminathan, Kadirampatti Mani Ganesh, Retna Ponmalar
Intensity-modulated radiation therapy (IMRT) requires a patient-specific quality assurance (QA) program to validate the treatment plan and a high level of dosimetric accuracy in the treatment delivery. Dosimetric verification generally consists of both absolute- and relative-dose measurements in a phantom using ionization chambers. Measurements were carried out with three different ionization chambers (Scanditronix FC 65G, Exradin A18, and PTW PinPoint 31014) to assess the effects of influence quantities such as the stability, pre- and post-irradiation leakage, stem effect, polarity, and ion recombination on the IMRT point-dose verification with two different orientations...
December 1, 2016: Radiological Physics and Technology
https://www.readbyqxmd.com/read/27796808/evaluation-of-basic-characteristics-of-a-semiconductor-detector-for-personal-radiation-dose-monitoring
#2
Kento Terasaki, Toshioh Fujibuchi, Hiroo Murazaki, Taku Kuramoto, Yoshiyuki Umezu, Yang Ishigaki, Yoshinori Matsumoto
Real-time radiation dose management is important because staff members working in interventional radiology may be exposed to relatively high doses of primary and scattered radiation from the body of a patient. In this study, we investigated the dependence of energy and dose rate of the commercially available semiconductor detector named Pocket Geiger (POKEGA) for personal monitoring in diagnostic X-rays. In the energy-dependence study, a suitable metal filter and the threshold level were examined for energy compensation using a Monte Carlo calculation code...
October 28, 2016: Radiological Physics and Technology
https://www.readbyqxmd.com/read/27787667/quantification-of-hazard-prediction-ability-at-hazard-prediction-training-kiken-yochi-training-kyt-by-free-response-receiver-operating-characteristic-froc-analysis
#3
Masahiro Hashida, Ryousuke Kamezaki, Makoto Goto, Junji Shiraishi
The ability to predict hazards in possible situations in a general X-ray examination room created for Kiken-Yochi training (KYT) is quantified by use of free-response receiver-operating characteristics (FROC) analysis for determining whether the total number of years of clinical experience, involvement in general X-ray examinations, occupation, and training each have an impact on the hazard prediction ability. Twenty-three radiological technologists (RTs) (years of experience: 2-28), four nurses (years of experience: 15-19), and six RT students observed 53 scenes of KYT: 26 scenes with hazardous points (hazardous points are those that might cause injury to patients) and 27 scenes without points...
October 27, 2016: Radiological Physics and Technology
https://www.readbyqxmd.com/read/27783357/three-dimensional-phase-contrast-magnetic-resonance-imaging-validated-to-assess-pulmonary-artery-flow-in-patients-with-chronic-thromboembolic-pulmonary-hypertension
#4
Masateru Kawakubo, Hiroshi Akamine, Yuzo Yamasaki, Atsushi Takemura, Kohtaro Abe, Kazuya Hosokawa, Junji Morishita, Michinobu Nagao
In this study, three-dimensional phase contrast magnetic resonance imaging (3D-PC MRI), a novel technique, was validated to assess pulmonary artery (PA) flow in patients with chronic thromboembolic pulmonary hypertension (CTEPH). The MR data of PAs from 3D-PC and two-dimensional PC (2D-PC) from before and after treatment for 3 patients with CTEPH were retrospectively analyzed. Additionally, 3D- and 2D-PC MR scans of PA were performed in 5 healthy volunteers. Correlation of stroke volumes (SVs) obtained by 3D-PC and 2D-PC was analyzed using Pearson's correlation coefficients...
October 25, 2016: Radiological Physics and Technology
https://www.readbyqxmd.com/read/27714568/louis-harold-gray-november-10-1905-july-9-1965-a-pioneer-in-radiobiology
#5
EDITORIAL
Masaru Sekiya, Michio Yamasaki
No abstract text is available yet for this article.
October 6, 2016: Radiological Physics and Technology
https://www.readbyqxmd.com/read/27699636/relation-between-one-and-two-dimensional-noise-power-spectra-of-magnetic-resonance-images
#6
Yuki Ichinoseki, Yoshio Machida
Our purpose in this study was to elucidate the relation between the one-dimensional (1D) and two-dimensional (2D) noise power spectra (NPSs) in magnetic resonance imaging (MRI). We measured the 1D NPSs using the slit method and the radial frequency method. In the slit method, numerical slits 1 pixel wide and L pixels long were placed on a noise image (128 × 128 pixels) and scanned in the MR image domain. We obtained the 1D NPS using the slit method (1D NPS_Slit) and the 2D NPS of the noise region scanned by the slit (2D NPS_Slit)...
October 3, 2016: Radiological Physics and Technology
https://www.readbyqxmd.com/read/27699635/optimizing-ct-technique-to-reduce-radiation-dose-effect-of-changes-in-kvp-iterative-reconstruction-and-noise-index-on-dose-and-noise-in-a-human-cadaver
#7
Kevin J Chang, Scott Collins, Baojun Li, William W Mayo-Smith
For assessment of the effect of varying the peak kilovoltage (kVp), the adaptive statistical iterative reconstruction technique (ASiR), and automatic dose modulation on radiation dose and image noise in a human cadaver, a cadaver torso underwent CT scanning at 80, 100, 120 and 140 kVp, each at ASiR settings of 0, 30 and 50 %, and noise indices (NIs) of 5.5, 11 and 22. The volume CT dose index (CTDIvol), image noise, and attenuation values of liver and fat were analyzed for 20 data sets. Size-specific dose estimates (SSDEs) and liver-to-fat contrast-to-noise ratios (CNRs) were calculated...
October 3, 2016: Radiological Physics and Technology
https://www.readbyqxmd.com/read/27696210/investigation-of-noise-sources-for-digital-radiography-systems
#8
Lutfi Ergun, Turan Olgar
The performance of digital radiography systems can be evaluated in terms of spatial resolution and noise. Noise plays an important role in the achievable image quality for detecting small and low-contrast structures in digital images created by these systems. Our aim in this study was to investigate the noise sources both in the spatial and frequency domain for three digital radiography systems, one digital fluoroscopy system, and one digital mammography system, and to obtain information about the effective operating dose range of these detectors...
October 1, 2016: Radiological Physics and Technology
https://www.readbyqxmd.com/read/27696286/radiation-dose-optimization-for-the-bolus-tracking-technique-in-abdominal-computed-tomography-usefulness-of-real-time-iterative-reconstruction-for-monitoring-scan
#9
Yuya Ishikawa, Atsushi Urikura, Tsukasa Yoshida, Keisuke Takiguchi, Yoshihiro Nakaya
The purpose of this study was to optimize the monitoring dose, obtained using the conventional filtered back projection (FBP) method and iterative reconstruction algorithms, for the bolus tracking technique. A phantom study was performed to assess the effect of the scan start time in patients grouped according to different body weights. An oval torso phantom was used for simulating the time enhancement curve of the bolus tracking technique. To reproduce image noise levels in the two body weight groups, the phantom diameter was adjusted with a water-equivalent material...
September 30, 2016: Radiological Physics and Technology
https://www.readbyqxmd.com/read/27645287/radiation-doses-for-pregnant-women-in-the-late-pregnancy-undergoing-fetal-computed-tomography-a-comparison-of-dosimetry-and-monte-carlo-simulations
#10
Yuta Matsunaga, Ai Kawaguchi, Masanao Kobayashi, Shigetaka Suzuki, Shoichi Suzuki, Koichi Chida
The purposes of this study were (1) to compare the radiation doses for 320- and 80-row fetal-computed tomography (CT), estimated using thermoluminescent dosimeters (TLDs) and the ImPACT Calculator (hereinafter referred to as the "CT dosimetry software"), for a woman in her late pregnancy and her fetus and (2) to estimate the overlapped fetal radiation dose from a 320-row CT examination using two different estimation methods of the CT dosimetry software. The direct TLD data in the present study were obtained from a previous study...
September 19, 2016: Radiological Physics and Technology
https://www.readbyqxmd.com/read/27631427/improvement-in-visualization-of-carotid-artery-uniformity-using-silent-magnetic-resonance-angiography
#11
Yasuhiro Fujiwara, Yoshiyuki Muranaka
Three-dimensional time-of-flight magnetic resonance angiography (TOF MRA) has been widely used in clinics. TOF MRA can cause dephasing artifacts, which lead to an intraluminal signal decrease. Silent MRA is a novel imaging technique that uses arterial spin labeling to achieve an ultrashort echo time (uTE), which is expected to decrease these effects and allow for accurate assessment of the flow in blood vessels. This study quantified the accuracy of Silent MRA images for visualizing the turbulent flow in flow-phantom and in vivo studies...
September 8, 2016: Radiological Physics and Technology
https://www.readbyqxmd.com/read/27586848/simplified-estimation-method-for-dose-distributions-around-field-junctions-in-proton-craniospinal-irradiation
#12
Haruo Yamashita, Yuki Kase, Shigeyuki Murayama
In radiotherapy involving craniospinal irradiation (CSI), field junctions of therapeutic beams are necessary, because a CSI target is generally several times larger than the maximum field size of the beams. The purpose of this study was to develop a simplified method for estimating dose uniformity around the field junctions in proton CSI. We estimated the dose profiles around the field junctions of proton beams using a simplified field-junction model, in which partial lateral dose distributions around the field edge were assumed to be approximated using the error function...
September 1, 2016: Radiological Physics and Technology
https://www.readbyqxmd.com/read/27539271/quantification-of-the-accuracy-limits-of-image-registration-using-peak-signal-to-noise-ratio
#13
Yoshinori Tanabe, Takayuki Ishida
A new method was developed for quantifying the accuracy limits of image registration devices and the distortion of anatomical structures in verification images without image registration. A correlation was found between peak signal-to-noise ratio (PSNR) and the amount of parallel movement (1-10 mm at 1-mm intervals) of a rectangular parallelepiped phantom [correlation coefficient (CC) -0.91, contribution ratio (CR) 0.83]. Rotating the phantom from 1° to 10° at 1° intervals produced a similar correlation with PSNR (CC -0...
August 18, 2016: Radiological Physics and Technology
https://www.readbyqxmd.com/read/27534969/relative-diffusion-of-paramagnetic-metal-complexes-of-mri-contrast-agents-in-an-isotropic-hydrogel-medium
#14
Bimali Sanjeevani Weerakoon, Toshiaki Osuga
The observation of molecular diffusion by means of magnetic resonance imaging (MRI) is significant in the evaluation of the metabolic activity of living tissues. Series of MRI examinations were conducted on a diffusion model to study the behaviour of the diffusion process of different-molecular-weight (MW) paramagnetic MRI contrast agents in an isotropic agar hydrogel medium. The model consisted of a solidified 1 % agar gel with an initial concentration of 0.5 mmol/L contrast solution layered on top of the gel...
August 17, 2016: Radiological Physics and Technology
https://www.readbyqxmd.com/read/27531215/estimation-of-ambient-dose-equivalent-distribution-in-the-18-f-fdg-administration-room-using-monte-carlo-simulation
#15
Shuji Nagamine, Toshioh Fujibuchi, Yoshiyuki Umezu, Kazuhiko Himuro, Shinichi Awamoto, Yuji Tsutsui, Yasuhiko Nakamura
In this study, we estimated the ambient dose equivalent rate (hereafter "dose rate") in the fluoro-2-deoxy-D-glucose (FDG) administration room in our hospital using Monte Carlo simulations, and examined the appropriate medical-personnel locations and a shielding method to reduce the dose rate during FDG injection using a lead glass shield. The line source was assumed to be the FDG feed tube and the patient a cube source. The dose rate distribution was calculated with a composite source that combines the line and cube sources...
August 16, 2016: Radiological Physics and Technology
https://www.readbyqxmd.com/read/27431651/evaluation-of-modern-camera-calibration-techniques-for-conventional-diagnostic-x-ray-imaging-settings
#16
Francisco Albiol, Alberto Corbi, Alberto Albiol
We explore three different alternatives for obtaining intrinsic and extrinsic parameters in conventional diagnostic X-ray frameworks: the direct linear transform (DLT), the Zhang method, and the Tsai approach. We analyze and describe the computational, operational, and mathematical background differences for these algorithms when they are applied to ordinary radiograph acquisition. For our study, we developed an initial 3D calibration frame with tin cross-shaped fiducials at specific locations. The three studied methods enable the derivation of projection matrices from 3D to 2D point correlations...
July 18, 2016: Radiological Physics and Technology
https://www.readbyqxmd.com/read/27394728/dose-reduction-technique-in-diagnostic-x-ray-computed-tomography-by-use-of-6-channel-multileaf-collimators
#17
Fumio Hashimoto, Atsushi Teramoto, Yasuki Asada, Shoichi Suzuki, Hiroshi Fujita
Recently, region-setting computed tomography (CT) has been studied as a region of interest imaging method. This technique can strongly reduce the radiation dose by limiting the irradiation field. Although mathematical studies have been performed for reduction of the truncation artifact, no experimental studies have been performed so far. In this study, we developed a three-dimensional region-setting CT system and evaluated its imaging properties. As an experimental system, we developed an X-ray CT system with multileaf collimators...
July 9, 2016: Radiological Physics and Technology
https://www.readbyqxmd.com/read/27380307/fully-parametric-imaging-with-reversible-tracer-18-f-flt-within-a-reasonable-time
#18
Nobuyuki Kudomi, Yukito Maeda, Tetsuhiro Hatakeyama, Yuka Yamamoto, Yoshihiro Nishiyama
PET enables quantitative imaging of the rate constants K 1, k 2, k 3, and k 4, with a reversible two tissue compartment model (2TCM). A new method is proposed for computing all of these rates within a reasonable time, less than 1 min. A set of differential equations for the reversible 2TCM was converted into a single formula consisting of differential and convolution terms. The validity was tested on clinical data with (18)F-FLT PET for patients with glioma (n = 39). Parametric images were generated with the formula that was developed...
July 5, 2016: Radiological Physics and Technology
https://www.readbyqxmd.com/read/27294264/dynamic-chest-radiography-flat-panel-detector-fpd-based-functional-x-ray-imaging
#19
REVIEW
Rie Tanaka
Dynamic chest radiography is a flat-panel detector (FPD)-based functional X-ray imaging, which is performed as an additional examination in chest radiography. The large field of view (FOV) of FPDs permits real-time observation of the entire lungs and simultaneous right-and-left evaluation of diaphragm kinetics. Most importantly, dynamic chest radiography provides pulmonary ventilation and circulation findings as slight changes in pixel value even without the use of contrast media; the interpretation is challenging and crucial for a better understanding of pulmonary function...
July 2016: Radiological Physics and Technology
https://www.readbyqxmd.com/read/27286844/acknowledgment
#20
(no author information available yet)
No abstract text is available yet for this article.
July 2016: Radiological Physics and Technology
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