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Radiological Physics and Technology

Bram van Ginneken
Half a century ago, the term "computer-aided diagnosis" (CAD) was introduced in the scientific literature. Pulmonary imaging, with chest radiography and computed tomography, has always been one of the focus areas in this field. In this study, I describe how machine learning became the dominant technology for tackling CAD in the lungs, generally producing better results than do classical rule-based approaches, and how the field is now rapidly changing: in the last few years, we have seen how even better results can be obtained with deep learning...
February 16, 2017: Radiological Physics and Technology
Nobuhiro Yada, Hideo Onishi, Masahiro Miyai, Kentarou Ozasa, Takashi Katsube, Keiichi Onoda, Masuo Haramoto, Yasushi Yamamoto, Shuhei Yamaguchi, Hajime Kitagaki
We evaluated a novel normal database (NDB) generated using single photon emission computed tomography (SPECT) data obtained from healthy brains by using a SPECT/CT system, analyzed using a resolution recovery (RR) technique applied to the three-dimensional stereotactic surface projection (3D-SSP) technique. We used a three-dimensional ordered subset expectation maximization method (3D-OSEM) with applied scatter correction (SC), attenuation correction, and RR to reconstruct the data. We verified the accuracy of the novel NDB's values (Z, extent, and error scores), and compared the novel NDB to the 3D-SSP technique by using simulated misery perfusion-related patient data from a conventional NDB...
February 4, 2017: Radiological Physics and Technology
Masayuki Kanamoto, Tosiaki Miyati, Kazuki Terashima, Kei Katahira, Ryoji Ida, Daisaku Suga, Nobukazu Fuwa
The purpose of this study was to compare between superparamagnetic iron oxide (SPIO)-enhanced three-dimensional balanced turbo field-echo (B-TFE) sequence with T2 preparation pulse (T2 prep) and T2*-weighted imaging (T2*WI) for the simultaneous detection of hepatocellular carcinoma (HCC) and vessel thrombus. For 1.5-T magnetic resonance imaging, SPIO was administered to 23 patients with a portal or venous tumor thrombus, and B-TFE with T2 prep and T2*WI were acquired. Regions of interest in the B-TFE and T2*WI were selected for the tumor, liver, tumor thrombus, and vessels...
February 3, 2017: Radiological Physics and Technology
Katsuyuki Taguchi
Energy-sensitive photon counting detectors (PCDs) have recently been developed for medical X-ray computed tomography (CT) imaging and a handful of prototype PCD-CT systems have been built and evaluated. PCDs detect X-rays by using mechanisms that are completely different from the current CT detectors (i.e., energy integrating detectors or EIDs); PCDs count photons and obtain the information of the object tissues (i.e., the effective atomic numbers and mass densities) to be imaged. Therefore, these PCDs have the potential not only for evolution-to improve the current CT images such as providing dose reduction-but also for a revolution-to enable novel applications with a new concept such as molecular CT imaging...
January 30, 2017: Radiological Physics and Technology
Yoshiki Owaki, Kazumasa Inoue, Hiroto Narita, Keisuke Tsuda, Masahiro Fukushi
Strontium-89 (Sr-89) chloride is a targeted palliative therapy used for painful bone metastasis in which repeated doses can be administered, and its usefulness has been reported in the case of bone metastasis of various primary tumors. However, the effectiveness of the pain relief treatment is only described using a subjective index such as the visual analog scale, which lacks objectivity. Although various attempts at quantifying the effectiveness of Sr-89 chloride therapy have been reported using nuclear medicine imaging for energy peaks around 70-80 keV, the principle of Sr-89 chloride imaging has not been explained...
January 4, 2017: Radiological Physics and Technology
Shota Hosokawa, Kazumasa Inoue, Daisuke Kano, Fuminori Shimizu, Kazuya Koyama, Yoshihiro Nakagami, Yoshihisa Muramatsu, Masahiro Fukushi
Whereas Monte Carlo (MC) simulation is widely utilized in estimation of the scatter component, a simulation model which can calculate the scatter fraction (SF) of each patient is needed for making an accurate image quality assessment for clinical PET images based on the noise equivalent count. In this study, an MC simulation model was constructed which can calculate the SF for various phantoms. We utilized the Geant4 toolkit based on MC simulation to make a model of a PET scanner with a scatter phantom, and SFs calculated with this model were compared with the SF (SFconstant: 44%) measured with use of an actual PET scanner...
December 28, 2016: Radiological Physics and Technology
Hiroshi Watanabe, Kimiya Noto, Tomokazu Shohji, Yasuyoshi Ogawa, Toshioh Fujibuchi, Ichiro Yamaguchi, Hitoshi Hiraki, Tetsuo Kida, Kazutoshi Sasanuma, Yasushi Katsunuma, Takurou Nakano, Genki Horitsugi, Makoto Hosono
The goal of this study is to develop a more appropriate shielding calculation method for computed tomography (CT) in comparison with the Japanese conventional (JC) method and the National Council on Radiation Protection and Measurements (NCRP)-dose length product (DLP) method. Scattered dose distributions were measured in a CT room with 18 scanners (16 scanners in the case of the JC method) for one week during routine clinical use. The radiation doses were calculated for the same period using the JC and NCRP-DLP methods...
December 26, 2016: Radiological Physics and Technology
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
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
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
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
Masaru Sekiya, Michio Yamasaki
No abstract text is available yet for this article.
October 6, 2016: Radiological Physics and Technology
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
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
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
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
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
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
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
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
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