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Radiological Physics and Technology

Yoshiyuki Ishimori, Masahiko Monma, Hiraku Kawamura
Although slice thickness accuracy is important for the performance of magnetic resonance imaging systems, long scan times are required to perform reliable measurements. Inclined slabs and wedges are conventionally used as test devices to obtain slice profiles. In this study, a novel dedicated device with a widened slab was created, and its efficacy was compared with that of a conventional wedge. The signal-to-noise ratio (SNR) of the profile and the coefficient of variation (CV) of the measured slice thickness were measured...
June 19, 2018: Radiological Physics and Technology
Tatsuya Hayashi, Kei Fukuzawa, Hiroshi Kondo, Hiroshi Onodera, Rie Tojo, Shimpei Yano, Tosiaki Miyati, Jun'ichi Kotoku, Takahide Okamoto, Keiko Toyoda, Hiroshi Oba
This phantom study assessed the effect of Gd-EOB-DTPA on T1 bias (difference in T1 between water and fat) of the proton density fat fraction when using magnetic resonance spectroscopy. Phantoms containing varying fat percentages, without and with Gd-EOB-DTPA (precontrast and postcontrast, respectively), were scanned with repetition times ranging from 1000 to 5000 ms. The relationship between the proton density fat fraction at a reference repetition time of 5000 ms and that using different repetition times, was evaluated in the precontrast and postcontrast phantoms using linear regression and Bland-Altman analyses...
June 1, 2018: Radiological Physics and Technology
Chizuru Okamoto, Yoshie Kodera
We acquired a direct-type flat panel detector (FPD) developed for mammography systems and investigated its physical image properties, as its characteristics may affect future mammography in the clinic. The pixel size of the detector is 50 µm, the smallest size used in clinical mammography. Amorphous selenium (a-Se) film is used in direct-type FPDs. Due to its inferior temperature properties, the temperature of the imaging room should be set to approximately 25 °C. A novel a-Se film with superior heat resistance has been developed by the HAMAMATSU photonics KK Electron Tube Division that is suitable for high electric field driving...
May 29, 2018: Radiological Physics and Technology
Jonathan Lalrinmawia, Kham Suan Pau, Ramesh Chandra Tiwari
The present study examined the mechanical attributes of 135 conventional diagnostic X-ray machines in Mizoram, India. The purpose of studying the X-ray mechanical parameters, such as congruency, perpendicularity of the central beam, and half-value layer, was to improve the quality of the diagnostic image and reduce the patient dose. A battery-operated portable dosimeter was used to measure output radiation of the X-ray machine. The half-value layer was measured at a constant accelerating potential of 70 kVp and tube load...
May 18, 2018: Radiological Physics and Technology
Yasuo Takatsu, Yuko Shimada, Tosiaki Miyati, Toshiki Shiozaki, Katsusuke Kyotani
During liver computed tomography (CT), scanning is performed with the raised arm position and an inhalation technique. However, for liver magnetic resonance imaging (MRI), the arms are placed at the sides of the body and an exhalation technique is used. This study was aimed at evaluating the effect that the patient's arm position and respiration technique had on the ability to detect mammary glands in the scan range to discover unexpected mammary lesions during the liver MRI examination. Liver MRI and CT images were compared for 337 female patients...
May 14, 2018: Radiological Physics and Technology
Chiharu Kai, Yoshikazu Uchiyama, Junji Shiraishi, Hiroshi Fujita, Kunio Doi
In the post-genome era, a novel research field, 'radiomics' has been developed to offer a new viewpoint for the use of genotypes in radiology and medicine research which have traditionally focused on the analysis of imaging phenotypes. The present study analyzed brain morphological changes related to the individual's genotype. Our data consisted of magnetic resonance (MR) images of patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD), as well as their apolipoprotein E (APOE) genotypes...
May 10, 2018: Radiological Physics and Technology
Chisako Muramatsu
Computer-aided diagnosis systems for assisting the classification of various diseases have the potential to improve radiologists' diagnostic accuracy and efficiency, as reported in several studies. Conventional systems generally provide the probabilities of disease types in terms of numerical values, a method that may not be efficient for radiologists who are trained by reading a large number of images. Presentation of reference images similar to those of a new case being diagnosed can supplement the probability outputs based on computerized analysis as an intuitive guide, and it can assist radiologists in their diagnosis, reporting, and treatment planning...
May 8, 2018: Radiological Physics and Technology
Akihiro Furuta, Hideo Onishi, Hizuru Amijima
This study aimed to evaluate the effect of ventricular enlargement on the specific binding ratio (SBR) and to validate the cerebrospinal fluid (CSF)-Mask algorithm for quantitative SBR assessment of 123 I-FP-CIT single-photon emission computed tomography (SPECT) images with the use of a 3D-striatum digital brain (SDB) phantom. Ventricular enlargement was simulated by three-dimensional extensions in a 3D-SDB phantom comprising segments representing the striatum, ventricle, brain parenchyma, and skull bone. The Evans Index (EI) was measured in 3D-SDB phantom images of an enlarged ventricle...
June 2018: Radiological Physics and Technology
Ryota Sato, Toru Shirai, Yo Taniguchi, Takenori Murase, Yoshitaka Bito, Yoshihisa Soutome, Hisaaki Ochi
To realize susceptibility-weighted imaging in vertical-field magnetic resonance imaging (MRI), we developed an image-processing method called "susceptibility difference weighted imaging" (SDWI). In SDWI, contrasts are enhanced using a susceptibility map calculated by using a weighted least-square algorithm with a small iteration number. Experiments were performed on human volunteers to compare image contrast obtained from the conventional method (SWI) and SDWI. In horizontal-field MRI, SDWI results show that veins and deep-gray-matter nuclei were visualized as well as those with SWI...
June 2018: Radiological Physics and Technology
Masaki Ogawa, Shingo Omata, Hirohito Kan, Nobuyuki Arai, Marehiko Asai, Misugi Urano, Yuta Shibamoto
We aimed to investigate the utility of the isoFSE sequence, one of the variable flip angle 3D fast-spin echo sequences, on 3T-MR for displaying vessel walls and diagnosing vertebrobasilar artery dissection (VAD). We retrospectively evaluated 12 initial and 28 follow-up images from 12 patients diagnosed with either intracranial VAD or carotid artery dissection. The image quality for displaying the vessel wall was scored using a five-point scale (1 poor, 5 excellent) on initial T1-weighted isoFSE images for each region of the arteries...
June 2018: Radiological Physics and Technology
Xiaoming Zheng
The purpose of this work was to present body size and tube voltage-dependent equations for optimal selection of image acquisition parameters in guiding clinical X-ray imaging. The dose output of X-ray tubes was expressed as a function of the image acquisition parameters of tube voltage (kVp), tube current-exposure time product (mAs), and body size (d). Dose power (n) to kVp was determined to be a linear function of body size in an earlier phantom study. Tube voltage-dependent attenuation coefficients of water were used to determine the kVp effect on the depth dose of X-rays from the body's entrance surface...
June 2018: Radiological Physics and Technology
Daiki Tabata, Haruo Isoda, Kaori Kato, Hiroki Matsubara, Takafumi Kosugi, Takashi Kosugi, Masaki Terada, Atsushi Fukuyama, Yoshiaki Komori, Shinji Naganawa
We developed a method of velocimetry based on an optical flow method using quantitative analyses of tagged magnetic resonance (MR) images (tagged MR-optical flow velocimetry, tMR-O velocimetry). The purpose of our study was to examine the accuracy of measurement of the proposed tMR-O velocimetry. We performed retrospective pseudo-electrocardiogram (ECG) gating tagged cine MR imaging on a rotating phantom. We optimized imaging parameters for tagged MR imaging, and validated the accuracy of tMR-O velocimetry...
June 2018: Radiological Physics and Technology
Sofia Spampinato, Anna Maria Gueli, Pietro Milone, Luigi Angelo Raffaele
The study is aimed at a verification of dose changes for a computed tomography automatic tube-current modulation (ATCM) technique. For this purpose, anthropomorphic phantom and Gafchromic® XR-QA2 films were used. Radiochromic films were cut according to the shape of two thorax regions. The ATCM algorithm is based on noise index (NI) and three exam protocols with different NI were chosen, of which one was a reference. Results were compared with dose values displayed by the console and with Poisson statistics...
June 2018: Radiological Physics and Technology
Kyohei Fukata, Satoru Sugimoto, Chie Kurokawa, Akito Saito, Tatsuya Inoue, Keisuke Sasai
The difficulty of measuring output factor (OPF) in a small field has been frequently discussed in recent publications. This study is aimed to determine the OPF in a small field using 10-MV photon beam and stereotactic conical collimator (cone). The OPF was measured by two diode detectors (SFD, EDGE detector) and one micro-ion chamber (PinPoint 3D chamber) in a water phantom. A Monte Carlo simulation using simplified detector model was performed to obtain the correction factor for the detector measurements...
June 2018: Radiological Physics and Technology
Nobuyuki Kanematsu, Naruhiro Matsufuji, Taku Inaniwa
The original version of this article unfortunately contained a mistake. Figure 2 was published with fake signals in panels (a) and (b) which are corrected in this Erratum. The authors are not responsible for this procedural lapse.
June 2018: Radiological Physics and Technology
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
A diameter of glass bottles in phantoms in the above article (2 cm) was incorrect. The correct diameter is 4.5 cm.
June 2018: Radiological Physics and Technology
Keisuke Usui, Keisuke Sasai, Koichi Ogawa
This study aimed to verify the validity of generating treatment plans for volumetric arc therapy (VMAT) for prostate cancer using magnetic resonance (MR) imaging with a dose calculation algorithm in Acuros XB (Eclipse version 13.6; Varian Medical Systems, Palo Alto, CA, USA) based on deterministically solving the linear Boltzmann transport equations. Four different classes were applied to prostate MR images: MRW (all water equivalent); MRW+B (water and bone); MRS+B (soft tissue and bone); and MRS+B+G (soft tissue, bone, and rectal gas)...
June 2018: Radiological Physics and Technology
Yuji Nakaguchi, Takeshi Oono, Masato Maruyama, Yoshinobu Shimohigashi, Yudai Kai, Yuya Nakamura
In this study, we evaluated the basic performance of the three-dimensional dose verification system COMPASS (IBA Dosimetry). This system is capable of reconstructing 3D dose distributions on the patient anatomy based on the fluence measured using a new transmission detector (Dolphin, IBA Dosimetry) during treatment. The stability of the absolute dose and geometric calibrations of the COMPASS system with the Dolphin detector were investigated for fundamental validation. Furthermore, multileaf collimator (MLC) test patterns and a complicated volumetric modulated arc therapy (VMAT) plan were used to evaluate the accuracy of the reconstructed dose distributions determined by the COMPASS...
June 2018: Radiological Physics and Technology
Maria D Falco, Salvatore Masala, Matteo Stefanini, Paolo Bagalà, Daniele Morosetti, Eros Calabria, Alessia Tonnetti, Gianluca Verona-Rinati
Interventional radiology is based on minimally invasive procedures that allow diagnosis and percutaneous treatment of diseases in almost all organ systems. Such procedures have many benefits, but they also contribute significantly to collective radiation dose. In this regard, effective dose (E) is a convenient quantity to estimate patients' stochastic radiation risk. However, E cannot be accurately evaluated immediately. In the present study, we aimed to estimate the E value in 15 selected interventional procedures...
June 2018: Radiological Physics and Technology
Yuuji Inoue, Masami Yoneyama, Masanobu Nakamura, Atsushi Takemura
The two-dimensional Cartesian turbo spin-echo (TSE) sequence is widely used in routine clinical studies, but it is sensitive to respiratory motion. We investigated the k-space orders in Cartesian TSE that can effectively reduce motion artifacts. The purpose of this study was to demonstrate the relationship between k-space order and degree of motion artifacts using a moving phantom. We compared the degree of motion artifacts between linear and asymmetric k-space orders. The actual spacing of ghost artifacts in the asymmetric order was doubled compared with that in the linear order in the free-breathing situation...
June 2018: Radiological Physics and Technology
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