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Radiological Physics and Technology

Ayako Yagahara, Yuki Yokooka, Guoqian Jiang, Shintarou Tsuji, Akihisa Fukuda, Naoki Nishimoto, Kunio Kurowarabi, Katsuhiko Ogasawara
Describing complex mammography examination processes is important for improving the quality of mammograms. It is often difficult for experienced radiologic technologists to explain the process because their techniques depend on their experience and intuition. In our previous study, we analyzed the process using a new bottom-up hierarchical task analysis and identified key components of the process. Leveraging the results of the previous study, the purpose of this study was to construct a mammographic examination process ontology to formally describe the relationships between the process and image evaluation criteria to improve the quality of mammograms...
January 10, 2018: Radiological Physics and Technology
Mohammad Mehdi Firoozabadi, Elaheh Jimabadi, Mahdi Ghorbani, Marziyeh Behmadi
The CSM40 137Cs source model is currently being used in clinical brachytherapy. According to the recommendations of task group No. 43 (TG-43) of the American Association of Physicists in Medicine, dosimetry parameters of brachytherapy sources should be determined by two independent investigators before their clinical use. The aim of this study was to determine the TG-43 dosimetry parameters for a medium-dose-rate CSM40 137Cs source. The determined dosimetric parameters included the air kerma strength, dose rate constant, radial dose function, and anisotropy function...
January 3, 2018: Radiological Physics and Technology
Yoshinori Tsuji, Satoshi Saitoh, Junji Takahashi, Chisato Abe, Tatsuya Hayashi, Masahiro Kobayashi
The controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA) technique can decrease scan time. The purpose of this study was to determine whether an arterial phase scan can be performed in 5 s using the CAIPIRINHA short-scan and a reference scanning technique. The generalized autocalibrating partially parallel acquisition (GRAPPA), the CAIPIRINHA routine (CAIPI-routine), and the CAIPIRINHA short-scanning (CAIPI-short) methods were compared. The scan time for each method was preset to 20 s, 15 s, and 10 s, respectively...
January 3, 2018: Radiological Physics and Technology
Yohei Miura, Katsuhiro Ichikawa, Ichiro Fujimura, Takanori Hara, Takashi Hoshino, Shinji Niwa, Masao Funahashi
The 320-detector row computed tomography (CT) system, i.e., the area detector CT (ADCT), can perform helical scanning with detector configurations of 4-, 16-, 32-, 64-, 80-, 100-, and 160-detector rows for routine CT examinations. This phantom study aimed to compare the quality of images obtained using helical scan mode with different detector configurations. The image quality was measured using modulation transfer function (MTF) and noise power spectrum (NPS). The system performance function (SP), based on the pre-whitening theorem, was calculated as MTF2/NPS, and compared between configurations...
January 2, 2018: Radiological Physics and Technology
Abdel-Razzak M Al-Hinnawi, Bassam O Al-Naami, Haytham Al-Azzam
This paper explores the benefits of interactive three-dimensional (3D) visualization of stimuli using a computer aided detection (CAD) system of pulmonary embolisms (PEs), on computed tomography pulmonary angiography (CTPA) views. We designed a new CAD method that prompts the PE sites on CTPA views; we then utilized two interactive approaches of 3D visualization to assess CAD performance. This collaboration allows different methodologies to be used to assess PE-CAD performance, by comparison with the common method in which radiologists are prompted with CAD stimuli directly on the CTPA views...
December 28, 2017: Radiological Physics and Technology
Toshiyuki Terunuma, Aoi Tokui, Takeji Sakae
Robustness to obstacles is the most important factor necessary to achieve accurate tumor tracking without fiducial markers. Some high-density structures, such as bone, are enhanced on X-ray fluoroscopic images, which cause tumor mistracking. Tumor tracking should be performed by controlling "importance recognition": the understanding that soft-tissue is an important tracking feature and bone structure is unimportant. We propose a new real-time tumor-contouring method that uses deep learning with importance recognition control...
December 28, 2017: Radiological Physics and Technology
Hitoshi Saito, Teruhiro Ito, Takakiyo Tsujiguchi, Masaru Yamaguchi, Ikuo Kashiwakura
This study aimed to analyze the temporal sensitivity profile (TSP) shapes and temporal resolutions of computed tomography (CT) and investigate the effect of a combination of a given rotation time and helical pitch on the TSP and image quality. The study was performed on 16- and 64-row CT scanners, and the TSP and temporal resolution were measured using the impulse method. A shorter gantry rotation time and larger helical pitch improved the temporal resolution of both CT scanners. Although the measured TSP shapes were dependent on the helical pitch, the maximum helical pitch did not improve the temporal resolution of either CT scanner...
December 20, 2017: Radiological Physics and Technology
Akihiro Haga, Wataru Takahashi, Shuri Aoki, Kanabu Nawa, Hideomi Yamashita, Osamu Abe, Keiichi Nakagawa
Radiomics, which involves the extraction of large numbers of quantitative features from medical images, has attracted attention in cancer research. In radiomics analysis, tumor segmentation is a crucial step. In this study, we evaluated the potential application of radiomics for predicting the histology of early stage non-small cell lung cancer (NSCLC) by analyzing interobserver variability in tumor delineation. Forty patient datasets were included in this study, 21 involving adenocarcinomas and 19 involving squamous cell carcinomas...
December 5, 2017: Radiological Physics and Technology
Kenichiro Yamamura, Yasuo Takatsu, Toshiaki Miyati
In acoustic-stimulated functional magnetic resonance imaging (fMRI), tasks are performed by subjects either during imaging in the presence of scanning noise or during non-imaging periods without scanning noise. Suitable syllables for voice tasks performed with MRI-compatible headphones are limited during the imaging period with scanning noise. However, suitable syllables for voice tasks during the non-imaging period, without scanning noise, are not yet known. This study aimed to identify suitable syllables for voice tasks during both imaging and non-imaging periods...
December 4, 2017: Radiological Physics and Technology
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
(no author information available yet)
No abstract text is available yet for this article.
November 20, 2017: Radiological Physics and Technology
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
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...
December 2017: Radiological Physics and Technology
Masahiro Endo
No abstract text is available yet for this article.
October 20, 2017: Radiological Physics and Technology
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
Shinichiro Mori, Christian Graeff, Nobuyuki Kanematsu
No abstract text is available yet for this article.
October 7, 2017: Radiological Physics and Technology
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
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
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
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
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