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Radiological Physics and Technology

John M Boone, Andrew M Hernandez, J Anthony Seibert
Conventional mammographic dosimetry has been developed over the past 40 years. Prior to the availability of high-resolution three-dimensional breast images, certain assumptions about breast anatomy were required. These assumptions were based on the information evident on two-dimensional mammograms; they included assumptions of thick skin, a uniform mixture of glandular and adipose tissue, and a median breast density of 50%. Recently, the availability of high-resolution breast CT studies has provided more accurate data about breast anatomy, and this, in turn, has provided the opportunity to update mammographic dosimetry...
June 1, 2017: Radiological Physics and Technology
Aogu Yamaguchi, Tsukasa Sasaki
We aimed to obtain high-stable computed tomography (CT) values for CT angiography (CTA). We verified the optimal use of the new protocol for long-range scanning using a contrast material flow phantom (Ichikawa, CT imaging theory. Igaku syoin Publishing, Tokyo, 8; Awai et al., Am J Roentgenol 186(2):379-385, 1) to obtain high-stable CT values (Fig. 2). We have developed a novel contrast injection method called the stable line imaging protocol (SLIP). This method involved a gradual reduction in the rate of administration of the contrast medium, which was accompanied by simultaneous administration of saline to compensate for the resultant decrease in the rate of administration...
June 1, 2017: Radiological Physics and Technology
Anchali Krisanachinda, Suphot Srimahachota, Kosuke Matsubara
Workers involved in interventional cardiology procedures receive high eye lens doses if radiation protection tools are not properly utilized. Currently, there is no suitable method for routine measurement of eye dose. In Thailand, the eye lens equivalent doses in terms of Hp(3) of the interventional cardiologists, nurses, and radiographers participating in interventional cardiology procedures have been measured at 12 centers since 2015 in the pilot study. The optically stimulated luminescence (OSL) dosimeter was used for measurement of the occupational exposure and the eye lens dose of 42 interventional cardiology personnel at King Chulalongkorn Memorial Hospital as one of the pilot centers...
May 27, 2017: Radiological Physics and Technology
Keita Takahashi, Shinichi Awamoto, Shinya Takarabe, Kazuhisa Ogawa, Yasuhiko Nakamura
The objective of this work was to evaluate the maximum luminance (L max) level of medical liquid crystal displays (LCDs) as a function of backlight hours (BLH) annually. The L max values for 249 2-megapixel color LCDs (RadiForce RX210, EIZO Corporation) were measured in February 2014, 2015, and 2016. Four near-range luminance meters and the built-in type luminance meters, each with an LCD, were used for the measurements. The average and standard deviation (SD) of BLH measured in 2014 was 15,371 ± 8219 h...
May 2, 2017: Radiological Physics and Technology
Norio Hayashi, Akio Ogura, Toshio Tsuchihashi, Daisuke Takahashi, Tsuyoshi Matsuda, Shinya Seino, Tsukasa Doi
The purpose of this study was to evaluate the magnetization and demagnetization of magnetic dental attachments in a 3.0-T magnetic resonance imaging (MRI) scanner. A high-field-strength (3.0 T) MRI scanner (Achieva 3.0 T, Philips, Amsterdam, Netherlands) was used. Magnetic flux leakage was measured using a gaussmeter. To evaluate the magnetization and demagnetization of the magnetic assemblies and keepers caused by the moving in and out of the MRI scanner, the magnetic force of the attachments was measured before and after the table was moved in and out...
April 27, 2017: Radiological Physics and Technology
Yoichiro Shimizu, Junji Morishita
This paper describes the development of an automated method of extraction of biological fingerprints (BFs), including detection of image orientation in chest radiographs. The image orientation of a target image was recognized and modified by examination of normalized cross-correlation values between a target image and averaged male and female images with correct image orientation. Templates of BFs were extracted from averaged images. Then, each BF in the target image was extracted from locations that showed the highest cross-correlation value between the template of BF in the averaged image and the corresponding BF in the target image...
April 27, 2017: Radiological Physics and Technology
Shiro Nishiyama, Satoru Ishibashi, Ryo Takahashi, Hidenobu Tachibana
An add-on micro multi-leaf collimator (mMLC) is used for stereotactic radiosurgery (SRS) and brain stereotactic radiotherapy (SRT), in which rotational radiotherapy may make more complex and time-consuming. We performed a retrospective study of an independent dose calculation verification for brain SRS and SRT in two institutions to show the accuracy of the verification system and propose a tolerance value for the verification. Several comparisons of static plans and patients' plans were conducted using a phantom measurement, and patients' plans using the patients' own computed tomography image...
April 19, 2017: Radiological Physics and Technology
Sayed Ahmad Zikri Bin Sayed Aluwee, Xiangrong Zhou, Hiroki Kato, Hiroshi Makino, Chisako Muramatsu, Takeshi Hara, Masayuki Matsuo, Hiroshi Fujita
We propose an approach to supporting pre-surgical planning for the uterus by integrating medical image analysis and physical model generation based on 3D printing. With our method, we first segment the patient-specific anatomy and lesions of the uterus on MR images; then, we create a 3D physical model, an exact replica of the patient's uterus in terms of size and softness, with transparency for easy observation of the internal structures of the uterus. In our experiments, we created pre-surgical models of hysterectomy for five patients who had been diagnosed to have uterine endometrial cancer...
April 12, 2017: Radiological Physics and Technology
Shunichi Motegi, Takehiro Shimada, Norio Hayashi, Hiroyuki Nagase, Ayako Taketomi-Takahashi, Yoshito Tsushima
We propose a practical method for setting the optimal inversion times (TI) for double inversion recovery (DIR) sequences. Our method used the measurement of signal intensity (SI) from real images to set the optimal TI for white-matter (WM) and gray-matter (GM)-attenuated inversion recovery (WAIR and GAIR, respectively) images. 3D-DIR images of healthy volunteers were obtained on 1.5- and 3.0-T magnetic resonance (MR) scanners and the SIs of GM, WM, and cerebrospinal fluid (CSF) were evaluated on real images...
April 9, 2017: 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...
June 2017: Radiological Physics and Technology
Akio Ogura, Aoi Kamakura, Youhei Kaneko, Tomoya Kitaoka, Norio Hayashi, Anna Taniguchi
Medical images are increasingly being rendered as digital images that are displayed on a monitor to provide diagnoses. However, these images are often rendered in grayscale. In this context, we compare the detectability of low-contrast signals between digital grayscale images and color-scale images. Low-contrast phantom images were rendered with the use of five color tables (gray, blue, red, yellow, and green). The 32 acquired images sorted in random order were evaluated by nine observers, and their observations were subjected to receiver operating characteristic analysis...
March 27, 2017: Radiological Physics and Technology
Carina Marques Coelho, Raquel Calçada, Sofia Rodrigues, Juan Antonio Barragán, Ana Cravo Sá, Ana Paula Macedo, Maria de Fátima Monsanto
This study aimed to assess the administered dose based on portal imaging in craniospinal pediatric irradiation by evaluating cases in which portal images did or did not account for the total administered dose. We also intended to calculate the mean increase in total administered dose. Data were collected from General University Hospital Gregorio Marañón; we evaluated the total dose administered, total dose planned, number of portal images per treatment and corresponding monitor units of two different groups: one in which the dose from portal images is deducted from the total administered dose (D), and another in which it was not (N)...
March 21, 2017: Radiological Physics and Technology
Kunio Doi, Fujio Araki, Masahiro Endo, Tomoyuki Hasegawa, Shigehiko Katsuragawa, Yoshie Kodera, Shigeru Sanada
No abstract text is available yet for this article.
March 2017: 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...
March 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...
March 2017: 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...
March 2017: Radiological Physics and Technology
Masaru Sekiya, Michio Yamasaki
No abstract text is available yet for this article.
March 2017: 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...
March 2017: 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...
March 2017: 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...
March 2017: Radiological Physics and Technology
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