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Development of a System for Measuring Wall Shear Stress in Blood Vessels using Magnetic Resonance Imaging and Computational Fluid Dynamics.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In conclusion, the system presented here appears to be useful for measuring the WSS in blood vessels and for analyzing the cause and/or extent of atherosclerosis, and our results suggest that the inlet velocity profile should be carefully considered. PMID: 18367824 [PubMed - in process]
Source: Igaku Butsuri: Japanese Journal of Medical Physics - March 28, 2008 Category: Physics Authors: Yoshida K, Nagao T, Okada K, Miyazaki S, Yang X, Yamazaki Y, Murase K Tags: Igaku Butsuri Source Type: journals

[Evaluation of relative electrometer calibration factor with user beam.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this report, a relative electrometer calibration factor was determined by comparison between a calibrated combination and a non-calibrated electrometer under identical irradiation conditions at the user site. To estimate uncertainties of user electrometer calibration, comparison was made between calibration factors obtained by ionization current under a linac photon beam and DC current with a precision DC source instrument. It was found that the variation of electrometer readings to pulse ionization current is negligible under the steady photon beam output and dose monitor system. Therefore relative electrometer calibra...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - March 28, 2008 Category: Physics Authors: Hatanaka S, Fujisaki T, Myojoyama A, Hiraoka T, Saitoh H Tags: Igaku Butsuri Source Type: journals

Phase mutual information for MRI and PET image registration: parameter selection of Log-Gabor filter.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Phase mutual information as a similarity measure has been demonstrated to perform comparably to an intensity method even when there is no strong intensity relationship between images. The estimation of local phase is significantly affected by the choice of bandpass filter and its parameter selection. The effect of the parameter selection of Log-Gabor filter on local phase estimation and performance of registration has been studied. The Log-Gabor filter is mainly constructed using two parameters, the center frequency w(0) and bandwidth B. Forty-two different transformations for magnetic resonance imaging (MRI) and simul...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - March 28, 2008 Category: Physics Authors: Yang X, Soma T, Murase K Tags: Igaku Butsuri Source Type: journals

The dynamic motion of pseudo-sputum mucin solution on a vibrating plate.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The motion of pseudo-sputum (20% solution of mucin) on a vibrating plate has been investigated using a function generator and an amplifier. Many finger-like liquid columns have appeared at appropriate frequencies (100-130 Hz) from a droplet of the solution on a vibrating plate. The viscosity of the mucin solution was measured using a capillary viscometer of the Maron-Krieger-Sisko type, and it was shown that the shear-thinning viscosity occurred in the lower frequency region contrary to the fact that the most abnormal viscosity of the rheological dilatancy fluid emerges in higher frequency than the frequency in which i...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - March 28, 2008 Category: Physics Authors: Tarao N, Takagi O Tags: Igaku Butsuri Source Type: journals

[Enactment of TR14969:2007-Quality Management System for Medical Devices; Guide to the Application of JIS Q 13485:2005.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 17917437 [PubMed - in process]
Source: Igaku Butsuri: Japanese Journal of Medical Physics - October 6, 2007 Category: Physics Authors: Iinuma T Tags: Igaku Butsuri Source Type: journals

Analysis of the effective point of measurement of a thimble chamber dosimeter set parallel to the X-ray beam axis.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we analyzed the effective point in parallel installation, and considered the prediction and evaluation of measurement point displacement. Relative dosimetry was carried out by installing the thimble ionization chamber in both perpendicular and parallel configurations. We then searched for the measurement point that coincided with the PDD of the perpendicular installation by using the displacement of the measurement point of the parallel installation. We found that the effective point of measurement for relative photon beam dosimetry depends on every detail of the chamber design, including the cavity length a...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - October 6, 2007 Category: Physics Authors: Shimono T, Nanbu H, Koshida K, Kikuchi Y Tags: Igaku Butsuri Source Type: journals

[Usefulness of the classification technique of cerebral artery for 2D/3D registration.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Several papers have proposed 2D/3D registration methods of the cerebral artery using magnetic resonance angiography (MRA) and digital subtraction angiography (DSA). Since differences between vessels in a DSA image and MRA volume data cause registration failure, we previously proposed a method to extract vessels from MRA volume data using a technique based on classification of the cerebral artery. In this paper, we evaluated the usefulness of this classification technique by evaluating the reliability of this 2D/3D registration method. This classification method divides the cerebral artery in MRA volume data into 12 seg...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - October 6, 2007 Category: Physics Authors: Takemura A, Suzuki M, Kikuchi Y, Okumura Y, Harauchi H Tags: Igaku Butsuri Source Type: journals

A new parameter enhancing breast cancer detection in computer-aided diagnosis of X-ray mammograms.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The purpose of this study was to introduce a new parameter which enhances breast cancer detection using X-ray mammography. We used the database of X-ray mammograms generated by the Japan Society of Radiological Technology. The new parameter called 'quasi-fractal dimension (Q-FD)' was calculated from the relationship between the cutoff values for the maximum image intensity in the lesion set at 21 levels from 20% to 100% at equal intervals and the number of pixels with an intensity exceeding the cutoff value. In addition to Q-FD, the image features such as curvature (C) and eccentricity (E) were extracted. The conventio...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2006 Category: Physics Authors: Tanki N, Murase K, Nagao M Tags: Igaku Butsuri Source Type: journals

[Comparison evaluation of polymer gel with a water phantom.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We have investigated the properties of three polymergels: G gel, A gel, and C gel. These polymer gels changed only the chemical reagent for the gel. The water equivalence was determined by comparing the polymer gels macroscopic photon and electron interaction cross sections over the energy range from 10 KeV to 50 MeV and by Monte Carlo modeling of percentage depth doses. Polymer gels have a chemical reagent for the gel and monomer concentration and therefore their mass density is up to 1.70-2.91 % higher than water. This results in differences between the cross section ratios of the polymer gels and water of up to 0.01...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2006 Category: Physics Authors: Haneda K, Okudo H, Yoshioka M, Hayashi S, Usui S, Tominaga T Tags: Igaku Butsuri Source Type: journals

Automatic anatomical labeling method of cerebral arteries in MR-angiography data set.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
To improve the accuracy and robustness of 2D/3D registration of digital subtraction angiography images and magnetic resonance angiography (MRA) data, we have developed an automatic method for anatomical labeling of the cerebral arteries in MRA data. The anatomical labeling method is a location-based method which segments an artery tree to branches and classifies the branches into labeled segments, i.e., internal carotid arteries (ICA), basilar artery (BA), middle cerebral arteries (MCA), A1 segments of the anterior cerebral artery (ACA(A1)), other segments of the anterior cerebral artery (ACA), posterior communication ...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2006 Category: Physics Authors: Takemura A, Suzuki M, Harauchi H, Okumura Y Tags: Igaku Butsuri Source Type: journals

[Evaluation of therapeutic carbon-beam attenuation in inhomogeneous layered phantoms: Comparison with the present method using a water phantom.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study evaluates carbon-beam attenuation in inhomogeneous layered phantoms and compares their results with beam attenuation in a water phantom. The phantoms consist of plates of tissue-equivalent materials for the x-rays; these plates are stacked along the beam direction. The beam attenuation in the lung-cancer phantom (with bone) is about 23%, similar to the result in the water phantom, attenuation in the lung-cancer phantom (without bone) is about 25%, which is higher than the result in the water phantom by 2%. Finally, the beam attenuation in the liver-cancer phantom is about 33%, which is lower than the result in t...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2006 Category: Physics Authors: Magara T, Kikumura R, Kameoka S, Ikeda T, Maruyama K Tags: Igaku Butsuri Source Type: journals

[Development of the QA/QC-tools for CT number calibration of the treatment planning CT-scanner.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In order to support a routine QA of the CT number for treatment planning, we developed a phantom and a sample holder for easy handling. At most particle radiotherapy facilities in Japan, the CT number is calibrated by the poly-binary calibration method using liquid samples of 100% ethanol and 40% K(2)HPO(4) which are set in a cylindrical water phantom. However it is hard to remove air bubbles from the calibration liquid sample and maintain its stable concentration for a long time. So much time is needed for QA of the CT number. The new sample holder, which we developed, was able to keep a stable concentration of the li...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2006 Category: Physics Authors: Kusano Y, Minohara S, Ishii T, Fujimori K, Ikeda N, Kondo T, Tubuku H, Ito A, Uchida H Tags: Igaku Butsuri Source Type: journals

[Evaluation of daily quality assurance for proton therapy at National Cancer Center Hospital East.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
It is very important for proton therapy to make and carry out a quality assurance (QA) program. Operators and medical personnel have to avoid any trouble during treatment and provide patients with high quality and reliable treatment. A proton therapy machine consists of an accelerator, gantry and various beam modifying devices. Although QA for proton therapy is complicated and difficult, we tried to realize daily QA for proton therapy. Two main purposes in daily QA are stable operation of the accelerator and reliable control of the irradiation system. In order to determine the daily QA issues, past problems were consid...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2006 Category: Physics Authors: Kohno R, Nishio T, Miyagishi T, Matsumura K, Saito H, Uzawa N, Sasano T, Nakamura T, Ogino T Tags: Igaku Butsuri Source Type: journals

Design and inital evaluation of a 4-layer DOI-PET system: the jPET-D4.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PET scanners are an important component in functional brain imaging devices. Several PET scanners have been developed during the last two decades for brain research studies. We are developing a high-performance brain PET scanner, jPET-D4. This scanner is designed to achieve not only high spatial resolution but also high sensitivity using four-layered depth-of-interaction (DOI) detectors. The scanner has five block detector rings with the ring diameter of 390 mm and each block detector ring consists of 24 DOI detectors. In previous work, we have demonstrated that 3 mm FWHM uniform spatial resolution within the field-of-...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2006 Category: Physics Authors: Yoshida E, Yamaya T, Watanabe M, Kitamura K, Kobayashi A, Hasegawa T, Obi T, Haneishi H, Fukushi M, Murayama H Tags: Igaku Butsuri Source Type: journals

An inter-crystal scatter correction method for DOI PET image reconstruction.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we propose to model an ICS probability by using a Monte Carlo simulator. The probability is given as a statistical relationship between the gamma photon first interaction crystal pair and the detected crystal pair. It is then used to improve the system matrix of a statistical image reconstruction algorithm, such as ML-EM in order to correct for the position error caused by ICS. We apply the proposed method to simulated data of the jPET-D4, which is a four-layer DOI PET being developed at the National Institute of Radiological Sciences. Our computer simulations show that image contrast is recovered successful...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2006 Category: Physics Authors: Lam CF, Hasegawa N, Obi T, Yamaguchi M, Yamaya T, Murayama H Tags: Igaku Butsuri Source Type: journals

Performance of model observers for lesion detection in SPECT imaging.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Conclusion: This study will be useful for understanding the performance of model observers when evaluating lesion detection in SPECT imaging. PMID: 17344642 [PubMed - in process]
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2006 Category: Physics Authors: Murase K, Mukai W, Fukami S, Matsumoto K, Yang Z Tags: Igaku Butsuri Source Type: journals

[Impact of optimization algorithms on the intensity map in IMRT treatment planning.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In conclusion, it is important to understand impacts of optimization algorithms on the intensity map and the dose distribution. PMID: 17344641 [PubMed - in process]
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2006 Category: Physics Authors: Shimada M, Nakamura M, Miyabe Y, Yamamoto T, Teshima T, Narita Y, Mizowaki T, Nagata Y, Hiraoka M Tags: Igaku Butsuri Source Type: journals

[Medical imaging: its medical economics and recent situation in Japan.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Two fields of radiology, medical imaging and radiation therapy, are coded separately in medical fee system, and the health care statistics of 2003 shows that expenditure on the former was 5.2% of the whole medical cost and the latter 0.28%. Introduction of DPC, an abbreviation of Diagnostic Procedure Combination, was carried out in 2003, which was an essential reform of medical fee payment system that have been managed on fee-for-service base throughout, and 22% of beds for acute patients care are under the control of DPC payment in 2006. As medical imaging procedures are basically classified in inclusive payment in DP...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2006 Category: Physics Authors: Imai K Tags: Igaku Butsuri Source Type: journals

[Nationwide survey of nuclear medicine practice and estimation of collective effective dose in Japan.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
For the estimation of collective effective dose from radiopharmaceuticals used in nuclear medicine diagnosis, a national survey was carried out in Japan. The survey contents covered radiopharmaceutical use, sex, age, activity, and so on of each patient in October 1997 and the monthly number of examinations in 1997. The annual number of diagnostic examinations using radiopharmaceuticals was 0.82 million for males and 0.74 million for females. The frequency of examination was about 3% for patients less than 17 years old and about 60% for those more than 60 years old. Effective dose was calculated on the basis of such lit...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2006 Category: Physics Authors: Matsumoto M, Nishizawa K, Iwai K, Akahane K, Maruyama T Tags: Igaku Butsuri Source Type: journals

New technique for visualizing cerebral vessels in MR angiographic images using three-dimensional discrete wavelet transform.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Visualization techniques for magnetic resonance (MR) angiographic images are generally based on the projection ray concept; for example, maximum intensity projection (MIP) and volume rendering (VR). A new technique based on a different concept from projection rays is explored in this study: three-dimensional (3-D) discrete wavelet transforms are used for visualizing cerebral vessels in the MR angiographic image. This technique successfully visualizes cerebral vessels and represents the spatial relationship between the cerebral vessels, as in the case of VR. The proposed technique is, thus, indicated to be promising for...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2006 Category: Physics Authors: Zuo H, Suzuki S, Sotoda M, Uesugi M, Kudo K Tags: Igaku Butsuri Source Type: journals

[Evaluation of the accuracy of line spread function (LSF) and point spread function (PSF) measured in the computed tomography.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We propose a method to estimate the accuracy of the line spread function (LSF) in computed tomography (CT). When we assume an object for scanning has a shape and CT-value in the x-y scan-plane that are constant in the z-direction perpendicular to the scan-plane, blurring in the image of the object is predicted with calculation by the LSF measured in the scanner. When using the precise LSF, the calculated image must agree well with the scanned image of the phantom corresponding to the object. Then, verification of LSF is performed by comparing the calculated image with the scanned image. We measured the LSF in our scann...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2006 Category: Physics Authors: Kunii M, Wada S, Ohkubo M, Harata M, Nishizawa K, Matsumoto T Tags: Igaku Butsuri Source Type: journals

[Measurement of the air kerma using dosimeters embedded in an acrylic phantom in interventional radiology.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, dosimeters (consisting of a parallel plate ionization chamber, glass dosimeter and OSL dosimeter) were embedded in the phantom surface to detected scattered radiation accurately. As a result, when dosimeters were embedded in the phantom surface, the air kerma was increased compared with that when dosimeters were placed on the phantom. This suggested that embedded dosimeters were able to detect scattered radiation from the phantom. PMID: 16788288 [PubMed - in process]
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2006 Category: Physics Authors: Kawabe A, Shibuya K, Takeda Y Tags: Igaku Butsuri Source Type: journals

Dosimetric properties of the liquid ionization chamber electronic portal imaging device (EPID).Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In the relation between the pixel values of the electronic portal imaging device (EPID) and dose rate, pixel values have been reported to be proportional to the square roots of the dose rates although some researchers have reported that each EPID pixel value was almost proportional to the dose rates when they were more than 1 Gy/min. To resolve this contradiction, in this study we have investigated the dosimetric properties of the liquid ionization chamber EPID based on a two-dimensional matrix of liquid- filled ionization chambers. Our results show that the pixel values of this EPID were proportional to the square roo...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2006 Category: Physics Authors: Tateoka K, Ouchi A, Waka M, Nakata K, Nagase D, Shimizume K, Saikawa T, Hareyama M Tags: Igaku Butsuri Source Type: journals

Resonance of sputum spigot with air vibration.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A mathematical model calculation has been presented on the resonant frequency of the oscillating sputum spigot in a cylindrical pipe, with which we investigated similar phenomena in bronchial tubes. We confirmed the theoretical results by two types of experiments using pseudo-sputum (5 and 10% solutions of mucin) spigots instead of a human pulmonary one, and found the model was suitable for estimating the effects of clinical vibrational treatments expectorating sputum spigots plugged in small bronchi. The main points of the paper are summarized as follows. 1. The validity of the fluid model used was verified using repo...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2006 Category: Physics Authors: Tarao N Tags: Igaku Butsuri Source Type: journals

[Elucidation of the energy absorption spectra of the (11)C beam in a plastic scintillator.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Heavy ion therapy using the energetic (12)C beam is successfully under way at HIMAC, Japan. The method is more advantageous than traditional radiation therapy in dose concentration owing to the Bragg peak and high relative biological effectiveness. A research study using the (11)C beam for heavy ion therapy in the future has been carried out in order to develop the capability of monitoring the dose distribution. Our group has examined the total energy absorption spectrum of the (11)C beam in a plastic scintillator. We could clearly observe the total absorption peak of (11)C in the energy spectrum and, in addition, we f...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2006 Category: Physics Authors: Hanada T, Kikumura R, Kodama K, Hashimoto M, Kanazawa M, Kitagawa A, Suda T, Maeda K, Maruyama K Tags: Igaku Butsuri Source Type: journals

[Sensitometry of Mammographic Screen-film System Using Bootstrap Aluminum Step-Wedge.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, the bootstrap sensitometry with the mammographic screen-film system was studied for two types of aluminum step-wedges. Characteristic X-ray energy curves were determined using mammographic and general radiographic aluminum step-wedges devised to prevent scattered X-rays generated from one step penetrating into the region of another one, and dependence of the characteristic curves on the wedges was also discussed. No difference was found in the characteristic curves due to the difference in the step-wedges for mammography and general radiography although there was a slight difference in shape at the shoulder ...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2005 Category: Physics Authors: Abe S, Imada R, Terauchi T, Fujisaki T, Monma M, Nishimura K, Saitoh H, Mochizuki Y Tags: Igaku Butsuri Source Type: journals

[A Generator of Mono-energetic Electrons for Response Test of Charged Particle Detectors.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We designed and fabricated a generator of mono-energetic electrons for the response test of charged particle detectors, which is used to measure fragmented particles of the carbon beam for cancer therapy. Mono-energetic electrons are extracted from (90)Sr by analyzing the energy of beta rays in the generator with a magnetic field. We evaluated performance parameters of the generator such as the absolute energy, the energy resolution and the counting rates of extracted electrons. The generator supplies mono-energetic electrons from 0.5MeV to 1.7MeV with the energy resolution of 20% in FWHM at higher energies than 1.0MeV...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2005 Category: Physics Authors: Matsubayashi F, Yoshida K, Maruyama K Tags: Igaku Butsuri Source Type: journals

Lossless compression based on inter-frame coding for MDCT.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Many images are generated by medical equipment and the number of images to be stored increases yearly. To cope with the large digital storage and transmission requirements, data compression techniques have been studied. In the present study, grayscale data (2 bytes/pixel) were divided into high bytes and low bytes, and then the original medical images were also divided into high byte (1byte/pixel format) and low byte (1byte/pixel format) images. Inter-frame coding with and without division into high and low byte images was applied to MDCT images. Prediction (inter-frame) coding is a very common method to compress seque...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2005 Category: Physics Authors: Nakayama K, Ichiba Y, Kojima K, Suzuki M Tags: Igaku Butsuri Source Type: journals

Validation of the blurring of a small object on CT images calculated on the basis of three-dimensional spatial resolution.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We determine three-dimensional (3D) blurring of a small object on computed tomography (CT) images calculated on the basis of 3D spatial resolution. The images were characterized by point spread function (PSF), line spread function (LSF) and slice sensitivity profile (SSP). In advance, we systematically arranged expressions in the model for the imaging system to calculate 3D images under various conditions of spatial resolution. As a small object, we made a blood vessel phantom in which the direction of the vessel was not parallel to either the xy scan-plane or the z-axis perpendicular to the scan-plane. Therefore, when...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2005 Category: Physics Authors: Okubo M, Wada S, Saito M Tags: Igaku Butsuri Source Type: journals

Structural inhomogeneity in mammography quality control phantoms detected by refraction-enhanced synchrotron radiation imaging.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Synchrotron radiation imaging with the refraction-enhancement mode visualized structural inhomogeneities in phantoms used for image quality control of mammography. Eight phantoms were examined, all of which were manufactured in the United States and approved by the American College of Radiology as dedicated phantoms. In addition to fiber- and mass-mimicking test objects, each phantom has 5 groups of calcification specks of various sizes. Synchrotron radiation (SR) imaging was performed at Spring-8, a synchrotron radiation facility in Japan. Images were obtained with monochromatic 20-keV x-ray beams, a radiation field o...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2005 Category: Physics Authors: Imamura K, Ehara N, Inada Y, Kanemaki Y, Nakajima Y, Miyamoto K, Fukuda M, Umetani K, Uesugi K, Ochiai Y Tags: Igaku Butsuri Source Type: journals

[Clinical calibration dosimetry in JSMP-01: measurements using plane-parallel ion chambers.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we present Standard dosimetry 01 as the JSMP-01 protocol for the convenience of users. This protocol is based on using an ion chamber having a (60)Co absorbed dose to water calibration coefficient, N(D,w), which is calculated from a (60)Co exposure calibration coefficient, N(c). We present dose comparisons between a reference chamber and various plane-parallel chambers. The absorbed dose to water was compared at the calibration depth of 5 cm for a (60)Co beam and d(c) = 0.6R(50) - 0.1 (cm) for electron beams according to JSMP-01. The absorbed dose to water calibration coefficients, [N(D,w)](Co) and [N(D,w)](...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2005 Category: Physics Authors: Araki F, Kumagai K, Yoshiura T, Oura H, Tachibana M, Moribe N, Tajima H, Yoshida A, Kido T Tags: Igaku Butsuri Source Type: journals

[Clinical calibration dosimetry in JSMP-01: measurements using Farmer-type cylindrical ion chambers.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we present Standard dosimetry 01 as the JSMP-01 protocol for the convenience of users. This protocol is based on using an ion chamber having a (60)Co absorbed dose to water calibration coefficient, N(D,w), which is calculated from a (60)Co exposure calibration coefficient, N(c). We present dose comparisons between a reference chamber and various Farmer-type cylindrical chambers with different wall materials. The absorbed dose to water was compared at the calibration depths of 5 cm for a (60)Co beam, 10 cm for photons, and d(c) = 0.6 R(50) - 0.1 (cm) for electrons according to JSMP-01. The JARP chamber in the...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2005 Category: Physics Authors: Araki F, Kumagai K, Yoshiura T, Oura H, Tachibana M, Moribe N, Tajima H, Yoshida A, Kido T Tags: Igaku Butsuri Source Type: journals

[Investigation of Energy Subtraction in a CT System.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Developments in CT units for medical diagnoses permit to energy subtraction in CT radiography. Experiments were done for CT energy subtraction using a TOS phantom, self-made phantom and dry human skull at two tube voltages of 80kV and 135kV. The TOS phantom filled with water had six compartments of air, polyoxymethylene, polymethyl methacrylate, polyamide and polypropylene. The self-made phantom which included a cylinder filled with contrast medium was used for the contrast vessel. Bone contents disappeared selectively from images of both the self-made phantom and the human skull. In these cases, disappearance of selec...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2005 Category: Physics Authors: Yonemura M, Kabusaki R, Yoshida H Tags: Igaku Butsuri Source Type: journals

Experimental evaluation of conversion factors, N(D,w)/N(X), for Roos-type and Advanced-Markus-type plane-parallel ionization chambers.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A Japanese code of practice for clinical dosimetry, titled "Standard Dosimetry of Absorbed Dose in External Beam Radiotherapy" was published by the Japan Society of Medical Physics (JSMP) in 2002. It mostly followed IAEA Technical Reports Series No. 398, which was based on N(D,w), i.e., the calibration factor in terms of absorbed dose to water for a dosimeter. The Japanese primary standard dosimetry laboratory, however, has not supplied N(D,w) but N(X), as the calibration factor in terms of exposure. The unique feature of the Japanese code was provision of a data table of calculated conversion factors, N(D,w) / N(X) va...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2005 Category: Physics Authors: Fukumura A, Endo M, Kanai T, Takeshita M, Sakama M, Ito A, Takahashi Y, Hoshina M, Kusano Y, Takase E, Gunaratne J Tags: Igaku Butsuri Source Type: journals

Effect of J coupling and T2 Relaxation in Assessing of Methyl Lactate Signal using PRESS Sequence MR Spectroscopy.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Conclusions: For evaluation of the lactate peak, we recommend the use of the positive in-phase signal because it is larger than the negative in-phase signal. The influence of the asymmetric PRESS sequence, which may cause loss and over expression of lactate signal, should be considered in the calculation of the quantification. The T2 relaxation time should be also considered in the calculation of the lactate value since it affects the value considerably. PMID: 16135894 [PubMed - in process]
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2005 Category: Physics Authors: Isobe T, Matsumura A, Anno I, Kawamura H, Muraishi H, Umeda T, Nose T Tags: Igaku Butsuri Source Type: journals

[Evaluation on the effect of dosimetry using a depth of calibration point or a depth of temporary dose maximum in high energy electron beams.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study evaluated the difference in the absorbed dose at the depth dose maximum (D(dmax)) and D(r) calculated from the absorbed dose at the calibration point. Further, the difference in the absorbed dose (D(dmax)) at "measured maximum depth (d(max))" was evaluated using "temporary maximum depth (d(max*))." In the experiment at a depth interval of 0.1 g cm(-2), no difference was observed between D(dmax) and D(r). However, in the experiment at a depth interval of 0.3 g cm(-2) the differences between D(dmax) and D(r) increased to 6.4% and 5.2% at 4 MeV and 6 MeV, respectively. Subsequently, at all energy levels the differe...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2005 Category: Physics Authors: Haneda K, Hatakeyama N, Koyama T Tags: Igaku Butsuri Source Type: journals

[Theoretical considerations for evaluating the degree of random-periodicity of graphic noise.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Graphic noise properties are usually evaluated using the Wiener spectrum. However, this approach is not appropriate for periodic noise for two reasons. One is that it takes infinite values at the spatial frequencies of periodic noise. The other is that when adopting a numerical integration, it allows unstable values at each spatial frequency, depending on the integral region. Introducing three types of spectra (W(1), W(2), and W(3)) in connection with the Wiener spectrum, we propose a practical approach to evaluation of periodic noise. Graphic images sometimes contain noise that is not totally random and not perfectly ...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2005 Category: Physics Authors: Iwasaki A, Kodera Y, Hirota J, Kubota M, Kimura H, Osanai T, Kudo S, Abe Y Tags: Igaku Butsuri Source Type: journals

[Polarity effects of commercial plane-parallel ionization chamber in therapeutic electron dosimetry-Results with C-134A ionization chamber.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, the polarity effects of a C-134A ionization chamber, a major commercially available plane-parallel ionization chamber in Japan, were characterized as a function of mean energy at various depths. Polarity effects were measured at representative depths along depth dose curves of nominal 4, 6, 9, 12 and 15 MeV electron beams, and were compared with previously reported results. Polarity errors for the ionization chamber studied were shown to monotonically increase with decreasing mean energy at a given depth and were maximal at about 1-2 MeV. It was also shown that polarity errors depended on the energy of the i...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2005 Category: Physics Authors: Fujisaki T, Hiraoka T, Saitoh H, Nakajima M, Kuramoto A Tags: Igaku Butsuri Source Type: journals

[A comparison of the helmet output factors for five Gamma-Knife units.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A radiophotoluminescent (RPL) glass rod dosimeter (GRD) and a small active volume p-type silicon diode detector are used for the measurement of the helmet output factors from five Gamma-Knife units, which include four Model B units and a Model C unit. The output factors for the five units measured with the GRD from 14, 8 and 4 mm helmets relative to the 18 mm helmet are 0.984 +/- 0.003, 0.951 +/- 0.003 and 0.884 +/- 0.006, respectively. Similarly, the corresponding output factors measured with the p-type silicon diode detector are 0.983 +/- 0.002, 0.952 +/- 0.003 and 0.867 +/- 0.015, respectively. The output factors ar...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2005 Category: Physics Authors: Araki F, Ikegami T, Ishidoya T Tags: Igaku Butsuri Source Type: journals

[2D imaging simulations of a small animal PET scanner with DOI measurement: jPET-RD.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present a preliminary study on the design of a high sensitivity small animal DOI-PET scanner: jPET-RD (for Rodents with DOI detectors), which will contribute to molecular imaging. The 4-layer DOI block detector for the jPET-RD that consists of scintillation crystals (1.4 mm x 1.4 mm x 4.5 mm) and a flat panel position-sensitive photomultiplier tube (52 mm x 52 mm) was previously proposed. In this paper, we investigate imaging performance of the jPET-RD through numerical simulations. The scanner has a hexagonal geometry with a small diameter and a large axial aperture. Therefore DOI information is expected to improve res...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2005 Category: Physics Authors: Yamaya T, Kitamura K, Hagiwara N, Obi T, Hasegawa T, Yoshida E, Tsuda T, Inadama N, Wada Y, Murayama H Tags: Igaku Butsuri Source Type: journals

[Feasibility study on a noninvasive measurement system for boron concentration.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The kinematics of boron compounds in vivo is crucial to fully and safely utilize boron neutron capture therapy. In this paper, we proposed a prompt gamma-ray Compton scatter camera (PG-CSC), which can evaluate the 3-D kinematics of boron compounds without invasion. This PG-CSC combines a Compton camera with prompt gamma-ray analysis. The results of its design optimization and tests using simulations showed that one-hour-measurement was sufficient to evaluate a 3-D boron concentration distribution in a rat's brain with the resolution of 1 mm in FWHM. PMID: 15961923 [PubMed - in process]
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2005 Category: Physics Authors: Ishikawa M, Hirasawa M, Tomitani T, Murayama H, Hoshi M Tags: Igaku Butsuri Source Type: journals

[An analysis of a new method for estimating the range of hand motion using tele-rehabilitation.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We compared estimated axes obtained from the upper arm outline, which changes during movement, with the skeleton axis obtained from an x-ray image in terms of range of motion. Statistical analysis showed that the estimated axes corresponded to the skeleton axis in each range of motion of the hand. The analysis was superior to the conventional approach. PMID: 15795504 [PubMed - in process]
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2004 Category: Physics Authors: Yamashita K, Kawamura T, Ishiwatari H, Mutou H, Matuura K, Okano A Tags: Igaku Butsuri Source Type: journals

[Comparative evaluation of absorbed dose and image quality in X-ray head CT scanning for hospital facilities in Gunma.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In conclusion, it was proposed that the technologists should reconsider the parameters of the head X-ray CTs, in cases where their output dose far exceeds the standard. PMID: 15795503 [PubMed - in process]
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2004 Category: Physics Authors: Nagashima H, Shiraishi A, Ogura T, Shimosegawa M, Kashikura K, Hoshina M, Kawaharada Y, Igarashi H Tags: Igaku Butsuri Source Type: journals

[Experimental study on treatment planning verification using a positron emitting (10)C beam for heavy-ion radiotherapy.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
An advantage of heavy-ion therapy is its good dose concentration. A limit for full use of this desirable feature comes from range ambiguities in treatment planning. The treatment planning is based on X-ray CT measurements, and the range ambiguities are mainly due to an error in calibration of the CT number. The heavy-ion ranges are related to electron density of the medium while the CT numbers are defined using the X-ray attenuation coefficient. The range verification method using positron emitter beams has been developed to reduce the range ambiguities. In this verification, probing beams of positron emitters are impl...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2004 Category: Physics Authors: Iseki Y, Urakabe E, Kanazawa M, Kitagawa A, Tomitani T, Suda M, Sato S, Kanai T Tags: Igaku Butsuri Source Type: journals

Mammographic x-ray spectra measured by Compton spectroscopy using a high resolution Schottky CdTe detector.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Analysis of x-ray spectra is important for quality assurance (QA) and quality control (QC) of radiographic systems. This is especially true for mammographic x-ray imaging systems which require low-contrast detectability. Under clinical conditions, the measurement of diagnostic x-ray spectra is difficult because of pulse pile-up due to the high fluence rate of incident x-ray photons. However, it is difficult to set a long source-to-detector distance to reduce the number of photons detected per unit time for mammographic x-ray units. Compton spectroscopy is a suitable tool to deal with this problem. Detection of 90-degre...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2004 Category: Physics Authors: Maeda K, Matsumoto M Tags: Igaku Butsuri Source Type: journals

[Relationship between line spread function (LSF), or slice sensitivity profile (SSP), and point spread function (PSF) in CT image system.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In the CT image system, we revealed the relationship between line spread function (LSF), or slice sensitivity profile (SSP), and point spread function (PSF). In the system, the following equation has been reported; I(x,y) = O(x,y) ** PSF(x,y), in which I(x,y) and O(x,y) are CT image and object function, respectively, and ** is 2-dimensional convolution. In the same way, the following 3-dimensional expression applies; I'(x,y,z) = O'(x,y,z) *** PSF'(x,y,z), in which z-axis is the direction perpendicular to the x/y-scan plane. We defined that the CT image system was separable, when the above two equations could be transfo...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2004 Category: Physics Authors: Ohkubo M, Wada S, Kobayashi T, Lee Y, Tsai DY Tags: Igaku Butsuri Source Type: journals

[Online-conference using JGN.]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Telemedicine and online conference systems have some benefits so that equalizing medical level, improving efficiency of medical care and improving service for patients. It is possible to give advice and to support its medical projects stationed in other facility and to provide the same quality treatments for patients. In this paper, we set up an experimental network system to teleconference using JGN (Japan Gigabit Network) and tried to discussion alternatively for case study between Kanazawa university and Fukui red cross hospital, 70 km away. The JGN used in this study is an ultra-high-speed network for the purpose o...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2004 Category: Physics Authors: Nakayama K, Kojima K, Suzuki M, Kikuchi Y, Iwahara M, Matsui O, Noguchi M Tags: Igaku Butsuri Source Type: journals

Monochromatic polycapillary imaging utilizing a computed radiography system.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A fundamental study on quasi-parallel radiography using a polycapillary plate and a copper-target x-ray tube is described. In the experiments, the tube voltage was regulated from 12 to 22 kV, and the tube current was regulated within 3.0 mA by the filament temperature. The exposure time was controlled in order to obtain optimum x-ray intensity, and the maximum focal spot dimensions were approximately 2.0 x 1.5 mm. The thickness and the inner capillary tube diameter of the polycapillary were 1.0 mm and 25 microm, respectively. Monochromatic x-rays were produced using a 10 microm-thick nickel filter with a tube voltage o...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2004 Category: Physics Authors: Sagae M, Sato E, Hayashi Y, Tanaka E, Mori H, Kawai T, Obara H, Ichimaru T, Takayama K, Ido H Tags: Igaku Butsuri Source Type: journals

[A study of the security and transmission of medical information using JGN (Japan Gigabit Network)]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, A 10 Mbps communication link of the JGN is used to transmission and reception of detailed and large medical information from remote places. Kanazawa University, NTT west kanazawa hospital, toyama city hospital and fukui red cross hospital are connected to the JGN through a router. IPsec system, which is the security protocol, is used for the security of data transmission between each facilities. In result, the date transmission rate using IPsec is 7 Mbps. The average translation rates of CT images (512 x 512, 16bit) and MRI images (256 x 256, 16bit) are 0.8 s/flame and 0.2 s/flame, respectively. PMID: 15...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2004 Category: Physics Authors: Nakayama K, Kojima K, Suzuki M, Kikuchi Y, Iwahara M Tags: Igaku Butsuri Source Type: journals

[Simultaneous spatial resolution correction in SPECT reconstruction using OS-EM algorithm]Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Single photon emission computed tomography (SPECT) is widely used for Nuclear Medicine. The low spatial resolution is mainly due to the limited collimator resolution. We have developed ordered subsets-expectation maximization (OS-EM) algorithm incorporating three dimensional spatial resolution correction (3D-SRC;horizontal and vertical direction) for distance-dependent blurring. In this paper we evaluate the fundamental properties of OS-EM algorithm including distance-dependent resolution correction using some phantoms (cubic phantom, cardiac and brain phantoms) and 12 patients performed 99mTc-tetrofosmin myocardial SP...
Source: Igaku Butsuri: Japanese Journal of Medical Physics - January 1, 2004 Category: Physics Authors: Maeda H, Yamaki N, Natsume T, Takeda K, Hasebe S, Kinda A, Motomura N Tags: Igaku Butsuri Source Type: journals