Visualization of Human Brain Cortical Layers Using Quantitative Parameter Mapping on a 3 Tesla Scanner


Development of numerical phantom converting from electron microscopic analysis to multi-component water fraction for MRI simulator.


A novel analysis method to determine surface radiation dose taking into account the incident angle of X-rays during a helical scanning CT examination

The 3rd International Conference on Radiological Physics and Technology (ICRPT)


A correction method for image blurring to derive accurate quantitative material information using an energy resolving photon counting detector


Suitability of High Tube Voltage Imaging for General Radiography When Using Energy Resolving Photon Counting Detectors


Direct dose measurement method during chest CT examination by taking into consideration the X-ray incident direction

European Congress of Radiology, ECR 2024


Determining Imaging Parameters of a Gradient-echo Technique for Myelin Water Fraction.


Applicability of high tube voltage imaging to achieve accurate quantitative images when applying photon counting detectors to general radiography


Quantitative Parameter Mapping of Brain Structure and Components in Parkinsons Disease and Progressive Supranuclear Palsy

RSNA2023 (Radiological Society of North America)


Automatic determination algorithm of intrinsic parameters on response function of energy-resolving photon counting imaging detector

The 2023 IEEE Nuclear Science Symposium and Medical Imaging Conference


Blurring correction for calculating functional images using an energy resolving photon counting detector


How can we establish direct radiation dose measurement during CT examinations?

The 109th Scientific Assembly and Annual Meeting of the Radiological Society of North America (RSNA2023)


Will general radiography become more valuable when exploiting the performance of a photon counting detector?


Metabolic Analysis Within an Atherosclerotic Plaque Using Chemical Exchange Saturation Transfer Imaging


Evidence of exposure dose reduction outside the scanning region during fast scan chest CT examination through the use of an X-ray shield

20th International Conference on Solid State Dosimetry (SSD20)


An active-type personal dosimeter having functions to derive both incident direction and absolute dose of scattered X-rays during clinical X-ray examinations


Myelin Water Atlas Template Derived from Quantitative Parameter Mapping


Evaluation of Biological Metabolic Activity within an Atherosclerotic Plaque using Chemical Exchange Saturation Transfer Imaging


Diffusion weighted-viscosity imaging for atherosclerotic plaques


A novel function for wearable dosimeters: to determine both incident direction and absolute dose of X-rays during IVR procedure

The 2nd International Conference on Radiological Physics and Technology (ICRPT)


A correction method for object edge blurring that is effective for quantitative analysis using photon counting imaging


Suitability of High-Tube-Voltage Imaging When Using Energy Resolving Photon Counting Detector (ERPCD): Simulation Study


A wearable active-type dosimeter having novel functions to derive both incident direction and absolute dose of scattered X-rays during IVR procedures


Development of a B1 correction method without additional scanning VFA T1 map.


Evaluation of Blood Flow and Plaque Vulnerability in Carotid Artery Stenosis Focusing on Morphological and Component Characteristics


Evaluation of brain tumor and surrounding tissue activity using multi-pool CEST imaging on 3 Tesla scanner

Joint Annual Meeting ISMRM-ESMRMB & ISMRT 31st Annual Meeting


Development of self-calibrating B1 correction for three-dimensional variable flip angle T1 mapping


Conversion map from quantitative parameter mapping to myelin water fraction


Determination of Alzheimer's disease based on morphology and atrophy using machine learning combined with automated segmentation.


Bone and soft-tissue image generation method based on one shot X-ray exposure using a photon-counting detector

Joint International Conference on Radiological Physics and Technology


Variable flip angle T1 mapping without acquiring data for B1 correction


Determination of white matter structure index for voxel basedmorphometry and connectivity analysis.


Endogenous/exogenous tracers in CEST for pH measurement at 3T MRI


Characterization of Movement Disorders Using Multimodal Neuroimaging


What Is The Extracellular pH Of Brain Tumors And How Can We Detect Brain Tumors Using Gadolinium-based-contrast Agents?

RSNA2021 (Radiological Society of North America)


Is it possible to evaluate morphological carotid artery stenosis information using NASCET criteria?


Bone and soft-tissue images extraction through derivation of effective atomic number image using photon-counting detector


Bone and soft-tissue images extraction through derivation of effective atomic number image using photon-counting detector.


Brain Tumor Characterization and Assessment using Automatic Detection of Extracellular pH Change


Derivation of Water Exchange Constants between Components using Quantitative Parameter Mapping (QPM)


Myelin imaging derived quantitative parameter mapping compared to myelin water fraction


How can we perform actual dose measurement? Clinically applicable procedures and its impact


Calculation of Concentration of Contrast Media, Relaxivity, Extracellular pH and Oxygen Extraction Fraction for Brain Tumor Characterization


Characterization of Brain Tumors using Amide Proton and Nuclear Overhauser Effect at 3 Tesla MR Scanner


Chemical Exchange Saturation Transfer Imaging for Atherosclerotic Plaques


Estimation of X-ray energy spectrum for CT scannerfrom percentage depth dose measurement


Dose calibration factor of an OSL dosimeter during CT examination to measure exposure dose of patients taking into consideration proper X-ray quality


Multicomponent T1 Relaxometry Analysis using Quantitative Parameter Mapping Magnetic Resonance Imaging


Multi-components analysis of brain using ultrashort echo time magnetic resonance imaging


How does synthetic MRI depict biological information? A step toward planning for deep brain stimulation (DBS)


Simultaneously Calculation of Concentration of Contrast Media, Relaxivity, and Oxygen Extraction Fraction using Quantitative Parameter Mapping

RSNA2019 (Radiological Society of North America)


Photon counting technique: How to analyze a novel quantitative image?


Feasibility study of photon counting detector for producing effective atomic number image

IEEE Nuclear Science Symposium and Medical Imaging Conference


Novel Disk-Shaped OSL Dosimeter Having Smaller Angular Dependence

19th International Conference on Solid State Dosimetry (SSD19)


Development of a Clinically Applicable Rectum Dosimeter for Brachytherapy using an Optically Stimulated Luminescence Dosimeter


Practical calibration curve for a small-type OSL dosimeter to measure exposure dose of patients during medical X-ray diagnosis


Precise dose calibration method of OSL dosimeter with help of X-ray spectra toward exposure dose evaluation of eye lens


Calculation of molar relaxivity and concentration map of Gd-DTPA map using quantitative parameter map before and after injection for brain metastasis


Chemical exchange saturation transfer imaging depending on several neurodegenerative diseases at 3T


Myelin imaging derived from quantitative parameter mapping


Comparing neural networks for synthesizing FLAIR images from T1WI and T2WI


Effective atomic number image produced with energy-resolved photon counting detector toward the development of next-generation plain X-ray diagnosis


Evaluation of dose to risk organ during brachytherapy for cervical cancer using a novel passive rectum dosimeter


Actual dose measurements of assistant during pediatric X-ray examination with a precisely calibrated optically stimulated luminescence dosimeter


Determining the difference of calibration factors in diagnostic X-rays and mono-energetic X-rays of the small type OSL dosimeter for a more precise dose evaluation in diagnostic X-ray examinations


Where do the scattering X-rays to eye lens exposure come from during neonatal cardiac CT examination?


Why are shear stiffness and estimated intravoxel incoherent motion map correlated in the liver?


Which number of b-value is better for accurate calculation of virtual MR elastography?


Quantitative evaluation of local offset frequency for CEST imaging

The 3rd Annual Scientific Meeting of the Japanese Chapter of ISMRM


Chemical exchange saturation transfer imaging for brain tumors

RSNA2018 (Radiological Society of North America)


Trial study for development of a novel-formed dosimeter having lower angular dependence

18th Asia-Oceania Congress of Medical Physics (AOCMP)


Reproduction of response functions of a multi-pixel-type energy-resolved photon counting detector while taking into consideration interaction of X-rays, charge sharing and energy resolution

25th International Symposium on Room-Temperature Semiconductor X-ray & Gamma-ray Detectors


First Trial of Actual Dose Measurement of Organ at Risk During Brachytherapy for Cervical Cancer in Tokushima University Hospital

Second International Seminar and Workshop on Technological Competency as Caring in the Health Science


Does the amount of signal change depend on calcium concentration in lipid-rich core plaque?


T1 dependency of magnetization transfer effect in human brain


Nuclear Overhauser enhancement effect of low B1 power CEST RF in human brain at 3.0 T


Chemical exchange saturation transfer imaging for neurodegenerative diseases


Radiation dose measurement in pediatric CT examination using nanoDot dosimeters, a small type Optically Stimulated Luminescence (OSL) dosimeter

5th Asian and Oceanic IRPA Regional Congress on Radiation Protection (AOARP5)


Proper Calibration Factor of Small Type OSL Dosimeter for Evaluating Eye Lens Dose of Operators during X-ray Fluoroscopic Procedure

th Asian and Oceanic IRPA Regional Congress on Radiation Protection (AOARP5)


Eye lens dose evaluation of medical staff during the X-ray fluoroscopic procedure using Optically Stimulated Luminescence dosimeter ~ Influence of incident X-ray energy fluctuation on response of the dosimeter ~

51st Annual Meeting of TWSRT and the 25th East Asia Conference of Radiological Technologists


51st Annual meeting of Taiwan Society of Radiation Technology


Phantom study toward accurate measurement of eye lens dose exposure of operator during transfemoral cardiac catheterization using fluoroscopy examination with an OSL dosimeter

[Aim and objectives] During transfemoral cardiac catheterization procedure using fluoroscopy, the operator is exposed to scattered X-rays. We focused our attention on the accurate dose measurement of eye lens using a small-type OSL dosimeter. The eye lens is exposed with X-rays scattered by patient and those penetrating protective goggles, therefore, the OSL dosimeter should be calibrated with the appropriate radiation. The aim of this study is to perform accurate calibration of OSL dosimeter for the determination of eye lens dose exposure. [Materials and Methods] A phantom study was performed under clinical conditions in which the catheterization procedure was assumed. Then, using a CdTe detector, energy spectrum of scattered X-ray was measured at the eye lens position. Irradiation conditions were set at 74 kV, 0.9 mA, 15 fps, and 30 minutes. Air kerma and absorbed dose of OSL dosimeter were derived from the measured spectrum, and calibration factor of OSL dosimeter was calculated from their ratio. Using Monte-Carlo simulation, necessary corrections concerning beam hardening in protective goggles and back scattering from head of operator were properly calculated. [Result] Using fluoroscopy, X-ray spectrum was obtained, and the spectrum was corrected for by response function of CdTe detector and the Klein-Nishina formula. The calibration factor for scattered X-rays was determined and this calibration factor was in good agreement with that determined with 80 kV direct X-ray. [Conclusion] We evaluated the difference in calibration factor caused by scattered X-ray. Then, we found that calibration factor for measuring the eye lens dose exposure was similar to the data for 80 kV direct X-ray.


Universal calibration curve for a small-type OSL dosimeter to be used for direct dose measurements of direct, scattered and penetrating X-rays in the diagnostic region

Radiological Society of North America (RSNA)

(1)Aims: We hope to find a suitable dosimeter, which can measure incident, scattered and penetrating X-rays. In this study, we propose a new procedure to calibrate the OSL dosimeter. (2)Experiment & results: Initially, we constructed a calibration curve of air-kerma (direct X-rays) with comparison between the OSL dosimeter and an ionization chamber. Second, we evaluated the accuracy of the above calibration curve when the following conditions were applied; 1) entrance-skin dose, and 2) air-kerma of scattered X-rays and 3) penetrating X-rays through a soft-tissue equivalent phantom. We then found that the above calibration curve can be used in all situations if we adopt 15% of uncertainty. Finally, the X-ray spectra related to those conditions were measured, and with the data on basic characteristics of the dosimeter, the result of 15% uncertainty was verified mathematically. (3)Conclusion: With 15% uncertainty, we can use the OSL dosimeter without considerations of energy dependence, angular dependence etc. This study enabled the OSL dosimeter to manage the exposure dose of medical staff, assistants and patients.


Practical phantom study using small-type OSL dosimeter toward direct dose measurement during pediatric CT examination


Which is More Important for Quantitative Susceptibility Mapping? SNR of Phase vs Spin Dephasing.


Can OSL dosimetry measurement be applied to MR imaging during MR-LINAC treatment?

RSNA2017 (Radiological Society of North America)


Potential of photon counting technique for next-generation type X-ray diagnostic system: To provide new medical image concerning effective atomic numbers using plain X-ray


Development of a new in-vivo measurement system by means of OSL dosimeters during brachytherapy for cervical cancer


Evaluating the Influence of the Small-type Optically Stimulated Luminescence (OSL) Dosimeter on CT Images for Radiation Dose Measurement of Patient

The 3rd International Conference on Radiological Science and Technology


Precise calibration factor of small-type OSL dosimeter with the aim toward analysis of exposure doses caused by scattering X-ray in the diagnostic region


Direct measurement of exposure doses using a small-type OSL dosimeters during pediatric CT examination


Novel material identification method using three energy bins of a photon counting detector taking into consideration Z-dependent beam hardening effect correction with the aim of producing an X-ray image with information of effective atomic number

2017 IEEE Nuclear Science Symposium & Medical Imaging Conference


Direct Dose Measurement of Patients during Pediatric Computed Tomography Examination

International Symposium On Radiation Safety and Detection Technology (ISORD-9)


Energy and Angular Dependence of the small type OSL Dosimeter in Diagnostic and Nuclear Medicine Regions using Monte Carlo Simulation


Direct Radiation Dose Measurement of Rectum during High-Dose-Rate 192Ir Brachytherapy for Cervical Cancer Treatment


Applicability of Practical Calibration of a Small-type OSL Dosimeter For Measuring the Exposure Doses Effected by Scattered and Penetrating X-rays


Development of Novel Rectum Dosimeter using OSL sheet with the aim of Direct Dose Measurement of Organ Dose during Brachytherapy


CEST and Binding Water MT Separation in Brain Tumor by Multi Pool Model CEST Peak Extraction Method


Baseline of Chemical Exchange Saturation Transfer Imaging for Brain


小型光刺激發光劑量計測量診斷範圍之輻射劑量的可能性評估

小型光刺激發光劑量計測量診斷範圍之輻射劑量的可能性評估

The 50th Annual Meeting of TWSRT and the International Conference of Medical Imaging


Basic study for internal dose evaluation during CT examination by means of small-type OSL dosimeter

[Aims and objectives] We plan to manage the patient dose exposure during computed tomography (CT) examination using a small-type OSL dosimeter. The OSL dosimeter can measure entrance skin dose (ESD) directly, but the internal dose can't be measured. The aim of this study is to clarify the relationship between the ESD and internal dose during the CT examination. [Methods and materials] We constructed an abdominal phantom, in which OSL dosimeters can be implanted in, and used this phantom to measure external and internal doses during CT examination. The typical irradiation conditions were as follow, 64 rows of detectors, 120 kV, 600 mA, PF (pitch factor) = 1.484 in helical scan mode. Additionally, we analyzed the contribution of X-rays, which were generated from different angles to the dosimeter; namely, angular dependences of 0-360 degrees at 45 degree intervals were evaluated experimentally. [Results] The ESDs and internal doses showed similar values, however the deviations between them were completely different; maximum deviation of ESD was found to be 30% and that of internal dose was at the most 5%. The deviation in ESDs is explained by the phenomenon in which some dosimeters were irradiated by direct X-ray and others were not. However, the small deviation between internal doses was explained by the phenomenon in which dosimeters were mainly irradiated by scattered X-rays. [Conclusion] In this study, we analyzed the relationship between ESD and internal dose for direct dose measurement of patient dose undergoing CT examination. The ESDs show relatively large fluctuations, on the other hand, the internal doses show small deviations.


Phase Correction for Quantitative Susceptibility Mapping (QSM) using T2* Mapping

The 5th International Congress on Magnetic Resonance Imaging

Objectives : The purpose of this study is to develop a phase correction method focusing on the SNR of phase and to improve the quantitative measurement of QSM. Methods : On a 3.0 T MRI system (Discovery MR750; GE Healthcare), using three-dimensional spoiled gradient-echo (3D-SPGR) sequence with multiple TEs were used in this study. The imaging parameters were TE, 12 echoes from 3.1 to 51.7 ms (ΔTE = 4.4 ms); repetition time, 55.5 ms; spatial resolution, 1.0 × 1.0 × 1.0 mm; and pixel bandwidth, 244.1 Hz. We conducted a phantom experiment in this study. Five tubes were filled with different concentrations (100, 150, 200, 250, and 300 mg/mL) of calcium hydroxyapatite samples. In this study, we focused on the computation of off-set frequency of each voxel (i.e., field map estimation). At first, we calculate the TE having the maximum for our setting number of echo from the measured T2* map. Second, the ``appropriate TE dataset'' was defined as the maximum SNR dataset with appropriate TE and two datasets with neighboring TE. Third, after estimating the field map using the appropriate TE dataset, a corrected phase angle at each phase angle of the appropriate TE dataset was calculated from a mean resultant length which is the length of the average vectors calculated from all phase angles. Then, the corrected phase angle was defined from mean resultant length. Finally, all phase angles in FOV were corrected for each appropriate TE dataset. Results : The linearity of the relationship between the measured susceptibility and the concentration of hydroxyapatite in the corrected phase dataset was significantly higher than other methods (R = 0.30 VS 0.97). Conclusions : The correction method in QSM using phase correction method makes it possible to more accurately obtain susceptibility information of tissue having a short T2*.


Preliminary study for exposure dose measurement of people assisting during a pediatric X-ray procedure by means of a small-type OSL dosimeter

[Aims and objectives] During a pediatric X-ray procedure, medical staff or other people such as parents may assist to hold children during the X-ray examination. In this situation, these assistances are exposed by scattered X-rays, but there are no precise data concerning exposure doses. The aim of this study is to measure exposure dose of people assisting during the X-ray procedure. [Methods and materials] We used small-type OSL dosimeter (Landauer), which was sufficiently initialized. The detection limit of our system was estimated to be 0.5 micro-Gy. The OSL dosimeter was attached outside the lead protector which was worn by the assistant. In order to reduce contamination from background X- and/or gamma-rays, the exposed dosimeters were analyzed within 12 hours. The X-ray diagnostic system consisted of X-ray equipment and flat-panel detector which has auto-exposure control. The typical irradiation condition was SID=1.1 m, 3.2 mAs, and 53 kV. [Results] The exposure doses of assistances in the position outside the lead protector were approximately 3 micro-Gy. We measured 5 cases, in which patient's ages were 7 months to 1 year 6 months. Patient age showed no significant differences in exposure doses. [Conclusion] For the first time, using the small-type OSL dosimeter, we measured exposure dose of people assisting during a pediatric X-ray examination in a position outside the lead protector. The measured value was extremely low. Our actual data supports the justification of the situation in which someone should hold a child during an X-ray procedure.


T1 dependence of magnetization transfer effect for macromolecules

Purpose: To assess the relationship between T1 and magnetization transfer (MT) effect on macromolecules, we determined T1 map derived from variable flip angle (VFA) method with MT pulse. Materials and Methods: On a 3.0 T magnetic resonance (MR) system, we performed a phantom study using spoiled gradient-echo sequences; TR, 600 ms; TE, 5.8 ms; FA, 5, 20, 40, 60, and 90 degrees; without and with MT pulse (offset frequency, 800 ,1200 , and 1600 Hz). The phantom components were six samples; water and polyethylene glycol (PEG) solutions at different concentrations (10, 20, 30, 40, and 50 wt%). We calculated T1 maps from image datasets without and with MT pulse. Then, the MT ratio (MTR) maps were calculated from each FA image. Results: The mean T1 range without MT pulse for each sample was from 1200 to 2039 ms. The mean T1 ranges with MT pulse of each sample were from 1322 to 1886 at 800 Hz; from 1310 to 1926 ms at 1200 Hz; from 1300 to 1909 ms at 1600 Hz. The MTR of each sample showed the highest value at FA 5 degrees and offset 800 Hz. The mean MTR values of each sample were 6.54 ± 2.78, 3.94 ± 1.92, 2.50 ± 1.67, 1.96 ± 1.33, 1.44 ± 1.15, and 1.78 ± 1.53%. Conclusion: Determination of T1 with MT pulse makes it possible to obtain more detailed information of macromolecules.


An improvement of signal-to-noise ratio for phase image


Development of a novel method based on a photon counting technique with the aim of precise material identification in clinical X-ray diagnosis

Progress in Biomedical Optics and Imaging - Proceedings of SPIE


Response functions of multi-pixel type CdTe detector --- toward development of precise material identification in diagnosti x-ray images by means of photon counting


Uncertainty estimation of dose measured with a small-type optically stimulated luminescence dosimeter for CT scanning --- Basic study for estimating entrance skin dose and internal organ dose

22nd International Conference on Medical Physics ICMP

Purpose: In the diagnostic X-ray region, we have verified that a small-type optically stimulated luminescence (OSL) dosimeter can measure entrance-skin-dose (ESD) without consideration of energy and angular dependences if we adopted a systematic uncertainty of 15%. The aim of the present study is to estimate the uncertainty of the dose measured during X-ray CT scanning. During CT examinations, X-rays are collimated to a thin beam, therefore some X-rays directly irradiate the small dosimeter and other X-rays do not. These phenomena are related to the function of the beam width and distances between beams. Methods: Using a 320-rows CT scanner, phantom studies were performed. For estimating the accuracy of measuring the ESD, the OSL dosimeters and Gafchromic films were placed on the abdomen of the water phantom and irradiated simultaneously. Then, measured doses were compared. For estimating the accuracy of the internal dose measurement (organ dose), the OSL dosimeters were embedded in a hand-made acrylic phantom. Results: The ESDs measured with the OSL dosimeters and the Gafchromic films were consistent, and we found that the deviations of measured doses with OSL dosimeters from the averaged value were at most 25% under general irradiation conditions used during CT scanning. Conclusions: We summarized that research technicians should consider an additional 25% systematic uncertainty when a small-type OSL dosimeter is applied to measure the dose during CT scanning. An additional 25% uncertainty is slightly high, but in consideration we can reliably measure X-ray dose without consideration of placements of the dosimeters.


Calculation of energy and angular dependences of the small-type OSL dosimeter in the diagnostic and nuclear medicine regions using the Monte-Carlo simulation code

Purpose: The International Commission on Radiation Protection (ICRP) reviewed the threshold of the cataract, and recommended the new dose limits as 100 mSv / 5 y and 50 mSv / y. To estimate the eye lens dose, the small type optically stimulated luminescence dosimeter, nanoDot is expected to use. The aim of this study is to evaluate the angular and energy dependences of the nanoDot OSL dosimeter for the precise measurement of the eye lens dose. Method: Using the Monte-Carlo simulation code (electron gamma shower ver. 5: EGS5), the simplified OSL dosimeter was modeled. Then, taking account of the secondary electron equilibration, angular dependence of 0-360 degrees and energy dependence of 10 keV-2 MeV were calculated. Moreover, we performed experiments using the diagnostic X-ray equipment, and the obtained results were compared with the simulation. Results: In the diagnostic X-ray region, angular dependences were found to be almost flat except for 90 and 270 degrees (side directions), and these trends were in good agreement with the experiments. The energy dependence was defined as measured value divided by air-kerma. In this definition, rapid change was not observed in the energy region of 20 keV-2 MeV. Conclusions: In this study, we simulate the response of the small-type OSL dosimeter, nanoDot, using the Monte-Carlo simulation code. The nanoDot dosimeter was expected to be a proper dosimeter for the evaluation of the eye lens dose, especially caused by the scattered radiations in the medical diagnosis.


Universal dose calibration of the small-type OSL dosimeter for diagnostic X-rays - direct, scattered and penetrating X-rays -

Purpose: The small type optically stimulated luminescence dosimeter, nanoDot is expected to apply to the evaluation of eye lens dose. Dose calibration of nanoDot is carried out by the air kerma of the X-ray, however the main component of eye lens exposure is scattered X-ray in the medical field. Therefore we evaluated the reliability of the dose calibration of nanoDot dosimeter in different quality of X-rays. Method: The main calibration line was determined by the air-kerma of 83 kV X-rays in dose range of 4 Gy to 2 mGy. In addition, to evaluate the reliability of the calibration line in different X-ray qualities, the response of nanoDots were compared with the air kerma of scattered X-ray and penetrated X-ray, and/or entrance skin dose. In the same manner, 55 and 108 kV X-rays were irradiated. Then the differences between the main calibration and other data were evaluated. Results: The measured data of each conditions were in good agreement with the main calibration line derived by the air kerma of 83 kV X-ray. Even in 4 Gy irradiated dosimeters, most of the results were in inside of +/-15% deviations from the calibration line. Conclusions: In this study, we evaluated the reliability of the calibration of the small-type OSL dosimeter, nanoDot. The nanoDot calibrated by the air kerma of 83 kV X-ray can be applied to the air kerma of scattered X-ray and penetrated X-ray and/or entrance skin dose of diagnostic X-rays when we adopt 15% systematic uncertainty.


Proposal of an appropriate echo time-input function for quantitative susceptibility mapping.

International Conference On Medical Physics (ICMP) 2016

Purpose To improve the quantitative assessment for both diamagnetic and paramagnetic materials, we developed a quantitative susceptibility mapping (QSM) method using an appropriate echo time (TE)-input function. Methods On 3.0 T MR system, we performed a phantom experiment using a multi-echo spoiled gradient-echo (12 echos; delta TE = 4.4 ms). The phantom consisted of gadopentetate dimeglumine (Gd-DTPA) and hydroxyapatite samples, which were made using three different concentrations of each material. After a multiple TE dataset was acquired, T2* values were calculated from the dataset. When a field map estimation was computed, the appropriate T2* value was used as TE-input function. Next, phase unwrapping and background removal were performed. Finally, the reconstruction of QSM was performed. Moreover, we compared susceptibility values derived from TE-input function and conventional methods. Results The mean T2* values of each Gd-DTPA and hydroxyapatite sample were 365 ± 74, 194 ± 9, 86 ± 3, 24 ± 2, 14 ± 1, and 11 ± 1 ms, respectively. Compared with the conventional method, the proposed TE-input function method indicated good positive linearity for the relationship between the Gd-DTPA concentration and susceptibility (slope = 0.26 ppm/mmol/L, R2 = 0.97, P = 0.11). Additionally, the proposed TE-input function method indicated good negative linearity for the relationship between the concentration and hydroxyapatite susceptibility (slope = -0.0019 ppm/mg/mL, R2 = 1.00, P = 0.02). Conclusions QSM with the TE-input function makes it possible to evaluate simultaneously diamagnetic and paramagnetic materials. e.g. Gd-DTPA and hydroxyapatite.


Basic study for material identification toward development of a next generation type X-ray diagnosis detector based on a photon counting technique

Purpose: X-ray diagnosis is widely used for obtaining medical images. Recently, a photon counting system has been developed and applications for X-ray imaging are expected to be developed. One of the advantages for applying the photon counting is to obtain new information about material identification in the medical image. The aim of this study is to propose a novel method for material identification. Methods: Assuming that a CdTe detector measures one pixel of a two-dimensional imaging detector, the following experiments were performed. First, 40 kV X-rays generated with diagnostic X-ray equipment were measured. Second, four different phantoms (soft-tissue equivalent, bone-equivalent, acrylic, aluminum) were placed in front of the CdTe detector and the X-ray spectra penetrating the phantoms were measured. Then, the measured spectra were divided into two regions, and analyzed by our method. At this time, the beam hardening effects in the measured spectra were corrected. Finally, effective atomic numbers were determined and compared with theoretical values. Results: Our method works well to identify the four different materials by analyzing the measured X-ray spectra. The relationship between accuracy of determined effective atomic numbers and statistics of measured X-ray spectra was evaluated. Then we found the possibility to establish the accuracy of +/-0.1 in atomic number using our method. Conclusions: For developing a next generation type medical imaging system using a photon counting technique, we proposed a novel method in which an effective atomic number can be determined. The detailed analysis concerning the vision of clinical application is now in progress.


How do you Determine the Echo Time When Calculation of Quantitative Susceptibility Mapping (QSM)?

Radiological Society of North America (RSNA) 2016

TEACHING POINTS The purpose of this exhibit is to learn that 1. It is important to know dependence of signal loss due to T2* decay, corresponding to echo time (TE) and susceptibility of biomaterial. 2. Magnetic susceptibility have paramagnetic and diamagnetic characterization, i.e., these indicate positive and negative values, respectively. TABLE OF CONTENTS/OUTLINE -Aims The aim of our study is to investigate the difference in magnetic susceptibility for various TEs. -Method On a 3.0 T MR system, we performed a phantom experiment. The phantom consisted of Gd-DTPA and hydroxyapatite samples which were made using three different concentrations of each. In order to investigate the difference in the magnetic susceptibility of each TE, multiple TEs were acquired and several TE datasets were made. Then, we analyzed with each dataset. -Results The TEs = 3.1, 7.5 and 11.9 ms datasets indicated highest positive linearity for the Gd-DTPA samples (slope = 0.244, R2 = 0.998, P = 0.021). Moreover, the TEs = 3.1, 7.5 and 11.9 ms datasets indicated highest negative linearity for the hydroxyapatite samples (slope = -0.001, R2 = 0.997, P = 0.035). -Conclusion QSM makes it possible to accurately calculation of magnetic susceptibility by using the appropriate TE.


Hybrid assessment of gadopentetic acid and bone structure with ultrashort echo time imaging

Purpose To clarify the phase cycles of Gd-DTPA and calcium carbonate (CaCO3), we evaluated the quantitative susceptibility map (QSM) for dual-ultrashort echo time (UTE) imaging in a phantom experiment. Materials and Methods On a 3.0 T MR system, we performed a phantom study using a three-dimensional dual UTE sequence (TE, 32 µs and 3.2 ms). The phantom components were made from different concentrations of a Gd-DTPA solution (0.1, 0.5, and 1 wt%) and CaCO3 sections. The QSM algorithm was applied to the dual (32 µs and 3.2 ms) and single (32 µs) UTE datasets. We then set the region-of-interest for each material section on QSM images, and measured susceptibility values. Furthermore, linear regression analyses were used to determine the significance between Gd-DTPA concentration and susceptibility for each TE dataset. Results The mean susceptibility value of CaCO3 calculated from the dual UTE showed 1.09 ± 0.35 ppm. Additioally, the mean susceptibility values of 0.1, 0.5, and 1.0 wt% Gd-DTPA calculated from the dual UTE were -0.14 ± 0.03, -0.61 ± 0.02, and -1.24 ± 0.03 ppm. Moreover, there was a negative correlation between Gd-DTPA concentration and susceptibility derived from dual UTE (R2 = 0.9995, P = 0.0141). In contrast, there was no correlation between these values derived from single UTE (R2 = 0.00157, P = 0.9747). Conclusion QSM using dual UTE imaging makes it possible to simultaneously evaluate Gd-DTPA and CaCO3, i.e., bone tumor imaging with contrast-enhanced MRI.


Universal calibration curve for a small-type OSL dosimeter to be used for direct dose measurements of direct, scattered and penetrating X-rays in the diagnostic region

Radiological Society of North America (RSNA)

(1)Aims: We hope to find a suitable dosimeter, which can measure incident, scattered and penetrating X-rays. In this study, we propose a new procedure to calibrate the OSL dosimeter. (2)Experiment & results: Initially, we constructed a calibration curve of air-kerma (direct X-rays) with comparison between the OSL dosimeter and an ionization chamber. Second, we evaluated the accuracy of the above calibration curve when the following conditions were applied; 1) entrance-skin dose, and 2) air-kerma of scattered X-rays and 3) penetrating X-rays through a soft-tissue equivalent phantom. We then found that the above calibration curve can be used in all situations if we adopt 15% of uncertainty. Finally, the X-ray spectra related to those conditions were measured, and with the data on basic characteristics of the dosimeter, the result of 15% uncertainty was verified mathematically. (3)Conclusion: With 15% uncertainty, we can use the OSL dosimeter without considerations of energy dependence, angular dependence etc. This study enabled the OSL dosimeter to manage the exposure dose of medical staff, assistants and patients.


Convenient measurement method using small-type OSL dosimeters for evaluation of doses in CT scans: uncertainty evaluation, entrance-skin dose of phantom, and organ dose of cadaver

(1)Aims Because the OSL dosimeter used in this research is small in size, when the dosimeters are attached to the patients, it should be considered that certain dosimeters are directly irradiated by the collimated X-ray beam and others are not. (2)Experiments First, we investigated the precision and accuracy of the OSL dosimeters as functions of ``number of detectors (rows)'' and ``pitch factor'' using a CT scanner. In this experiment, the true entrance skin doses (ESDs) and its distribution of a water phantom was measured with Gafchromic film. (3)Results & Discussion We estimated that OSL dosimeters can measure doses within an uncertainty of 25% for most irradiation conditions. Additionally, we demonstrated the application of dose measurements using the OSL dosimeters; 1) ESDs of a body phantom were measured, and 2) organ doses of a cadaver were directly determined for the first time. These data are valuable for the education of dose reductions. Our method using the OSL dosimeter is convenient, therefore everyone can share our results for improvement of clinical CT examinations.


Simple improvement method of uniformity of MR elastography on liver


Small size OSL dosimeter to measure patient exposure dose in X-ray diagnosis - Evaluation of invisibility -

14th international congress of the international radiation protection association


Comparison with statistical analysis of signal correction in diffusion weighted MR image


Development of leaf electroscope to understand ionization for novice practical training


Compact irradiation system for evaluation of basic characteristics of the nanoDot OSL dosimeter toward direct measurement of exposure dose of patients


Noise estimation for diffusion weighted MR image


Evaluation of energy dependence of nanoDot optically stimulated luminescence (OSL) dosimeter using characteristic X-ray induced by medical X-ray equipment

European Congress of Radiology (General&Voice of EPOS), 2016


Precise determination of the scattered X-ray contamination rate using diagnostic X-ray equipment for the construction of the secondary X-ray field


Fabrication and analysis of phantoms providing the equal-image-density for basic experiment of next-generation-type X-ray diagnosis


Proposal of quantitative identification method of a small-type OSL dosimeter: Verification that the dosimeter is not detected in the medical image


Experimental evaluation of response functions of a CdTe detector in the diagnostic region with the aim of carrying out a basic experiment concerning a next generation photon counting system


Precise measurement of the angular and energy dependences of small-type OSL dosimeter in the diagnostic energy region


A Fundamental Experiment for Novel Material Identification Method Based on a Photon Counting Technique: Using Conventional X-Ray Equipment (PosNo=M3CP-125)

IEEE Nuclear Science Symposium & Medical Imaging Conference


Optimization of imaging parameter in contrast-enhanced three-dimensional T1 weighted MRI with fat saturation for head disease

European Congress of Radiology 2015 (EPOS)


Development of new educational apparatus to visualize scattered X-rays


Dynamic Oxygen-Enhanced MRI of Cerebro-Spinal Fluid: Inversion Recovery Fast Advanced Spin Echo (IR-FASE) Vs. FASE.

Annual Meeting of the European Society for Magnetic Resonance in Medicine and Biology (ESMRM2013)


Comparison between Proton MR spectroscopy and MIB-1 labeling index of brain tumors


Why do we have to calculate T1 when evaluation of carotid plaque?


Hemodynamics Quantitative Analysis of Urinary Bladder Tumor


Why Do We Have to Calculate T1 Value when Evaluation of Urinary Bladder Tumor?


Development numerical phantom of MR signal for multi-component analysis in biological tissues

生体構造解析を目的としたMR信号数値ファントムの開発

第80回日本放射線技術学会総会学術大会

第80回日本放射線技術学会総会学術大会


Clinical study of atherosclerosis using derivation viscosity function

粘稠度導出法を用いたアテローム性動脈硬化症の臨床検討

第80回日本放射線技術学会総会学術大会

第80回日本放射線技術学会総会学術大会

【目的】 拡散係数と粘稠度の関係は線形性を示すことが知られているが，以前に我々が開発した粘稠度算出手法は課題を残した．本研究の目的は，拡散強調画像(DWI)を用いて粘稠度を導出する手法を改良し，アテローム性動脈硬化症のプラークの物性を評価することである． 【方法】 本研究は，3テスラMRI装置を用いて検討を行った．ファントム実験は，濃度の異なるグリセリン水溶液(20–60%)を作成し，恒温水槽内を37 ℃の状態にして粘稠度を計測した．各濃度の水溶液からファントムを作成し，エコープラナー法を用いて DWI を撮像した．撮影パラメータは，繰り返し時間(TR)，10000 ms;エコー時間(TE)，63.5 ms;b値，0–1500 s/mm2 に設定した．DWI の信号値を単一指数関数モデルで曲線近似し，ADC を算出した．実測した水溶液の粘稠度と ADC の関係を直線近似により粘稠度関数を導出した．臨床検討は，頸動脈内膜剥離術(CEA)が施行され，粥腫形成ありと病理診断された頸動脈狭窄症患者(27名:平均年齢74±6.2歳)の DWI を撮像した．撮影パラメータは，TR，3000 ms;TE，52.1 ms;b値，0，250，500 s/mm2に設定した．ファントム実験と同様に，DWI の信号値から算出した ADC 値を粘稠度関数に当てはめ粘稠度を求め可視化した．各症例群間の粘稠度を比較した． 【結果】 グリセリン水溶液の粘稠度は，濃度により粘稠度が高値になった．ファントムのDw-MRIから算出した粘稠度の算出式は，y=-0.79x+2.94 となった．ここで，y は粘稠度，x はADCとする．臨床検討において，全症例の平均 ADC 値は，1.72 ± 0.489 [× 10-3 mm2/s]，平均粘稠度値は 0.003 ± 0.386 [µPa·s] となった．症候性および出血の有無で粘稠度を比較すると有意な差があった(P < 0.05および < 0.01)．


CEST イメージングの高分子濃度と pH 緩衝液依存性の検討

CEST イメージングの高分子濃度と pH 緩衝液依存性の検討

第51回日本放射線技術学会秋季学術大会

第51回日本放射線技術学会秋季学術大会


4D-flow MRIから導出した流体パラメータと頸動脈狭窄率の関係

4D-flow MRIから導出した流体パラメータと頸動脈狭窄率の関係

第51回日本放射線技術学会秋季学術大会

第51回日本放射線技術学会秋季学術大会


AcidoCEST contrast media exhibiting pH dependence on a 3T clinical MRI system


アテローム性動脈硬化症におけるプラーク性状評価のための粘稠度MRI

アテローム性動脈硬化症におけるプラーク性状評価のための粘稠度MRI

第 79 回日本放射線技術学会総会学術大会

第 79 回日本放射線技術学会総会学術大会


第 79 回日本放射線技術学会総会学術大会

第 79 回日本放射線技術学会総会学術大会


アテローム性動脈硬化症におけるプラーク形成の潜在的危険因子の評価

アテローム性動脈硬化症におけるプラーク形成の潜在的危険因子の評価

第50回日本放射線技術学会秋季学術大会

第50回日本放射線技術学会秋季学術大会


第50回日本放射線技術学会秋季学術大会

第50回日本放射線技術学会秋季学術大会


Quantitative parameter mapping of brain tumor extracellular pH for therapeutic efficacy


Development of a neural network based skull stripping algorithm for quantitative parameter mapping both before and after injection of contrast media


EPI-589の筋萎縮性側索硬化症を対象とした探索的医師主導試験(EPIC-ALS)

第63回日本神経学会学術大会

第63回日本神経学会学術大会


第12回 日本安定同位体 生体ガス医学応用学会

第12回 日本安定同位体 生体ガス医学応用学会


ディスポ型自作直腸線量計を用いた子宮頸がん治療における線量の実測

ディスポ型自作直腸線量計を用いた子宮頸がん治療における線量の実測

第3回日本放射線安全管理学会・日本保健物理学会合同大会

第3回日本放射線安全管理学会・日本保健物理学会合同大会


CEST MRIを用いた頚動脈プラーク診断 Chemical exchange saturation transfer MRI for carotid plaque imaging


A pilot study of extracellular pH measurement using iopamidol acido-chemical exchange transfer imaging on a 3T MRI


VFA法における多変量正規分布の確率密度関数を用いたB1補正手法の提案

VFA法における多変量正規分布の確率密度関数を用いたB1補正手法の提案

第49回日本磁気共鳴医学会大会

第49回日本磁気共鳴医学会大会


白質領域に対する非剛体処理に伴う数値解析の影響

白質領域に対する非剛体処理に伴う数値解析の影響

第49回日本磁気共鳴医学会大会

第49回日本磁気共鳴医学会大会


Myelin Water Fraction(MWF)におけるT2* cut-off値の検討

第49回日本磁気共鳴医学会大会

第49回日本磁気共鳴医学会大会


蒸し大豆食品の継続摂取が運動不足の健常人の筋量や筋力に及ぼす影響

蒸し大豆食品の継続摂取が運動不足の健常人の筋量や筋力に及ぼす影響

第75回日本栄養・食糧学会大会

第75回日本栄養・食糧学会大会


腫瘍悪性度の定量に向けた造影剤濃度，緩和能，細胞外pHの同時算出手法 の開発

腫瘍悪性度の定量に向けた造影剤濃度，緩和能，細胞外pHの同時算出手法 の開発

日本分子イメージング学会

日本分子イメージング学会


Estimation of CT X-ray spectrum from reconstructed images using a deep neural network

第121回日本医学物理学会

第121回日本医学物理学会


Automatic detection of extracellular pH change in brain tissue using deep learning based semantic segmentation

Japanese Journal of Radiological Technology


第77回日本放射線技術学会総会学術大会

第77回日本放射線技術学会総会学術大会


可変フリップアングル法を用いたT1値算出における線形近似と非線形近似の比較

可変フリップアングル法を用いたT1値算出における線形近似と非線形近似の比較

第77回日本放射線技術学会総会学術大会

第77回日本放射線技術学会総会学術大会


Quantitative Parameter Mapping(QPM) を用いたコンポーネント間スピン交換定数の導出

第48回日本磁気共鳴医学会大会Web開催

第48回日本磁気共鳴医学会大会Web開催


Which contrast agent is more sensitive to extracellular pH change on brain tumor ?


Comparison of functional connectivity using resting state functional MRI in movement disorders.

運動異常症の安静時 fMRIにおける脳機能ネットワークの検討

第48回日本磁気共鳴医学会大会Web開催

第48回日本磁気共鳴医学会大会Web開催


Spatially smoothing processing of quantitative values in voxel-based morphometry (VBM) analysis

第76回日本放射線技術学会総会学術大会WEB開催

第76回日本放射線技術学会総会学術大会WEB開催


Dual-type active dosimeter having a novel algorithm to identify incident angles of X-rays

第76回日本放射線技術学会総会学術大会WEB開催

第76回日本放射線技術学会総会学術大会WEB開催


Estimation of X-ray energy spectrum for CT scanner from percentage depth dose measurement

第119回⽇本医学物理学会学術⼤会WEB開催

第119回⽇本医学物理学会学術⼤会WEB開催


Simultaneous Quantitative Calculation of Concentration of Contrast Agent, Relaxivity, and Extracellular pH Map


Phantom study using novel shaped OSL dosimeters having smaller angular dependence toward actual dose measurement during clinical X-ray examination

第76回日本放射線技術学会総会学術大会

第76回日本放射線技術学会総会学術大会


頸動脈狭窄の定量評価を目的とした4D-flow流体解析

頸動脈狭窄の定量評価を目的とした4D-flow流体解析


Calculation of extracellular pH using quantitative parameter mapping


Comparison of estimation parameters of relaxation rate and susceptibility for myelin content with quantitative parameter mapping

To evaluate myelin content derived from QPM, we compared relaxation rate and susceptibility using simultaneously acquired imaging datasets. The relaxation rate and susceptibility derived from QPM enabled us to simultaneously and specifically evaluate structural changes and brain iron homeostasis.


医療用連続X線を用いたフォトンカウンティング検出器による実効原子番号画像

医療用連続X線を用いたフォトンカウンティング検出器による実効原子番号画像

第2回量子線イメージング研究会

第2回量子線イメージング研究会


子宮頸癌RALSにおける自作直腸線量計を用いた実臨床データとその分析

子宮頸癌RALSにおける自作直腸線量計を用いた実臨床データとその分析

日本放射線腫瘍学会小線源治療部会第21回学術大会

日本放射線腫瘍学会小線源治療部会第21回学術大会


子宮頸癌の腔内照射における直腸線量実測に向けたディスポーザブル型直腸線量計の開発

日本放射線腫瘍学会小線源治療部会第21回学術大会

日本放射線腫瘍学会小線源治療部会第21回学術大会


第75回日本放射線技術学会総会学術大会

第75回日本放射線技術学会総会学術大会


Actual Dose Measurement of Assistants while Positioning Patients during Pediatric X-ray Examination Using a Small-type Optically Stimulated Luminescence Dosimeter

第75回放射線技術学会総会学術大会

第75回放射線技術学会総会学術大会


An experiment toward proposing a way to reduce eye lens exposure dose using small-type OSL dosimeter during neonatal cardiac CT examination

第75回放射線技術学会総会学術大会

第75回放射線技術学会総会学術大会


Trial production and evaluation of characteristics of novel-shaped optically stimulated luminescence dosimeter having lower angular dependence

第75回放射線技術学会総会学術大会

第75回放射線技術学会総会学術大会


Calculation of molar relaxivity and concentration map of Gd-DTPA map using quantitative parameter map before and after injection for brain metastasis


小型OSL線量計の診断用X線に対する応答のエネルギー依存性の精密評価

小型OSL線量計の診断用X線に対する応答のエネルギー依存性の精密評価

日本放射線安全管理学会 第17回 学術大会

日本放射線安全管理学会 第17回 学術大会


Comparison of curve fitting models of intravoxel incoherent motion analysis for shear stiffness

第46回日本放射線技術学会秋季学術大会

第46回日本放射線技術学会秋季学術大会

【目的】 拡散強調画像(DWI)から生体の硬さを推定するために，intravoxel incohernet motion(IVIM)手法を用いた3つの曲線解析手法を評価した． 【方法】 1.5テスラMRI装置(GE社製)にて，ファントム実験を行なった．ファントムは，異なる濃度のagar(0.75，1.0，1.5，2.0wt%)をアクリルボックスの中に配列し，1 wt%のagarで満たした．DWIはsingle shot echo planner imagingを用いて，複数のb値(0，20，50，100，200，400，600，800，1000，1200，1500 s/mm2)に設定し撮像した．MR elastography(MRE)はMR touchを用いて，ドライバー周波数120 Hzに設定し撮像した．DWIは，関心領域を各サンプル内に設定し，各b値の信号値を取得した後，mono-exponential, bi-exponential, stretched-exponentialモデルを用いて曲線解析を行い，各種パラメータ(ADC，f，D*，D，DDC，α)を算出した．このとき，MREのせん弾性率とDWIから取得した各種パラメータを比較した． 【結果】 MREから算出した0.75，1.0，1.5，2.0 wt%ファントムのせん弾性率は，6.5，10.6，30.8，40.0 kPaであった．bi-exponentialモデルから算出したD*は，MREのせん弾性率と負の相関を示した(r = 0.57)．stretched-exponentialモデルから算出したα値は，MREのせん弾性率と負の相関を示した(r = 0.80)． 【結論】 stretched exponential モデルを用いた拡散解析は，生体内の組織の硬さを測定するのに有用な手法である．


Quantitative analysis of local-offset frequency in chemical exchange saturation transfer (CEST) imaging

CESTイメージングにおける局所オフセット周波数の定量評価法の開発

第46回日本放射線技術学会秋季学術大会

第46回日本放射線技術学会秋季学術大会

【目的】 この研究の目的は，CEST画像における局所のオフセット周波数を定量的に評価することである． 【方法】 3テスラMRI装置(GE社製)にて，CESTイメージングを用いてファントム実験を行った．アクリルボックスの底にプラスチックを格子状に配列し，アルブミン水溶液(45 g/L)を封入したファントムを作成した．CESTイメージングの撮像シーケンスはsingle shot fast spin-echo法を使用し，オフセット周波数帯域，±7 ppm(Δ0.5 ppm); 最大B1，5.16 μTに設定した．オフセット周波数補正ありと無しのデータセットを取得した．MTパルスを付加しない画像(S0)と，各オフセット周波数(1，2，3.5 ppm)の画像に対して，ファントムの中心部および辺縁部の格子に関心領域を設定し，信号値を測定した．各関心領域について，S0画像の信号値で正規化し比較した． 【結果】 中心部と左右辺縁部では，オフセット周波数が高くなるほど信号値は基準値に近づいた．上下辺縁部では，オフセット周波数補正なしの場合に周波数2 ppmで最も基準値との差が大きくなった．各オフセット周波数での全領域で，オフセット周波数補正ありの場合は補正なしと比較して，全て基準値に近づいた． 【結論】 我々が提案した解析手法は，CEST後処理の評価指標として系統誤差を特定するのに有用である．


Quantitative Parameter Mapping(QPM)を用いたミエリン描出能の検討: ポリエチレングリコールを用いた ファントム実験

第46回日本放射線技術学会秋季学術大会

第46回日本放射線技術学会秋季学術大会

【目的】 quantitative parameter mapping(QPM)-MRIは，一度の撮像で定量値マップや任意のコントラスト画像を計算できる手法である．本研究は，myelinと分子量の近いポリエチレングリコール(PEG)と水の含有量の違いによる信号変化を定量するために，QPM-MRIを用いて検討した. 【方法】 3テスラMRI装置(日立社製)にて，3D-partially radio frequency-spoiled steady state gradient-echo法を用いてファントム実験を行った． PEG(平均分子量，420)と水の含有量が異なる水溶液(0-50 wt%)サンプルを配置したファントムを作成した．QPM-MRIの撮像条件は，TE，4.6-22.1 ms(∆TE，3.5 ms);TR，20，40 ms;フリップ角，10，25，35，40 deg.;RF phases，2，5，8，20，22とした．QPMデータセット撮像後，T1，T2*，PDの定量値マップを作成した．定量値画像の各サンプル内に関心領域を設定し，定量値を比較した． 【結果】 PEG溶液(0，10，20，30，40，50 wt%)の測定した定量値は，T1，510 ± 25，342 ± 19，229 ± 13，152 ± 21，130 ± 17，118 ± 14 ms;T2*，338 ± 22，300 ± 22，275 ± 39，214 ± 36，179 ± 23，189 ± 28 ms;PD，218 ± 15，142 ± 6，99 ± 6，84 ± 10，71 ± 4，77 ± 12であった．PEG濃度が高くなるとT1，T2*，PDの減少する傾向を示した． 【結論】 分子量の近いmyelinでも同様の傾向を示すことが予想されるので，水含有量の変化がmyelinの信号変化に影響を及ぼす可能性があることを実験的に示すことができた．QPM-MRIは，加齢や疾患によるmyelin体積減少の評価に応用できる可能性がある．


角度依存性の少ない小型OSL線量計の開発に向けた一考察

角度依存性の少ない小型OSL線量計の開発に向けた一考察

第46回日本放射線技術学会秋季学術大会

第46回日本放射線技術学会秋季学術大会


Evaluating reproducibility and gender differences of cerebral perfusion in healthy volunteers observed by multi-delay post labeling delay time ASL Multi-PLD

ASL法により観察された健常ボランティアにおける脳灌流の再現性と性差の評価

第46回日本磁気共鳴学会大会

第46回日本磁気共鳴学会大会


Determination of the thresholding values for virtual MR elastography


Construction of voxel-based morphometry of R1 and R2* derived from quantitative parameter mapping

第46回日本磁気共鳴医学会大会

第46回日本磁気共鳴医学会大会

The aim of our study is to construct of VBM using relaxation rate derived from QPM magnetic resonance imaging, i.e., novel Synthetic MRI. VBM of relaxation rates derived from QPM enable to made high quality and accuracy region matching for quantitative analysis of hemodynamic in brain.


Chemical exchange saturation transfer imaging for brain tumors

日本分子イメージング学会

日本分子イメージング学会


小型OSL線量計を用いたIVR術者水晶体被ばく線量測定に向けた線量値の信頼性の検証

日本保健物理学会第51回研究発表会

日本保健物理学会第51回研究発表会


Rectum Dose Measurements Using Novel Dosimetric System During High-Dose-Rate 192Ir Brachytherapy Treatment of Cervical Cancer

第74回日本放射線技術学会総会学術大会

第74回日本放射線技術学会総会学術大会


Proposal of Accurate Calibration for Measuring Eye Lens Dose of the Operator during Transfemoral Cardiac Catheterization with Fluoroscopic System Using an OSL dosimeter

第74回日本放射線技術学会総会学術大会

第74回日本放射線技術学会総会学術大会


Virtual MR elastography using IVIM stretched model

Japanese Journal of Radiological Technology


Virtual-magnetic resonance elastography (MRE) using intravoxel incoherent motion (IVIM) stretched model

第129回日本医学放射線学会中国・四国地方会

第129回日本医学放射線学会中国・四国地方会


小型OSL線量計を用いた超精密測定に向けた固有効率の決定

小型OSL線量計を用いた超精密測定に向けた固有効率の決定

第45回日本放射線技術学会秋季学術大会

第45回日本放射線技術学会秋季学術大会


第45回日本放射線技術学会秋季学術大会

第45回日本放射線技術学会秋季学術大会


lipid-rich-core プラークの物性に着目したマルチコンポーネント解析MRI

第45回日本放射線技術学会秋季学術大会

第45回日本放射線技術学会秋季学術大会


Off-set frequency correction in brain for quantitative susceptibility mapping


定量的磁化率マッピング(QSM)のためのオフセット周波数補正法の提案

定量的磁化率マッピング(QSM)のためのオフセット周波数補正法の提案

Society of Advanced Medical Imaging (SAMI) 2017


Simulation study for effective reduction procedure of scattered Xrays toward high accuracy material identification based on photon counting technique

第113回日本医学物理学会学術大会

第113回日本医学物理学会学術大会


First observation of dose exposure to assistants during pediatric X-ray procedure by means of a small-type OSL dosimeter

第73回日本放射線技術学会総会学術大会

第73回日本放射線技術学会総会学術大会


Visualization of entrance surface dose during CT examination using small-type OSL dosimeter

第73回日本放射線技術学会総会学術大会

第73回日本放射線技術学会総会学術大会


Evaluation of Mechanical Waves of MR Elastography

[Purpose] The purpose of our study is to assess the mechanical waves that occur during MR elastography using circular statistical analysis. [Methods] On a 1.5 T MR system, we performed a phantom experiment. The phantom was composed of two blocks of agar at a concentration of 0.75 and 1.0 wt%. All imaging data were acquired using gradient echo (GRE) specialized for MRE. The imaging parameters were TE, 19.4 ms; repetition time, 50 ms; field of view, 420 × 420 mm; slice thickness, 80 mm; bandwidth 32.3 kHz; motion-encoding gradient frequency, 60 Hz; driver amplitude, 70. After acquiring the dataset, MRE images were calculated from a multi scale direct inversion algorithm. Additionally, we measured mean wavelength values of offset phase images obtained during MRE using circular statistical analysis. [Results] Mean shear stiffness values at 0.75 wt% and 1.0 wt% agar concentrations were 1.95 ± 0.35 and 6.45 ± 0.97 kPa, respectively. Mean wavelength values for each agar concentration at three column line profile settings (from left to right side) were 1000 and 1920 mm for the 20th column, 760 and 1880 mm for the 90th column, and 160 and 1960 mm for the 160th column, respectively. [Conclusion] Circular statistical analysis makes it possible to obtain and evaluate more detailed information during MRE.


小型OSL線量計を用いた小児X線撮影における介助者被ばく実測に向けた現状と課題

小型OSL線量計を用いた小児X線撮影における介助者被ばく実測に向けた現状と課題

医用画像情報学会(MII)平成28年度秋季(第176回)大会

医用画像情報学会(MII)平成28年度秋季(第176回)大会


How to make a phantom for quantitative susceptibility mapping.

第44回日本放射線技術学会秋季学術大会

第44回日本放射線技術学会秋季学術大会


MTパルスを付加したT1値の算出

MTパルスを付加したT1値の算出

第44回日本放射線技術学会秋季学術大会

第44回日本放射線技術学会秋季学術大会


第44回日本放射線技術学会秋季学術大会

第44回日本放射線技術学会秋季学術大会


Availability to measure the entrance skin dose using the small-type OSL dosimeter during the CT scanning

小型OSL線量計を用いたCTスキャンにおける入射皮膚線量実測の有用性

第44回日本放射線技術学会秋季学術大会

第44回日本放射線技術学会秋季学術大会


Study to expand the dose calibration curve of small-type OSL dosimeter toward scattered and penetrating X-rays for management of radiation exposure in the diagnostic region

第44回日本放射線技術学会秋季学術大会

第44回日本放射線技術学会秋季学術大会


Evaluation of angular dependence of the small type OSL dosimeter for gamma rays of 137Cs and 60Co using simulation code EGS5

シミュレーションコードEGS5を用いた137Csと60Coのγ線に対する小型OSL線量計の角度依存性の評価

第44回日本放射線技術学会秋季学術大会

第44回日本放射線技術学会秋季学術大会

【目的】 被ばく線量を測定する際，線量計の装着部位，光子の入射角は臨床条件によって変化するため，角度依存性を評価することは重要になる．本研究ではnanoDotの利用範囲を高エネルギー領域に拡張するために，137Csと60Coの 線に対する角度依存性をモンテカルロシミュレーションで評価した．効率よく計算を行うために，電子平衡を考慮した独自の小さい照射体系を構築した． 【方法】 モンテカルロシミュレーションコード(EGS5)を用いた．小さい領域で電子平衡を達成させるために，nanoDotの周りに5 mmの厚みを有する球形のアクリルをビルドアップ物質として配置した照射体系を作成した．nanoDotの組成や構造はすでに報告されている論文のデータを参考にした．137Csと60Coの 線をそれぞれnanoDotに対し0°∼360°の範囲で15°間隔で照射し，線量計に付与された総エネルギーを計算した．得られた角度依存性のデータは0°方向で規格化し，他の角度と比較評価した．照射野はアクリル球の直径(2.42 cm)に設定した．また統計誤差は1%未満になるように粒子数を4×109に設定した． 【結果】 角度依存性のデータは90°と270°方向を除いて0°方向とよく一致しており，この結果はすでに報告されている診断領域のデータと同様の傾向を示していた．90°と270°方向のデータに着目したとき，診断領域では0°方向と比較して値が30%低下したのに対し，137Csと60Co では約5%低下した値が得られた． 【まとめ】 被ばく線量測定において，線量計の角度依存性やエネルギー依存性は評価されなければならない．本研究では，137Csと60Coに対する被ばく線量測定においてnanoDotの角度依存性の影響は約5%の確度で保証されていることを示した．nanoDotは核医学や治療領域で臨床利用が期待できる線量計である．


Evaluation of lower limit of measured value by means of small type OSL dosimeter for diagnostic X-rays

診断用X線に対する小型OSL線量計の測定下限値の評価

第44回日本放射線技術学会秋季学術大会

第44回日本放射線技術学会秋季学術大会

【目的】 小児のX線撮影においては，散乱X線によって介助者が被ばくをする．我々は，小型OSL線量計(nanoDot)を用いて低線量域の散乱X線による被ばくを測定することを計画している．本研究の目的は，線量測定システムの線量下限値を評価することである． 【方法】 実験は，診断用X線装置を用いて行った．まず，十分にアニーリングしたnanoDotを準備し，バックグラウンドを読み取った．次に，線量校正曲線を作成するために，自由空気条件および軟部組織等価ファントム上でnanoDotを照射し，対応する計数値と電離箱線量計の測定値を比べた．照射条件は，管電圧55, 83, 108 [kV]，管電流時間積0.5, 1, 2, 4, 7, 10, 20, 40, 100, 200 [mAs]，X線焦点-線量計距離150, 250 [cm]とした．各測定点での誤差評価を行い，線量校正曲線と矛盾がないかどうかを評価した．最後に，測定点での誤差が100%となる線量下限値を求めた． 【結果】 基準の校正曲線を83 [kV]の自由空気条件で取得し，異なる実験条件によって取得した実験データを矛盾なく説明できる系統誤差を評価したところ，±15%となることがわかった．線量計のバックグラウンドと計数値の統計誤差および系統誤差を用いて，誤差の伝播式から測定下限値を見積もったところ，5.0×10-4 [mGy]となった． 【まとめ】 我々は，小型OSL線量計の測定システムの線量下限値を評価するために，校正曲線を作成した．測定誤差が100%となるnanoDotの線量下限値を求めたところ，5.0×10-4 [mGy]となった．今後，小児X線撮影における介助者の散乱X線被ばくを実測する予定である．


Basic study for internal dose evaluation of CT examination by means of small-type OSL dosimeter

第44回日本放射線技術学会秋季学術大会

第44回日本放射線技術学会秋季学術大会

【目的】 我々はCT検査の被曝線量の管理に向けて，小型OSL線量計を用いた基礎研究を行っている．入射皮膚表面ではPitch Factor (PF)ごとに線量分布にばらつきが生じるが，体内では散乱X線が発生することで，臓器に対する吸収線量はPFによる影響が少なくなることが想定される．本研究では，体内における吸収線量評価に着目して基礎実験を行った． 【方法】 東芝製の320列CT装置を使用し，アクリル板(計10枚)の中心部分に小型OSL線量計を埋め込めるように加工した自作の腹部ファントムを用いた実験を行った．線量計は体軸方向に10個並べ1セットとし，ファントム表面から1 cmごとに10 cmの深さまでのデータを取得した．照射条件は64列，管電圧120 kV, 管電流600 mA，PFは1.484とした．また，各照射方向からの寄与を評価するために，X線管を45度ごとに固定し，全ての線量計が照射される条件下での実験も行った． 【結果】 PF1.484のヘリカルスキャンによる体軸方向の10個の線量の測定値のばらつきは，表面位置では20∼30%程度であり，中心(10 cm位置)に近づくにつれて数%まで減少した．この変動の原因は，OSL線量計に直接X線が照射されているかどうかの有無によって生じており，この揺らぎをOSL線量計で測定を行ったときの誤差と定義した．全ての線量計が照射されている条件下での0∼360度までの寄与を積分した値とヘリカルスキャンの実験結果との比較をおこない，上述の誤差に矛盾が無いことを確認した． 【まとめ】 小型OSL線量計を自作したファントムに埋め込み，CT検査における体内の吸収線量の誤差を評価するための基礎実験を行った．CT検査における吸収線量の変動は深部にいくにつれて散乱線の影響で均され，数%程度であることが明らかになった．今後，異なる条件化での実験を重ね，CT検査における体内の吸収線量評価に向けた知見を得たいと考えている．


Noise estimation of phantom phase image in ultra-short echo time imaging

Purpose: To estimate accurately noise of phase rotation, we evaluated a signal phase of ultra-short echo time (UTE) imaging. Materials and Methods: On 3.0T MR system, we performed a phantom experiment using a dual-echo UTE imaging. The imaging parameters were TE, 0.032 ms (first-echo) and 3.3 ms (second-echo); matrix sizes, 256 ×256; slice, 16. The phantom consisted of Gd-DTPA and hydroxyapatite samples, which were made using three different concentrations of each material; Gd-DTPA, 0.5, 1.0, and 2.5 mmol/L; hydroxyapatite, 100, 200, and 350 mg/mL. Then, region of interest analysis was performed on two phase images, e.g., first-echo, and second-echo phase images. Results: The mean first-echo phase values on each Gd-DTPA (0.5, 1.0, and 2.5 mmol/L) and hydroxyapatite (100, 200, and 350 mg/mL) sample were 32.4 ± 0.04, 32.2 ± 0.04, 32.0 ±0.01, 32.4 ± 0.02, 43.6 ± 0.03, and 60.0 ± 0.01 degree, respectively. The mean second-echo phase values on each Gd-DTPA (0.5, 1.0, and 2.5 mmol/L) and hydroxyapatite (100, 200, and 350 mg/mL) sample were 39.1 ± 0.04, 36.0 ± 0.04, 35.5 ± 0.05, 137.9 ± 0.06, 83.4 ± 0.06, and 88.02 ± 0.06 degree, respectively. The mean background phase value first-echo, and second-echo were 33.5 ± 0.11 and 87.1 ± 0.12 degree, respectively. Discussion & Conclusion: The phase rotation of hydroxyapatite occurred difference of phase value in each sample, i.e., this leads good contrast in UTE image. In contrast, the phase rotation of Gd-DTPA at TE 0.032 ms is small enough to estimate noise because the Gd-DTPA phase values were almost equal. Thus, UTE imaging may lead to noise derived from a phase rotation. Noise estimation using UTE imaging may render it possible to obtain more detailed information of paramagnetic materials, e.g., Gd-DTPA.


診断領域X線による介助者被ばくの実測に向けた小型OSL線量計の読取装置の改良

診断領域X線による介助者被ばくの実測に向けた小型OSL線量計の読取装置の改良

医用画像情報学会平成28年度年次(第175回)大会

医用画像情報学会平成28年度年次(第175回)大会


Simulation of blood signal in non-contrast-enhanced MR angiography with three-dimension fast spin-echo sequence

三次元高速スピンエコー法を用いたMR angiographyにおける血液信号シミュレーション

第72回日本放射線技術学会総会学術大会

第72回日本放射線技術学会総会学術大会


Dependence on echo time for quantitative susceptibility mapping (QSM) MRI.


Normalization of time-dependent signal change of MRI


Proposal of a New Analytic Method for the Determination of Both Atomic Number and Sample Thickness Based on a Photon Counting Technique Using Diagnostic X-rays

第72回日本放射線技術学会学術大会_Next Generation Session(学生選抜セッション)

[Purpose] Currently researchers are focusing attention on a photon counting system to be used for next generation X-ray diagnosis. Although there are many research articles concerning the development of a detector, few studies have been published about analytic methodologies. Currently, X-ray procedures are widely applied to medical examinations; therefore a proposal of a new technique has a spillover effect on the development of diagnosis. In this study, we proposed a new analytic method in which both the effective atomic number and thickness of the sample can be derived. [Methods] X-ray spectra are measured after penetrating the substances. Then, concerned the different energies (E1, E2), μ1t and μ2t were numerically determined and the ``normalized liner attenuation factor'' was calculated by means of μ1t and μ2t. Here, to derive effective atomic number of the sample, we proposed a calibration curve between normalized linear attenuation factor and atomic number Z based on a well-known database. Moreover, to derive the thickness of the sample another calibration curve determined Z and mass attenuation factor was derived. Using the determined mass attenuation factor, thickness of the substance can be analyzed. Experiments were carried out in which X-ray spectra after penetrating soft-tissue-equivalent phantoms (Kyoto kagaku, XUR) having thicknesses of 20-160 mm and bone-equivalent phantoms (Kyoto kagaku, BE-H) having thicknesses of 4.1-41.5 mm were measured with a CdTe detector (EMF Japan, EMF123). The thicknesses of these phantoms were optimized so as to obtain equal-image densities when a traditional X-ray diagnosis system was used to take the X-ray image. [Results] Our method can differentiate two-types of phantoms. The determined atomic numbers were consistent with theoretical values of 11.7 (bone) and 7.0 (soft-tissue). In addition, the derived thicknesses were also in good agreement with the real thicknesses in the dimension of ρt [g/cm2]. [Conclusion] We proposed a new analytic method to derive effective atomic number and thickness of the sample.


Basic study for separation measurement between 137Cs and 90Sr using small type OSL dosimeter

小型OSL線量計を用いた137Csと90Srの分離測定に関する基礎的研究

第72回日本放射線技術学会学術大会

第72回日本放射線技術学会学術大会

[目的] 福島原発で飛散した放射性核種において，長期間にわたり線量測定の対象となるものには物理学的半減期の長い137Csと90Srが考えられる．137Csはγ線を放出するため，Ge半導体検出器により放射能を測定することができる．90Srは90Yと永続平衡状態で存在するβ線放出核種で，主に液体シンチレータなどで測定される．137Csと90Srが混合する放射線場において一般の線量計を用いて簡易的に放射能を分離測定することができれば，安全管理に役立つ．今回我々は，厚みの薄い小型OSL線量計(nanoDot)に着目し，137Csと90Srが混合する線源を想定して，それぞれの核種の放射能を推定するための基礎検討を行った． [方法] モンテカルロシミュレーションコードEGS5を用いて，nanoDotと1 mmの鉛フィルターで覆ったnanoDotを作成した．137Csと90Srから放出されるγ線とフェルミ関数を用いた理論式より計算したβ線スペクトルを順次nanoDotに照射し，応答関数を計算した．また，137Csのγ線放出と競合過程にある内部転換電子の応答関数も計算した．nanoDotに付与される線量は放射能と応答関数の積の総和である．フィルターありとなしで得られた線量に対し，137Csと90Srのそれぞれの放射能を未知数とした連立方程式を定義した．最後に，137Csと90Srを適当な割合で混合させた4π線源を作成し，nanoDotに照射し，連立方程式を用いて放射能を分離測定できるかを検討した． [結果および考察] 前述の連立方程式を解くことで，nanoDotを用いて137Csと90Srが混合する線源からそれぞれの核種の放射能を算出することができた．nanoDotと鉛フィルターを併用することで，β線放出核種とγ線放出核種が混合する放射線場においても各々の放射能を推定できる可能性が示唆された．


Phantom Study for Entrance-Skin Doses Measurement in the Diagnostic X-ray Region using a Small-type OSL dosimeter Comparison of the doses measured with other detectors-

第72回日本放射線技術学会学術大会

第72回日本放射線技術学会学術大会

[Aims] Recently, a small-type optically stimulated luminescence(OSL) dosimeter, named nanoDot, was developed by Landauer Inc. It is expected to be a convenient detector to measure the entrance-skin dose(ESD) because this dosimeter does not interfere with the medical image. Up to now, we have reported on a calibration curve for the ESD measurement and image evaluation. From our previous research, it was clarified that the nanoDot OSL dosimeter can directly measure the ESD based on the calibration curve without considering BSF. For the clinical application of the nanoDot OSL dosimeter, it is important to verify the adequacy of our measurement method. In this presentation, we compared and evaluated the ESD measured with the nanoDot OSL dosimeter to that of other detectors. [Materials and Methods] X-rays were generated by diagnostic X-ray equipment. We used a soft-tissue equivalent phantom instead of a human body, and the nanoDot OSL dosimeter was placed in front of the phantom. X-rays were irradiated under general clinical conditions and a measured count was derived using a reading device. The count was converted to the ESD using our calibration curve. In the measurements using an ionization chamber and a thermo-luminescence dosimeter(TLD), we used standard methodologies. Additionally, the guidance level suggested in the IAEA was used as a reference. [Results and conclusion] In the present study, the ESDs for various places on the human bodies were measured. For example, for the chest radiography, the ESD measured with the nanoDot OSL dosimeter was 0.24 [mGy]. Here, the guidance level found in the IAEA is 0.4 [mGy], and the ESDs measured with the ionization chamber and TLD were 0.26 and 0.27 [mGy], respectively. Our results were consistent with those of other detectors. In conclusion, it was found that the nanoDot OSL dosimeter is a convenient detector to measure the ESD without interfering with medical image.


Evaluation for detection efficiency of small type OSL dosimeter for the nuclear medicine region using EGS5

EGS5を用いた核医学検査領域における小型OSL線量計の検出効率の評価

第72回日本放射線技術学会学術大会

第72回日本放射線技術学会学術大会

[目的] 近年，小型OSL線量計(nanoDot) (1cm(縦)×1cm(横)×0.2cm(厚さ))を用いた被ばく線量の実測に向けた研究が盛んにおこなわれている．我々は診断領域におけるnanoDot線量計の角度依存性およびエネルギー依存性を評価し，本学会で報告してきた．一方で，核医学検査領域などの高エネルギー光子線を対象にした場合，発生する二次電子の飛程が長くなるため，二次電子平衡を考慮しなければならない．我々は前年の秋季学術大会において，電子平衡を成立させるための効率的な照射体系を提案した．本研究では提案体系をnanoDotに適用し，100-1500 keVにおけるnanoDotの検出効率のエネルギー依存性を評価した． [方法] モンテカルロシミュレーションコードEGS5を用いて，nanoDotの全面をファントムで覆う体系を作成した．ファントム厚と照射野の大きさはファントム中で発生する二次電子の最大飛程を含むように決定した．照射粒子には100-1500 keVの単色光子を用いた．nanoDotに入射する光子フルエンスと空気の質量吸収係数から入射空気カーマ(Kcol)を算出し，吸収線量(D)との比(D/Kcol)を検出効率とした．また提案体系の有用性を示すために，nanoDotのみで構成される照射体系でのシミュレーションを行い，提案体系と同様の解析を行った． [結果および考察] 提案体系を用いた場合，200-1500 keVの範囲でD/Kcol は一定の値を示した．一方で，nanoDotのみを配置した場合，100-400 keVの範囲で提案体系と矛盾無い結果が得られたが，500 keV以上でD/Kcolが系統的に低下した．この結果は，提案体系が二次電子平衡を考慮した有効な検出効率の評価手法であることを示している．


Development of leaf electroscope toward understanding ionization for beginners

初学者の電離作用の理解に向けた箔検電器の開発

第72回日本放射線技術学会学術大会

第72回日本放射線技術学会学術大会

[目的] 放射線と物質との相互作用を理解することは初学者にとって重要である．診療放射線技師の養成校で使用される教科書では放射線の電離作用について冒頭に述べられているが，光電効果やコンプトン散乱などの知識を習得していない初学者にとってこの現象を理解することは難しい．本研究の目的はX線の電離作用を可視化する箔検電器を製作し，X線の物理的特性の理解に向けた初学者実習を提案することである． [方法] 製作した箔検電器はX線の照射部分とその電離作用を検出できる箔の存在する部分で構成されている．これらの空間は自作のアクリルおよび金属メッシュのセパレータで仕切ることができる．さらに真空ポンプを用いて真空状態を生成する機能を付加した．あらかじめ箔検電器に正電荷を帯電させ，箔の開いた状態を生成した．X線の照射を行い，これらの付加機能を用いて電離作用を確認した． [結果および考察] セパレータを設置しないとき箔は閉じた．これはX線を照射することによって生じた電子が箔の電荷に結合する物理的現象を示している．アクリルおよび金属メッシュのセパレータを設置したとき箔は開いた状態を保った．アクリルのセパレータは電離空間と箔の存在する空間を隔てる働きをしており，金属メッシュのセパレータは箔の電場を遮断する働きをしていることを示している．さらに真空ポンプを使用したとき，箔は開いた状態を維持した．これは真空状態では電子の生成が不十分であることを示している． [結論] セパレータと真空状態を生成する機能を有する箔検電器を製作した．この装置により簡便にX線の電離作用を理解することができ，初学者に対して教育効果を発揮することが期待できる．


Fabrication of the equal-image-density materials for basic experiment of next-generation-type X-ray diagnosis system

第72回日本放射線技術学会学術大会

第72回日本放射線技術学会学術大会

[Purpose] X-ray equipment is widely used for diagnosis in the medical field. Using a CR (computed radiography) system, signal (contrast) of the image is determined by the products of the energy and quantity of X-rays. Therefore, when the products of linear attenuation coefficient and thickness are similar among the materials, we cannot differentiate the different materials. Identification will be essential for X-ray diagnosis in the near future. Recently, a photon counting system with energy resolving capability is attracting attention in the medical field. At present, the system has been progressing, but currently a fundamental study is needed. The aim of this study is to fabricate ``equal-image-density materials'' which give the same digital value, and to analyze the materials in terms of the influence on the contamination rate from scattered X-ray and heel effect on the obtained image. [Methods] Using machine tools, we ground down commercially available materials, bone-equivalent, soft-tissue-equivalent, aluminum and acrylic, so as to obtain the equal-image-density. Our materials were cubic shapes having 4 cm square and different thickness of 0.2-18 cm. Then, the influences of the scattered X-rays and the heel effect were evaluated experimentally. The contamination rate from scattered X-rays was determined by the collimator method. The heel effect on the obtained digital value was measured by an experiment in which the X-ray equipment was tilted at a 5 degree angle. [Results] For 40 kV and 100 kV X-rays, equal-image-density materials were fabricated. We found that the contamination rates from scattered X-ray were 8-60% for 40 kV X-rays and 10-53% for 100 kV X-rays. For the heel effect the intensity differences were 1-15% for 40 kV X-rays and 0.1-9% for 100 kV X-rays. [Conclusion] We fabricated equal-image-density materials, and then, using the materials, we analyzed the influences of the contamination rate and the heel effect. They are considered to be valuable for fundamental studies for next-generation detection systems such as a photon counting system.


Practical calibration curve for entrance-skin dose measurement using small-type OSL dosimeter

第72回日本放射線技術学会学術大会

第72回日本放射線技術学会学術大会

Aims It is becoming increasingly important to manage the exposure dose for patients in the diagnostic X-ray region. Generally, the dose is estimated by an ionization chamber based on an air-kerma measurement. The dosimeter cannot be applied to actual clinical settings because they interfere with the medical image. Recently, a small-type optically stimulated luminescence(OSL) dosimeter, called nanoDot, was newly developed by Landauer, Inc. Because the OSL dosimeter does not interfere with the medical image in the diagnostic X-ray region, the dosimeter is hoped to be a convenient detector used for the measurement of patient exposure dose. In this study, we proposed the measurement method using a small-type OSL dosimeter for clinical application used to measure patient dose. Materials and Methods First, based on the generally adopted method using an ionization chamber, the air-kerma was measured in free-air condition, and then the entrance-skin dose(ESD) was estimated by correction of the back-scatter factor(BSF). Second, measured values of the OSL dosimeter were derived in the same experimental conditions. Then, a calibration curve, which has a relationship between the measured value and the ESD, was derived. Third, we clarified the uncertainty of the calibration curve considering the angularity, energy dependences, etc. Finally, we measured the ESD based on a general clinical setting, and the derived ESD was compared to those measured with other dosimeters and guidance level of IAEA. Results and conclusion The calibration curve shows good linearity. It was found that the accuracy of the curve was 15%. The accuracy was consistent with the error cause discussed above. The ESD derived by our calibration curve was consistent with the other reference values. Based on the present study, the OSL dosimeter is further expected to be a useful dosimeter for measuring the ESD of the patients without affecting the medical image.


nanoDot OSL線量計の診断用X線領域におけるエネルギー依存性

nanoDot OSL線量計の診断用X線領域におけるエネルギー依存性

日本放射線安全管理学会第14回学術大会

日本放射線安全管理学会第14回学術大会


undamental experiment of the OSL dosimeter using diagnostic X-ray equipment∼evaluation of effect on medical images when we wear the dosimeter∼

OSL線量計の診断領域X線に対する基礎実験∼線量計着用における医用画像への影響評価∼

日本放射線安全管理学会第14回学術大会

日本放射線安全管理学会第14回学術大会


Comparison of normalization methods for linearity of MR signal

MR信号の線形評価を目的とした正規化手法の比較

第43回日本放射線技術学会秋季学術大会

第43回日本放射線技術学会秋季学術大会


Two dimensional material identification method based on a photon counting technique using low-energy X-ray spectrum

第43回日本放射線技術学会秋季学術大会

第43回日本放射線技術学会秋季学術大会


Comparison with statistical analysis of noise correction in diffusion weighted MR image

拡散強調画像の統計学的信号補正の比較

第43回日本放射線技術学会秋季学術大会

第43回日本放射線技術学会秋季学術大会


High accuracy measurement of contamination rate of scattered X-ray in air-kerma to construct secondary standard using diagnostic X-ray apparatus

第43回日本放射線技術学会秋季学術大会

第43回日本放射線技術学会秋季学術大会


Basic research for clinical application of the OSL dosimeter in the diagnostic region -Estimation of irradiation conditions not to identify the dosimeter on the medical image-

第43回日本放射線技術学会秋季学術大会

第43回日本放射線技術学会秋季学術大会


Measurement of energy dependence for small type OSL dosimeter by means of diagnostic X-ray equipment

第43回日本放射線技術学会秋季学術大会

第43回日本放射線技術学会秋季学術大会


Visualization of scattered X-ray in diagnostic region by means of CR system

CRシステムを用いた診断領域の散乱X線可視化装置の開発

第43回日本放射線技術学会秋季学術大会

第43回日本放射線技術学会秋季学術大会


Basic study for calculation of exposure dose of small type OSL dosimeter for high energy photon beam by means of simulation code(EGS5)

第43回日本放射線技術学会秋季学術大会

第43回日本放射線技術学会秋季学術大会


Physics education for beginners using self-produced leaf electroscope Toward the understanding of ionization-

自作箔検電器を用いた初学者の物理教育-電離作用の理解に向けて-

第43回放射線技術学会秋季学術大会

第43回放射線技術学会秋季学術大会


3D-ASL法による脳血管流速測定値に対する通過時間補正の検討:加齢による影響について

第46回日本磁気共鳴医学会大会

第46回日本磁気共鳴医学会大会


水浸出土木材の含浸物質濃度と緩和時間変化

水浸出土木材の含浸物質濃度と緩和時間変化

第43回日本磁気共鳴医学会大会

第43回日本磁気共鳴医学会大会


Signal correction of diffusion weighted MR imaging with application of the Rician distribution

ライス分布を用いた拡散強調画像の信号補正

第43回日本磁気共鳴医学会大会

第43回日本磁気共鳴医学会大会


100-2000keVの光子線に対する小型OSL線量計の効率的な照射体系の提案

100-2000keVの光子線に対する小型OSL線量計の効率的な照射体系の提案


低エネルギーX線スペクトルのフォトンカウンティングに基づく2次元的物質同定法の提案

医用画像情報学会 第172回大会

医用画像情報学会 第172回大会


Influence of the Transit Time Correction for on Quantitative Cerebral Blood Flow (CBF) Values of Young and Elderly Subjects Using the 3D-ASL Method with Different Labeling Durations

The 71 th Annual Scientific Congress of JSRT


磁化移動効果を用いたポリエチレングリコールの浸透性測定

磁化移動効果を用いたポリエチレングリコールの浸透性測定

第42回日本磁気共鳴医学会大会

第42回日本磁気共鳴医学会大会


MRIを用いた水浸出土木材の内部性状の可視化 ―磁化移動効果を用いたポリエチレングリコールの浸透性測定―

日本文化財科学会第31大会

日本文化財科学会第31大会


第41回日本磁気共鳴医学会大会

第41回日本磁気共鳴医学会大会


テスラ MRI における酸素吸入下での脳脊髄液の経時的な信号変化

テスラ MRI における酸素吸入下での脳脊髄液の経時的な信号変化

第41回日本磁気共鳴医学会大会

第41回日本磁気共鳴医学会大会


プロトン密度強調(PDw)画像を用いない腎血流量定量の試み

プロトン密度強調(PDw)画像を用いない腎血流量定量の試み

第41回日本磁気共鳴医学会大会

第41回日本磁気共鳴医学会大会


頭蓋内腫瘍診断における造影T1強調3D-FSPGR-SPAIR法の最適化

頭蓋内腫瘍診断における造影T1強調3D-FSPGR-SPAIR法の最適化

第40回日本磁気共鳴医学会大会

第40回日本磁気共鳴医学会大会


頭部領域における 3 次元fast spoiled gradient-echo (3D-FSPGR) 法を用いた造影脂肪抑制 T1 強調 MRI の最適化

第68回日本放射線技術学会総会学術大会

第68回日本放射線技術学会総会学術大会


膀胱癌のADCとDCE - MRIパラメ-タの比較

膀胱癌のADCとDCE - MRIパラメ-タの比較

第39回日本磁気共鳴医学会大会

第39回日本磁気共鳴医学会大会


第67回日本放射線技術学会総会学術大会

第67回日本放射線技術学会総会学術大会


Plaque characteristics in carotid artery using three-dimensional Look-Locker sequence

第38回日本磁気共鳴医学会大会

第38回日本磁気共鳴医学会大会


高速スピンエコー法を用いた組織 T1・T2同時計測MRI

高速スピンエコー法を用いた組織 T1・T2同時計測MRI

第66回日本放射線技術学会総会学術大会

第66回日本放射線技術学会総会学術大会


組織血流動態定量解析: T1 Dynamic Contrast -Enhanced Fast Spin-Echo (T1DCE-FSE) MRIのモデルフィッティングに関する考察

第37回日本磁気共鳴医学会大会

第37回日本磁気共鳴医学会大会


動脈における低角再収束パルス高速スピンエコー法を用いた血流抑制血管壁MRI

動脈における低角再収束パルス高速スピンエコー法を用いた血流抑制血管壁MRI

第65回日本放射線技術学会総会学術大会

第65回日本放射線技術学会総会学術大会


高速スピンエコー法を用いたT1値計測のT2補正

高速スピンエコー法を用いたT1値計測のT2補正

第51回日本放射線技術学会近畿部会学術大会

第51回日本放射線技術学会近畿部会学術大会


高速スピンエコー法による前立腺ダイナミック T1値計測MRIの試み

高速スピンエコー法による前立腺ダイナミック T1値計測MRIの試み

第63回日本放射線技術学会総会学術大会

第63回日本放射線技術学会総会学術大会


Fast Recovery Fast spin echo (FR-FSE) 法を用いた脂肪抑制T2 強調画像の検討

第16回日本乳癌画像研究会

第16回日本乳癌画像研究会


高速spin-echo法を用いた組織T1値計測に関する検討

高速spin-echo法を用いた組織T1値計測に関する検討

第50回日本放射線技術学会近畿部会学術大会

第50回日本放射線技術学会近畿部会学術大会