Toshizo Katsuda

Tokai Gakuin University, Kagamigahara, Gifu, Japan

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Publications (69)20.21 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: According to the 2011 ICRP statement, the threshold in absorbed dose for the lens of the eye is now considered to be 0.5 Gy. Therefore, it is important to keep the eye lens doses during head computed tomography examination as low as reasonably achievable. In this study, the two lenses and the occiput doses associated with patient setup errors and head size were evaluated using phantoms developed for pediatric patients. The phantoms were made using flexible acrylic sheets in a cylindrical shape [diameters of 6 (premature baby), 8 (neonate), 10 (infant), and 12 cm (child)] and placed on the end of the CT bed. The bed position was raised from the center for each phantom size. The two lenses and the occiput doses at each setup were measured using radiochromic film. By raising the bed position, the two lenses doses decreased at all phantom sizes. However, the occiput doses changed in a complex manner according to the phantom size. In this study, decreasing the distance from the lens to the X-ray tube (i.e. raising the bed position) is an effective way to reduce the absorbed dose of the lens. However, when the occiput was positioned at the center of the gantry aperture, the occiput dose peaked in all phantom sizes. In addition, the results indicated a complex dose distribution in pediatric head CT when taking into account the bed position (patient setup errors) and phantom sizes. Furthermore, beam slice width and pitch are important factor in determining the maximum absorbed dose. To keep radiation doses during CT examination as low as reasonably achievable, it is important to clarify the influence of CT scanning settings on CT dose.
    No preview · Article · Jan 2015
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    ABSTRACT: Pre-ultraviolet rays exposure is a useful method to reduce non-uniformity error of radiochromic films. However, dust and scratch noises such as spike noise disturb precise measurement. To reduce these noises, median filter processing is applied for pre-subtraction and subtraction images. To reduce non-uniformity error of the thickness unevenness of Gafchromic EBT film, ultraviolet rays were exposed to correct data. There were three kinds of images obtained: first ultraviolet exposure image, second ultraviolet exposure image and the subtraction image of both. Median filer processing was performed on all these images. Eleven kinds of median filter radius factors (0.0 to 5.0) were applied using image analysis software. Data and graphs were then estimated. The maximum pixels value of dust was 229 on the second ultraviolet exposure image of film 3. After median filter preprocessing, the pixel value of the noises were similar to the minimum value. A 2.0-radius median filer is a useful factor for processing. Noise reduction that affected data of estimated images may be applied to measure radiation doses on a variety of radiochromic films. Ultraviolet exposure and subtraction method with median filter processing enable precise measurement and high spatial resolution dose distribution.
    No preview · Article · Jan 2015
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    ABSTRACT: Gafchromic film has been used for X-ray dose measurement in diagnostic examinations. Their use has been initiated for three-dimensional X-ray dose measurement by using the high-resolution characteristics of Gafchromic films in computed tomography. However, it is necessary to solve the problem of nonuniform thickness in the active layers of Gafchromic films. A double exposure technique using X-rays is performed in therapeutic radiology; it is difficult to use in a diagnostic examination because of the heel effect. Therefore, it is suggested that ultraviolet (UV) rays be substituted for X-rays. However, the appropriate UV wavelength is unknown. In this study, we aimed to determine which UV wavelengths are effective to expose Gafchromic XR-RV3 and XR-SP2. UV lamps with peak wavelengths of 245 nm, 310 nm, and 365 nm were used. The three UV wavelengths were used to irradiate Gafchromic XR-RV3 and XR-SP2 films for 60 min, and irradiation was repeated every 60 min for 600 min thereafter. Films were scanned after each irradiation period on a flatbed scanner. The images were split into their red-green-blue components, and red images were stored using ImageJ version 1.44o image analysis software. Regions of interest (ROI), 0.5 inches in diameter, were placed at the centers of the subtracted Gafchromic film images, and graphs of UV irradiation duration and mean pixel values were plotted. There were reactions to UV-A on both Gafchromic XR-RV3 and XR-SP2; those to UV-B were moderate. However, UV-C demonstrated few reactions with Gafchromic XR-RV3 and XR-SP2. From these results, irradiation with UV-A may be able to correct nonuniformity errors. Uniform UV-A irradiation of Gafchromic films with large areas is possible, and UV rays can be used as a substitute for X-rays in the double exposure technique.
    No preview · Article · Jan 2015
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    ABSTRACT: Radiation doses during computed tomography (CT) examinations are generally evaluated by CT dose index (CTDI). The CTDI is measured by means of a CTDI phantom, which is placed in the center of the CT gantry aperture. However, patients are not always positioned in the centered in clinical settings. In this study, dose distributions associated with patient setup errors and head size were evaluated using phantoms developed for pediatric patients. The phantoms were made using flexible acrylic sheets in a cylindrical shape [diameters of 6 (premature baby), 8 (neonate), 10 (infant), and 12 cm (child)] and placed on the end of the CT bed. The bed position was lowered from the center by up to a radius length for each phantom size. Dose distributions in the phantoms were measured using radiochromic film. By lowering the bed position, the surface doses at 0° increased and those at 180° and the center doses decreased. However, the other measurement positions exhibited complex changes depending on the phantom size. In addition, the shapes of the dose profile curves varied according to the distance from the X-ray tube (i.e. location in the gantry aperture). In this study, the surface doses became smaller with decreasing distance from the X-ray tube. Therefore, decreasing the distance from the lens to the X-ray tube would be an effective way to reduce the absorbed dose of the lens. However, the dose distributions in the phantoms varied in a complex manner depending on patient setup errors and phantom size. In addition, beam slice width and pitch were important factors in determining the amount of the CT dose.
    No preview · Chapter · Jan 2015
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    ABSTRACT: Although GAFCHROMIC EBT3 (EBT3) as a radiochromic film shows only slight energy dependency errors in comparison with other radiochromic films, the influence of energy dependence in the diagnosis energy range (less than 100 keV) is larger in the high energy range (over 100 keV). Based on this characteristic, adaptation of the EBT3 dosimetry in the diagnosis range was investigated. The energy response of the EBT3 in the diagnosis range at 30, 40, 50, 60 keV was measured using the density-absorbed dose calibration curve of the absorbed dose versus film density for the EBT3. Various data (degree of leaning, coefficient of determination) of each effective energy were compared. The density - absorbed dose calibration curves were linearly correlated in each of the effective energies. There was an energy dependent error of approximately 0.2% from 30 to 60 keV. As a result, it can be seen that the EBT3 is available in the diagnosis energy range. However, the influence of the non-uniformity error caused by the repeatability of the scan method must be considered because EBT3 distortion has a serious influence on measurement precision.
    No preview · Article · Jan 2015
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    ABSTRACT: Gafchromic films are used for X-ray dose measurements during diagnostic examinations and have begun to be used for three-dimensional X-ray dose measurements using the high-resolution characteristics of Gafchromic films for computed tomography. However, the problem of unevenness in Gafchromic film active layers needs to be resolved. Double exposures using X-rays are performed during therapeutic radiology, although this is difficult for a diagnostic examination because of a heel effect. Thus, it has been suggested that ultraviolet (UV) radiation be used as a substitute for X-rays. However, the appropriate UV wavelength has not been determined. Thus, we conducted this study to decide an appropriate UV wavelength. UV peak wavelengths of 245 nm (UV-A), 310 nm (UV-B), and 365 nm (UV-C) were used to irradiate EBT2 and EBT3 films. Each UV wavelength was irradiated for 5, 15, 30, and 60 min, and irradiation was then repeated every 60 min up to 360min. Gafchromic films were scanned after every irradiation using a flatbed scanner. Images were split into RGB images, and red images were analyzed using ImageJ, version 1.44, image analysis software. A region of interest (ROI) one-half inch in diameter was placed in the center of subtracted Gafchromic film images, and UV irradiation times were plotted against mean pixel values. There were reactions in the front and back of Gafchromic EBT3 and the back of Gafchromic EBT2 with UV-A and UV-B. However, UV-C resulted in some reactions in both sides of Gafchromic EBT2 and EBT3. The UV-A and UV-B wavelengths should be used.
    No preview · Article · Jan 2015
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    ABSTRACT: Gafchromic films (GAFs) are used for the Xray dose measurement in the diagnostic examination. It is begun to use for the three-dimensional X-rays dose measurement using the high-resolution characteristic in computed tomography. However, it is necessary to solve a problem of unevenness of active layer of GAFs. It is suggested that the ultraviolet (UV) is substitute as an X-ray. However, wavelength of appropriate UV are unidentified. This study is to decide a wavelength of the UV. Peak wavelength of 245 nm, 310 nm and 365 nm UV were irradiate to the EBT2 and EBT3. The UV rays were irradiated for 5, 15, 30 and 60 minutes, and irradiation was repeated afterwards until 360 minutes every 60 minutes. The images were split in RGB, and R images were used. ROI of the diameter 1/2 inch was set in the center of subtracted GAF images, and the graph of UV irradiation time and the mean pixel value were made. There was a reaction in front and back of GAF EBT3 and back of EBT2 in UV-A and B. However, UV-C had few reactions with both aspects of GAF EBT2 and EBT3. It should be used UV-A for a fact because a wavelength of UV-B may affect the human body.
    No preview · Article · Jan 2015 · IFMBE proceedings
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    ABSTRACT: Bone mineral density (BMD) is affected by lean body mass and body weight to various degrees in the course of aging. The attempt of this study is to determine the optimal time to begin prevention of osteoporosis. In this study, female hospital employees aged 20-59 years were divided into 2 age groups, 20-39 years and 40-59 years based on age at peak BMD, and the relations of total BMD, subtotal BMD and lumbar spine BMD to lean body mass and body weight were examined in both groups. Subtotal BMD was calculated by subtracting head BMD from total BMD along with whole body measurement. While persistent positive correlations were found among all factors in the 20-39-year-old group, subtotal BMD and lumbar spine BMD were positively correlated to lean body mass in the 40-59-year-old group. Thus, lean body mass and body weight appeared to exert a profound influence on subtotal BMD in those aged 20-39 years, but lean body mass in those aged 40-59 years. Lean body mass appears to provide the best prediction of subsequent development of osteoporosis. © 2015, Kobe University School of Medicine. All rights reserved.
    No preview · Article · Jan 2015
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    ABSTRACT: To improve the safety of the use of a power injector for pediatric contrast CT, we newly developed a saline test injection mode for a power injector and investigated its usefulness. We used an injection route and investigated the relationship of the injection pressure to the injection rate of saline and the contrast medium. From this relationship, we investigated it was possible to estimate the change of pressure injection of contrast medium from the pressure change of saline injection. The correlation between the saline test injection pressure and the contrast medium injection pressure was investigated in 64 clinical cases. The detection rate of side effects from the saline test injection was investigated in 473 patients. Regarding the correlation between the injection rate and pressure for both saline and contrast, the pressure rose as the rate increased. The contrast medium injection pressure could be estimated from the correlation observed with saline. The clinical data were obtained had a relationship similar to that with phantom data. The detection rate of side effects from the saline test injection was 4.4 % in the clinical cases. In these cases, examinations were completed by re-establishing an injection route or administering hypnotics. Our results suggest that contrast medium pressure can be estimated from a saline test injection, thus aiding in prediction of the risk of injection abnormality. Reactions to injections could be observed in the present study, facilitating the prevention of examination failure. Countermeasures can be taken against the cause of the reaction, and the examination can be performed after confirming the absence of a reaction to injection. Therefore, a saline test injection may be useful in pediatric contrast CT.
    No preview · Article · Jun 2013
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    ABSTRACT: Recently developed radiochromic films can easily be used to measure absorbed doses because they do not need development processing and indicate a density change that depends on the absorbed dose. However, in GAFCHROMIC EBT2 dosimetry (GAF-EBT2) as a radiochromic film, the precision of the measurement was compromised, because of non-uniformity problems caused by image acquisition using a flat-bed scanner with a transmission mode. The purpose of this study was to improve the precision of the measurement using a flat-bed scanner with a reflection mode at the low absorbed dose dynamic range of GAF-EBT2. The calibration curves of the absorbed dose versus the film density for GAF-EBT2 were provided. X-rays were exposed in the range between ~0 and 120 mGy in increments of about 12 mGy. The results of the method using a flat-bed scanner with the transmission mode were compared with those of the method using the same scanner with the reflection mode. The results should that the determination coefficients (r 2 ) for the straight-line approximation of the calibration curve using the reflection mode were higher than 0.99, and the gradient using the reflection mode was about twice that of the one using the transmission mode. The non-uniformity error that is produced by a flat-bed scanner with the transmission mode setting could be almost eliminated by converting from the transmission mode to the reflection mode. In light of these findings, the method using a flat-bed scanner with the reflection mode (only using uniform white paper) improved the precision of the measurement for the low absorbed dose range.
    No preview · Article · Mar 2013 · Australasian physical & engineering sciences in medicine / supported by the Australasian College of Physical Scientists in Medicine and the Australasian Association of Physical Sciences in Medicine
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    ABSTRACT: The ability of radiographers to detect cancer on radiographs was compared to that of physicians to assess the competence of radiographers as film readers in gastric cancer screening. After obtaining permission for the screening and analysis of data, a test set of films from 100 patients who underwent gastric cancer screening using radiographic examination was evaluated. Films were selected from 137 744 patients and 197 cases of cancer. Screening was performed at the Osaka Cancer Prevention and Detection Center in Japan between April 2004 and March 2008. Eleven radiographers affiliated to the screening center and 37 physician readers scored the test set on a 4-point scale blinded to the other participants' scores. Receiver operating characteristic (ROC) analysis was performed to evaluate the interpretation performance, and the area under the ROC curve (AUC) was defined as the ability of the radiographer or physician reader to detect cancer. The results showed that the average ability of radiographers to detect cancer (AUC, 0.82) was identical to that of physician readers (p = 0.96, Welch's t test), suggesting that radiographers can assume the role of film readers in gastric cancer screening.
    No preview · Article · Jan 2013
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    ABSTRACT: Proximal femoral bone mineral density (BMD) can be measured by dual energy X-ray absorptiometry method in the neck, trochanter, intertrochanter, total and Ward's triangle area. Ward's triangle area of the proximal femur is a smaller area to measure than the others, and the position varies, depending on the status of inner rotation of the target leg. In this study, the measurements of the proximal femoral BMD in women were carried out on the neck, trochanter, intertrochanter, total and Ward's triangle area with the, subjects' legs turned 15 degrees toward the inside. The Ward's BMD were measured using Ward's cognitive method, in which the measured BMD were compared among age groups of 50-59, 60-69, 70-79 and 80-89 to determine whether this process could reveal decreased femoral BMD in elderly women. The correlation between BMD and age was tested using the Pearson correlation coefficient. In all measured parts, the BMD of women age 50-59 were significantly higher than those of women age 80-89. The correlations between BMD and age were negative in all measured parts, and the most negative correlation was between age and Ward's BMD. The study using Ward's cognitive method showed an inverse correlation between Ward's BMD and age in women.
    Preview · Article · Feb 2012 · Acta medica Okayama
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    ABSTRACT: High-density barium sulfate (HDB) has been recommended by the Japanese Society of Gastroenterological Cancer Screening (JSGCS) and used in many medical facilities. However, it is not confirmed that the new method using HDB is superior in diagnostic validity compared to the conventional method using moderate-density barium sulfate (MDB). Pre viously, the authors reported that both methods showed simi lar validity in terms of sensitivity and specificity in gastric cancer screening. In this study, sensitivity and specificity were re-examined in more detail by area under receiver-operating characteristic (ROC) curves (AUC) analysis, especially on the sex (male, female) and the ages (>50, <50, >55, <55, >60, <60) of subjects. The results showed that the diagnostic validity of the method using HDB is almost same to that of the conven tional method using MDB. Clinical improvement in gastric cancer screening is in need of further studies on the new me thod using HDB. Keywordsgastric cancer screening–high-density barium sulfate–sensitivity and specificity–AUC analyses–sex and ages of subjects
    Full-text · Chapter · Dec 2011
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    ABSTRACT: The aim of this study was to determine whether additional radiographs, as judged necessary by the radiographer, improves cancer detection during gastric cancer screening. We analyzed 144 gastric cancer cases among 137 744 individuals who underwent X-ray screening for gastric cancer. Radiographs were obtained by 17 radiographers at a screening center in Japan from April 2004 to March 2008. Additional radiographs were taken based on the radiographer's judgment in cases of suspected cancer. During double-blind reinterpretation of the cancer case radiographs by two radiologists, we determined the number of cancer cases that were detected by standard radiographs alone. We next determined the number of cancer cases detected using both standard radiographs and additional radiographs. Compared to the number of cancer cases detected with standard radiographs alone (120 cases detected, 24 cases undetected), the number of cancer cases detected with both standard and additional radiographs (137 cases detected, 7 cases undetected) significantly increased (17 cases; P < 0.001, McNemar test). We found that taking additional radiographs, when judged necessary by the radiographer during radiographic gastric cancer screening, improves cancer detection.
    No preview · Article · Apr 2011 · Japanese journal of radiology
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    ABSTRACT: Although the half-value layer (HVL) is one of the important parameters for quality assurance (QA) and quality control (QC), constant monitoring has not been performed because measurements using an ionization chamber (IC) are time-consuming and complicated. To solve these problems, a method using radiochromic film and step-shaped aluminum (Al) filters has been developed. To this end, GAFCHROMIC EBT2 dosimetry film (GAF-EBT2), which shows only slight energy dependency errors in comparison with GAFCHROMIC XR TYPE-R (GAF-R) and other radiochromic films, has been used. The measurement X-ray tube voltages were 120, 100, and 80 kV. GAF-EBT2 was scanned using a flat-bed scanner before and after exposure. To remove the non-uniformity error caused by image acquisition of the flat-bed scanner, the scanning image of the GAF-EBT2 before exposure was subtracted after exposure. HVL was evaluated using the density attenuation ratio. The effective energies obtained using HVLs of GAF-EBT2, GAF-R, and an IC dosimeter were compared. Effective energies with X-ray tube voltages of 120, 100, and 80 kV using GAF-EBT2 were 40.6, 36.0, and 32.9 keV, respectively. The difference ratios of the effective energies using GAF-EBT2 and the IC were 5.0%, 0.9%, and 2.7%, respectively. GAF-EBT2 and GAF-R proved to be capable of measuring effective energy with comparable precision. However, in HVL measurements of devices operating in the high-energy range (X-ray CT, radiotherapy machines, and so on), GAF-EBT2 was found to offer higher measurement precision than GAF-R, because it shows only a slight energy dependency.
    No preview · Article · Mar 2011 · Australasian physical & engineering sciences in medicine / supported by the Australasian College of Physical Scientists in Medicine and the Australasian Association of Physical Sciences in Medicine
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    ABSTRACT: Purpose: Videofluoroscopy is generally considered a "gold standard" technique for diagnosing dysphagia; however this technique exposes subjects to radiation. Ultrasonography is applied widely in clinical practice because of low cost, safety of the technique, and absence of radiation exposure. The purpose of this study was to investigate the application of B+M-mode ultrasound imaging as a new approach to quantify activity patterns of the geniohyoid muscles during swallowing and to assess the effect of bolus volume in healthy subjects. Subject and Methods: 25 healthy volunteers (13 male, 12 female) completed three repetitions each of four swallowing conditions: 1-, 5-, 10-, and 20-ml water bolus swallows. Simultaneous B/M-mode images were captured at two regions along the lateral geniohyoid muscle wall. Frozen frames of the moving image were analyzed, and the moving distance of the geniohyoid muscle wall from the resting point was measured (X axis, time; Y axis, perpendicular to the range of motion). We measured moving distance of the geniohyoid muscle wall during contraction and duration of movement of the geniohyoid muscle. Results: In all cases, ultrasonographic images of the geniohyoid muscle movement during swallowing were easily visualized using the real-time B/M-mode. The average moving distance and the average duration of movement of the geniohyoid muscle during swallowing increased gradually by bolus volume increased. Mean moving distance was significantly increased at bolus volume of 20ml compared to 1ml, 5ml, and 10ml, and with 10ml compared to 1ml. Mean duration was significantly increased at bolus volume of 20ml compared to 1ml, 5ml, 10ml. Conclusion: B/M-mode ultrasound imaging provides a simple and noninvasive technique to visually assess the lateral geniohyoid muscle wall and may provide a clinical method for direct evaluation for swallowing.
    No preview · Article · Jan 2011
  • K. Hayashida · T. Katsuda · K. Yamamoto · Y. Takeda
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    ABSTRACT: Proximal femoral bone mineral density (BMD) can be measured by dual energy X-ray absorptiometry (DXA) method in the parts of neck, trochanter, intertrochanter, total and Ward’s. Ward’s is a measuring part smaller than others, and the position varies on the status of inner rotation of target leg. Therefore, Ward’s BMD is higher than neck and trochanter BMD in coefficient of variation (CV). On the other hand, it is reported that Ward’s BMD decreases with aging more remarkably than those of lumber vertebra and total neck do. In this study, the measurements of proximal femoral BMD were carried out on 5 parts of neck, trochanter, intertrochanter, total and Ward’s, in the condition of subject leg turned inside 15 degrees. Ward’s BMD were measured with Ward’s cognitive method. The measured BMD were compared among age groups of 50-59, 60-69, 70-79 and 80-89. The correlation between BMD and age was tested using Pearson. On 5 parts, the BMD of age 50 - 59 were significantly higher than those of age 80 - 89. The correlations between BMD and age were negative on 5 parts and the most negative one was on Ward’s. The study using Ward’s cognitive method showed remarkable nagative relation between Ward’s BMD and age.
    No preview · Chapter · Jan 2011
  • T. Akagawa · T. Gotanda · T. Katsuda · R. Gotanda
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    ABSTRACT: Complete video-assisted thoracic surgery (VATS) is a well established method that is commonly used for the treatment of small-sized peripheral lung cancer. Noninvasive tests using computed tomography angiography (CTA) that elucidate the branching pattern of bronchi and pulmonary vessels are an important preliminary step in order to conduct a rapid and safe surgical VATS procedure for lung cancer. We created and evaluated a scanning protocol to obtain rapid and accurate three-dimensional (3D) images. We evaluated our protocol on twenty patients with lung cancer and the data were used to create 3D images as well as to analyze and understand the branching pattern of bronchi and pulmonary vessels for the purpose of preoperative 3DCTA. Both pulmonary arterial and venous phase computed tomography (CT) values were measured using the region of interest (ROI) at the pulmonary artery (PA) where the ROI was located in the left atrium that connected the pulmonary vein (PV). The average CT values of PA and PV on pulmonary artery phase images were 356.9±144.3 (HU) and 126.7±82.9 (HU), respectively. Moreover, average CT values of PA and PV on pulmonary venous phase images were 127.7±59.6 (HU) and 352.0±113.5 (HU), respectively. We demonstrated that our scanning protocol for preoperative 3D CT angiography using 64 multidetector row computed tomography divided pulmonary vessels into arteries and veins rapidly and accurately. Preoperative 3D CT pulmonary angiography imaging using our scanning protocol was useful for performing VATS.
    No preview · Article · Jan 2011 · IFMBE proceedings
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    ABSTRACT: This study was performed to evaluate pediatric hydrocephaly patients with shunt failure. We objectively evaluated ventricular variations by head computed tomography (CT) analysis in which the histogram shape was compared between the normal and shunt failure states. To identify the characteristics of the histogram shape during ventricular enlargement in the presence of hydrocephaly, histograms in the normal state with favorable shunt function and ventricular enlargement were prepared for 6 hydrocephaly patients in whom visually apparent ventricular enlargement was noted on imaging, and alterations in the histogram shape with alterations in the ventricle size were investigated. When the ventricle enlarged, the convex or downward slope on the lower CT value side representing the ventricle rose on the histogram, while the convex on the higher CT value side representing the brain became smaller, suggesting that ventricular size changes can be judged objectively based on changes in the heights of the convex or downward slope on the lower value side and convex on the higher value side on histogram. The histogram shape in a state of ventricular enlargement was apparently different from that in the normal state. Histogram analysis of head CT images is useful for pediatric hydrocephaly patients.
    No preview · Chapter · Jan 2011
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    ABSTRACT: Although the half-value layer (HVL) is one of the important parameters for quality assurance (QA) and quality control (QC), constant monitoring has not been performed because measurements using an ionization chamber (IC) are time-consuming. To solve these problems, a method using radiochromic film and step-shaped aluminum (Al) filters has been developed. In this study, GAFCHROMIC EBT2 dosimetry film (GAF-EBT2) and GAFCHROMIC XR TYPE-R dosimetry film (GAF-R) has been used. The measurement X-ray tube voltage was 120 kV. Two radiochromic films were scanned using a flat-bed scanner. To remove the nonuniformity error of scanned images, image J version 1.40g image analysis software has been used. HVL was evaluated using the density attenuation ratio. The HVLs and second HVLs of GAF-EBT2, GAF-R, and an IC dosimeter were compared. The HVLs (second HVLs) at 120 kV using GAF-EBT2, GAF-R, and an IC dosimeter were 4.47 mm (10.97 mm), 4.17 mm (8.61 mm), and 4.03 mm (10.35 mm) respectively, and the effective energies were 40.6 keV, 39.3 keV, and 38.7 keV, respectively. The difference ratios of the second HVLs using GAF-EBT2 (GAF-R) and an IC dosimeter were 6.0% (- 16.8%), -10.6% (-11.6%), and 5.1% (-0.2%), respectively. In addition, the difference ratio of the second HVLs at 120 kV using GAF-EBT2 and GAF-R was 27.4%. GAF-EBT2 and GAF-R proved to be capable of measuring effective energy within an error range of less than 5%. However, in HVL measurements of devices operating in the high-energy range (X-ray CT, radiotherapy machines, and so on), GAF-EBT2 was found to offer higher measurement precision than GAF-R, because it shows only a slight energy dependency.
    No preview · Article · Jan 2011 · IFMBE proceedings

Publication Stats

136 Citations
20.21 Total Impact Points

Institutions

  • 2015
    • Tokai Gakuin University
      Kagamigahara, Gifu, Japan
  • 2013
    • National Cerebral and Cardiovascular Center
      Ōsaka, Ōsaka, Japan
  • 2008-2010
    • Himeji Dokkyo University
      Himezi, Hyōgo, Japan
  • 2007-2008
    • Okayama University
      • • Graduate School of Health Sciences
      • • Faculty of Health Sciences
      Okayama, Okayama, Japan
  • 2006
    • Okayama University of Science
      Okayama, Okayama, Japan
  • 1996-1998
    • Osaka Medical Center for Cancer and Cardiovascular Diseases
      Ōsaka, Ōsaka, Japan