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Latest digital radiographic technology permits dynamic chest radiography during the cardiac beating and/or respiration, which allows for real-time observation of the lungs. This study aimed to assess the capacity of dynamic flat-panel detector (FPD) imaging without the use of contrast media to estimate cardiovascular parameters based on image parameters of a porcine model under fluid loading. Three domestic pigs were intubated, and mechanical ventilation was provided using a ventilator under anesthesia. A porcine model involving circulatory changes induced by fluid loading (fluid infusion/blood removal) was developed. Sequential chest radiographs of the pigs were obtained using a dynamic FPD system within the first 5 min after fluid loading. Image parameters such as the size of the heart shadow and mean pixel values in the lungs were measured, and correlations between fluid loading and cardiovascular parameters (blood pressure [BP], cardiac output [CO], central venous pressure [CVP], and pulmonary arterial pressure [PAP]) were analyzed based on freedom-adjusted coefficients of determination (Rf2). Fluid loading was correlated with radiographic lung density and the size of the heart shadow. Radiographic lung density was correlated with the left and right heart system-related parameters BP, CO, CVP, and PAP. The size of the heart shadow correlated with the left heart system-related parameters CO and BP. Dynamic FPD imaging allows for the relative evaluation of cardiovascular parameters based on image parameters. This diagnostic method provides radiographic image information and estimates relative circulatory parameters. Supplementary Information The online version contains supplementary material available at 10.1007/s12194-021-00626-2.

Noriyuki Ohkura,1 Rie Tanaka,2 Satoshi Watanabe,1 Johsuke Hara,1 Miki Abo,1 Yusuke Nakade,3 Junsei Horii,4 Yukihiro Matsuura,4 Dai Inoue,5 Munehisa Takata,6 Masaya Tamura,6 Isao Matsumoto,6 Shigeru Sanada,7 Kazuo Kasahara1 1Kanazawa University Hospital, Respiratory Medicine, Ishikawa, Japan; 2Kanazawa University, College of Medical, Pharmaceutical & Health Sciences, Ishikawa, Japan; 3Kanazawa University Hospital, Clinical Laboratory, Ishikawa, Japan; 4Kanazawa University Hospital, Department of Radiology, Ishikawa, Japan; 5Kanazawa University Hospital, Radiology, Ishikawa, Japan; 6Kanazawa University, Thoracic, Cardiovascular and General Surgery, Ishikawa, Japan; 7Komatsu University, Faculty of Health Sciences, Ishikawa, JapanCorrespondence: Noriyuki Ohkura Email n-ohkura@med.kanazawa-u.ac.jpObjective: The aim of this study was to identify the relationships between parameters obtained from dynamic-ventilatory digital radiography (DR) and ventilatory disorders.Methods: This study comprised 273 participants with respiratory diseases who underwent spirometry and functional residual capacity measurements (104 with normal findings on spirometry as controls, 139 with an obstructive lung disorder, 30 with a restrictive lung disorder) were assessed by dynamic-ventilatory DR. Sequential chest radiography images of the patient’s slow and maximum breathing were captured at 15 frames per second by a dynamic flat-panel imaging system. The system measured the following parameters: lung area at maximum inspiration divided by height (lung area_in/height), changes in tracheal diameter due to respiratory motions, rate of tracheal narrowing, diaphragmatic motion, and rate of change in lung area due to respiratory motion. Relationships between these parameters and ventilatory disorders were analyzed.Results: Lung area_in/height in patients with restrictive disorders showed significant decreases. Tracheal diameter change and tracheal narrowing rate in patients with obstructive disorders were significantly increased compared to both the control participants and patients with restrictive disorders. Patients with obstructive disorders and patients with restrictive disorders showed decreased diaphragmatic motion and lung area change rate. With the restrictive disorders as references, the area under the curve (AUC), sensitivity and specificity of lung area_in/height were 0.88, 0.77, and 0.88, respectively. With the obstructive disorders as references, the AUC, sensitivity and specificity of tracheal narrowing rate were 0.67, 0.53 and 0.81, respectively.Conclusion: Dynamic-ventilatory DR shows potential as a method for the detection and evaluation of ventilatory disorders in patients with respiratory diseases.Keywords: dynamic digital radiography, pulmonary function tests, spirometry, COPD, interstitial lung disease

Dynamic X-ray (DXR) is a functional imaging technique that uses sequential images obtained by a flat-panel detector (FPD). This article aims to describe the mechanism of DXR and the analysis methods used as well as review the clinical evidence for its use. DXR analyzes dynamic changes on the basis of X-ray translucency and can be used for analysis of diaphragmatic kinetics, ventilation, and lung perfusion. It offers many advantages such as a high temporal resolution and flexibility in body positioning. Many clinical studies have reported the feasibility of DXR and its characteristic findings in pulmonary diseases. DXR may serve as an alternative to pulmonary function tests in patients requiring contact inhibition, including patients with suspected or confirmed coronavirus disease 2019 or other infectious diseases. Thus, DXR has a great potential to play an important role in the clinical setting. Further investigations are needed to utilize DXR more effectively and to establish it as a valuable diagnostic tool.

Objective: The aim of this study was to determine the utility of dynamic-ventilatory digital radiography (DR) for pulmonary function assessment in patients with airflow limitation. Methods: One hundred and eighteen patients with airflow limitation (72 patients with lung cancer before surgery, 35 patients with chronic obstructive pulmonary disease [COPD], 6 patients with asthma, and 5 patients with asthma-COPD overlap syndrome) were assessed with dynamic-ventilatory DR. The patients were instructed to inhale and exhale slowly and maximally. Sequential chest X-ray images were captured in 15 frames per second using a dynamic flat-panel imaging system. The relationship between the lung area and the rate of change in the lung area due to respiratory motion with respect to pulmonary function was analyzed. Results: The rate of change in the lung area from maximum inspiration to maximum expiration (Rs ratio) was associated with the RV/TLC ratio (r = 0.48, p < 0.01) and the percentage of the predicted FEV1 (r = –0.33, p < 0.01) in patients with airflow limitations. The Rs ratio also decreased in an FEV1-dependent manner. Conclusion: The rate of change in the lung area due to respiratory motion evaluated with dynamic DR reflects air trapping. Dynamic DR is a potential tool for the comprehensive assessment of pulmonary function in patients with COPD.

Dynamic chest radiography (DCR) is a flat-panel detector (FPD) -based functional X-ray imaging, which is performed as an additional examination in chest radiography. The large field of view of FPDs permits real-time observation of motion/kinetic findings on the entire lungs, right and left diaphragm, ribs, and chest wall; heart wall motions; respiratory changes in lung density; and diameter of the intrathoracic trachea. Since the dynamic FPDs had been developed in the early 2000s, we focused on the potential of dynamic FPDs for functional X-ray imaging and have launched a research project for the development of an imaging protocol and digital image-processing techniques for the DCR. The quantitative analysis of motion/kinetic findings is helpful for a better understanding of pulmonary function, because the interpretation of dynamic chest radiographs is challenging and time-consuming for radiologists, pulmonologists, and surgeons. Recent clinical studies have demonstrated the usefulness of DCR combined with the digital image processing techniques for the evaluation of pulmonary function and circulation. Especially, there is a major concern in color-mapping images based on dynamic changes in radiographic lung density, where pulmonary impairments can be detected as color defects, even without the use of contrast media or radioactive medicine. Dynamic chest radiography is now commercially available for the use in general X-ray room and therefore can be deployed as a simple and rapid means of functional imaging in both routine and emergency medicine. This review article describes the current status and future prospects of DCR, which might bring a paradigm shift in respiratory diagnosis.

Dynamic chest radiography (2D x-ray video) is a low-dose and cost-effective functional imaging method with high temporal resolution. While the analysis of rib-cage motion has been shown to be effective for evaluating respiratory function, it has been limited to 2D. We aim at 3D rib-motion analysis for high temporal resolution while keeping the radiation dose at a level comparable to conventional examination. To achieve this, we developed a method for automatically recovering 3D rib motion based on 2D-3D registration of x-ray video and single-time-phase computed tomography. We introduce the following two novel components into the conventional intensity-based 2D–3D registration pipeline: (1) a rib-motion model based on a uniaxial joint to constrain the search space and (2) local contrast normalization (LCN) as a pre-process of x-ray video to improve the cost function of the optimization parameters, which is often called the landscape. The effects of each component on the registration results were quantitatively evaluated through experiments using simulated images and real patients’ x-ray videos obtained in a clinical setting. The rotation-angle error of the rib and the mean projection contour distance (mPCD) were used as the error metrics. The simulation experiments indicate that the proposed uniaxial joint model improved registration accuracy. By searching the rotation axis along with the rotation angle of the ribs, the rotation-angle error and mPCD significantly decreased from 2.246 ± 1.839° and 1.148 ± 0.743 mm to 1.495 ± 0.993° and 0.742 ± 0.281 mm, compared to simply applying De Troyer’s model. The real-image experiments with eight patients demonstrated that LCN improved the cost function space; thus, robustness in optimization resulting in an average mPCD of 1.255 ± 0.615 mm. We demonstrated that an anatomical-knowledge based constraint and an intensity normalization, LCN, significantly improved robustness and accuracy in rib-motion reconstruction using chest x-ray video.

The aims of this study were to address the relationship between respiratory changes in image density of the lungs and tidal volume, to compare the changes between affected and unaffected lobes, and to apply this new technique to the diagnosis of atelectasis.Our animal care committee approved this prospective animal study. Sequential chest radiographs of 4 pigs were obtained under respiratory control with a ventilator using a dynamic flat-panel detector system. Porcine models of atelectasis were developed, and the correlation between the tidal volume and changes in pixel values measured in the lungs were analyzed. The mean difference in respiratory changes in pixel values between both lungs was tested using paired t tests. To facilitate visual evaluation, respiratory changes in pixel values were visualized in the form of a color display, that is, as changes in color scale.Average pixel values in the lung regions changed according to forced respiration. High linearity was observed between changes in pixel values and tidal volume in the normal models (r = 0.99). Areas of atelectasis displayed significantly reduced changes in pixel values (P0.05). Of all atelectasis models with air trapping and air inflow restriction, 92.7% (19/20) were visualized as color-defective or color-marked areas on functional images, respectively.Dynamic chest radiography allows for the relative evaluation of tidal volume, the detection of ventilation defects in the lobe unit, and a differential diagnosis between air trapping and air inflow restriction, based on respiratory changes in image density of the lungs, even without the use of contrast media.

We developed a functional digital radiography system that provides physiological and functional information of the chest and/or joints using an X-ray flat-panel detector (FPD) system. During chest examination, sequential chest radiographs are taken from inspiration to expiration in order to analyze diaphragmatic movements. Pixel value changes in localized areas of the lung are then assessed to analyze ventilation and circulation. For limb joints, such as the wrist, shoulder, and knee, sequential radiographs during flexion and extension or rotational movement are considered, and movement angles are analyzed. These imaging techniques and quantitative analyses are promising in screening examinations because they provide physiological and functional information. The entrance surface dose for the detector is approximately 1.9 mGy for chest examination, which is comparable to the dose limit recommended by the International Atomic Energy Agency. Recent related studies are reviewed in this paper.

金沢大学高度モビリティ研究所 / 金沢大学理工研究域機械工学系, Convalescence of distal radius bone fracture, which is major disease for elderly people, requires speedy improvement of the contracture for wrist joint angles. The contracture is the case that wrists stiffen up and the range of their motion tends to be restricted by fixing them for long time after bone fracture. Recently, traction of the wrist during flexing and extending the wrist joint is considered to be efficient as the rehabilitation procedure. Previously, we developed an equipment that can apply the constant traction force to the wrist during flexing and extending the wrist joint. By using the equipment, we observed the dynamic motion of carpals in the wrist by radiography and found that the ratio of displacement of radius - lunate joint (R-L joint) to that of wrist angle increases by the traction. However, as the obtained images by radiography were not so clear and 2 dimensional data by projecting the texture of carpal, the displacement and rotation of carpal couldn't be measured precisely. We have developed a new equipment that can hold a wrist joint being pulled at flexion or extension posture for MRI photography. MRI can take detail 3 dimensional images. By using the equipment, the study reveals that lunar, which constitutes R-L joint as a major carpel, rotates by traction of the wrist and its rotation extends the motion range of R-L joint to dorsiflexion side. Furthermore, the interosseous distance of capitate - lunate joint (C-L joint) tends to extent by the traction at neutral and dorsiflexion positions, and it may have influence on the extension of the motion range of R-L joint.

To assess the capacity of dynamic flat-panel detector imaging without the use of contrast media to detect pulmonary embolism (PE) based on temporal changes in radiographic lung density during cardiac beating.Sequential chest radiographs of six pigs were acquired using a dynamic flat-panel detector system. A porcine model of PE was developed, and temporal changes in pixel values in the imaged lungs were analyzed during a whole cardiac cycle. Mean differences in temporal changes in pixel values between affected and unaffected lobes were assessed using the paired t test. To facilitate visual evaluation, temporal changes in pixel values were depicted using a colorimetric scale and were compared to the findings of contrast-enhanced images.Affected lobes exhibited a mean reduction of 49.6% in temporal changes in pixel values compared to unaffected lobes within the same animals, and a mean reduction of 41.3% compared to that before vessel blockage in the same lobe. All unaffected lobes exhibited significantly-increased changes in pixel values after vessel blockage (p0.01). In all PE models, there were color-deficient areas with shapes and locations that matched well with the perfusion defects confirmed in the corresponding contrast-enhanced images.Dynamic chest radiography enables the detection of perfusion defects in the lobe unit based on temporal changes in image density, even without the use of contrast media. Quantification and visualization techniques provide a better understanding of the circulation-induced changes depicted in dynamic chest radiographs.

This study aimed to evaluate the usefulness of dynamic radiography using a dynamic flat-panel detector (FPD) system after hip resurfacing arthroplasty (HRA). A total of 32 hips of 26 patients who underwent HRA were included. Sequential images of active abduction in the supine position and flexion in the 45° semilateral position were obtained using the FPD system. We examined the imaging findings of impingement between the acetabular component and femoral neck with cooperative motion at maximal exercise. Moreover, the central component coordinate of the acetabulum and femoral head sides was measured. For abduction motion, impingement was detected in two (6.3 %) hips between the superior portion of the femoral neck and acetabular component. For flexion motion, impingement was detected in 19 (59.4 %) hips. There were no findings of subluxation between the acetabular component and femoral neck after impingement, but cooperative motion of lumbar and pelvic flexion was observed. There was no significant difference in the center-to-center distance regardless of the presence or absence of impingement. Detailed postoperative kinematics of the hips after HRA showed that the proposed dynamic FPD system could reveal acquired impingement and cooperative motion as dynamic images and possibly reveal findings that would be unobservable using static images.

Digital subtraction angiography (DSA) has been used in head and abdomen. However, in recent years, the use of cardiac DSA has been reported. In this report, we discuss the development of a DSA method with heart rate to clearly visualize blood vessels of pediatric patients. The patients included five children who underwent pulmonary artery angioplasty. We used a process to resize the original images and performed two kinds of subtraction methods as well as visually evaluated the images and performed comparisons between pairs of images using the Scheffe's method. Subtraction techniques were used to eliminate motion artifacts of the heart, thoracic vertebra, ribs, and diaphragm. Visualization of the image of blood vessels of pulmonary arteries using the subtraction technique with heart rate was superior to the visualization of the conventional DSA images of peripheral blood vessels of the lung and pulmonary arteries. Use of subtraction technique with heart rate makes it possible to obtain more detailed information on pediatric cardiac angiography images noninvasively.

Introduction: Global spinal balance and its relationship to the pelvis have received much attention, and various formulae have been used to predict postoperative spinopelvic alignment for spinal surgery. However, previous studies had limitations because no consideration was given to the dynamic factor. Methods: Fifteen healthy adults without any lumbar disorder (group A) and 9 L4-spondylolisthesis patients (Group B) volunteered to participate in the study. Sequential images were captured with the subjects in the standing position with maximal forward bending followed by backward bending using a dynamic flat panel detector system. Spinopelvic parameters (LL: lumbar lordosis, SA: sacrofemoral angle, SS: sacral slope, PI: pelvic incidence, DP: distance of the horizontal movement of the pelvis) were evaluated. We also investigated the relationship between LL and SA (lumbar/hip [L/H] ratio) as the spinopelvic rhythm. Results: In group A, the mean change in LL was 83.2 ± 9.5°; change in SA, 45.4 ± 16.6°; SS, 42.6 ± 8.9°; PI, 43.2 ± 7.7°; DP, 15.7 ± 3.4 cm, and L/H ratio, 3.6 ± 2.7. However, spinopelvic rhythm changed over time, because the change in LL was larger than the change in SA from the middle of the rising motion to the upright position. In group B, the mean change in LL was 50.3 ± 8.0°; SA, 56.9 ± 16.0°; SS, 27.5 ± 13.5°; PI, 47.4 ± 10.4°; DP, 12.7 ± 6.8 cm; and L/H ratio, 1.0 ± 0.5. Conclusions: When compared with the change in LL, individual differences were largely noted in the change in SA. These results demonstrated that the range of hip joint motion under physiological conditions, unlike anatomical motion, differed substantially between individuals. Therefore, spinopelvic rhythm is dependent on the change in SA.

Pulmonary function is generally evaluated based on the overall capacity of both lungs; this evaluation is performed by a pulmonary functional test using a spirometer. Diaphragm movement has a direct association with pulmonary function. Therefore, evaluation of diaphragm motion is also helpful for estimating pulmonary function in the lung unit. The purpose of this study was to investigate the utility of dynamic analysis of the diaphragm using dynamic flat-panel detector (FPD) imaging for pulmonary function assessment in the lung unit. Sequential chest radiographs of four pigs (body weight approximately 20−30 kg) were obtained using a dynamic FPD system under respiratory control with a ventilator (100, 200, 300, 400, and 500 mL). Diaphragm excursion was measured and then analyzed the correlation with inspired volume. We also created porcine models of atelectasis by a catheter procedure and investigated whether lungs affected by atelectasis could be detected as reduced diaphragm excursion. To facilitate visual evaluation, temporal cross-sectional images were created, with the x-axis representing time, using a linear interpolation method. There was a strong correlation between inspired volume and diaphragm excursion (r e 0.96). In porcine models of atelectasis, diaphragm movement of an affected lung was restricted and was reduced, on average, to 44p of that in unaffected lungs. Reduction in diaphragm movement was also observed in the temporal cross-sectional images. Dynamic FPD imaging allows for relative pulmonary function assessment based on diaphragm movement, and unilateral abnormalities could be detected as reduced diaphragm excursion, even with a normal inspired volume.

Dose conformity in thoracic and abdominal ion-beam radiotherapy is degraded by respiratory motion. To improve conformity, an image-guided respiration-gated system can be used in the treatment room. The purpose of this study was to estimate the organ doses and effective doses to patients from an image-guided respiration-gated system. Glass dosemeters were inserted into an adult anthropomorphic phantom and were attached to the surface on the phantom. The phantom was placed on the treatment couch, and the imaging dose from fluoroscopy was evaluated. In addition to the organ doses, the effective doses were also estimated according to the ICRP Publication 103. The irradiation time is over 3-5 min per beam angle. When image acquisition conditions were assumed for thoracic treatment, the effective doses and maximal skin doses were 0.48-0.79 mSv and 5.9-9.9 mGy, respectively. The estimated doses can be the base data for considering radiological protection in the radiotherapy.

Introduction We described the dynamic effects of traction on the radiolunate and capitolunate joints in a living body to explore the possibility of range of motion exercise of the wrist joint under traction as a new method of exercise. Methods Dynamic radiography was conducted while creating wrist passive movements by using manual traction and machinery traction with a measurement device. Subjects were 20 healthy men. The change in the percentage of contribution of the radiolunate and capitolunate joints with or without traction was calculated. Results Manual traction: During palmar flexion, the percentage of contribution of the radiolunate angle was increased from 39.4% to 49.9%, and the capitolunate angle was decreased from 60.6% to 50.1% with traction. During dorsiflexion, the radiolunate angle was increased from 60.2% to 70.0%, and the capitolunate angle was decreased from 39.8% to 30.0% with traction. Machinery traction: During palmar flexion, the radiolunate angle was increased from 46.1% to 56.4%, and the capitolunate angle was decreased from 53.9% to 43.6% with traction. During dorsiflexion, the radiolunate angle was increased from 68.7% to 72.0%, and the capitolunate angle was decreased from 31.3% to 28.0% with traction. Conclusions The movement of the radiolunate joint was increased and that of the capitolunate joint decreased with the addition of traction. Range of motion exercise with traction has the potential to be applied to an advanced rehabilitation program targeting the radiolunate joint under specific pathological conditions.

To evaluate the patient identification ability of radiographers, previous and current chest radiographs were assessed with observer study utilizing a receiver operating characteristics (ROCs) analysis. This study included portable and conventional chest radiographs from 43 same and 43 different patients. The dataset used in this study was divided into the three following groups: (1) a pair of portable radiographs, (2) a pair of conventional radiographs, and (3) a combination of each type of radiograph. Seven observers participated in this ROC study, which aimed to identify same or different patients, using these datasets. ROC analysis was conducted to calculate the average area under ROC curve obtained by each observer (AUCave), and a statistical test was performed using the multi-reader multi-case method. Comparable results were obtained with pairs of portable (AUCave: 0.949) and conventional radiographs (AUCave: 0.951). In a comparison between the same modality, there were no significant differences. In contrast, the ability to identify patients by comparing a portable and conventional radiograph (AUCave: 0.873) was lower than with the matching datasets (p=0.002 and p=0.004, respectively). In conclusion, the use of different imaging modalities reduces radiographers' ability to identify their patients.

We investigated dose reduction ability of an iterative reconstruction technology for low-dose computed tomography (CT) for lung cancer screening. The Sinogram Affirmed Iterative Reconstruction (SAFIRE) provided in a multi slice CT system, Somatom Definition Flash (Siemens Healthcare) was used. An anthropomorphic chest phantom (N-1, Kyoto Kagaku) was scanned at volume CT dose index (CTDIvol) of 0.50-11.86 mGy with 120 kV. For noise (standard deviation) and contrast-to-noise ratio (CNR) measurements, CTP486 and CTP515 modules in the Catphan (The Phantom Laboratory) were scanned. Radiological technologists were participated in the perceptual comparison. SAFIRE reduced the SD values by approximately 50% compared with filter back projection (FBP). The estimated dose reduction rates by SAFIRE determined from the perceptual comparison was approximately 23%, while 75% dose reduction rate was expected from the SD value reduction of 50%.

Distal radius bone fracture is major disease for elderly people. As its cure needs fixing the wrist for long time, the wrist often stiffens up and the range of its motion tends to be restricted, which is generally called “contracture”. As the contracture interferes with their daily life, the speedy improvement of the contracture are strongly required. Thus, the rehabilitation of the wrist joint is necessary. Recently, the traction of the maniphalanx during flexing and extending the wrist joint is considered to be efficient as the rehabilitation procedure. However, the recovering mechanism by the traction is not clear. The investigation of its mechanism will improve the rehabilitation procedure and be available for development of rehabilitation equipment. However adjusting the magnitude and direction of the traction force to the maniphalanx applied manually during such rehabilitation procedure is almost impossible. Thus, we developed a rehabilitation equipment for the investigation. The equipment mainly consists of a wrist traction device and a round-rail base. The wrist traction device can pull maniphalanx toward finger direction by constant weights, and slide roundly. Thus, the equipment can applied the constant traction force to the wrist during flexing and extending the wrist joint. By the equipment, the dynamic motion of carpals in the wrist is observed by X-ray photography. As a result, it is found that the displacement range of radius - lunate joint (R-L joint) is extended by the traction. Namely, if R-L joint suffers contracture highly, the discussed rehabilitation procedure well moves R-L joint and can improve its movability.

Volume rendering (VR) is a technique commonly used for the reconstruction of three-dimensional (3D) digital subtraction angiography (DSA) images, and the rendering parameters greatly affect the characteristics of the 3D image. This study aimed to test whether the optimal VR parameters for 3D DSA could be estimated from the contrast effects in rotational two-dimensional (2D) DSA images acquired using 3D DSA. Simulated blood vessels filled with various concentrations of contrast medium were scanned, and the 3D DSA data sets were reconstructed. The syngo AX vessel analysis software that was able to analyze 3D DSA VR image was used for objective measures. Raw data projection images of the 3D DSA data sets in which the mean diameter was calculated as a true value by the software at nine different thresholds for vessel segmentation were selected. In each image set, five images of all 133 rotational 2D DSA images were selected, and the contrast-enhanced area was extracted using a region-growing algorithm. Mean values and standard deviations of each contrast-enhanced area were calculated, and as the thresholds for vessel segmentation of the software increased by 500 every time, significant differences were observed in the mean values (P

Dynamic chest radiography combined with computer analysis allows quantitative analyses on pulmonary function and rib motion. The accuracy of kinematic analysis is directly linked to diagnostic accuracy, and thus body motion compensation is a major concern. Our purpose in this study was to develop a computerized method to reduce a breathing body motion in dynamic chest radiographs. Dynamic chest radiographs of 56 patients were obtained using a dynamic flat-panel detector. The images were divided into a 1 cm-square and the squares on body counter were used to detect the body motion. Velocity vector was measured using cross-correlation method on the body counter and the body motion was then determined on the basis of the summation of motion vector. The body motion was then compensated by shifting the images based on the measured vector. By using our method, the body motion was accurately detected by the order of a few pixels in clinical cases, mean 82.5% in right and left directions. In addition, our method detected slight body motion which was not able to be identified by human observations. We confirmed our method effectively worked in kinetic analysis of rib motion. The present method would be useful for the reduction of a breathing body motion in dynamic chest radiography.

To evaluate the relationship between our proposed sonographic classification of testicular tumors by tissue harmonic imaging and histological type. We retrospectively analyzed 58 testicular tumors and tumor-like lesions [seminomatous germ cell tumor (SGCT): 28; non-seminomatous germ cell tumor (NSGCT): 16; lymphoid and hematopoietic tumor (LHT): 7; Leydig cell tumor: 1; epidermal cyst: 2; and tumor of paratesticular structure (TPS): 4]. We divided a sonographic image into six types for morphological criteria and three types for color Doppler criteria. We examined the relationship between the sonographic classification and histological type. For morphological criteria, there were 21 cases of Type I (36%), 15 Type II (26%), 9 Type III (15%), five Type IV (9%), five Type V (9%), and three Type VI (5%). For color Doppler criteria, there were 47 cases classified as hypervascular (81%), eight as hypovascular (14%), and three as avascular (5%). Most of the SGCTs were divided into types I and II; the NSGCTs into types III, IV, and V; the LHTs into only type II; and the TPSs into type VI. We established a sonographic classification of testicular tumors with various histological types. This sonographic classification is potentially useful for estimating the histological type of testicular tumors.

The non-local means method is a high-performance noise reduction method that utilizes the structural similarity of an image. The non-local means method generally assumes the noise is Gaussian, and the noise strength is distributed evenly over an image. In the normal non-local means, the weighting function for the noise reduction strength is controlled by a single fixed parameter. However, the non-local means method is not suitable for application to X-ray images, due to the existence of Poisson noise, in its current form. In this paper, we propose an image denoising method using non-local means for an image with Poisson noise. The weighting function in the proposed method adjusts the weight parameter based on the estimated noise strength from the pixels in a local region. As a result, the proposed method provides good noise reduction performance for Poisson noise without recourse to a variance stabilizing transformation. We demonstrate that the noise reduction of the proposed method is an improvement of 0.1–0.9 dB compared to the standard non-local means.

PURPOSE To design an evaluation method for lumbar spine and hip joint function using dynamic radiography using a flat-panel detector (FPD) system. METHOD Sixteen healthy subjects (males; age range, 22-60 years; median, 27 years) and 9 patients (7 males and 2 females; age range, 67-85 years; median, 73 years) with L4 degenerative spondylolisthesis were examined using a dynamic FPD system (CANON Inc.). Sequential images were captured with the subjects in the standing position with maximal forward bending followed by backward bending for 10 s. The lateral lumbar radiographs were obtained at 2 frames/s (fps). The flexion-extension angles of L1 and S1 were measured on those images. RESULTS AND DISCUSSION The range of motion (ROM) of the lumbar joints was significantly larger in the healthy group (82.4 ± 8.7°) than in the disease group (50.4 ± 8.5°; p

We evaluated clinical images to investigate the usefulness of adaptive iterative dose reduction algorithm (AIDR) in the field of acute cerebral infarction. We did receiver operating characteristic (ROC) analysis by 4 radiologists using 50 clinical images (abnormal case=24, normal case=26) which were reconstructed by AIDR and filtered back projection (FBP). The area under the curve (AUC) value from average ROC curve of observers were 0.79 with the FBP and 0.87 with the AIDR (P=0.31). The standard deviation of AUC was 0.06 with the FBP and 0.03 with the AIDR. More in detail, the AUC value of Expert group (over 10 years of experience) increased to 0.06 by using AIDR compared with FBP method. On the other hand, in Beginner group (less than 10 years of experience) there was 0.09 increase. Therefore, there was some possibility to reduce the variation of diagnostic accuracy among observer and the diagnostic accuracy improvement of the doctor in a few Experience group, by using AIDR for acute cerebral infarction computed tomography (CT) examination.

An image-processing technique for separating bones from soft tissue in static chest radiographs has been developed. The present study was performed to evaluate the usefulness of dynamic bone images in quantitative analysis of rib movement. Dynamic chest radiographs of 16 patients were obtained using a dynamic flat-panel detector and processed to create bone images by using commercial software (Clear Read BS, Riverain Technologies). Velocity vectors were measured in local areas on the dynamic images, which formed a map. The velocity maps obtained with bone and original images for scoliosis and normal cases were compared to assess the advantages of bone images. With dynamic bone images, we were able to quantify and distinguish movements of ribs from those of other lung structures accurately. Limited rib movements of scoliosis patients appeared as a reduced rib velocity field, resulting in an asymmetrical distribution of rib movement. Vector maps in all normal cases exhibited left/right symmetric distributions of the velocity field, whereas those in abnormal cases showed asymmetric distributions because of locally limited rib movements. Dynamic bone images were useful for accurate quantitative analysis of rib movements. The present method has a potential for an additional functional examination in chest radiography.