[Multicenter Follow-up Survey on Radiation Dose Levels in Cardiovascular X-ray Apparatus under Percutaneous Coronary Intervention Conditions].

It is important to optimize the exposure dose when conducting interventional radiology, but optimization is difficult for medical centers to achieve independently. In 2005, we administered a questionnaire on the measurement of dose rates and awareness of exposure reduction when performing percutaneous coronary intervention. Ten years later, we conducted a follow-up survey of the same 31 centers to determine the current situation and identify trends. The results of the survey showed that the mean fluoroscopy dose rate decreased to 55% of the 2005 value, from 28.2 to 15.6 mGy/min, and the mean radiography dose rate decreased to 71% of the 2005 value, from 4.2 to 3.0 mGy/s. Dose rates for both fluoroscopy and radiography decreased by 84% of facilities. The results also indicated greater cooperation by physicians compared to 10 years ago. In particular, there was a considerable increase in the exchange of ideas with physicians regarding exposure, suggesting a stronger level of interest in exposure. The overall score for questionnaire items was 33% higher than that in the previous survey. These results show that in the past 10 years, awareness of exposure reduction has improved, and dose optimization has been a major factor in the downward trend in dose rates in radiography and fluoroscopy.

[Multicenter Survey on Radiation Dose of Cardiac Intervention].

We conducted a nationwide survey of multiple institutions and collected data of various interventional procedures in the field of cardiology. Included in the analysis were 126 institutions, 381 X-ray systems, and 805 protocols. The dose values were compared with the Japanese diagnostic reference levels (DRLs) 2015. Fluoroscopy time, air kerma at the patient entrance reference point (Ka, r), and air kerma-area product (PKA ) were analyzed for various interventional procedures in 5,734 cardiology patients. The fluoroscopic dose rate (FDR) for pulmonary vein isolation (PVI) was less than half that of the 75th percentile of the Japanese DRLs 2015. The 75th percentiles of fluoroscopy time, Ka, r, and PKA for the respective interventional procedures were as follows: 11.0 min, 735 mGy, and 64 Gyï½¥cm2 for diagnostic coronary angiography (CA); 13.2 min, 839 mGy, and 75 Gyï½¥cm2 for CA + left ventriculography; 34.4 min, 1,810 mGy, and 148 Gyï½¥cm2 for percutaneous coronary intervention (PCI) excluding chronic total occlusion; 80.1 min, 4,338 mGy, and 312 Gyï½¥cm2 for PCI for chronic total occlusion; 74.4 min, 833 mGy, and 90 Gyï½¥cm2 for PVI; and 34.0 min, 795 mGy, and 94 Gyï½¥cm2 for transcatheter aortic valve implantation, respectively. In assessing dose values in interventional radiology, the difficulty of the technique needs to be considered, and the DRL values for FDR, fluoroscopic time, Ka, r, and PKA for each interventional procedure are considered necessary when reassessing or updating DRLs.

A study on fluoroscopic images in exposure reduction techniques - Focusing on the image quality of fluoroscopic images and exposure images.

The quality of the present day fluoroscopic images is sufficiently high for use as exposure images depending on the environment where the fluoroscopic images are recorded. In some facilities which use fluoroscopic images as exposure images they are recorded with a radiological x-ray diagnostic device equipped with a fluoroscopic storage function. There are, however, cases where fluoroscopic images cannot be used as exposure images because the quality of the fluoroscopic image cannot be assured in the environment where the fluoroscopic images are recorded. This poses problems when stored fluoroscopic images are used in place of exposure images without any clearly established standard. In the present study, we establish that stored fluoroscopic images can be used as exposure images by using gray values obtained from profile curves. This study finds that replacement of stored fluoroscopic images with exposure images requires 20.1 or higher gray scale value differences between the background and signal, using a 20 cm thick acrylic phantom (here an adult abdomen as representing the human body) as the specific geometry. This suggests the conclusion that the gray value can be considered a useful index when using stored fluoroscopic images as exposure images.

[Multicenter Survey of the Display Air Kerma and Actual Measured Values in IVR X-ray Apparatus].

PURPOSE: We conducted a multicenter study to investigate the current status of difference between the actual values at the patient entrance reference point (PERP) and display air kerma. METHODS: We exposure dose and fluoroscopy dose were measured by 32 apparatuses at 32 member institutions of the Japanese Society of Circulation Imaging Technology (CITEC) under unified conditions, and the actual measured values and display air kerma were compared. We entrance doses during fluoroscopy and imaging were measured at the PERP, with focus detector distance (FDD) 110 cm, a copper plate of 3.5 mm in thickness adhered to the front face of flat panel detector (FPD) as absorber, field-of-view (FOV) 18 cm, and the frame rate of 15 f/s, excluding the bed. Display air kerma were recorded at the same time. JIS (Z 4751-2-43: 2012) specify "The reference air kerma rate and the cumulative reference air kerma shall not deviate from their respective display air kerma by more than ±35% over the range of 6 mGy/min and 100 mGy to the maximum value." The number of apparatuses display air kerma deviated from this condition and its percentage were obtained. RESULTS: The mean difference percentage between actual measured values and display air kerma in 32 apparatuses was approximately 15.6%, with some apparatuses showing substantially different display air kerma. CONCLUSION: In order to estimate patients' skin exposure dose from display air kerma more accurately, it is necessary to perform calibration of the apparatus by regular dose measurement or convert values.

[Standardization of Analysis Conditions and Prediction of Increase Prediction Using Blood Flow Analysis Software for Cerebral Aneurysms: Phantom Study and Clinical Study].

In recent years, reports have been made that predict the state of aneurysm by performing computational fluid dynamics (CFD) analysis using cerebral aneurysm blood flow analysis software. However, analysis results are not constant and there are various opinions, and it is conceivable that the image quality and analysis conditions of medical images used for CFD analysis are not standardized. In this study, CFD analysis of cerebral aneurysm phantom was performed, and image quality and analysis conditions were standardized. Then, we investigated whether increase of cerebral aneurysm and prediction of rupture are possible. From this study, stable results of wall shear stress analysis were obtained under slice thickness 1.0 mm or less, CT value 400 HU or more, reconstruction function as soft part function, image SD under 10 HU. In addition, as the size of the cerebral aneurysm became larger, wall shear stress tended to be lower, and the same tendency was shown also in clinical cases. Although CFD analysis using software dedicated to blood flow analysis did not reach the prediction of rupture, it can be evaluated based on the quantitative values for the aneurysm increase at the preceding stage and plays an important role in prediction there is a possibility.

Evaluation of image lag in a flat-panel, detector-equipped cardiovascular X-ray machine using a newly developed dynamic phantom.

We developed a dynamic phantom for use in routine checks. This phantom can be used to physically evaluate image lag that occurs in dynamic images. It has a unique measurement method. ROIs on the target are chosen, and, with the position of ROIs fixed on the image, changes in pixel value are detected physically when the target passes through the ROIs over time and perceived as image lag. Thus, it was possible to physically detect different intensities of image lag lasting less than one second while maintaining the same intensity trends. The checking technique we propose with the dynamic phantom that we developed could be effective for routine checking of fluoroscopy X-ray machines, and could become an established method.

[Usefulness of virtual vessel images in ppi for treatment of complete obstruction of leg arteries].

Following recent rapid advances in devices and treatment technology, indications for percutaneous peripheral intervention (PPI) have been expanded to include complex lesions (long-segment lesions, completely obstructed chronic lesions, etc.) and even lesions of the superficial femoral artery and arteries distal to the popliteal artery. However, when PPI is used for treatment of complete obstruction, treatment can take a long time or its outcome can be less satisfactory for reasons such as difficulty in assessing the vascular distribution/arrangement or the direction of calcification in the obstructed area or excessively long lesions. In the present study, we conducted three-dimensional image processing of CT data from leg arteries conventionally used for preoperative diagnosis. Using this processing technique, we created virtual images of the blood vessels of the completely obstructed area and mapped these virtual vessel images onto the fluoroscopic monitor image during catheter treatment. The usefulness of this technique for PPI was then evaluated. We succeeded in creating virtual vessel images of the completely obstructed parts of leg arteries with the use of preoperative CT images of leg arteries that we then mapped onto the fluoroscopic monitor images during treatment. We were successful in mapping virtual images onto the abdominal aorta in 96.8% of cases and in 95.7% with the common iliac artery. This technique is thus able to supply reliable information on vascular distribution/arrangement, suggesting that it can enable the surgeon to advance the treatment device precisely along the vessels, making it useful for treatment with PPI. The study additionally showed that differences in the angle of imaging affect the manual mapping of the CT images onto angiograms.

[A review of the position adopted by patients when acquiring images of the base of the hamate hook].

The hamate bone, one of the carpal (wrist) bones, has a large uncinate process protruding from the palm side. In sports such as golf and tennis, the hamate bone can break if is subjected to a high external force, such as from the handle of a racquet or club. At our hospital we take X-ray images of the hamate bone from two directions: an axial image through the carpal tunnel and an image at the base of the hamate hook (conventional method). While the conventional method makes it easy to create images of the base of the hamate hook, the patient may suffer pain during image-taking because the hamate bone is pulled to cause radial flexion. We therefore investigated a method of imaging that would create three-dimensional computed tomography (3DCT) images of the base of the hamate hook in which the patient would only have to only rotate the wrist externally and elevate the fore-arm without any radial flexion. Our results suggest that it is possible to obtain images of the base of the hamate hook as clear as those acquired using the conventional method with the patient in a comfortable and painless position taking images at an external rotation angle of 50.3° and a forearm elevation angle of 20.3°.

[Nationwide Questionnaire Survey on Disaster Power Outage Countermeasures in the Radiology Departments of Hospitals].

PURPOSE: To identify the countermeasures and current status of disaster power outages in the radiology departments of hospitals. METHODS: A web-based questionnaire survey of 600 hospitals nationwide was conducted. The questionnaire survey covered 34 items, including availability of power in the radiology department in the event of a disaster and the impact of power outages on medical equipment in the radiology department. RESULTS: In all, 242 facilities (40.3%) responded to our survey. During power outages, 55.8%-68.2% of facilities were able to use CT, digital radiography, and angiography systems with their private generators. In 28.1%-40.7% of facilities, medical information systems were not available in all laboratories. In addition, power outages caused equipment malfunctions in 81.4% of facilities' radiology departments. CONCLUSION: We have identified the power supplied by private generators to the radiology department's medical equipment and medical information systems. Many medical equipment have malfunctioned due to power outages. Therefore, drills should be conducted to simulate various situations caused by power outages.

[Proposal for an auxiliary tool designed to reduce retake rates for lateral radiography of the knee joint].

The reproducibility of lateral radiography of the knee joint in the lateral position is low because patient positioning can be easily affected by passive rotation of the knee joint. We calculated the correction angle of the femoral external rotation and the lower leg elevation and developed our own auxiliary tool for obtaining a lateral view image. We were able to obtain, in a single attempt, an image with misalignment of the condyle limited to less than 7 mm. Our tool also contributed to the reduction of the re-imaging rate, suggesting its usefulness in contributing to a lower re-imaging rate for lateral radiography of the knee joint.

[Observations of deterioration of photo-stimulable phosphor plates used in digital mammography and its effects on mammography diagnoses].

We noted that breast-like artifacts occur in photo-stimulable phosphor plates (PSPs) used for long periods in digital mammography systems. This prompted us to investigate the effects on mammography diagnoses of these artifacts. Our study took the form of a comparison between the images generated by a long-term use PSP (four years use) and a short-term use PSP. First, an acrylic phantom and an in-house-made phantom for visual evaluation were imaged using X-ray PSPs under the same exposure conditions. They were then scanned under the same conditions to generate images. The mean values of the digital signals were measured in the 35 locations of region of interest present in the images of the acrylic phantom. The images of the in-house-made phantom were then visually evaluated by five certified experts, who examined 22 clinical images taken with both PSPs while referring to a visual evaluation scale. Differences were detected in all the evaluated items: the short-term use PSP gave a higher rate than the long-term use PSP (p<0.01), suggesting that long-term use PSPs might adversely affect the results of diagnostic mammography.

Evaluation of the Performance of Different Types of Radiation Protection Gloves: A Cross-sectional Study.

ABSTRACT: Radiation exposure of a practitioner's fingers is a problem in interventional radiology, and radiation protection gloves (protective gloves) can help reduce such exposure. Several types of protective gloves are commercially available from various manufacturers. In the present study, we compared the protective effects and usability of four types of protective gloves. To investigate the radiation protection effect, we placed normal surgical gloves and the four types of protective gloves on phantom hands with thermoluminescent dosimeters (TLD) attached to the fingertips and the dorsum and palms of the hands. Next, they were irradiated with x rays, and the radiation dose was measured and compared using the TLDs. In terms of usability, 42 medical staff members completed a questionnaire that included seven items, such as finger movability, tactile sensation, grip, and overall satisfaction, which were scored on a 5-point scale. Consequently, the protective effects differed between the gloves, and radiation exposure was lower by 30% to 60% with these gloves compared with surgical gloves. In terms of usability, a difference of 2 to 4 points was noted between the gloves for each questionnaire item. These results suggest that radiation protective gloves can protect the surgeon's fingers from radiation exposure without reducing work efficiency by selecting gloves according to the surgical procedure.

[Relationship between Left Ventricle Myocardium Volume in Coronary Territories' Analysis and Fractional Flow Reserve].

This study aimed to investigate the feasibility of estimating functional ischemia information from coronary artery computed tomography (CACT) data (i.e., morphological information). Fifty-five suspected ischemic heart disease patients were included in this study. To calculate the ischemic myocardium percentage (LV myocardial territories volume of distal portion the stenotic lesion/total LV myocardial volume) from CACT data with "coronary territories analysis, Ziostation2", and compared with the ischemic LV myocardium percentage and the functional flow reserve (FFR). The results showed that ischemic LV myocardium percentage was correlated with the FFR (r=-0.57). The median ischemic LV myocardium percentage of the FFR-positive group (n=33) was 37.1% (interquartile range [IQR] 33, 41.4%) and that of the FFR-negative group (n=22) was 24.8% (IQR 19.6, 30.6%). The ischemic LV myocardium percentage was significantly higher in the FFR-positive group (p<0.01) than in the FFR-negative group. The receiver operating characteristic (ROC) curve showed that the cutoff value for the ischemic LV myocardium percentage was 30%, with the sensitivity of 90.9% and the specificity of 77.3%. In conclusion, myocardial ischemia to diagnosis of FFR may occur when ischemic LV myocardium percentage is over than 30% and is unlikely to occur when it is less than 30%. This study suggests that the analysis of CACT data may contribute to the diagnosis of functional ischemia.

[Multicenter Evaluation of Cine Angiography and Digital Subtraction Angiography Dose Rate for Various Angiography Programs: Comparison with Fluoroscopic Dose Rate].

We conducted a nationwide multicenter survey of various interventional radiology (IVR) procedures. Data were collected from 385 X-ray systems in 126 institutions, including 432 cine programs and 380 digital subtraction angiography (DSA) programs for diagnostic catheterization, percutaneous coronary intervention (PCI), ablation, transcatheter aortic valve implantation (TAVI), neurologic IVR, thorax IVR, abdominal IVR, and endovascular therapy (EVT). Fluoroscopic and cine dose rates were 10.1 mGy/min and 110.7 mGy/min, respectively, whereas for DSA programs, the median fluoroscopic and DSA dose rates were 8.0 mGy/min and 224.8 mGy/min, respectively. The DSA dose rate was more than twice the cine dose rate. The largest difference between dose rates was for diagnostic catheterization, which had a cine dose rate of 142.6 mGy/min and a fluoroscopic dose rate of 12.6 mGy/min (by a factor of 12.5), followed by EVT, which had a DSA dose rate of 216.0 mGy/min and a fluoroscopic dose rate of 7.7 mGy/min (by a factor of 29.6). The smallest difference between dose rates was for TAVI, which had a cine dose rate of 96.8 mGy/min and a fluoroscopic dose rate of 12.0 mGy/min (by a factor of 8.9), followed by neurologic IVR, which had a DSA dose rate of 227.9 mGy/min and a fluoroscopic dose rate of 9.6 mGy/min (by a factor of 22.6). Compared with the fluoroscopic dose rates, the cine dose rates were 9-13 times higher and the DSA dose rates were 22-30 times higher; the DSA dose rates were more than double the cine dose rates.

[The Effect of Radiation Protection Education for the Operators' Ocular Lens in Cardiac Catheterization].

The purpose of this study was to educate operators regarding cardiac catheterization using radiation protection slides prepared for this study and to consider whether or not this radiation protection education contributes to reducing the exposure of the operator's ocular lens. Thermoluminescent dosimeter (TLD) was installed at the outside left, inside left, outside right, and inside right of the X-ray protective eyewear of the operators performing the cardiac catheterization. The exposure dose rate before and after radiation protection education for 3 operators performing cardiac catheterization was compared. The exposure dose ratio was defined by dividing the TLD measurement value, which is the air kerma calculated by the X-ray diagnosis apparatus for the angiography. In other words, this can calculate the ratio of how much the operators are exposed to radiation from the dose of the patient per examination. When comparing the radiation dose ratio obtained from the dosimeter installed on the right outer side before and after education, p-value was <0.05 in the left anterior oblique-cranial and right anterior oblique- cranial, and a significant difference was recognized. The radiation protection education carried out in this study contributes to a reduction in the exposure dose of the operators.

[Improvement of method of determining fluoroscopy loading factor in digital angiographic x-ray system with a flat panel detector].

A catheterization study and treatment of coronary arteriopathy are performed by investigating the coronary artery from different angles to find the region to be treated. In doing so, our system always started from the initial value of the loading factor, using this only for the first time, and the system started from the last loading factor the second time and later, at all angles. Therefore, depending on the angle, the loading factor at the start of fluoroscopy sometimes became unstable, and it took time to stabilize. This made the starting image too dark (undershoot x-ray condition) or fogged by halation (overshoot x-ray condition). With the system manufacturer, we developed a tube voltage and tube current setting method for the initial value of the loading factor. We installed software which preset the loading factor at the start of fluoroscopy depending on the angle, and an auto memory function of the last loading factor for each angle. This function allows the system to control the tube voltage and tube current for any angle. As a result, the system can acquire a more stabilized image from the start of fluoroscopy. This method of determining the initial loading factor is an effective way to stabilize the fluoroscopy image quickly.

[Examination of safety improvement by failure record analysis that uses reliability engineering].

How the maintenance checks of the medical treatment system, including start of work check and the ending check, was effective for preventive maintenance and the safety improvement was verified. In this research, date on the failure of devices in multiple facilities was collected, and the data of the trouble repair record was analyzed by the technique of reliability engineering. An analysis of data on the system (8 general systems, 6 Angio systems, 11 CT systems, 8 MRI systems, 8 RI systems, and the radiation therapy system 9) used in eight hospitals was performed. The data collection period assumed nine months from April to December 2008. Seven items were analyzed. (1) Mean time between failures (MTBF) (2) Mean time to repair (MTTR) (3) Mean down time (MDT) (4) Number found by check in morning (5) Failure generation time according to modality. The classification of the breakdowns per device, the incidence, and the tendency could be understood by introducing reliability engineering. Analysis, evaluation, and feedback on the failure generation history are useful to keep downtime to a minimum and to ensure safety.

Relationship Between Coronary Fractional Flow Reserve and Computational Fluid Dynamics Analysis in Moderate Stenosis of the Coronary Artery.

Background: Fractional flow reserve (FFR) is used to evaluate the need for percutaneous coronary intervention (PCI) in cases of moderate stenosis of the coronary artery. Recently, diagnostic imaging support with computational fluid dynamics (CFD) analysis has been garnering attention. This study defines the relationship between FFR conducted for cardiac catheterization and CFD analyses conducted using coronary computed tomography (CT) for moderate stenosis, in addition to considering whether wall pressure (WP) and wall shear stress (WSS) can be used to evaluate ischemia. Methods and Results: Cases in which FFR was measured via coronary CT and cardiac catheterization was performed within 3 months were collected retrospectively. In the CFD analysis, WP and WSS were calculated and compared with FFR. Three groups were created to compare results of CFD analysis and FFR values according to the location of the stenosis: the right coronary artery, the left anterior descending artery, and the left circumflex artery. There was a correlation between FFR and WSS according to CFD analysis for moderate stenosis of the coronary artery, with a cut-off value for treatment able to be calculated. Conclusions: The results of this study suggest that ischemia can be evaluated by conducting CFD analysis (WSS) using coronary CT.

High-accuracy prediction of carcinogenicity by global quantitative analysis of post-translational modifications in a 28-day in vivo rat study.

A global quantitative analysis of post-translational modifications (PTMs) of distinct proteins was executed at the proteomic level using two-dimensional fluorescence differential gel electrophoresis. We evaluated the effects of 66 chemical compounds, including 15 genotoxic carcinogens, 28 non-genotoxic carcinogens, and 23 non-carcinogens, in the male F344 rat liver in a 28-day repeated dose study. In the master gel of rat liver protein, we identified 728 spots by hybrid quadrupole time-of-flight mass spectrometry. They collapsed into 356 distinct proteins. Of these, 126 were represented by two or more spots in the 2-D gel. We calculated the logarithmic ratio of volume changes of all 1028 combinations generated from 126 proteins and investigated the relevance to carcinogenicity. This quantitative proteomic study revealed the existence of several PTMs characteristic of carcinogens that may play an important role in early stage of carcinogenicity. Prediction of carcinogenicity from PTM data gave a higher concordance (92.4%) than prediction from protein expression data (74.2%). This novel approach holds great promise as a way of revealing the roles of charge modifications and molecular weight variations of proteins in biological processes.

[Exposed dose comparison between coronary computed tomographic angiography and coronary angiography: basic examination by phantom].

The new type of coronary angiography(CAG)that uses 40 mm volumetric computed tomography(VCT)has great potential for cardiac disease. However, it is still necessary to be cognizant of exposure dose. We measured doses of CAG by both VCT and cardiovascular X-ray using a body phantom within 170 glass dosimeters. VCT protocols were 120 kV, 570 mA, and 0.35 sec/rot with and without the dose-reduction features(small cardiac X-ray beam filter and ECG mA modulation). The cardiovascular X-ray protocol was Auto(65 - 77 kV)kV, Auto(41 - 46 mA)mA, 5 secx11 shots+11 min fluoroscopy(minimum protocol for screening). VCT with and without the dose-reduction features has the same dose distribution, however, the dose-reduction features reduced the amount of dose by about 40-50%. For VCT with those features, measured dose was about 70 mGy in the cardiac area and 60 mGy at the skin of the back, whereas those of cardiovascular X-ray were 10 mGy and 30 mGy. We measured detailed dose distributions and variations in the phantom, and we also demonstrated the possibility of VCT's dose-reduction features. The CT dose was still higher than that of cardiovascular X-ray, however, there were advantages of CT scanning, for instance, information about calcification, soft plaque, and 3D visualization. We think it is important to use both systems with an understanding of their advantages and limitations.