Effect of protective glasses on radiation dose to eye lenses during whole breast irradiation.

OBJECTIVES: The efficacy of radiotherapy for breast cancer has greatly improved owing to better irradiation methods. Radiotherapy aims to deliver therapeutic doses to predetermined target volumes while sparing surrounding healthy tissues. However, there are few reports on radiation exposure to eye lenses, and the recommended exposure limits to ocular lens have been substantially reduced in recent years. This study aimed to investigate the amount of radiation exposure to eye lenses using optically stimulated luminescence dosimeters (OSLDs) and determine whether wearing special protective devices to protect the eyes, as an organ at risk, during whole breast irradiation, is necessary. METHODS: This experiment used OSLDs on water-equivalent phantom to measure the change in scattered radiation dose due to the difference of irradiation field while using 4- and 6-MV photons of TrueBeam linear accelerator. Using a total treatment dose of 50 Gy, a target was positioned to approximate the breast, and a plan was formulated to deliver 2 Gy per treatment by tangential irradiation. The mean (SD) irradiation dose at the lens position outside the irradiation field was reported. RESULTS: The scattered radiation dose outside the irradiation field was more affected by the irradiation field size than by the radiation energy. The out-of-field irradiation dose with a larger field of view was higher than that with a smaller field of view. The use of 0.07- and 0.83-mm-thick lead shield protective glasses reduced the radiation dose by 56.1% (P < .001) and 55.6% (P < .001), respectively. CONCLUSIONS: In this experimental model, the amount of radiation the eye was exposed to during whole breast irradiation was determined by the distance of the eye from the radiation field edge and by wearing protective glasses. In clinical practice, the protection offered by eyeglasses may reduce the risk of long-term side effects and allow the use of higher intensive radiotherapy.

Development of a dynamic blood vessel phantom for evaluation of moving images.

In coronary angiography (CAG) and percutaneous coronary intervention (PCI), it is important for radiological technologists to optimize the balance between radiation dose and image quality for physicians to be able to perform CAG and PCI most effectively. Evaluation of image processing is necessary to ensure that technologists can optimally adjust image quality for clinical use to the extent that physicians require. However, few phantoms are available for evaluating fluoroscopic image processing, and this makes it necessary to adjust image quality in clinical settings while utilizing the image processing according to the manufacturer's recommendations. In this study, we developed a dynamic phantom that mimics a pulsating coronary artery for use in image quality analysis of moving images. We also examined whether processed images (image lag) can be physically analyzed. Two issues require special attention in creating a new phantom: establishing the exact position of the simulated blood vessel in the phantom, and providing good reproducibility. The study used the rotational motion of a disk to generate images, with a circular simulated blood vessel on the rotating acrylic disk, with the center of the simulated blood vessel shifted from the center of the acrylic disk. This enabled the reproduction of translational motion of the simulated blood vessel. As a result, because this phantom has signals and afterimages at the same position (of a simulated blood vessel), a quantitative evaluation of the afterimages became possible. In the evaluation of the image processing with the angiograph, it was shown that evaluations of image lag which are typically performed in clinical settings can be performed with the dynamic blood vessel phantom.

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.

[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 the Image Registration Program for Portal Images Using CR and DRR Images in Radiation Therapy].

In this study, computer simulations and experiments were used to verify the accuracy of a two-dimensional image registration program (program) for portal images that we previously developed. The program used a computed radiography cassette system and digitally reconstructed radiography images as planning images for external beam radiation therapy. Using this program, we also investigated the reason two-dimensional automatic image registration images experienced large misregistration in clinical practice using commercial image registration systems. Mutual information and normalized mutual information were used as the registration criteria. To investigate the influence of image background with or without a region of interest (ROI), results of image registrations were compared. Parameters of image registration were defined as translation in the horizontal and vertical directions (x and y, respectively) and rotation (θ) around the axis perpendicular to the x-y plane. There was no significant difference in image registration arising from the difference between mutual information and normalized mutual information. Image registration was improved with a ROI. Regardless of the registration criteria, errors in image registration with a ROI in the experimental study were ≤1.2 mm in directions x and y and ≤1.0 degree in rotation θ. We found that image registration required setting up as close to the planned position as possible.

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.

[Study of heart region of interest setting method in the hepatic functional reserve index of (99m)tc-diethylenetriamine pentaacetic Acid-galactosyl human serum albumin].

In this study we analyzed the influence of region of interest (ROI) selection on the uptake ratio of the liver to the liver plus heart at 15 min (LHL15) during (99m)Tc-galactosyl human serum albumin (GSA) scintigraphy and determined the optimal ROI by evaluating the individual effects of different ROIs in the heart on LHL15. Twenty patients were randomly selected from those who had undergone (99m)Tc-GSA scintigraphy GSA between April 2008 and June 2009. The liver body (L/B) ratio, liver uptake 15 min (LU15), and LHL15 were analyzed and compared among the following ROIs: entire heart, both ventricles, right ventricle, and left ventricle. There were significant differences in the L/B ratio and LU15 values among the different ROIs. However, LHL15 showed a tendency to shift toward a normal value when the size of the ROI was small (only the right or left ventricle), resulting in a lack of distinction between normal and abnormal LHL15 values. Furthermore, setting the entire heart as the ROI was difficult and reproducibility was low. Our results suggest that the use of both ventricles as the ROI provides optimal LHL15 values during (99m)Tc-GSA scintigraphy.

[Examination of the shoulder joint using true anterior-posterior photography, employing a body surface index].

Radiographic examination of the anterior part of the shoulder includes routine anterior-posterior imaging that enables easy visualization of traumatic injuries and true anterior-posterior imaging that enables the visualization of intra-articular injuries. The X-ray incident angle of true anterior-posterior imaging is affected by physique and posture. However, in many reports, the angle is uniformly determined on the basis of the antero-posterior axis and the horizontal plane. We previously reported that the glenohumeral joint can be visualized with good reproducibility by establishing a reference line on the basis of three points on the body as indicators, namely the posterior view of the under-surface of the acromion, the coracoid process, and the inferior angle of the scapula. However, visualizing the undersurface of the acromion using physical indicators to set the angle for imaging remains problematic. In previous reports, the angle was consistently set at 20° to the horizontal plane, regardless of physique or posture, which resulted in poor reproducibility. After examining the imaging techniques described in previous reports, we describe here an imaging technique using a reference line based on indicators on the surface of the scapula that enables the glenohumeral joint and the undersurface of the acromion to be visualized with good reproducibility.

[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°.

[Basic MRI Study in the Imaging Direction of a Diffusion-weighted Whole Body with Background Body Signal Suppression].

A diffusion-weighted whole body with background body signal suppression (DWIBS) is usually imaged as a whole body with Transverse (Tra). However, Tra has a large number of stations and a larger number than Coronal (Cor), so the scan time is longer. There are also drawbacks, such as signal unevenness between series. It is known that the effect of distortion is large in Cor. There is no report on it in Sagittal (Sag). Therefore, in this study, we focused on Sag and examined the imaging time, image distortion, fat suppression effect, and continuity between stations. In the examination by the phantom, the scan time was the shortest for Cor and the longest for Sag. In the strain evaluation, the effect of strain could be suppressed compared to Cor by using a rectangle field of view (FOV) in the anterior to posterior (AP) direction in Tra and Sag. There was no difference in the fat suppression effect depending on the imaging direction. Similar results were obtained in a study of 10 healthy volunteers, with Sag having the best continuity between stations.

[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.

[Effect of Kiken-Yochi training (KYT) induction on patient safety at the department of radiological technology].

PURPOSE: In this report, we evaluated whether radiological technologists' (RTs') awareness of patient safety would improve and what kind of effects would be seen at the department of radiological technology by introducing KYT [K: kiken (hazard), Y: yochi (prediction), T: (training)]. METHODS: KYT was carried out by ten RTs based on a KYT sheet for the department of radiological technology. To evaluate the effects of KYT, we asked nine questions each to ten participants before and after KYT enforcement with regard to their attitude to patient safety and to operating procedures for working safely. RESULTS: Significant improvements after KYT enforcement were obtained in two items concerning medical safety: It is important for any risk to be considered by more than one person; The interest in preventive measures against medical accident degree conducted now) and one concerning operating procedures (It is necessary to have a nurse assist during testing with the mobile X-ray apparatus) (p<0.05). CONCLUSIONS: Performing KYT resulted in improved awareness of the importance of patient safety. KYT also enabled medical staffers to evaluate objectively whether the medical safety measures currently performed would be effective for patients.

[Examination of Optimization of Exposure Dose by IVR Procedure Based on DRLs 2020].

DRLs 2020 has been revised, and Ka,r and PKA for each procedure have been set for IVR along with the reference fluoroscopic dose rate. The total dose of IVR includes fluoroscopic and digital acquisition (DA) doses, but in actual clinical practice, the ratio varies greatly depending on the procedure (diagnosis/treatment purpose and procedure content), and there are not many detailed data on the ratio. Therefore, we evaluated previous efforts that optimized radiation protection through examining dose for each procedure and the ratio of fluoroscopic and DA doses to total dose, and reviewing protocols. Since the ratio of fluoroscopy and DA dose differs depending on the procedure, it was suggested that the radiation dose exposed to patients can be optimized by sharing the dose information with physicians and constructing a protocol while considering the image quality for each procedure.

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.

[Development of the Radiation Protective Curtain for the Dose Reduction of Caregivers during Computed Tomography Examinations].

PURPOSE: During computed tomography (CT) examinations, it may be necessary to assist the patient to maintain an appropriate body position. However, there is little protective equipment available for caregivers who approach the gantry. This study aimed to evaluate the effectiveness of novel radiation protective curtains in reducing radiation exposure to caregivers while assisting patients, especially during CT examinations of the head. METHOD: The absorbed dose in air around the gantry during CT examinations of the head was measured using glass dosimeters. The measurement points from the center of the gantry were 40 to 120 cm in the front, 0 to 100 cm for each side in the right and left, and 60 to 180 cm from the floor. Measurements were performed at each 20-cm interval, and all points were accumulated 10 times. The absorbed dose in air in a CT room was compared with and without the protective curtains. Next, we assumed the height of the caregiver to be 170 cm, and measured the points for the crystalline lens, chest, and abdomen. Also, using the protective glasses and the protective apron, we measured the absorbed dose in air for the caregivers behind the protective curtains. RESULT: The absorbed exposure dose in air toward the crystalline lenses, chest, and abdomen was reduced more than 90% by using the protective curtains and more than 95% by using the protective apron and protective glasses in addition to them. CONCLUSION: This study showed the usefulness of protective curtains in reducing the absorbed exposure dose in air to caregivers.

[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.

Semiautomatic Treatment Planning for the Field-in-field Technique in Whole Brain Irradiation.

Objectives: In radiation therapy, the field-in-field (FIF) technique is used to prevent the administration of unnecessarily high doses to reduce toxicity. Recently, the FIF technique has been used for whole brain irradiation (WBI). Using the FIF technique, the volume that receives a higher than prescribed dose (hotspot) can be largely reduced; however, the treatment planning requires time. Therefore, to reduce the burden on the treatment planners, we propose a semiautomatic treatment planning method for the FIF technique. Methods: In the semiautomatic FIF technique, hotspot regions in a treatment plan without the FIF technique are identified three-dimensionally, and beams with blocks that cover the hotspot regions using a multileaf collimator (sub-beams) are automatically created. The sub-beams are added to the original plan, and weights are assigned based on the maximum dose of the original plan to decrease the doses in the hotspot regions. This method was applied to 22 patients previously treated with WBI, wherein treatment plans were originally created without the FIF technique. Results: In the semiautomatic FIF plans, the hotspots almost disappeared. The dose to 95% of the volume and the volume receiving at least 95% of the prescribed dose in the planning target volume decreased by only 0.3% ± 0.2% and 0.0% ± 0.1%, respectively, on average compared with those in the original plan. The average semiautomatic FIF processing time was 28 ± 4 s. Conclusions: The proposed method reduced the hotspot regions with a slight change in the target coverage.

Optimal apheresis treatment volume for the efficacy and safety of leukocytapheresis with Cellsorba in patients with active ulcerative colitis.

BACKGROUND: Leukocytapheresis (LCAP) is used as an adjunct therapy for patients with active ulcerative colitis (UC). Although, LCAP is routinely performed at 3,000 mL per session, we were interested to see that if this can be replaced with bodyweight (BW) adjusted volume. METHODS: In an open label prospective trial, the clinical response to BW adjusted LCAP (BWA-LCAP) was evaluated in 14 patients with active UC. Fourteen demography matched UC patients who had been treated with the routine 3,000 mL LCAP were randomly sampled from our database as a control group. All patients were given 10 weekly LCAP sessions. In the BWA-LCAP group, the processed blood volume (PBV) was set at 30 mL/kg × BW/session. Baseline demographic measures were not significantly different between the two groups. RESULTS: The average PBV in the BWA-LCAP group was 1971.0 ± 330.0 mL, range 1,020-2,460. In both groups, the average UC clinical disease activity index, the endoscopic index, and the concomitant prednisolone dosage were significantly and equally reduced during the course of 10 LCAP. Accordingly, at the end of the trial, no significant difference was seen in any outcome measure between the two groups. However, a significantly higher incidence of adverse event (AE) was observed in the routine 3,000 mL LCAP group as compared with the BWA-LCAP group (P < 0.01). CONCLUSIONS: The outcomes of this investigation showed that the therapeutic efficacy of LCAP based on 30 mL/kg × BW is similar to the routine 3,000 mL per session LCAP. However, BWA-LCAP should be favored if one is to see the full potential of LCAP without AE.

CT urography in the urinary bladder: to compare excretory phase images using a low noise index and a high noise index with adaptive noise reduction filter.

BACKGROUND: Although CT urography (CTU) is widely used for the evaluation of the entire urinary tract, the most important drawback is the radiation exposure. PURPOSE: To evaluate the effect of a noise reduction filter (NRF) using a phantom and to quantitatively and qualitatively compare excretory phase (EP) images using a low noise index (NI) with those using a high NI and postprocessing NRF (pNRF). MATERIAL AND METHODS: Each NI value was defined for a slice thickness of 5 mm, and reconstructed images with a slice thickness of 1.25 mm were assessed. Sixty patients who were at high risk of developing bladder tumors (BT) were divided into two groups according to whether their EP images were obtained using an NI of 9.88 (29 patients; group A) or an NI of 20 and pNRF (31 patients; group B). The CT dose index volume (CTDI(vol)) and the contrast-to-noise ratio (CNR) of the bladder with respect to the anterior pelvic fat were compared in both groups. Qualitative assessment of the urinary bladder for image noise, sharpness, streak artifacts, homogeneity, and the conspicuity of polypoid or sessile-shaped BTs with a short-axis diameter greater than 10 mm was performed using a 3-point scale. RESULTS: The phantom study showed noise reduction of approximately 40% and 76% dose reduction between group A and group B. CTDI(vol) demonstrated a 73% reduction in group B (4.6 ± 1.1 mGy) compared with group A (16.9 ± 3.4 mGy). The CNR value was not significantly different (P = 0.60) between group A (16.1 ± 5.1) and group B (16.6 ± 7.6). Although group A was superior (P < 0.01) to group B with regard to image noise, other qualitative analyses did not show significant differences. CONCLUSION: EP images using a high NI and pNRF were quantitatively and qualitatively comparable to those using a low NI, except with regard to image noise.