Radiation exposure in augmented fluoroscopic bronchoscopy procedures: a comprehensive analysis for patients and physicians.

Cancer is a major health challenge and causes millions of deaths worldwide each year, and the incidence of lung cancer has increased. Augmented fluoroscopic bronchoscopy (AFB) procedures, which combine bronchoscopy and fluoroscopy, are crucial for diagnosing and treating lung cancer. However, fluoroscopy exposes patients and physicians to radiation, and therefore, the procedure requires careful monitoring. The National Council on Radiation Protection and Measurement and the International Commission on Radiological Protection have emphasised the importance of monitoring patient doses and ensuring occupational radiation safety. The present study evaluated radiation doses during AFB procedures, focusing on patient skin doses, the effective dose, and the personal dose equivalent to the eye lens for physicians. Skin doses were measured using thermoluminescent dosimeters. Peak skin doses were observed on the sides of the patients' arms, particularly on the side closest to the x-ray tube. Differences in the procedures and experience of physicians between the two hospitals involved in this study were investigated. AFB procedures were conducted more efficiently at Hospital A than at Hospital B, resulting in lower effective doses. Cone-beam computed tomography (CT) contributes significantly to patient effective doses because it has higher radiographic parameters. Despite their higher radiographic parameters, AFB procedures resulted in smaller skin doses than did image-guided interventional and CT fluoroscopy procedures. The effective doses differed between the two hospitals of this study due to workflow differences, with cone-beam CT playing a dominant role. No significant differences in left and right eyeHp(3) values were observed between the hospitals. For both hospitals, theHp(3) values were below the recommended limits, indicating that radiation monitoring may not be required for AFB procedures. This study provides insights into radiation exposure during AFB procedures, concerning radiation dosimetry, and safety for patients and physicians.

Targeting M-MDSCs enhances the therapeutic effect of BNCT in the 4-NQO-induced murine head and neck squamous cell carcinoma model.

Purpose: Malignant head and neck squamous cell carcinoma (HNSCC) is characterized by a poor prognosis and resistance to conventional radiotherapy. Infiltrating myeloid-derived suppressive cells (MDSCs) is prominent in HNSCC and is linked to immune suppression and tumor aggressiveness. This study aimed to investigate the impact of boron neutron capture therapy (BNCT) on the MDSCs in the tumor microenvironment and peripheral blood and to explore the potential for MDSCs depletion combined with BNCT to reactivate antitumor immunity. Methods and materials: Carcinogen, 4-NQO, -induced oral tumors were irradiated with a total physical dose of 2 Gy BNCT in Tsing Hua Open Reactor (THOR). Flow cytometry and immunohistochemistry accessed the dynamics of peripheral MDSCs and infiltrated MDSCs within the tumor microenvironment. Mice were injected with an inhibitor of CSF-1 receptor (CSF-1R), PLX3397, to determine whether modulating M-MDSCs could affect mice survival after BNCT. Results: Peripheral CD11b+Ly6ChighLy6G- monocytic-MDSCs (M-MDSCs), but not CD11b+Ly6CloLy6Ghigh polymorphonuclear-MDSCs (PMN-MDSCs), increased as tumor progression. After BNCT treatment, there were temporarily decreased and persistent increases of M-MDSCs thereafter, either in peripheral blood or in tumors. The administration of PLX-3397 hindered BNCT-caused M-MDSCs infiltration, prolonged mice survival, and activated tumor immunity by decreasing tumor-associated macrophages (TAMs) and increasing CD8+ T cells. Conclusion: M-MDSCs were recruited into 4-NQO-induced tumors after BNCT, and their number was also increased in peripheral blood. Assessment of M-MDSCs levels in peripheral blood could be an index to determine the optimal intervention window. Their temporal alteration suggests an association with tumor recurrence after BNCT, making M-MDSCs a potential intervention target. Our preliminary results showed that PLX-3397 had strong M-MDSCs, TAMs, and TIL (tumor-infiltrating lymphocyte) modulating effects that could synergize tumor control when combined with BNCT.

Artificial intelligence system for the detection of Barrett's esophagus.

BACKGROUND: Barrett's esophagus (BE), which has increased in prevalence worldwide, is a precursor for esophageal adenocarcinoma. Although there is a gap in the detection rates between endoscopic BE and histological BE in current research, we trained our artificial intelligence (AI) system with images of endoscopic BE and tested the system with images of histological BE. AIM: To assess whether an AI system can aid in the detection of BE in our setting. METHODS: Endoscopic narrow-band imaging (NBI) was collected from Chung Shan Medical University Hospital and Changhua Christian Hospital, resulting in 724 cases, with 86 patients having pathological results. Three senior endoscopists, who were instructing physicians of the Digestive Endoscopy Society of Taiwan, independently annotated the images in the development set to determine whether each image was classified as an endoscopic BE. The test set consisted of 160 endoscopic images of 86 cases with histological results. RESULTS: Six pre-trained models were compared, and EfficientNetV2B2 (accuracy [ACC]: 0.8) was selected as the backbone architecture for further evaluation due to better ACC results. In the final test, the AI system correctly identified 66 of 70 cases of BE and 85 of 90 cases without BE, resulting in an ACC of 94.37%. CONCLUSION: Our AI system, which was trained by NBI of endoscopic BE, can adequately predict endoscopic images of histological BE. The ACC, sensitivity, and specificity are 94.37%, 94.29%, and 94.44%, respectively.

An Improved Endoscopic Automatic Classification Model for Gastroesophageal Reflux Disease Using Deep Learning Integrated Machine Learning.

Gastroesophageal reflux disease (GERD) is a common digestive tract disease, and most physicians use the Los Angeles classification and diagnose the severity of the disease to provide appropriate treatment. With the advancement of artificial intelligence, deep learning models have been used successfully to help physicians with clinical diagnosis. This study combines deep learning and machine learning techniques and proposes a two-stage process for endoscopic classification in GERD, including transfer learning techniques applied to the target dataset to extract more precise image features and machine learning algorithms to build the best classification model. The experimental results demonstrate that the performance of the GerdNet-RF model proposed in this work is better than that of previous studies. Test accuracy can be improved from 78.8% ± 8.5% to 92.5% ± 2.1%. By enhancing the automated diagnostic capabilities of AI models, patient health care will be more assured.

Machine learning framework for automatic image quality evaluation involving a mammographic American College of Radiology phantom.

PURPOSE: The image quality (IQ) of mammographic images is essential when making a diagnosis, but the quality assurance process for radiological equipment is subjective. We therefore aimed to design an automatic IQ evaluation architecture based on a support vector machine (SVM) dedicated to evaluating images taken of mammography American College of Radiology (ACR) phantom. METHODS: A total of 461 phantom images were acquired using mammographic equipment from 10 vendors. Two experienced medical physicists scored the images by consensus. The phantom datasets were randomly divided into training (80%) and testing (20%) sets. Each phantom image (with 6 fibers, 5 specks, and 5 masses) was detected by using bounding boxes, then cropped and divided into 16 pattern images. We identified 159 features for each pattern image. Manual scores were used to assign 3 labels (visible, invisible, and semivisible) to each pattern image. Multiclass-SVM models were trained with 3 types of patterns. Sub-datasets were randomly selected at 10% increments of the total dataset to determine a minimal effective training subset size for the automatic framework. A feature combination test and an analysis of variance were performed to identify the most influential features. RESULTS: The accuracy of the model in evaluating fiber, speck, and mass patterns was 90.2%, 98.2%, and 88.9%, respectively. The performance was equivalent when the sample size was at least 138 (30% of 461) phantom images. The most influential feature was the position feature. CONCLUSIONS: The proposed SVM-based automatic IQ evaluation framework applied to a mammographic ACR phantom accurately matched manual evaluations.

[The Effectiveness of Acupressure in Reducing Cancer-Related Fatigue: A Systematic Review and Meta-Analysis].

BACKGROUND: Acupressure is one of the recommended non-pharmacologic treatments for cancer-related fatigue (CRF) according to the National Comprehensive Cancer Network guidelines. However, few systematic review or meta-analysis studies have focused on the effect of acupressure on CRF. PURPOSE: The purpose of this study was to examine the effectiveness of acupressure in reducing CRF and to identify the effective acupoints and frequencies of acupressure treatments. METHODS: The search and screening procedures were conducted in accordance with PRISMA 2009 guidelines. The search database included Embase, CINAHL, Cochrane Library, MEDLINE and Google Scholar. RoB 2.0 and ROBINS-I were used as appraisal tools. The statistical analysis, including effect size estimation, was computed using RevMan 5.4. RESULTS: Twelve studies (15 sets of data) were included in the review and analysis. Nine hundred sixty patients with cancer who were currently undergoing or had completed treatment were enrolled as participants and received different levels of acupressure. The result showed the overall effect size of CRF in reducing acupressure to be SMD= -0.77, 95% CI [-0.90, -0.65]. In the subgroup analysis, the effect size of auricular acupressure was SMD= -0.98, 95% CI [-1.25, -0.71] and the body acupressure effect size was SMD= -0.70, 95% CI [-0.84, -0.56]. CONCLUSIONS / IMPLICATIONS FOR PRACTICE: Based on the results of this systematic review, acupressure may be applied to the body acupoints Hegu (LI4), Zusanli (ST36), and Sanyinjiao (SP6) once daily for 1-3 minutes each and to the auricular acupoints shenmen and subcortex once daily for 3 minutes each to effectively reduce cancer-related fatigue.

Compassionate Treatment of Brainstem Tumors with Boron Neutron Capture Therapy: A Case Series.

Brainstem tumors are heterogenous and cancerous glioma tumors arising from the midbrain, pons, and the medulla that are relatively common in children, accounting for 10% to 20% of all pediatric brain tumors. However, the prognosis of aggressive brainstem gliomas remains extremely poor despite aggressive treatment with chemotherapy and radiotherapy. That means there are many life-threatening patients who have exhausted all available treatment options and are beginning to face end-of-life stage. Therefore, the unique properties of highly selective heavy particle irradiation with boron neutron capture therapy (BNCT) may be well suited to prolong the lives of patients with end-stage brainstem gliomas. Herein, we report a case series of life-threatening patients with end-stage brainstem glioma who eligible for Emergency and Compassionate Use, in whom we performed a scheduled two fractions of salvage BNCT strategy with low treatment dosage each time. No patients experienced acute or late adverse events related to BNCT. There were 3 patients who relapsed after two fractionated BNCT treatment, characterized by younger age, lower T/N ratio, and receiving lower treatment dose. Therefore, two fractionated low-dose BNCT may be a promising treatment for end-stage brainstem tumors. For younger patients with low T/N ratios, more fractionated low-dose BNCT should be considered.

Predictors of cancer-related fatigue in women with breast cancer undergoing 21 days of a cyclic chemotherapy.

BACKGROUND: Breast cancer is the most common diagnosis and the leading cause of cancer death among women worldwide and ranks first among Asian and Taiwanese women. Cancer-related fatigue (CRF) affects patients' functioning significantly. AIMS: The aim of this study was to examine changes in cancer-related fatigue (CRF) and related factors among women with breast cancer undergoing a single chemotherapy, and to identify predictors of CRF's change over the course of the chemotherapy cycle. METHODS: Four self-report questionnaires were administered to assess CRF, sleep quality, depression and anxiety, and symptom distress. Heart rate variability (HRV) was assessed to evaluate autonomic nervous system activation related to CRF. Data were collected four times: (1) before initiation of the single chemotherapy cycle (T0), (2) after completion of the single cycle (T1), (3) 1 week post-chemo (T2), and (4) 3 weeks post-chemo (T3). Repeated measurement of variance and generalized estimating equations (GEE) were conducted to estimate the trajectories and predictors. RESULTS: One-hundred women with breast cancer (mean age 50.4 ± 9.42) participated. CRF (F = 7.46), sleep quality (F = 2.74), symptom distress (F = 9.99), anxiety (F = 5.72), and depression (F = 4.14) varied significantly over the single cycle of chemotherapy (p < .001), which the trajectories showed exacerbating at T2. HRV indicated a higher variation only on the day of injection (T0, T1). Results of the GEE revealed that anxiety, depression, and symptom distress were predictors of CRF's change over the single cycle of chemotherapy. LINKING EVIDENCE TO ACTION: CRF worsens at 1 week after a chemotherapy injection among Taiwanese women with breast cancer. Based on the risk predictors in CRF that included anxiety, depression, and symptom distress, multistrategy CRF-alleviating interventions should be provided prior to chemotherapy and targeted at the most disturbed period, that is, 1 week after injection.

Efficacy and Safety of Cone-Beam Computed Tomography-Derived Augmented Fluoroscopy Combined with Endobronchial Ultrasound in Peripheral Pulmonary Lesions.

BACKGROUND: The diagnostic yield of peripheral pulmonary lesions (PPLs) using radial endobronchial ultrasound (EBUS) remains challenging without navigation systems. Cone-beam computed tomography-derived augmented fluoroscopy (CBCT-AF) represents a recently developed technique, and its clinical utility remains to be investigated. OBJECTIVES: The aim of this study was to investigate the diagnostic yield of transbronchial biopsy (TBB) using a combination of CBCT-AF and radial EBUS. METHODS: We recruited consecutive patients with PPLs who underwent radial EBUS-guided TBB, with or without AF, between October 2018 and July 2019. Following propensity score 1:1 matching, we recorded the procedure-related data and measured their efficacy and safety. RESULTS: While 72 patients received EBUS-plus-AF, 235 patients received EBUS only. We included 53 paired patients following propensity score matching. The median size of lesions was 2.8 and 2.9 cm in the EBUS-plus-AF group and EBUS-only group, respectively. Diagnostic yield was higher in the former group (75.5 vs. 52.8%; p = 0.015). The diagnostic yield for the EBUS-plus-AF group was significantly higher for lesions ≤30 mm (73.5 vs. 36.1%; p = 0.002). Moreover, there was no significant difference in the complication rates (3.8 vs. 5.7%; p = 1.000). Twenty-four nodules (45.3%) were invisible by fluoroscopy in the EBUS-plus-AF group. All of them were identifiable on CBCT images and successfully annotated for AF. The mean radiation dose of total procedure, CBCT, and fluoroscopy was 19.59, 16.4, and 3.17 Gy cm2, respectively. CONCLUSIONS: TBB using a combination of CBCT-AF and EBUS resulted in a satisfactory diagnostic yield and safety.

Major adverse cardiac events and functional capacity in patients at intermediate risk undergoing transcatheter versus surgical aortic valve replacement for aortic stenosis with bicuspid valves.

BACKGROUND: Transcatheter aortic valve replacement (TAVR) is not always the optimal option for aortic valve stenosis (AS) patients with bicuspid aortic valves (BcAVs) and many studies exclude this group of patients. The aim of our study was to compare the rate of a major adverse cardiovascular event (MACE) and functional capacity in AS patients with BcAV after surgical aortic valve replacement (SAVR) and TAVR. METHODS: This study included 130 patients who underwent SAVR or TAVR from July 2013 to August 2018 at the Cheng Hsin General Hospital. The main outcome was MACE. Events recorded included noncardiovascular (CV) mortality, CV mortality, recurrent nonfatal stroke, recurrent nonfatal myocardial infarction (MI), and important events. The secondary outcome was functional recovery, which was defined according to the metabolic equivalent (MET) 6 months after the aortic procedure. RESULTS: The mean age of patients was 56.8 ± 26.9 years and the mean Society of Thoracic Surgeons score was 3.29 ± 4.69. Logistic regression analyses indicated that SAVR was a significant predictor of functional recovery. Patients who underwent SAVR had a higher rate of functional recovery (>3 METs; 87.8%, p = .000) and had a significantly higher odds ratio (3.56; 95% confidence interval, 1.19-10.63, p = .023). The Kaplan-Meier survival analysis showed that the MACE rate was not associated with the aortic procedure. CONCLUSIONS: Our analysis showed that SAVR is a significant predictor of better functional recovery and TAVR is associated with a lower level of functional capacity. In summary, TAVR is an acceptable option for AS patients with BcAV, and for a better prognosis, an early intervention aimed at improving functional capacity is highly recommended for this group of patients.

Effective dose for multiple and repeated radiation examinations in donors and recipients of adult-to-adult living donor liver transplants at a single center.

PURPOSE: To evaluate the effective doses received by donors and recipients, identify effective dose contributions, and make risk assessments. MATERIALS AND METHODS: It was a retrospective study. 100 Donors and 100 recipients were enrolled with an operative day from March 2016 to August 2017. The dose was analyzed for all radiation-related examinations over a period of 2 years, 1 year before and 1 year after the LDLT procedure. The effective doses of plain X-rays, CT, fluoroscopy, and nuclear medicine per patient were simulated by a Monte Carlo software, evaluated by the dose-length product conversion factors, evaluated by the dose-area product conversion factors, and evaluated by the activity conversion factors, respectively. The risks of radiation-induced cancer were assessed on the basis of the ICRP risk model. RESULTS: The median effective doses were 71 (range: 30-186) mSv for donors and 147 (32-423) mSv for recipients. The radiation examinations were mainly performed in the last three months of preoperative period to first month of postoperative period for recipients and donors. The HCC recipients received a higher effective dose, 195 (64-423) mSv, than those with other indications. The median radiation-induced cancer risk was 0.38 % in male and 0.48 % in female donors and was 0.50 % in male and 0.58 % in female recipients. CONCLUSION: Donors and recipients received a large effective dose, mainly from the CT scans. To reduce effective doses should be included in future challenges in some living donor liver transplants centers that often use CT examinations.

Bismuth shield affecting CT image quality and radiation dose in adjacent and distant zones relative to shielding surface: A phantom study.

BACKGROUND: To quantify image quality and radiation doses in regions adjacent to and distant from bismuth shields in computed tomography (CT). METHODS: An American College of Radiology accreditation phantom with four solid rods embedded in a water-like background was scanned to verify CT number (CTN) accuracy when using bismuth shields. CTNs, image noise, and contrast-to-noise ratios (CNRs) were determined in the phantom at 80-140 kVp. Image quality was investigated on image portions in the zones adjacent (A zone) to and distant (D zone) from a bismuth shield. Surface radiation doses were measured using thermoluminescent dosimeters. Streak artefacts were graded on a 3-point-scale. RESULTS: Changes in CTN caused by a bismuth shield resulted in changes in X-ray spectra. CTN changes were more apparent in the A zone than in the D zone, particularly for a low tube voltage. The degrees of CTN changes and image noise were proportional to the thickness of the bismuth shields. A 1-ply bismuth shield reduced surface radiation doses by 7.2%-15.5%. The overall CNRs were slightly degraded, and streak artefacts were acceptable. CONCLUSIONS: Using a bismuth shield could result in significant CTN changes and perceivable artefacts, particularly for a superficial organ close to the shield, and is not recommended for quantification CT examinations or follow-up CT examinations.

Predicting exercise capacity recovery immediately after mitral valve surgery.

BACKGROUND: This study presents the exercise capacity of postmitral valve surgery patients and determines predictors capable of affecting recovery. METHODS: A total of 302 patients with mitral regurgitation who had undergone mitral surgery at the Heart Center in Taiwan from 1 August 2013 to 31 December 2015 were included in the present study. Data related to specific predictors of operative outcome were collected, including demographic data, intraoperative factors, exercise tolerance, echocardiogram data, concurrent cardiovascular disease history, comorbidities, lifestyle risk factors, and surgery types. Postoperative exercise capacity was presented as peak oxygen consumption (VO2 ; mL of O 2 /kg/min) determined by exercise tests 3 weeks after surgery. Subjects were separated into two groups: a preserved recovery (peak VO 2 ≥ 65% of predicted VO 2max ) group and a poor recovery group (peak VO 2 < 65% of predicted VO 2max ). Preliminary univariate analysis was performed to test for possible relationships between predictive variables and exercise capacity. An analysis of all items shown to be significantly different between the two groups was then subjected to multivariate logistic regression analysis. Detected differences with P < .05 were considered significant. RESULTS: Among the 302 patients sampled, female sex (odds ratio [OR], 2.65; 95% confidence interval [95% CI], 1.58-4.47), obesity (OR, 0.26; 95% CI, 0.10-0.64), sedentary lifestyle (OR, 0.47; 95% CI, 0.28-0.79), and high preoperative New York Heart Association Functional Classification level (OR, 0.52; 95% CI, 0.31-0.87) were significant predictors of poor exercise capacity. CONCLUSIONS: Without complicated clinical procedures, physicians and medical teams could easily use these items of information to screen the exercise capacity of mitral valve surgery patients and prepare a suitable after surgery plan if needed or request a consultation as early as possible.

Impact of using the new American College of Radiology digital mammography phantom on quality survey in modern digital mammography systems: Evidence from nationwide surveys in Taiwan.

OBJECTIVE: The purpose of this study was to investigate the impact of the new American College of Radiology (ACR) digital mammography (DM) phantom in evaluating phantom image quality (IQ) and average glandular dose (AGD) in a nationwide survey on DM systems. METHODS: On-site surveys of 239 DM units were conducted in 2017 and 2018, and comparisons were made between ACR screen-film mammography (SFM) phantom and DM phantom for accessing phantom IQ and AGD. The phantom IQ was assessed using the weighted phantom score, considering the size of each detail. RESULTS: When switching from SFM phantom to DM phantom, no significant difference was found in AGD (p = 0.06). The mean weighted phantom score was significantly higher for DM phantom than for SFM phantom in terms of fibers and specks, and so was the total weighted phantom score (DM phantom vs. SFM phantom: 8.61 ± 1.04 vs. 8.23 ± 0.77, p < 0.0001). The phantom IQ is thus more precise and can detect small differences when using DM phantom and investigating DM systems, especially for specks and fibers. However, the overall passing rate was lower for DM phantom (84.1%) than for SFM phantom (91.2%). This can be explained by the lower passing rate for mass (84.5%) with the DM phantom. CONCLUSION: The ACR DM phantom provides better discernment to assess specks and fibers in DM systems. This study may serve as a reference for implementing a DM quality control program and when conducting large-scale surveys with the new DM phantom in the digital era.

Radiation dose for pediatric scoliosis patients undergoing whole spine radiography: Effect of the radiographic length in an auto-stitching digital radiography system.

OBJECTIVE: This study investigated the influence of spatial overlap and radiographic length (RL) on the effective dose (ED) and organ dose for pediatric patients undergoing whole spine radiography using an auto-stitching digital radiography (DR) system. METHODS: First, the system parameters were tested on a 10-year-old pediatric anthropomorphic phantom with a Shimadzu DR system, and the effects of the spatial overlap and RL on radiation doses were validated. The ED and organ dose were calculated on the basis of a Monte Carlo simulation program. Subsequently, 82 patients with adolescent idiopathic scoliosis were recruited. The spatial overlap and RL for each patient were modified to further investigate the dose reduction feasibility. RESULTS: RL and ED were appropriately correlated on the basis of patients' height. For a patient measuring 158 cm, the Shimadzu DR system was equipped with a 17-inch detector with a cut-off RL of 75 cm. The phantom simulations indicated that ED was reduced to a minimum value of 0.188 ± 0.001 mSv with a high RL for RL < 75 cm. The minimum value increased to 0.300 ± 0.002 mSv for an RL of 75 cm and dropped to 0.222 ± 0.001 mSv for the maximum RL. By employing optimized RLs for patients, EDs were significantly reduced (p < 0.05). Moreover, ED reductions were higher when longer RLs were employed. CONCLUSION: A decrease in the spatial overlap and number of radiographic acquisitions by adjusting RLs when possible could reduce ED and almost all organ doses. This study emphasized the effects of RL on the radiation dose and provided useful guidance for modifying the RL for patients to reduce the whole spine radiography dose using a modern auto-stitching DR system.

Adaptive Iterative Dose Reduction 3D Integrated with Automatic Tube Current Modulation for CT Coronary Artery Calcium Quantification: Comparison to Traditional Filtered Back Projection in an Anthropomorphic Phantom and Patients.

RATIONALE AND OBJECTIVES: We aimed to evaluate integrated adaptive iterative dose reduction 3D (AIDR 3D) algorithm in automatic tube current modulation (ATCM) for the quantification of coronary artery calcium score (CACS) and cardiac risk stratification. MATERIALS AND METHODS: A thoracic phantom with calcium inserts of known densities was scanned with filtered back projection (FBP) and AIDR 3D algorithms in small- and medium-sized phantoms. Twenty-four patients underwent two consecutive scans of CACS with FBP and AIDR 3D algorithms. The absolute Agatston score, Agatston score risk, volume score, and Agatston score percentile-based risk were compared, and concordance coefficients and agreement plots were made. RESULTS: Agatston and volume scores were significantly different between the phantom sizes (P < .01). There were no significant differences in the Agatston scores between FBP and AIDR 3D for the medium phantoms (P = .25). In the patients, there were no significant differences in Agatston and volume scores between FBP and AIDR 3D (P = .06 and P = .09, respectively). The correlation coefficients of Agatston and volume scores with AIDR 3D were excellent compared to those of FBP. There were no significant differences in Agatston score risk and Agatston score percentile-based risk between FBP and AIDR 3D (P = .74 and P = 1, respectively). There was mean dose reduction of 57.8% ± 18.6% for AIDR 3D. CONCLUSION: The absolute Agatston score differed between FBP and AIDR 3D reconstructions. However, the cardiac risk categorizations of the two methods were comparable. An integrated AIDR 3D algorithm with automatic tube current modulation enables radiation dose savings at a consistent noise level without sacrificing CACS.

Investigations of organ and effective doses of abdominal cone-beam computed tomography during transarterial chemoembolization using Monte Carlo simulation.

BACKGROUND: To investigate the organ dose, effective dose (ED), conversion factor, and the C-arm rotation angle effects on dose variations of abdominal C-arm cone-beam computed tomography (CBCT) during transarterial chemoembolization (TACE). METHODS: The organ doses and EDs for abdominal C-arm CBCT were retrospectively calculated according to a Monte Carlo technique for 80 patients. Dose variations from projections, ED to dose-area product (DAP) ratios, and effects of body mass index (BMI) on the ED and ED to DAP ratios were also analyzed. RESULTS: The kidney received the highest dose (14.6 ± 1.2 mSv). Organ dose deviations among C-arm rotation angles was highest for stomach (CV = 0.71). The mean ED of the the CBCT run during TACE was 3.5 ± 0.5 mSv, and decreased with increased BMI (R2 = 0.45, p < 0.001). The mean ED to DAP ratio was 0.27 ± 0.04 mSv·Gy- 1·cm- 2 and tended to decrease with increased BMI (R2 = 0.55, p < 0.001). The mean ED to DAP ratios were 0.29 ± 0.02, 0.26 ± 0.02, and 0.23 ± 0.03 mSv·Gy- 1·cm- 2 for patients with BMI < 25 kg/m2, 25-30 kg/m2, and ≥30 kg/m2, respectively. CONCLUSIONS: Suitable conversion factors for C-arm CBCT facilitate the use of DAPs for estimating the ED. The patient dose can be varied by adjusting the CBCT rotation angle setting, and dose reduction strategies can be further manipulated.

Susceptibility of iodine concentration map of dual-energy contrast-enhanced digital mammography for quantitative and tumor enhancement assessment.

Background Dual-energy (DE) contrast-enhanced digital mammography (DE-CEDM) provides additional information on tumor angiogenesis. Purpose To investigate the susceptibility of reconstructing color-coded iodine concentration maps on the basis of quantitative calibrations of the iodine concentration and contrast-to-noise ratio (CNR) in DE-CEDM applications. Material and Methods A custom-made phantom filled with iodine concentrations in the range of 0.1-10 mg/cm2 was used in calibrations. All DE images were acquired using the GE Senographe Essential system. From DE subtraction images, the image contrast and CNR were obtained, and the quantitative relationship between these two metrics and the iodine concentration at each phantom thickness was investigated. The quantitative CNR calibration curves were applied to reconstruct color-coded iodine maps on a pixel-by-pixel basis. Results Both the mean contrast and mean CNR increased linearly with the iodine concentration. The iodine concentration estimated from the iodine map reconstructed from quantitative CNR calibrations was highly consistent with the desired iodine concentration (R2 = 0.989), and smaller relative errors (in the range of 3.0-19.5%) were observed with iodine concentrations not less than 1 mg/cm2. Conclusion An iodine concentration map could be reconstructed based on the linear relationship between the CNR and iodine concentration. From the color-coded iodine concentration map, the contrast medium enhancement phenomenon could be further estimated quantitatively, and tumor enhancement patterns could be easily observed.

Impact of filter convolution and displayed field of view on estimation of coronary Agatston scores in low-dose lung computed tomography.

BACKGROUND: Coronary artery calcification (CAC) may be quantified on low-dose computed tomography (CT) of the lung (LDCT). This study aims to evaluate the effects of filter convolution (FC) and displayed field of view (dFOV) in a Toshiba 320-row CT scanner in quantifying CAC, and to compare the CAC scores obtained by LDCT with standard cardiac CT. METHODS: Fifty subjects (52 to 85years, mean 68.5, 36 males) with visible CAC underwent both standard cardiac CT and LDCT. CAC scores were obtained from standard cardiac CT using conventional FC12(22) (FC12 with 22-cm dFOV) and four different LDCT protocols: FC02(22), FC02(40), FC08(22), and FC08(40). CAC scores obtained by each LDCT protocol were compared with those obtained by standard cardiac CT. RESULTS: CAC scores obtained by all four LDCT protocols were well correlated with those by standard protocol (Pearson's coefficient=0.978 to 0.987, p<0.001; kappa=0.731 to 0.836, p<0.001). CAC scores obtained by FC08(22) showed the best agreement with standard cardiac CT (kappa=0.836, p<0.001). Under fixed dFOV, CAC scores in FC08 were significantly higher than in FC02 (p<0.001). Under fixed FC, CAC scores were significantly higher in 22-cm dFOV than in 40-cm dFOV (p≤0.006). CONCLUSIONS: Both FC and dFOV have significant impact on CAC scoring. To obtain reliable data, consistent parameters should be employed when quantifying CAC using LDCT. In a Toshiba 320-row CT scanner, CAC scores obtained by FC08(22) agree well with standard cardiac CT.

The Population Effective Dose of Medical Computed Tomography Examinations in Taiwan for 2013.

PURPOSE: To evaluate the annual effective dose per capita attributed to computed tomography (CT) examinations in 2013 and to predict the population effective dose from 2000 to 2013 in Taiwan. METHODS: A CT examination database collected from 30 hospitals was divided into 22 procedures and classified into six regions: head, neck, chest, abdomen, pelvis, and other, respectively. The effective doses in different regions were evaluated by dose-length product (DLP) multiplied by conversion factors. RESULTS: The CT scan dose parameters were collected from 4,407 patients. For the six scanned regions, the percentages of patients scanned were: head (39.8%), neck (3.9%), chest (23.3%), abdomen (26.7%), pelvis (4.8%), and other (1.6%), respectively. The DLPs per patient (mGy·cm/patient) were head (1,071±225), neck (1,103±615), chest (724±509), abdomen (1,315±550), pelvis (1,231±620) and other (1,407±937), respectively. The number of CT examinations increased rapidly, with an average annual growth rate of 7.6%. The number of CT examinations in 2013 was 2.6 times that in 2000. The population effective dose was 0.30 mSv per capita in 2000 and increased to 0.74 mSv per capita in 2013, with an annual growth rate of 7.2%. The growth trend indicates that the effective dose will continue to rise in Taiwan. CONCLUSION: Some strategies should be applied to cope with this growth. Defining the CT dose reference level stipulated in official recommendations and encouraging the use of iterative reconstruction imaging instead of filtered back-projection imaging could be a useful method for optimizing the effective dose and image quality.