Recurrent CT, cumulative radiation exposure, and associated radiation-induced cancer risks from CT of adults

Challenges for managing the cumulative effective dose for patients

Notwithstanding that 100 mSv is not a threshold for radiation effects, cumulative effective dose (CED) for patients of ≥100 mSv derived from recurrent imaging procedures with ionising radiation has been recently the topic of several publications. The International Commission on Radiological Protection has alerted on the problems to use effective dose for risk estimation in individual patients but has accepted to use this quantity for comparison the relative radiation risks between different imaging modalities. A new International Commission on Radiological Protection document on the use of effective dose (including medicine), is in preparation. Recently published data on the number of patients with CED ≥100 mSv ranged from 0.6 to 3.4% in CT and around 4% in interventional radiology. The challenges to manage the existing situation are summarised. The main aspects identified are: 1) New technology with dose reduction techniques. 2) Refinements in the application of the justification and optimisation for these groups of patients. 3) Patient dose management systems with alerts on the cumulative high doses. 4) Education on the proper use of cumulative effective dose for referrers and practitioners including information for patients. 5) Future research programmes in radiation biology and epidemiology may profit the patient dose data from the groups with high cumulative dose values.

Advanced imaging and trends in hospitalizations from the emergency department

Objective

The proportion of US emergency department (ED) visits that lead to hospitalization has declined over time. The degree to which advanced imaging use contributed to this trend is unknown. Our objective was to examine the association between advanced imaging use during ED visits and changes in ED hospitalization rates between 2007–2008 and 2015–2016.

Methods

We analyzed data from the National Hospital Ambulatory Medical Care Survey. The primary outcome was ED hospitalization, including admission to inpatient and observation units and outside transfers. The primary exposure was advanced imaging during the ED visit, including computed tomography, magnetic resonance imaging, and ultrasound. We constructed a survey-weighted multivariable logistic regression with binary outcome of ED hospitalization to examine changes in adjusted hospitalization rates from 2007–2008 to 2015–2016, comparing ED visits with and without advanced imaging.

Results

ED patients who received advanced imaging (versus those who did not) were more likely to be 65 years or older (25.3% vs 13.0%), non-Hispanic white (65.3% vs 58.5%), female (58.4% vs 54.1%), and have Medicare (26.5% vs 16.0%). Among ED visits with advanced imaging, adjusted annual hospitalization rate declined from 22.5% in 2007–2008 to 17.3% (adjusted risk ratio [aRR] 0.77; 95% CI 0.68, 0.86) in 2015–2016. In the same periods, among ED visits without advanced imaging, adjusted annual hospitalization rate declined from 14.3% to 11.6% (aRR 0.81; 95% CI 0.73, 0.90). The aRRs between ED visits with and without advanced imaging were not significantly different.

Conclusion

From 2007–2016, ED visits with advanced imaging did not have a greater reduction in admission rate compared to those without advanced imaging. Our results suggest that increasing advanced imaging use likely had a limited role in the general decline in hospital admissions from EDs. Future research is needed to further validate this finding.

REPEAT CHEST CT SCANS IN MODERATE-TO-SEVERE PATIENTS' MANAGEMENT DURING THE COVID-19 PANDEMIC: OBSERVATIONS FROM A SINGLE CENTRE IN WUHAN, CHINA

OBJECTIVE

To observe the rates of repeated computed tomographic scans (CTs) in a cohort of patients with coronavirus disease-2019 (COVID-19) and to assess the validity of repeat CTs.

METHODS

Each CT was recorded, and the validity of the repeated CTs was assessed.

RESULTS

The 394 patients underwent a total of 1493 CTs. Of the 394 patients, 260 received at least one non-value-added CT. Both the total number of CTs (median, 4; interquartile range (IQR), 3-5) and non-value-added CTs (median, 1; IQR, 0-1) per patient were strongly related to the disease duration (R2 = 0.566 for total CTs, R2 = 0.432 for non-value-added CTs, p < 0.001). The proportion of non-value-added CTs was potentially higher after 3 weeks from symptom onset (>35%).

CONCLUSIONS

There was a high rate of repeat CTs for the COVID-19 patients, and the proportion of non-value-added CTs increased with disease duration. Follow-up CT should be avoided without clinical decline.

ADVANCES IN KNOWLEDGE

As COVID-19 is impacting healthcare systems across the globe, we believe in our findings that serial chest CT imaging has limited clinical utility in basically stable COVID-19 patients, will help relieve some of this burden.

Low Dose Fluoroscopy During Ureteroscopy Does Not Compromise Surgical Outcomes

Objective: To evaluate whether reducing the dose of fluoroscopy to ¼ of standard dose during unilateral ureteroscopy for ureteral stone treatment would impact in a reduction of total radiation emitted and whether this strategy would impact operation time, stone-free rate, and complication rate. Methods: From August 2016 to August 2017, patients over 18 years submitted to ureteroscopy for ureteral stone between 5 and 20 mm were prospectively randomized for ¼ dose reduction or standard dose fluoroscopy. Patients with abnormal urinary anatomy such as horseshoe kidney, pelvic kidney, or duplex system were excluded from the study. Results: Ninety-four patients were enrolled. The fluoroscopic dose reduction strategy to ¼ of the standard dose was able to significantly reduce the cumulative radiation emitted by C-arm fluoroscopy and the dose area product (3.6 ± 4.5 mGy vs 16.2 ± 19.3 mGy, p = 0.0001 and 0.23 ± 0.52 mcGycm² vs 1.15 ± 2.74 mcGycm², p = 0.02, respectively). Fluoroscopy time was similar between groups (74.5 ± 84.8 seconds vs 88.3 ± 90 seconds, p = 0.44). There was no need to increase the fluoroscopy dose during any of the procedures. Surgical outcomes were not affected by fluoroscopic dose reduction strategy. Conclusion: Low dose fluoroscopy reduces the emitted radiation during ureteroscopy without compromising surgical outcomes.

Interstitial Lung Disease in Relatives of Patients with Pulmonary Fibrosis

Rationale: Although relatives of patients with familial pulmonary fibrosis (FPF) are at an increased risk for interstitial lung disease (ILD), the risk among relatives of sporadic idiopathic pulmonary fibrosis (IPF) is not known.Objectives: To identify the prevalence of interstitial lung abnormalities (ILA) and ILD among relatives of patients with FPF and sporadic IPF.Methods: Undiagnosed first-degree relatives of patients with pulmonary fibrosis (PF) consented to participate in a screening study that included the completion of questionnaires, pulmonary function testing, chest computed tomography, a blood sample collection for immunophenotyping, telomere length assessments, and genetic testing.Measurements and Main Results: Of the 105 relatives in the study, 33 (31%) had ILA, whereas 72 (69%) were either indeterminate or had no ILA. Of the 33 relatives with ILA, 19 (58%) had further evidence for ILD (defined by the combination of imaging findings and pulmonary function testing decrements). There was no evidence in multivariable analyses that the prevalence of either ILA or ILD differed between the 46 relatives with FPF and the 59 relatives with sporadic IPF. Relatives with decrements in either total lung or diffusion capacity had a greater than 9-fold increase in their odds of having ILA (odds ratio, 9.6; 95% confidence interval, 3.1-29.8; P < 0.001).Conclusions: An undiagnosed form of ILD may be present in greater than 1 in 6 older first-degree relatives of patients with PF. First-degree relatives of patients with both familial and sporadic IPF appear to be at similar risk. Our findings suggest that screening for PF in relatives might be warranted.

Analysis of Cataract in Relationship to Occupational Radiation Dose Accounting for Dosimetric Uncertainties in a Cohort of U.S. Radiologic Technologists

Cataract is one of the major morbidities in the U.S. population and it has long been appreciated that high and acutely delivered radiation doses of 1 Gy or more can induce cataract. Some more recent studies, in particular those of the U.S. Radiologic Technologists, have suggested that cataract may be induced by much lower, chronically delivered doses of ionizing radiation. It is well recognized that dosimetric measurement error can substantially alter the shape of the radiation dose-response relationship and thus, the derived study risk estimates, and can also inflate the variance of the estimates. In the current study, we evaluate the impact of uncertainties in eye-lens absorbed doses on the estimated risk of cataract in the U.S. Radiologic Technologists' Monte Carlo Dosimetry System, using both absolute and relative risk models. Among 11,345 cases we show that the inflation in the standard error for the excess relative risk (ERR) is generally modest, at most approximately 20% of the unadjusted standard error, depending on the model used for the baseline risk. The largest adjustment results from use of relative risk models, so that the ERR/Gy and its 95% confidence intervals change from 1.085 (0.645, 1.525) to 1.085 (0.558, 1.612) after adjustment. However, the inflation in the standard error of the excess absolute risk (EAR) coefficient is generally minimal, at most approximately 0.04% of the standard error.

The clinical utility of routine spinal radiographs by chiropractors: a rapid review of the literature

INTRODUCTION

When indicated by signs or symptoms of potentially serious underlying pathology (red flags), chiropractors can use radiographs to inform their diagnosis. In the absence of red flags, the clinical utility of routine or repeat radiographs to assess the structure and function of the spine is controversial.

OBJECTIVES

To determine the diagnostic and therapeutic utility of routine or repeat radiographs (in the absence of red flags) of the cervical, thoracic or lumbar spine for the functional or structural evaluation of the spine. Investigate whether functional or structural findings on repeat radiographs are valid markers of clinically meaningful outcomes. The research objectives required that we determine the validity, diagnostic accuracy and reliability of radiographs for the structural and functional evaluation of the spine.

EVIDENCE REVIEW

We searched MEDLINE, CINAHL, and Index to Chiropractic Literature from inception to November 25, 2019. We used rapid review methodology recommended by the World Health Organization. Eligible studies (cross-sectional, case-control, cohort, randomized controlled trials, diagnostic and reliability) were critically appraised. Studies of acceptable quality were included in our synthesis. The lead author extracted data and a second reviewer independently validated the data extraction. We conducted a qualitative synthesis of the evidence.

FINDINGS

We identified 959 citations, screened 176 full text articles and critically appraised 23. No relevant studies assessed the clinical utility of routine or repeat radiographs (in the absence of red flags) of the cervical, thoracic or lumbar spine for the functional or structural evaluation of the spine. No studies investigated whether functional or structural findings on repeat radiographs are valid markers of clinically meaningful outcomes. Nine low risk of bias studies investigated the validity (n = 2) and reliability (n = 8) of routine or repeat radiographs. These studies provide no evidence of clinical utility.

CONCLUSION

We found no evidence that the use of routine or repeat radiographs to assess the function or structure of the spine, in the absence of red flags, improves clinical outcomes and benefits patients. Given the inherent risks of ionizing radiation, we recommend that chiropractors do not use radiographs for the routine and repeat evaluation of the structure and function of the spine.

Electrical Impedance Tomography-Based Abdominal Subcutaneous Fat Estimation Method Using Deep Learning

This paper proposes a deep learning method based on electrical impedance tomography (EIT) to estimate the thickness of abdominal subcutaneous fat. EIT for evaluating the thickness of abdominal subcutaneous fat is an absolute imaging problem that aims at reconstructing conductivity distributions from current-to-voltage data. Existing reconstruction methods based on EIT have difficulty handling the inherent drawbacks of strong nonlinearity and severe ill-posedness of EIT; hence, absolute imaging may not be possible using linearized methods. To handle nonlinearity and ill-posedness, we propose a deep learning method that finds useful solutions within a restricted admissible set by accounting for prior information regarding abdominal anatomy. We determined that a specially designed training dataset used during the deep learning process significantly reduces ill-posedness in the absolute EIT problem. In the preprocessing stage, we normalize current-voltage data to alleviate the effects of electrodeposition and body geometry by exploiting knowledge regarding electrode positions and body geometry. The performance of the proposed method is demonstrated through numerical simulations and phantom experiments using a 10 channel EIT system and a human-like domain.

Metabolic Fingerprinting on Synthetic Alloys for Medulloblastoma Diagnosis and Radiotherapy Evaluation

Diagnostics is the key in screening and treatment of cancer. As an emerging tool in precision medicine, metabolic analysis detects end products of pathways, and thus is more distal than proteomic/genetic analysis. However, metabolic analysis is far from ideal in clinical diagnosis due to the sample complexity and metabolite abundance in patient specimens. A further challenge is real-time and accurate tracking of treatment effect, e.g., radiotherapy. Here, Pd-Au synthetic alloys are reported for mass-spectrometry-based metabolic fingerprinting and analysis, toward medulloblastoma diagnosis and radiotherapy evaluation. A core-shell structure is designed using magnetic core particles to support Pd-Au alloys on the surface. Optimized synthetic alloys enhance the laser desorption/ionization efficacy and achieve direct detection of 100 nL of biofluids in seconds. Medulloblastoma patients are differentiated from healthy controls with average diagnostic sensitivity of 94.0%, specificity of 85.7%, and accuracy of 89.9%, by machine learning of metabolic fingerprinting. Furthermore, the radiotherapy process of patients is monitored and a preliminary panel of serum metabolite biomarkers is identified with gradual changes. This work will lead to the application-driven development of novel materials with tailored structural design and establishment of new protocols for precision medicine in near future.

Radiation dose from computed tomography in patients with acute pancreatitis: an audit from a tertiary care referral hospital

BACKGROUND

There is a limited data on the radiation dose from computed tomography (CT) in patients with acute pancreatitis (AP). The present study evaluated the radiation dose from CT scans in patients with AP.

MATERIAL

A retrospective review of CT reports of patients with AP was conducted. The type of CT scan (non-contrast vs. single-phase vs. biphasic CT) was recorded. The mean number of CT scans and cumulative radiation dose was calculated. The indications and abnormalities on biphasic CT scans were recorded. The radiation doses between different types of the scan were compared.

RESULTS

495 CT studies in 351 patients were evaluated. In patients (n = 78, 22.2%) undergoing multiple CT scans, mean number of CT scans per patient and mean radiation dose were 2.64 ± 1.18 (range 2-9) and 24 ± 15 mSv (range 8.3-79.8 mSv), respectively. The mean radiation dose was significantly greater in patients with modified CT severity index ≥ 8 (n = 63) [25.08 mSv vs. 18.96 mSv, (P = 0.048)]. 61 (12.32%) biphasic scans were performed. A definite indication for a biphasic CT scan was identified in 20 (32.7%) patients. Arterial abnormalities were detected in 6 (9.8%) patients undergoing CT for defined indication. Mean radiation dose in this group was 13.26 ± 7.64 mSv (range 3.42-38.27 mSv) which was significantly greater than the single venous phase scan (7.96 ± 3.48 mSv, P < 0.001).

CONCLUSION

There is a potential for substantial radiation exposure from CT scans to patients with AP. Patients with severe AP and those undergoing biphasic scans have significantly higher radiation exposure. Hence, routine arterial phase acquisition should be avoided.

A method of rapid quantification of patient-specific organ doses for CT using deep-learning-based multi-organ segmentation and GPU-accelerated Monte Carlo dose computing

PURPOSE

One technical barrier to patient-specific computed tomography (CT) dosimetry has been the lack of computational tools for the automatic patient-specific multi-organ segmentation of CT images and rapid organ dose quantification. When previous CT images are available for the same body region of the patient, the ability to obtain patient-specific organ doses for CT - in a similar manner as radiation therapy treatment planning - will open the door to personalized and prospective CT scan protocols. This study aims to demonstrate the feasibility of combining deep-learning algorithms for automatic segmentation of multiple radiosensitive organs from CT images with the GPU-based Monte Carlo rapid organ dose calculation.

METHODS

A deep convolutional neural network (CNN) based on the U-Net for organ segmentation is developed and trained to automatically delineate multiple radiosensitive organs from CT images. Two databases are used: The lung CT segmentation challenge 2017 (LCTSC) dataset that contains 60 thoracic CT scan patients, each consisting of five segmented organs, and the Pancreas-CT (PCT) dataset, which contains 43 abdominal CT scan patients each consisting of eight segmented organs. A fivefold cross-validation method is performed on both sets of data. Dice similarity coefficients (DSCs) are used to evaluate the segmentation performance against the ground truth. A GPU-based Monte Carlo dose code, ARCHER, is used to calculate patient-specific CT organ doses. The proposed method is evaluated in terms of relative dose errors (RDEs). To demonstrate the potential improvement of the new method, organ dose results are compared against those obtained for population-average patient phantoms used in an off-line dose reporting software, VirtualDose, at Massachusetts General Hospital.

RESULTS

The median DSCs are found to be 0.97 (right lung), 0.96 (left lung), 0.92 (heart), 0.86 (spinal cord), 0.76 (esophagus) for the LCTSC dataset, along with 0.96 (spleen), 0.96 (liver), 0.95 (left kidney), 0.90 (stomach), 0.87 (gall bladder), 0.80 (pancreas), 0.75 (esophagus), and 0.61 (duodenum) for the PCT dataset. Comparing with organ dose results from population-averaged phantoms, the new patient-specific method achieved smaller absolute RDEs (mean ± standard deviation) for all organs: 1.8% ± 1.4% (vs 16.0% ± 11.8%) for the lung, 0.8% ± 0.7% (vs 34.0% ± 31.1%) for the heart, 1.6% ± 1.7% (vs 45.7% ± 29.3%) for the esophagus, 0.6% ± 1.2% (vs 15.8% ± 12.7%) for the spleen, 1.2% ± 1.0% (vs 18.1% ± 15.7%) for the pancreas, 0.9% ± 0.6% (vs 20.0% ± 15.2%) for the left kidney, 1.7% ± 3.1% (vs 19.1% ± 9.8%) for the gallbladder, 0.3% ± 0.3% (vs 24.2% ± 18.7%) for the liver, and 1.6% ± 1.7% (vs 19.3% ± 13.6%) for the stomach. The trained automatic segmentation tool takes <5 s per patient for all 103 patients in the dataset. The Monte Carlo radiation dose calculations performed in parallel to the segmentation process using the GPU-accelerated ARCHER code take <4 s per patient to achieve <0.5% statistical uncertainty in all organ doses for all 103 patients in the database.

CONCLUSION

This work shows the feasibility to perform combined automatic patient-specific multi-organ segmentation of CT images and rapid GPU-based Monte Carlo dose quantification with clinically acceptable accuracy and efficiency.

Computationally Efficient System Matrix Calculation Techniques in Computed Tomography Iterative Reconstruction

Background:

Relative to classical methods in computed tomography, iterative reconstruction techniques enable significantly improved image qualities and/or lowered patient doses. However, the computational speed is a major concern for these iterative techniques. In the present study, we present a method for fast system matrix calculation based on the line integral model (LIM) to speed up the computations without compromising the image quality. In addition, we develop a hybrid line–area integral model (AIM) that highlights the advantages of both LIM and AIMs.

Methods:

The contributing detectors for a given pixel and a given projection view, and the length of corresponding intersection lines with pixels, are calculated using our proposed algorithm. For the hybrid method, the respective narrow-angle fan beam was modeled by multiple equally spaced lines. The computed system matrix was evaluated in the context of reconstruction using the simultaneous algebraic reconstruction technique (SART) as well as maximum likelihood expectation maximization (MLEM).

Results:

The proposed LIM offers a considerable reduction in calculation times compared to the standard Siddon algorithm: 2.9 times faster. Differences in root mean square error and peak signal-to-noise ratio were not significant between the proposed LIM and the Siddon algorithm for both SART and MLEM reconstruction methods (P > 0.05). Meanwhile, the proposed hybrid method resulted in significantly improved image qualities relative to LIM and the Siddon algorithm (P < 0.05), though computations were 4.9 times more intensive than the proposed LIM.

Conclusion:

We have proposed two fast algorithms to calculate the system matrix. The first is based on LIM and was faster than the Siddon algorithm, with matched image quality, whereas the second method is a hybrid LIM–AIM that achieves significantly improved images though with its computational requirements.

Optimization of acquisition parameters for reduced-dose thoracic CT: A phantom study

PURPOSE

The purpose of this study was to analyze the impact of different options for reduced-dose computed tomography (CT) on image noise and visibility of pulmonary structures in order to define the best choice of parameters when performing ultra-low dose acquisitions of the chest in clinical routine.

MATERIALS AND METHODS

Using an anthropomorphic chest phantom, CT images were acquired at four defined low dose levels (computed tomography dose index [CTDI_vol]=0.15, 0.20, 0.30 and 0.40mGy), by changing tube voltage, pitch factor, or rotation time and adapting tube current to reach the predefined CTDI_vol-values. Images were reconstructed using two different levels of iteration (adaptive statistical iterative reconstruction [ASIR®]-v70% and ASIR®-v100%). Signal-to-noise ratio (SNR) as well as contrast-to-noise ratio (CNR) was calculated. Visibility of pulmonary structures (bronchi/vessels) were assessed by two readers on a 5-point-Likert scale.

RESULTS

Best visual image assessments and CNR/SNR were obtained with high tube voltage, while lowest scores were reached with lower pitch factor followed by high tube current. Protocols favoring lower pitch factor resulted in decreased visibility of bronchi/vessels, especially in the periphery. Decreasing radiation dose from 0.40 to 0.30mGy was not associated with a significant decrease in visual scores (P<0.05), however decreasing radiation dose from 0.30mGy to 0.15mGy was associated with a lower visibility of most of the evaluated structures (P<0.001). While image noise could be significantly reduced when ASIR®-v100% instead of ASIR®-v70% was used, the visibility-scores of pulmonary structures did not change significantly.

CONCLUSION

Favoring high tube voltage is the best option for reduced-dose protocols. A decrease of SNR and CNR does not necessarily go along with reduced visibility of pulmonary structures.

3T magnetic resonance for evaluation of adult pulmonary tuberculosis

OBJECTIVES

To evaluate image quality and detection rate of four 3T magnetic resonance imaging (MRI) sequences and MRI performances in pulmonary tuberculosis (TB) when compared to computed tomography (CT).

METHODS

Forty patients with pulmonary tuberculosis separately underwent CT and 3T-MRI with T1-weighted free-breathing star-volumetric interpolated breath-hold examination (Star-VIBE) and standard VIBE, T2-weighted two-dimensional fast BLADE turbo spin-echo (2D-fBLADE TSE) and three-dimensional isotropic turbo spin-echo (3D-SPACE). Four MRI sequences were compared in terms of detection rate and image quality, which consisted of signal to noise ratio (SNR), contrast to noise ratio (CNR) and 5-point scoring scale. The total sensitivity was also compared between CT and MRI. Inter-observer agreement on 5-point scoring scale was calculated by Cohen's kappa (k). SNR, CNR and 5-point scoring scale were compared using two-tailed pared t-test. Using CT as a reference, the MRI detection rate of pulmonary abnormality was evaluated by Pearson's Chi-square test. Furthermore, the sizes of the nodules (≥5 mm) were compared using intraclass correlation coefficient.

RESULTS

In this study, Free-breathing Star-VIBE had significantly better SNR and identical CNR compared with standard VIBE. 2D-fBLADE TSE had statistically higher SNR but uniform or inferior CNR compared with 3D-SPACE. Inter-observers showed excellent agreement on 5-point scoring scale. The average score of Star-VIBE and VIBE had no difference. The average score of 2D-fBLADE TSE was higher than 3D-SPACE. There were no statistical differences in the detection rates of non-calcified parenchymal lesions between Star-VIBE and standard VIBE, 2D-fBALDE TSE and 3D-SPACE. MRI is comparable to CT in detecting consolidation, cavity, non-calcified nodules of ≥5 mm and tree-in-bud signs compared to CT. MRI detected non-calcified nodules of ＜5 mm, 5-10 mm, ≥10 mm and calcified nodules with sensitivity of 69.6%, 90.6%, 100% and 89.5% respectively. In addition, the sizes of the nodules (≥5 mm) had statistical consistency. MRI is more sensitive in detecting caseous necrosis, liquefaction, active cavity, abnormalities of lymph nodes and pleura.

CONCLUSIONS

T1-weighted free-breathing Star-VIBE and T2-weighted 2D-fBLADE TSE, both with satisfactory image quality, are suitable for patients with pulmonary TB who need long-term follow-ups in clinical routine, especially for children, young women and pregnant women.

Assessment of uncertainties associated with Monte Carlo-based personalized dosimetry in clinical CT examinations

The clinical value of x-ray computed tomography (CT) has skyrocketed in the last decade while at the same time being the main source of medical exposure to the population. Concerns regarding the potential health hazards associated with the use of ionizing radiation were raised and an appropriate estimation of absorbed dose to patients is highly desired. In this work, we aim to validate our developed Monte Carlo CT simulator using in-phantom dose measurements and further assess the impact of personalized scan-related parameters on dosimetric calculations. We developed a Monte Carlo-based CT simulator for personalized organ level dose calculations, in which the CT source model, patient-specific computational model and personalized scanning protocol were integrated. The CT simulator was benchmarked using an ionization chamber and standard CT Dose Index phantom while the dosimetry methodology was validated through experimental measurements using thermoluminescent dosimeters (TLDs) embedded within an anthropomorphic phantom. Patient-specific scan protocols extracted from CT raw data and DICOM image metadata, respectively, were fed as input into the CT simulator to calculate individualized dose profiles. Thereby, the dosimetric uncertainties associated with using different protocol-related parameters were investigated. The absolute absorbed dose difference between measurements and simulations using the ionization chamber was less than 3%. In the case of the anthropomorphic phantom, the absolute absorbed dose difference between simulations and TLD measurements ranged from  -8.3% to 22%, with a mean absolute difference of 14% while the uncertainties of protocol-related input parameters introduced an extra absolute error of 15% to the simulated results compared with TLD measurements. The developed methodology can be employed for accurate estimation of organ level dose from clinical CT examinations. The validated methodology can be further developed to produce an accurate MC simulation model with a reduced computational burden.

Identification of amyloid plaques in the brain using an x-ray photon-counting strip detector

Brain aggregates of β amyloid (βA) protein plaques have been widely recognized as associated with many neurodegenerative diseases, and their identification can assist in the early diagnosis of Alzheimer’s disease. We investigate the feasibility of using a spectral x-ray coherent scatter system with a silicon strip photon-counting detector for identifying brain βA protein plaques. This approach is based on differences in the structure of amyloid, white and grey matter in the brain. We simulated an energy- and angular-dispersive X-ray diffraction system with an x-ray pencil beam and Silicon strip sensor, energy-resolving detectors. The polychromatic beam is geometrically focused toward a region of interest in the brain. First, the open-source MC-GPU code for Monte Carlo transport was modified to accommodate the detector model. Second, brain phantoms with and without βA were simulated to assess the method and determine the radiation dose required to obtain acceptable statistical power. For βA targets of 3, 4 and 5 mm sizes in a 15-cm brain model, the required incident exposure was about 0.44 mR from a 60 kVp tungsten spectrum and 3.5 mm of added aluminum filtration. The results suggest that the proposed x-ray coherent scatter technique enables the use of high energy x-ray spectra and therefore has the potential to be used for accurate in vivo detection and quantification of βA in the brain within acceptable radiation dose levels.

Combination of postoperative C-reactive protein value and computed tomography imaging can predict severe pancreatic fistula after pancreatoduodenectomy

BACKGROUND

Recent management after pancreatoduodenectomy recommends either omission of prophylactic drainage or early removal. This potentially makes the diagnosis of postoperative pancreatic fistula (POPF) difficult because the diagnosis is based on the amylase value of drain effluent. The aim of this study was to determine if severe POPF could be predicted independent of drainage information.

METHODS

Records of consecutive patients who underwent pancreatoduodenectomy between 2012 and 2018 were included for further analysis. The presence of a peripancreatic collection (PC) on routine postoperative (day7) computed tomography (early CT) and perioperative characteristics were analyzed.

RESULTS

PC appeared in 82/211 patients (39%) and was associated with clinically relevant POPF (p < 0.001). The C-reactive protein (CRP) on postoperative day5 was a good predictor of severe POPF (needing interventional therapy or Grade C) (area under the receiver operating characteristics curve, 0.802; 95% confidence interval, 0.702-0.875). Presence of a PC and a high CRP value were independent risk factors for severe POPF following multivariate analysis. The combination of CRP<5.0 mg/dL on postoperative day 5 and the absence of a PC had 98% negative predictive value.

CONCLUSION

The combination of CRP measurement and PC evaluation by early CT was useful in predicting severe POPF after pancreatoduodenectomy.

Unscheduled Radiologic Examination Orders in the Electronic Health Record: A Novel Resource for Targeting Ambulatory Diagnostic Errors in Radiology

PURPOSE

The aim of this study was to assess the prevalence of unscheduled radiologic examination orders in an electronic health record, and the proportion of unscheduled orders that are clinically necessary, by modality.

METHODS

This retrospective study was conducted from January to October 2016 at an academic institution. All unscheduled radiologic examination orders were retrieved for seven modalities (CT, MR, ultrasound, obstetric ultrasound, bone densitometry, mammography, and fluoroscopy). After excluding duplicates, 100 randomly selected orders from each modality were assigned to two physician reviewers who classified their clinical necessity, with 10% overlap. Interannotator agreement was assessed using κ statistics, the percentage of clinically necessary unscheduled orders was compared, and χ² analysis was used to assess differences by modality.

RESULTS

A total 494,503 radiologic examination orders were placed during the study period. After exclusions, 33,546 unscheduled orders were identified, 7% of all radiologic examination orders. Among 700 reviewed unscheduled orders, agreement was substantial (κ = 0.63). Eighty-seven percent of bone densitometric examinations and sixty-five percent of mammographic studies were considered clinically necessary, primarily for follow-up management. The majority of orders in each modality were clinically necessary, except for CT, obstetric ultrasound, and fluoroscopy (P < .0001).

CONCLUSIONS

Large numbers of radiologic examination orders remain unscheduled in the electronic health record. A substantial portion are clinically necessary, representing potential delays in executing documented provider care plans. Clinically unnecessary unscheduled orders may inadvertently be scheduled and performed. Identifying and performing clinically necessary unscheduled radiologic examination orders may help reduce diagnostic errors related to diagnosis and treatment delays and enhance patient safety, while eliminating clinically unnecessary unscheduled orders will help avoid unneeded testing.

Development of a computational tool for estimating computed tomography dose parameters

BACKGROUND

Computed Tomographic (CT) imaging procedures have been reported as the main source of radiation in diagnostic procedures compared to other modalities. To provide the optimal quality of CT images at the minimum radiation risk to the patient, periodic inspections and calibration tests for CT equipment are required. These tests involve a series of measurements that are time consuming and may require specific skills and highly-trained personnel.

OBJECTIVE

This study aims to develop a new computational tool to estimate the dose of CT radiation outputs and assist in the calibration of CT scanners. It may also provide an educational resource by which radiological practitioners can learn the influence of technique factors on both patient radiation dose and the produced image quality.

METHODS

The computational tool was developed using MATLAB in order to estimate the CT radiation dose parameters for different technique factors. The CT radiation dose parameters were estimated from the calibrated energy spectrum of the x-ray tube for a CT scanner.

RESULTS

The estimated dose parameters and the measured values utilising an Adult CT Head Dose Phantom showed linear correlations for different tube voltages (80 kVp, 100 kVp, 120 kVp, and 140 kVp), with R2 nearly equal to 1 (0.99). The maximum differences between the estimated and measured CTDIvol were under 5 %. For 80 kVp and low tube currents (50 mA, 100 mA), the maximum differences were under 10%.

CONCLUSIONS

The prototyped computational model provides a tool for the simulation of a machine-specific spectrum and CT dose parameters using a single dose measurement.

Occupational radiation exposure and excess additive risk of cataract incidence in a cohort of US radiologic technologists

OBJECTIVES

Previous analyses of cataract in radiation-exposed populations have assessed relative risk; radiogenic excess additive risk (EAR), arguably of more public health importance, has not been estimated. Previous analysis of a large prospective cohort of US radiologic technologists (USRT) quantified excess relative risk of cataract in relation to occupational radiation dose. We aim to assess EARs of cataract.

METHODS

We estimated EARs of cataract/cataract surgery in the USRT cohort using generalised additive models in relation to occupational radiation exposure, and assessed risk modification by a priori-selected cataract risk factors (diabetes, body mass index, smoking, race, sex, birth-year, ultraviolet B (UVB) radiation exposure).

RESULTS

There were 11 345 cataract diagnoses and 5440 of cataract surgery during 832 462 and 888 402 person-years of follow-up, respectively. Cumulative occupational radiation exposure was associated with self-reported cataract, but not with cataract surgery, with EAR/104 person-year Gy=94 (95% CI: 47 to 143, p<0.001) and EAR/104 person-year Gy=13 (95% CI: <0 to 57, p=0.551), respectively. There was marked (p<0.001) variation of EAR by age and by diabetes status, with risk higher among persons ≥75 years and diabetics. There were indications of elevated risk among those with higher UVB radiation (p=0.045), whites (p=0.056) and among those with higher levels of cigarette smoking (p=0.062). Elevated additive risk was observed for estimated occupational radiation eye-lens doses <100 mGy (p=0.004) with no dose-response curvature (p=0.903).

CONCLUSIONS

The elevated additive risks associated with low-dose radiation, if confirmed elsewhere, have important public health and clinical implications for radiation workers as well as regulatory measures.

Standing CT of the equine head: Reducing radiation dose maintains image quality

Multiple published studies involving computed tomographic (CT) examinations of the equine head utilise a wide range of mAs parameters for image acquisition. This prospective, experimental study assessed the effects of lowering mAs during CT image acquisition on image quality and scatter radiation on 10 cadaver equine heads. Each head was scanned three times at 300, 225, and 150 mAs, with all other scanning parameters remaining constant between series. An anthropomorphic phantom was positioned adjacent to each equine head during image acquisition, mimicking a human bystander, with an ionization chamber attached to the phantom at eye level. Each series was reconstructed using filtered back projection, using medium (H30) and high (H80) frequency reconstruction algorithms. Quantitative image quality assessment was performed by calculating signal to noise ratio (SNR) and contrast to noise ratio (CNR). Two qualitative image quality assessments were performed independently by three blinded board certified veterinary radiologists with a 4 week interval, using a visual grade analysis model adapted from peer reviewed medical literature. Ionization chamber measurements, calculated volume CT dose index (CTDIvol), and dose-length product (DLP) were recorded. Halving radiation dose during image acquisition from 300 to 150mAs resulted in comparable image quality between series. There was a statistically significant and linear relationship between mAs and scatter radiation to the bystander; halving mAs during image acquisition resulted in halving of scatter radiation. Results of this cadaveric study support the use of lower mAs settings during standing CT examinations of the equine head.

Patients undergoing recurrent CT scans: assessing the magnitude

OBJECTIVES

To assess percent of patients undergoing multiple CT exams that leads to cumulative effective dose (CED) of ≥ 100 mSv and determine their age distribution.

METHODS

Data was retrieved retrospectively from established radiation dose monitoring systems by setting the threshold value of 100 mSv at four institutions covering 324 hospitals. The number of patients with CED ≥ 100 mSv only from recurrent CT exams during a feasible time period between 1 and 5 years was identified. Age and gender distribution of these patients were assessed to identify the magnitude of patients in the relatively lower age group of ≤ 50 years.

RESULTS

Of the 2.5 million (2,504,585) patients who underwent 4.8 million (4,819,661) CT exams during the period of between 1 and 5 years, a total of 33,407 (1.33%) patients received a CED of ≥ 100 mSv with an overall median CED of 130.3 mSv and maximum of 1185 mSv. Although the vast majority (72-86%) of patients are > 50 years of age, nearly 20% (13.4 to 28%) are ≤ 50 years. The minimum time to accrue 100 mSv was a single day at all four institutions, an unreported finding to date.

CONCLUSIONS

We are in an unprecedented era, where patients undergoing multiple CT exams and receiving CED ≥ 100 mSv are not uncommon. While underscoring the need for imaging appropriateness, the consideration of the number and percent of patients with high exposures and related clinical necessities creates an urgent need for the industry to develop CT scanners and protocols with sub-mSv radiation dose, a goal that has been lingering.

KEY POINTS

• We are in an era where patients undergoing multiple CT exams during a short span of 1 to 5 years are not uncommon and a sizable fraction among them are below 50 years of age. • This leads to cumulative radiation dose to individual patients at which radiation effects are of real concern. • There is an urgent need for the industry to develop CT scanners with sub-mSv radiation dose, a goal that has been lingering.

Patients undergoing recurrent CT exams: assessment of patients with non-malignant diseases, reasons for imaging and imaging appropriateness

OBJECTIVE

To determine percent of patients without malignancy and ≤ 40 years of age with high cumulative radiation doses through recurrent CT exams and assess imaging appropriateness.

METHODS

From the cohort of patients who received cumulative effective dose (CED) of ≥ 100 mSv over a 5-year period, a sub-set was identified with non-malignant disease. The top 50 clinical indications leading to multiple CTs were determined. Clinical decision support (CDS) system scores were analyzed using a widely adopted standard of 1-3 (red) as "not usually appropriate," 4-6 (yellow) "may or may not be appropriate," and 7-9 (green) "usually appropriate." Clinicians reviewed patient records to assess compliance with appropriate use criteria (AUC).

RESULTS

9.6% of patients in our series were with non-malignant conditions and 1.4% with age ≤ 40 years. CDS scores (rounded) were 2% red, 38% yellow, 27% green, and 33% unscored CTs. Clinical society guidelines for CT exams, wherever available, were followed in 87.5 to 100% of cases. AUCs were not available for several clinical indications as also referral guidelines for serial CT imaging. More than half of CT exams were unrelated to follow-up of a primary chronic disease.

CONCLUSIONS

We are faced with a situation wherein patients in age ≤ 40 years require or are thought to require many CT exams over the course of a few years but the radiation risk creates concern. There is a fair number of conditions for which AUC are not available. Suggested solutions include development of CT scanners with lesser radiation dose and further development of appropriateness criteria.

KEY POINTS

We are faced with a situation wherein patients in age group 0-40 years and with non-malignant diagnosis require or are thought to require many CT exams over the course of a few years. More than half of CT exams were unrelated to follow-up of a primary chronic disease. Imaging guidelines and appropriateness use criteria are not available for many conditions. Wherever available, they are for initial work-up and diagnosis and there is a lack of guidance on serial CT imaging.

Multinational data on cumulative radiation exposure of patients from recurrent radiological procedures: call for action

OBJECTIVES

To have a global picture of the recurrent use of CT imaging to a level where cumulative effective dose (CED) to individual patients may be exceeding 100 mSv at which organ doses typically are in a range at which radiation effects are of concern METHODS: The IAEA convened a meeting in 2019 with participants from 26 countries, representatives of various organizations, and experts in radiology, medical physics, radiation biology, and epidemiology. Participants were asked to collect data prior to the meeting on cumulative radiation doses to assess the magnitude of patients above a defined level of CED.

RESULTS

It was observed that the number of patients with CED ≥ 100 mSv is much larger than previously known or anticipated. Studies were presented in the meeting with data from about 3.2 million patients who underwent imaging procedures over periods of between 1 and 5 years in different hospitals. It is probable that an additional 0.9 million patients reach the CED ≥ 100 mSv every year globally.

CONCLUSIONS

There is a need for urgent actions by all stakeholders to address the issue of high cumulative radiation doses to patients. The actions include development of appropriateness criteria/referral guidelines by professional societies for patients who require recurrent imaging studies, development of CT machines with lower radiation dose than today by manufacturers, and development of policies by risk management organizations to enhance patient radiation safety. Alert values for cumulative radiation exposures of patients should be set up and introduced in dose monitoring systems.

KEY POINTS

• Recurrent radiological imaging procedures leading to high radiation dose to patients are more common than ever before. • Tracking of radiation exposure of individual patients provides useful information on cumulative radiation dose. • There is a need for urgent actions by all stakeholders to address the issue of high cumulative radiation doses to patients.

Clinical Implication of Dosimetry of Computed Tomography- and Fluoroscopy-Guided Intrathecal Therapy With Nusinersen in Adult Patients With Spinal Muscular Atrophy

Background: Spinal muscular atrophy (SMA) is a genetic disorder that leads to progressive tetraparesis. Nusinersen is the first approved drug for the treatment of SMA and is administered via intrathecal injections. Neuromyopathic scoliosis and spondylodesis can impede lumbar punctures, thus necessitating the use of radiological imaging. Furthermore, dosimetry of this potentially lifelong therapy should be supervised.

Methods: Fluoroscopy-assisted or computed tomography (CT)-guided intrathecal injections of nusinersen were performed in adult patients with SMA type 2 and 3. The mean effective dose was compared in patients with and without spondylodesis as well as in those with SMA type 2 and 3. The dosimetry was analyzed in relation to the motor function evaluated with the Revised Upper Limb module (RULM) score and the Hammersmith Functional Motor Scale-Expanded (HFMSE) score.

Results: Fifteen patients with SMA type 2 and 3 underwent radiological imaging-assisted intrathecal injections. The mean effective dose per CT-guided injection per patient was 2.59 (±1.67) mSv (n = 12). The mean dose area product (DAP) per fluoroscopy-guided injection per patient was 200.48 (±323.67) μGym² (n = 3). With increase in the number of injections, the effective dose (r = −0.23) (p < 0.05) and the DAP (r = −0.09) (p > 0.05) decreased. The mean effective dose in 4 patients without spinal fusion (SMA type 2) was 1.39 (±0.51) mSv, whereas that in 8 patients with spondylodesis (SMA type 2 and 3) was 3.21 (±1.73) mSv. The mean effective dose in 5 SMA type 2 patients with spondylodesis was 2.68 (±1.47) mSv (n = 5) and in 3 SMA type 3 patients was 4.00 (±1.82) mSv. Dosimetry did not show significant correlation with the clinical severity of the disease (RULM score: r = −0.045, p > 0.05 and HFMSE score: r = −0.001, p > 0.05).

Conclusions: In SMA type 2 and 3 patients undergoing radiological imaging-assisted injections, the effective dose and DAP decreased during therapy with nusinersen. The mean effective dose in patients with spondylodesis was higher than that in patients without spondylodesis. Dosimetry should be monitored carefully in order to detect and prevent unnecessary radiation exposure.

Diagnosis and management of pancreatic cystic neoplasms: current evidence and guidelines

Pancreatic cystic neoplasms (PCN) are a heterogeneous group of pancreatic cysts that include intraductal papillary mucinous neoplasms, mucinous cystic neoplasms, serous cystic neoplasms and other rare cystic lesions, all with different biological behaviours and variable risk of progression to malignancy. As more pancreatic cysts are incidentally discovered on routine cross-sectional imaging, optimal surveillance for patients with PCN is becoming an increasingly common clinical problem, highlighting the need to balance cancer prevention with the risk of (surgical) overtreatment. This Review summarizes the latest developments in the diagnosis and management of PCN, including the quality of available evidence. Also discussed are the most important differences between the PCN guidelines from the American Gastroenterological Association, the International Association of Pancreatology and the European Study Group on Cystic Tumours of the Pancreas, including diagnostic and follow-up strategies and indications for surgery. Finally, new developments in the management of patients with PCN are addressed.

Development of pancreatic cancer during observation for hepatocellular carcinoma: A retrospective cohort study

BACKGROUND/AIMS

We aimed to investigate incidence, characteristics, and possible risk factors of pancreatic cancer in patients under observation for hepatocellular carcinoma (HCC) because the association of hepatitis virus B infection and pancreatic cancer has been reported.

PATIENTS AND METHODS

We performed a retrospective cohort study in the Gastroenterology Department of a University Hospital in Japan between 2004 and 2012. A total of 1848 patients who underwent treatment for HCC were included at the initiation of treatment for HCC (mean follow-up period, 33.6 months). The patients received trimonthly radiological follow-ups. Newly developed cases of pancreatic cancer during follow-up for HCC were compared with that of an age- and sex-matched theoretical cohort from national statistics. Possible predisposing factors for pancreatic cancer related to HCC were assessed. Cumulative probabilities of developing a pancreatic cancer were compared using log-rank test.

RESULTS

About 13 of 1848 patients developed pancreatic cancer (mean follow-up period, 45.2 months). The risk ratio for all patients was 3.02 (log-rank test: P =0.01). Statistical analyses showed no effects of the following factors on the development of pancreatic cancer: age, sex, follow-up period, alcohol intake, laboratory data, presence of hepatitis virus, characteristics of HCC, type of treatment, number of radiological examinations, and cumulative effective dose.

CONCLUSIONS

Increased incidence of pancreatic cancer was found in patients under observation for HCC in a relatively small cohort. HCC or other common underlying conditions might be a risk factor for development of pancreatic cancer.

Cumulative Doses of Ionizing Radiation From Computed Tomography: A Population-Based Study

OBJECTIVE

To assess cumulative radiation doses from computed tomography (CT), patient characteristics, and clinical indications for CT in a population-based sample.

PATIENTS AND METHODS

A cohort study using medical records linkage through the Rochester Epidemiology Project was conducted to ascertain all CT examinations in Olmsted County, Minnesota, performed between January 1, 2004, and December 31, 2013, among all adults who were alive for 3 or more years after the end of follow-up (to exclude exposures preceding death). Ten-year cumulative effective ionizing radiation doses were estimated on the basis of typical doses per CT modality. Among patients with high doses (≥100 mSv/10 years), CT scans were reviewed for clinical setting, indications, and results.

RESULTS

Of 54,447 adults (median age, 44.0 years at inclusion), 26,377 (48.4%) underwent at least one CT. Ten-year radiation doses from CT were 0.1 to 9.9 mSv in 15.8% of the population (8593 patients), 10 to 24.9 mSv in 16.9% (9502), 25 to 99.9 mSv in 13.8% (7492), and 100 mSv or greater in 1.9% (1041). Computed tomography of the abdomen and pelvis accounted for 67.2% of the estimated dose. In multivariable models, doses differed 1.21-fold to 2.16-fold between extreme categories of age, body mass index, education level, smoking status, and by race. Of 600 CTs in 200 patients with high doses, 70.5% were obtained for restaging of solid cancers and lymphoma, abdominal pain, infection, kidney stones, follow-up of nodules or masses, and chest pain/evaluation for pulmonary embolism.

CONCLUSION

Exposure to ionizing radiation from CT occurred disproportionally in specific subgroups of the population. A limited number of clinical indications contributed the majority of radiation among adults with high doses.

Totally fluoroless retrograde intrarenal surgery technique in prestented patients: tips and tricks

Treatment of urolithiasis has evolved greatly as retrograde intrarenal surgery (RIRS) has gained popularity nowadays being a gold standard therapy for renal stones up to 2 cm. Endourological procedures are traditionally fluoroscopic guided; thus, an increasing concern is the harm of radiation exposure, especially in the pediatric population. Therefore, performing fluoroless RIRS should be a feasible option for pediatric urologists. Herein, we describe the technique of totally fluoroless RIRS in presented patients and the tips to avoid radiation use at most.

Cumulative exposure to ionising radiation from diagnostic imaging tests: a 12-year follow-up population-based analysis in Spain

OBJECTIVES

To calculate each patient's cumulative radiation exposure and the recurrent tests during a 12-year study period, according to sex and age, in routine practice.

DESIGN

Retrospective cohort study.

SETTING

A general hospital with a catchment population of 224 751 people, in the Southeast of Spain.

PARTICIPANTS

Population belonged to the catchment area of that hospital in 2007. We collected all consecutive diagnostic imaging tests undergone by this population until 31 December 2018. We excluded: imaging tests that did not involve radiation exposure.

MAIN OUTCOME MEASURES

The cumulative effective dose and the recurrent imaging tests by sex and age at entry of study.

RESULTS

Of the 224 751 people, 154 520 (68.8%) underwent an imaging test. The population had 1 335 752 imaging tests during the period of study: 1 110 077 (83.0%) plain radiography; 156 848 (11.8%) CT; 63 157 (4.8%) fluoroscopy and 5670 (0.4%) interventional radiography. 25.4% of the patients who had a CT, underwent five or more CTs (5.4% in the 0-20 years age group). The median total cumulative effective dose was 2.10 mSv (maximum 3980.30) and 16.30 mSv (maximum 1419.30 mSv) if we considered only doses associated with CT. Women received more effective dose than men (median 2.38 vs median 1.90, p<0.001). A total of 7142 (4.6%) patients received more than 50 mSv, with differences in men and women (p<0.001) and 2.5% of the patients in the 0-20 years age group, if we considered only doses associated with CT.

CONCLUSIONS

Nearly 5% of patients received doses higher than 50 mSv during the 12-year period of study and 2.5% of the patients in the 0-20 years age group, if we considered only doses associated with CT. The rate of recurrent examinations was high, especially in older patients, but also relevant in the 0-20 years age group.

Patient Safety Analysis in Radiation Burden of Head Computed Tomography Imaging in 1185 Neurosurgical Inpatients

OBJECTIVE

We performed a retrospective analysis in a cohort of 1185 patients at our institution who were identified as undergoing ≥1 head computed tomography (CT) examinations during their inpatient stay on the neurosurgery service, to quantify the number, type, and associated radiation burden of head CT procedures performed by the neurosurgery service.

METHODS

CT procedure records and radiology reports were obtained via database search and directly validated against records retrieved from manual chart review. Next, dosimetry data from the head CT procedures were extracted via automated text mining of electronic radiology reports.

RESULTS

Among 4510 identified adult head CT procedures, 88% were standard head CT examinations. A total of 3.65 ± 3.60 head CT scans were performed during an average adult admission. The most common primary diagnoses were neoplasms, trauma, and other hemorrhage. The median cumulative effective dose per admission was 5.66 mSv (range, 1.06-84.5 mSv; mean, 8.56 ± 8.95 mSv). The median cumulative effective dose per patient was 6.4 mSv (range, 1.1-127 mSv; mean, 9.26 ± 10.0 mSv).

CONCLUSIONS

The median cumulative radiation burden from head CT imaging in our cohort equates approximately to a single chest CT scan, well within accepted limits for safe CT imaging in adults. Refined methods are needed to characterize the safety profile of the few pediatric patients identified in our study.

Awareness of Risks Associated with the Use of Plain X-Ray, Computed Tomography, and Magnetic Resonance Imaging Among Emergency Physicians and Comparison with that of Other Physicians: A Survey from Turkey

BACKGROUND Increased use of radiological imaging in all departments of medicine, especially in the Emergency Department, requires that physicians have a high level of knowledge regarding commonly used imaging methods and high awareness of the risks of examinations. MATERIAL AND METHODS The physicians were divided into 5 groups according to their specialties as emergency medicine physicians (EMPs), physicians from any specialty of internal sciences, physicians from any specialty of surgical sciences, general practitioners (GPs), and radiologists. A total of 700 physicians answered the questionnaire via email. RESULTS 15.7% of EMPs reported that they did not routinely perform any risk assessment before requesting computed tomography (CT); the rate was 17.9% for direct radiography and 29.3% for magnetic resonance imaging (MRI). The proportions of physicians who do not routinely perform risk assessments for direct radiography, CT, and MRI were as follows: 16.4%, 8.6%, and 19.3% in physicians from medical sciences, respectively; 25%, 22.9%, and 35% in physicians from surgical sciences, respectively; 24.3%, 14.3%, and 37.1% in GPs, respectively; and 27.1%, 22.1% and 37.1% in radiologists, respectively. In all radiological examinations, 1.4% of EMPs and ≤1.4% of other physicians routinely explain the risks associated with the imaging method to the patients, and discuss the risks and benefits of the imaging with the patients. CONCLUSIONS All physicians, including EMPs, need to undergo urgent training to increase their knowledge on risks of imaging methods and discussion of existing risks with patients.

Prevalence of pancreatic cystic lesions detected by magnetic resonance imaging in the Chinese population

BACKGROUND AND AIM

Incidental pancreatic cystic lesions (PCLs) are being diagnosed more frequently. However, little is known about the prevalence of PCLs in the Chinese population. The aim of the study was to assess the crude prevalence of PCLs in individuals who underwent magnetic resonance imaging (MRI).

METHODS

Data from consecutive patients who underwent MRI without pancreatic indications were included. MRI images were reviewed for the presence of pancreatic cysts. The prevalence of PCLs and high-risk PCLs in different gender and age groups was calculated. To assess the crude prevalence, the prevalence and demographic data were standardized on the basis of Chinese national population data in 2017.

RESULTS

A total of 10 987 individuals were included (7344 men). Incidental PCLs were identified in 212 individual (128 men). The prevalence of PCLs was 1.93%, and PCLs were more often discovered in women (1.74% vs 2.31%, P = 0.043). Prevalence increased with age (r = 0.804, P < 0.001). The prevalence of high-risk PCLs was 0.12% (n = 13). Gender predominance and age distribution showed no difference between high-risk PCLs and low-risk PCLs (P = 0.234 and P = 0.855), but cysts located in the pancreatic head were more likely to develop into high-risk PCLs (P = 0.001). After data standardization, the crude prevalence of PCLs was 1.31%, and PCLs were more often discovered in women (1.11% vs 1.5%, P < 0.001). The crude prevalence of high-risk PCLs was 0.07%.

CONCLUSION

Pancreatic cystic lesions in the Chinese population are not rare. The prevalence of PCLs increased with age and is higher in the female population. The prevalence of high-risk PCLs should not be ignored.

Cost-Effectiveness of Computed Tomography Angiography in Management of Tiny Unruptured Intracranial Aneurysms in the United States

Background and Purpose—

Our study aims to evaluate the cost-effectiveness of computed tomography angiography (CTA) for surveillance of tiny unruptured intracranial aneurysms and the impact of CTA radiation-induced brain tumor on the overall effectiveness of CTA.

Methods—

A Markov decision model was constructed from a societal perspective starting with patients 30-, 40-, or 50-year-old, with incidental detection of unruptured intracranial aneurysm ≤3 mm and no prior history of subarachnoid hemorrhage. Five different management strategies were assessed (1) annual CTA surveillance, (2) biennial CTA, (3) CTA follow-up every 5 years, (4) coiling and subsequent magnetic resonance imaging follow-up, and (5) annual CTA surveillance for the first 2 years, followed by every 5-year CTA follow-up. Probabilistic, 1-way, and 2-way sensitivity analyses were performed.

Results—

The base case calculation shows every 5-year CTA follow-up to be the most cost-effective strategy, and the conclusion remains robust in probabilistic sensitivity analysis. It remains the dominant strategy when the annual rupture risk of nongrowing unruptured intracranial aneurysms is smaller than 2.66% or the rupture risk in growing aneurysms is <57.4%. The radiation-induced brain cancer risk is relatively low, and sensitivity analysis shows that the radiation-induced cancer risk does not influence the conclusions unless the risk exceeds 663-fold of the base case values.

Conclusions—

Given the current literature, every 5-year CTA imaging follow-up is the cost-effective strategy in patients with aneurysms ≤3 mm, resulting in better health outcomes and lower healthcare spending. Patients with aneurysms at high risk of rupture might need more aggressive management.

Indian guidelines on imaging of the small intestine in Crohn's disease: A joint Indian Society of Gastroenterology and Indian Radiology and Imaging Association consensus statement

The Indian Society of Gastroenterology (ISG) Task Force on Inflammatory Bowel Disease and the Indian Radiological and Imaging Association (IRIA) developed combined ISG-IRIA evidence-based best-practice guidelines for imaging of the small intestine in patients suspected to have or having Crohn's disease. The 29 consensus statements, developed through a modified Delphi process, are intended to serve as reference for teaching, clinical practice, and research.

PATIENTS DOSE ESTIMATION IN CT EXAMINATIONS USING SIZE SPECIFIC DOSE ESTIMATES

The present work reports data of radiation exposure to the patients during head, chest, pelvis and abdomen CT examinations performed on a third-generation 16-slice CT machine. Radiation exposure was estimated using size specific dose estimates (SSDE) method, which takes into account patient's physical dimensions in phantom measured computed tomography dose index (CTDI) value. The reported median CT dose volume index CTDIvol values in head, chest, pelvis and abdomen examinations were 26.76, 16.27, 29.81 and 14.74 mGy, respectively. The median doses evaluated using SSDE methodology for the above mentioned procedure were 54.1, 23.1, 42.8 and 20.1 mGy, respectively. Our results showed variation in dose values estimated using CTDI and SSDE methods in all examinations. The evaluated SSDE values were also compared to the values derived from data reported by the American Association of Physicist in Medicine (AAPM). SSDE values in present measurements are 4-8% lower than AAPM values. The present results show that CTDI parameters recorded on CT console should not be used to specify patient dose during CT procedures.

Analysis of a multicentre cloud-based CT dosimetric database: preliminary results

BACKGROUND

To manage and analyse dosimetric data provided by computed tomography (CT) scanners from four Italian hospitals.

METHODS

A radiation dose index monitoring (RDIM) software was used to collect anonymised exams stored in a cloud server. Since hospitals use different names for the same procedure, digital imaging and communications in medicine (DICOM) tags more appropriate to describe exams were selected and associated to study common names (SCNs) from a radiology playbook according to scan region and use of contrast media. Retrospective analysis was carried out to describe population and to evaluate dosimetric indexes and inaccuracies associated with SCNs.

RESULTS

More than 400 procedures were clustered into 95 SCNs, but 78% of exams on adults were described with only 10 SCNs. Median values of dose-length product (DLP) and volumetric CT dose index (CTDI_vol) for three analysed SCNs were in agreement with those previously published. The percentage of inaccuracies does not heavily affect the dosimetric analysis on the whole cloud, since variations in median values reached at most 8%.

CONCLUSIONS

Implementation of a cloud-based RDIM software and related issues were described, showing the strength of the chosen playbook-based clustering and its usefulness for homogeneous data analysis. This approach may allow for optimisation actions, accurate assessment of the risk associated with radiation exposure, comparison of different facilities, and, last but not least, collection of information for the implementation of the 2013/59 Euratom Directive.