A simulation study of in-beam visualization system for proton therapy by monitoring scattered protons.

Recently, in-beam positron emission tomography (PET) has been actively researched for reducing biological washout effects and dose monitoring during irradiation. However, the positron distribution does not precisely reflect the dose distribution since positron production and ionization are completely different physical processes. Thus, a novel in-beam system was proposed to determine proton dose range by measuring scattered protons with dozens of scintillation detectors surrounding the body surface. While previous studies conducted a preliminary experiment with a simple phantom, we simulated more complex situations in this paper. Especially, we conducted three stepwise simulation studies to demonstrate the feasibility of the proposed method. First, a simple rectangular phantom was reproduced on simulation and irradiated with protons for obtaining current values and Monte Carlo (MC) dose. Next, we trained a deep learning model to estimate 2-dimensional-dose range (2D-DL dose) from measured current values for simulation (A). We simulated plastic scintillators as detectors to measure the scattered protons. Second, a rectangular phantom with an air layer was used, and 3D-DL dose was estimated in simulation (B). Finally, a cylindrical phantom that mimics the human body was used for confirming the estimation quality of the simulation (C). Consequently, the position of the Bragg peak was estimated with an error of 1.0 mm in simulation (A). In addition, the position of the air layer, as well as the verifying peak position with an error of 2.1 mm, was successfully estimated in simulation (B). Although the estimation error of the peak position was 12.6 mm in simulation (C), the quality was successfully further improved to 9.3 mm by incorporating the mass density distribution obtained from the computed tomography (CT). These simulation results demonstrated the potential of the as-proposed verification system. Additionally, the effectiveness of CT utilization for estimating the DL dose was also indicated.

Understanding abdominal pelvic computerized tomography scan usage amongst adolescent blunt trauma patients treated at adult trauma centers.

INTRODUCTION: The algorithm for evaluating adolescent patients with blunt trauma includes abdominal pelvic CT (APCT). The aim of this study is to evaluate the utility of APCT in this context. METHODS: We performed a retrospective review of adolescent (11 to 18 years of age) blunt trauma patients at an urban adult level 1 trauma center from January 2015 to December 2019. The primary outcome was the prevalence of positive findings on APCT scan.  Additionally, clinical risk factors concerning for intra-abdominal injury were analyzed. RESULTS: There were 546 patients evaluated for blunt trauma and the prevalence of APCT within the population was 59.3% (95% CI 54.2%-64.9%). Of the patients who received APCT, 123 (37.9%) had positive findings on APCT. Only 25 patients (7.7% of those who underwent APCT) required abdominal surgery while 40 patients (12.3%) had intraabdominal injury that did not require surgery. Risk factors were present in 100% of patients with intraabdominal injury and absent in 28.7% of patients without intraabdominal injury. Abnormal abdominal exam, abnormal FAST, positive chest x-ray and elevated transaminases were independently associated with intraabdominal injury. CONCLUSIONS: Our study found that adolescent blunt trauma patients treated at our trauma center had a higher rate of APCT usage, but a comparable rate of positive findings when compared with the most recent literature. Future studies should focus on reducing the number of patients who undergo APCT despite an absence of clinical risk factors.

Revisiting racial disparities in ED CT utilization during the Affordable Care Act era: 2009-2018 data from the NHAMCS.

OBJECTIVE: To examine the trends in CT utilization in the emergency department (ED) for different racial and ethnic groups, factors that may affect utilization, and the effects of increased insurance coverage since passage of the Affordable Care Act in 2010. MATERIALS AND METHODS: Data from the National Hospital Ambulatory Medical Care Survey (NHAMCS) for the years 2009-2018 were used for the analysis. The NHAMCS is a cross-sectional survey which has random and systematical samples of more than 200,000 visits to over 250 hospital EDs in the USA. Patient demographic characteristics, source of payment/insurance, clinical presentation, and disposition from the ED were recorded. Descriptive statistics and multivariate logistic regression were performed. RESULTS: Between 2009 and 2018, the rate of uninsured patients in the ED decreased from 18.1% to as low as 9.9%, but this was not associated with a decrease in the disparity in CT utilization between non-Hispanic Black and non-Hispanic White patients. CT use rate increased 38% over the study period. Factors strongly associated with CT utilization include age, source of payment, triage category, disposition from the ED, and residence. After controlling for these factors, non-Hispanic White patients were 21% more likely to undergo CT than non-Hispanic Black patients, though no disparity was seen for Hispanic or Asian/other groups. CONCLUSION: Despite increased insurance coverage over the sample period, racial disparities between non-Hispanic Black and non-Hispanic White patients persist in CT utilization, though no disparity was seen for Hispanic or Asian/other patients. The source of this disparity remains unclear and is likely multifactorial.

Repeated sinus CT imaging after recent head imaging.

OBJECTIVES: Excessive use of sinus CT is a significant problem in medical imaging, resulting in unnecessary costs and radiation exposure. This study assesses frequency of sinus CT performed after recent head imaging has already adequately evaluated the sinuses. METHODS: A retrospective search of the PACS database of an academic medical center was performed to identify cases of sinus CT imaging in 2017. Cases were excluded if sinus CT was performed related to trauma, tumor, operative evaluation, or acute infection other than sinusitis (orbital cellulitis, intracranial abscess). Studies with separate imaging covering the sinuses ordered at the same time as sinus CT or performed previously within 4 weeks were identified and clinical information was recorded. RESULTS: Of 735 sinus CTs performed, 19 (5%) had same-day head imaging and 30 (8%) had previous head imaging within 4 weeks, adding up to a cumulative 13% of cases with recent head imaging. The average patient age was 42, with 13 pediatric cases. Of ordering providers, residents ordered the highest percentage of sinus CTs with same-day head imaging (84%) and previous imaging within 4 weeks (63%). The sinuses were described in all head CT radiology reports, while 10 of 12 brain MRI reports did not mention the sinuses. CONCLUSION: In one year, 13% of patients receiving sinus CTs at our institution had recent head imaging. A focused education effort for ordering providers to avoid repeating sinus imaging, and for radiology to comment on sinuses on head imaging, may reduce unnecessary sinus CTs.

Impact of the COVID-19 pandemic on emergency department CT for suspected diverticulitis.

PURPOSE: This study examined the impact of the COVID-19 pandemic on emergency department CT use for acute nontraumatic abdominal pain, to better understand why imaging volume so drastically decreased during the COVID-19 pandemic. METHODS: This was a retrospective review of emergency imaging volumes from January 5 to May 30, 2020. Weekly volume data were collected for total imaging studies, abdominopelvic CT, and abdominopelvic CTs positive for common causes of acute nontraumatic abdominal pain. Two emergency radiology attendings scored all diverticulitis cases independently, and weekly volume data for uncomplicated and complicated diverticulitis cases was also collected. Volume data prior to and during the COVID-19 pandemic was compared, using 2019 volumes as a control. RESULTS: During the COVID-19 pandemic, overall emergency imaging volume decreased 30% compared to 2019 (p = 0.002). While the number of emergency abdominopelvic CTs positive for appendicitis and small bowel obstruction did not significantly change during the COVID-19 pandemic, the number of cases of diverticulitis decreased significantly compared to 2019 (p = 0.001). This reduction can be specifically attributed to decreased uncomplicated diverticulitis cases, as the number of uncomplicated diverticulitis cases dropped significantly (p = 0.002) while there was no significant difference in the number of complicated diverticulitis cases (p = 0.09). CONCLUSIONS: Reduced emergency abdominopelvic CT volume during the COVID-19 pandemic can partially be explained by decreased imaging of lower acuity patients. This data may help formulate future strategies for imaging resource utilization with an improved understanding of the relationship between perceived imaging risk and symptom acuity.

Randomized control trial comparing an Alvarado Score-based management algorithm and current best practice in the evaluation of suspected appendicitis.

BACKGROUND: An objective algorithm for the management of suspected appendicitis guided by the Alvarado Score had previously been proposed. This algorithm was expected to reduce computed tomography (CT) utilization without compromising the negative appendectomy rate. This study attempts to validate the proposed algorithm in a randomized control trial. METHODS: A randomized control trial comparing the management of suspected acute appendicitis using the proposed algorithm compared to current best practice, with the rate of CT utilization as the primary outcome of interest. Secondary outcomes included the percentage of missed diagnosis, negative appendectomies, length of stay in days, and overall cost of stay in dollars. RESULTS: One hundred sixty patients were randomized. Characteristics such as age, ethnic group, American Society of Anesthesiologist score, white cell count, and symptom duration were similar between the two groups. The overall CT utilization rate of the intervention arm and the usual care arm were similar (93.7% vs 92.5%, p = 0.999). There were no differences in terms of negative appendectomy rate, length of stay, and cost of stay between the intervention arm as compared to the usual care arm (p = 0.926, p = 0.705, and p = 0.886, respectively). Among patients evaluated with CT, 75% (112 out of 149) revealed diagnoses for the presenting symptoms. CONCLUSION: The proposed AS-based management algorithm did not reduce the CT utilization rate. Outcomes such as missed diagnoses, negative appendectomy rates, length of stay, and cost of stay were also largely similar. CT utilization was prevalent as 93% of the study cohort was evaluated by CT scan. TRIAL REGISTRATION: The study has been registered at ClinicalTrials.gov (NCT03324165, Registered October 27 2017).

Reducing emergency department (ED) computed tomography (CT) utilization in women treated for gynecologic cancers.

OBJECTIVES: The objective of this quality improvement (QI) project was to decrease the rate of low-value computed tomography (CT) imaging in established gynecologic oncology patients presenting to the emergency department (ED). METHODS: This was a cohort study with a before and after design that evaluated implementation of a QI project designed to decrease CT utilization in established gynecologic oncology patients in the ED. The pre-intervention cohort included patients admitted through the ED from 4/1/17 to 5/31/18, while the post-intervention cohort was from 6/1/18 to 5/31/19. The intervention included gynecologic oncology consultation before CT on patients who had imaging within the prior 3 weeks. Details regarding CT, ED length of stay (LOS), and oncologic history were abstracted. The value of CT was determined by consensus from 2 reviewers. Prospective data monitoring evaluated for patient safety. RESULTS: Prior to intervention, there were 129 unique ED encounters in gynecologic oncology patients leading to admission. CT scans were performed in 101 (78.3%) encounters, 57.7% of which were deemed to be of low-value. Following implementation, the CT utilization rate decreased significantly from median monthly rate of 75.2% to 49.1% (p < 0.00001), and the ED LOS decreased from 8.1 to 6.9 h (p = 0.0102). The number of CT scans deemed to be low-value in the post-intervention group decreased to 2 (3.8%). CONCLUSIONS: Implementation of an early consultation policy and imaging guidelines led to a significant decrease in unnecessary CT utilization and shorter ED LOS in gynecologic oncology patients presenting to the ED.

Increasing Use, Geographic Variation, and Disparities in Emergency Department CT for Suspected Urolithiasis.

PURPOSE: The aim of this study was to examine changing characteristics of utilization and potential disparities in US emergency department (ED) patients undergoing CT of the abdomen and pelvis (CTAP) for suspected urolithiasis. METHODS: A retrospective study was conducted among all patients from 2006 to 2015 with a primary diagnosis of suspected urolithiasis within the Nationwide Emergency Department Sample, the largest publicly available all-payer ED database in the United States. The annual numbers of ED visits for suspected urolithiasis and associated CTAP examinations per visit were determined. The compound annual growth rate for CTAP was calculated. Using multivariate logistic regression analyses, patient demographics and payer and hospital characteristics were evaluated as potential independent predictors of utilization. RESULTS: Nationwide, the number of ED visits per year for suspected urolithiasis increased from 1,057,119 in 2006 to 1,246,041 in 2014 (relative +17.9%), whereas the annual use of CTAP increased from 24.6% to 49.4% per visit (relative +100.8%; CAGR +8.0%). Multivariate analysis showed higher CTAP use associated with higher patient household income ZIP code quartile (odds ratio [OR] for wealthiest/poorest, 1.48), private payer (ORs, 1.21 versus Medicare and 1.22 versus Medicaid), Northeast geographic region (ORs, 5.07 versus Midwest, 4.16 versus West, and 1.77 versus South), hospital urban status (OR, 1.42), and nonteaching hospitals (OR, 1.20) (P < .05 for all). CONCLUSIONS: The relative use of CTAP in ED patients presenting with suspected urolithiasis doubled between 2006 and 2014 and showed marked geographic variation. Among ED patients with suspected urolithiasis, CTAP was more frequent in patients from higher household income ZIP codes, with private insurance, in the Northeast, and at urban and nonteaching hospitals.

The Impact of Risk Standardization on Variation in CT Use and Emergency Physician Profiling.

OBJECTIVE: The purpose of this study is to use detailed electronic health record data to profile the use of condition-specific, risk-standardized imaging by emergency physicians. MATERIALS AND METHODS: CT utilization in four emergency departments in a single health care system was retrospectively analyzed. The primary outcome for analysis was indication-specific, risk-standardized CT utilization. We constructed seven clinical cohorts on the basis of the presence or absence of a traumatic indication for the most frequently performed CT studies. Risk standardization was performed using machine learning algorithms and hierarchic logistic regression models. Variation in CT utilization for each cohort was analyzed using coefficients of variation and box plots, the effect of risk standardization on physician profiling was determined using slope diagrams and kappa values, and within-physician correlation was assessed using correlation coefficients and matrices. RESULTS: For the seven cohorts, the number of physicians ordering more than 25 CT studies for a particular indication ranged from 70 to 88, and the number of ED visits ranged from 17,458 to 117,489. The unadjusted variation was large for each indication (coefficient of variation, 30.2-57.9). Risk standardization resulted in reduced but persistent variation for all indications (coefficient of variation, 12.3-22.3). Among indication-specific models, risk standardization resulted in reclassification by two or more deciles for 14.0-39.1% of physicians. The R value for within-physician correlation varied from 0.02 to 0.80 and was highest between chest and abdominal imaging for trauma. CONCLUSION: In this multisite study of CT utilization, risk standardization had a substantial impact on variation in CT utilization and emergency physician profiling. Administrators and payers should include risk standardization in future measures of physician imaging to ensure valid assessment of performance and achieve improvements in emergency care value.

Imaging Gently.

Advances in medical imaging are invaluable in the care of pediatric patients in the emergent setting. The diagnostic accuracy offered by studies using ionizing radiation, such as plain radiography, computed tomography, and fluoroscopy, are not without inherent risks. This article reviews the evidence supporting the risk of ionizing radiation from medical imaging as well as discusses clinical scenarios in which clinicians play an important role in supporting the judicious use of imaging studies.

Clinical utility and cost analysis of routine postoperative head CT in elective aneurysm clippings.

OBJECTIVE Postoperative head CT scanning is performed routinely at the authors' institution on all neurosurgical patients after elective aneurysm clippings. The goal of this study was to determine how often these scans influence medical management and to quantify the associated imaging costs. METHODS The authors reviewed the medical records and accounting database of 304 patients who underwent elective (i.e., nonruptured) aneurysm clipping performed by 1 surgeon (M.T.L.) from 2010 to 2014 at the University of California, San Francisco. Specifically, the total number of postoperative head CT scans, radiographic findings, and the effect of these studies on patient management were determined. The authors obtained the total hospital costs for these patients, including the cost of imaging studies, from the hospital accounting database. RESULTS Overall, postoperative CT findings influenced clinical management in 3.6% of cases; specifically, they led to permissive hypertension in 4 patients for possible ischemia, administration of mannitol for edema and high-flow oxygen for pneumocephalus in 2 patients each, seizure prophylaxis in 1 patient, Plavix readjustment in 1 patient, and return to the operating room for an asymptomatic epidural hematoma evacuation in 1 patient. When patients were stratified on the basis of postoperative neurological examination, findings on CT scans altered management in 1.1%, 4.8%, and 9.0% of patients with no new neurological deficits, a nonfocal examination, and focal deficits, respectively. The mean total hospital cost for treating patients who undergo elective aneurysm clipping was $72,227 (± $53,966) (all values are US dollars), and the cost of obtaining a noncontrast head CT scan was $292. Neurologically intact patients required 99 head CT scans, at a cost of $28,908, to obtain 1 head CT scan that influenced medical management. In contrast, patients with a focal neurological deficit required only 11 head CT scans, at a cost of $3212, to obtain 1 head CT scan that changed clinical management. CONCLUSIONS Although there are no clear guidelines, the large number and high cost of CT scans needed to treat neurologically intact elective aneurysm patients suggest that careful neurological monitoring may be more clinically useful and a better use of hospital resources than routine postoperative CT.

Rising utilization of CT in adult fall patients.

OBJECTIVE. Falls are a common cause of emergency department (ED) visits in the United States. We evaluated trends in CT utilization for adult fall patients in the United States from 2001 to 2010. MATERIALS AND METHODS. Using the National Hospital Ambulatory Medical Care Survey, we identified all visits from 2001 to 2010 of adult patients presenting to EDs after falls. This database surveys approximately 500 EDs annually for 4 weeks, providing national estimates on ED resource utilization and outcomes. We studied trends in CT utilization and proportion of visits with life-threatening conditions (intracranial hemorrhage, organ laceration, axial skeletal fractures) after falls. We also studied the association between CT utilization rates and demographic characteristics and admission status. RESULTS. A total of 22,166 unweighted observations representing 73,241,368 visits were identified. The proportion of adult fall patient visits during which CT was performed increased from 11.4% in 2001 to 28.0% in 2010 (p < 0.0001), whereas the proportion of adult fall visits with life-threatening conditions increased from 5.7% to 8.2% (p < 0.0001). On adjusted analysis (adjusting for life-threatening condition and demographic variables), each successive year was independently associated with CT utilization (odds ratio, 1.21 [95% CI, 1.21-1.21]). The odds of CT utilization in 2010 compared with 2001 were 2.62 (95% CI, 2.61-2.62). CONCLUSION. There was a 2.5-fold increase in CT utilization among adult fall patient visits from 2001 to 2010. When demographic and clinical variables were controlled for, increasing year was independently associated with CT utilization. These findings suggest that CT may be overutilized among adult fall patients.