Exam Protocols Research Articles

Space Radiology: Emerging Nonsonographic Medical Imaging Techniques and the Potential Applications for Human Spaceflight.

Space medicine is a multidisciplinary field that requires the integration of medical imaging techniques and expertise in diagnosing and treating a wide range of acute and chronic conditions to maintain astronaut health. Medical imaging within this domain has been viewed historically through the lens of inflight point-of-care ultrasound and predominantly research uses of cross-sectional imaging before and after flight. However, space radiology, a subfield defined here as the applications of imaging before, during, and after spaceflight, will grow to necessitate the involvement of more advanced imaging techniques and subspecialist expertise as missions increase in length and complexity. While the performance of imaging in spaceflight is limited by equipment mass and volume, power supply, radiation exposure, communication delays, and personnel training, recent developments in nonsonographic modalities have opened the door to their potential for in-mission use. Additionally, improved exam protocols and scanner technology in combination with artificial intelligence algorithms have greatly advanced the utility of possible pre- and postflight studies. This article reviews the past and present of space radiology and discusses possible use cases, knowledge gaps, and future research directions for radiography, fluoroscopy, computed tomography, and magnetic resonance imaging within space medicine, including both the performance of new exam types for new indications and the increased extraction of information from exams already routinely obtained. Through thoughtfully augmenting the use of these tools, medical mission risk may be reduced substantially through preflight screening, inflight diagnosis and management, and inflight and postflight surveillance.

Detection of abdominopelvic lymph nodes in multi-parametric MRI

Reliable localization of lymph nodes (LNs) in multi-parametric MRI (mpMRI) studies plays a major role in the assessment of lymphadenopathy and staging of metastatic disease. Radiologists routinely measure the nodal size in order to distinguish benign from malignant nodes, which require subsequent cancer staging. However, identification of lymph nodes is a cumbersome task due to their myriad appearances in mpMRI studies. Multiple sequences are acquired in mpMRI studies, including T2 fat suppressed (T2FS) and diffusion weighted imaging (DWI) sequences among others; consequently, the sizing of LNs is rendered challenging due to the variety of signal intensities in these sequences. Furthermore, radiologists can miss potentially metastatic LNs during a busy clinical day. To lighten these imaging and workflow challenges, we propose a computer-aided detection (CAD) pipeline to detect both benign and malignant LNs in the body for their subsequent measurement. We employed the recently proposed Dynamic Head (DyHead) neural network to detect LNs in mpMRI studies that were acquired using a variety of scanners and exam protocols. The T2FS and DWI series were co-registered, and a selective augmentation technique called Intra-Label LISA (ILL) was used to blend the two volumes with the interpolation factor drawn from a Beta distribution. In this way, ILL diversified the samples that the model encountered during the training phase, while the requirement for both sequences to be present at test time was nullified. Our results showed a mean average precision (mAP) of 53.5% and a sensitivity of ∼78% with ILL at 4 FP/vol. This corresponded to an improvement of ≥10% in mAP and ≥12% in sensitivity at 4FP (p ¡ 0.05) respectively over current LN detection approaches evaluated on the same dataset. We also established the out-of-distribution robustness of the DyHead model by training it on data acquired by a Siemens Aera scanner and testing it on data from the Siemens Verio, Siemens Biograph mMR, and Philips Achieva scanners. Our pilot work represents an important first step towards automated detection, segmentation, and classification of lymph nodes in mpMRI.

Head and neck exam practices of dental professionals.

Periodic examination of the head and neck includes screening for oral cancer, which is largely performed in dental offices by vigilant oral healthcare providers. The aim of this study was to assess practice patterns among Virginia dentists in performing head and neck exams and the referral rates of biopsies after completion of head and neck exams. We hypothesized that not all dentists perform head and neck exams and there is a difference between dentists who refer patients for a biopsy and those that perform biopsies. General dentists and dental specialists who are members of the Virginia Dental Association were invited to participate in a cross-sectional survey study through REDCap to self-report their head and neck exam protocols. A total of 224 providers completed the survey. The majority of respondents were general dentists with more than 20 years in practice, who practice in a private setting, and see more than 10 patients in a day. All respondents stated they perform intraoral examinations, but 10 respondents stated they do not perform extraoral examinations. Nearly a third of respondents reported doing their own biopsies. Although only 8.5% of oral healthcare providers in Virginia responded to our survey, respondents are following the 2017 ADA good practice statement by providing their patients with head and neck exams to screen for oral cancer. Additional education pertaining to extraoral anatomy, malignant transformation of oral potentially malignant disorders, and pathology procedures may be helpful to clinicians.

The AIUM Practice Parameter for the Performance of the Musculoskeletal Ultrasound Examination.

The AIUM Practice Parameter for the Performance of the Musculoskeletal Ultrasound Examination.

Diagnostic ultrasound of the residual limb: A narrative review.

Globally, 57.7million people lived with traumatic limb loss in 2017, with the prevalence of amputation in the United States alone expected to reach 3.6million by 2050. Pain is a common complication after limb loss, with up to 59% of patients experiencing residual limb pain (RLP). Although RLP is often due to a structural etiology, it is difficult to treat because the exact structure involved is frequently not apparent on history and physical examination alone. This narrative review aims to summarize the available literature on diagnostic ultrasound of the residual limb and examine the utility of ultrasound in identifying specific pathology. A total of 31 peer-reviewed manuscripts published between 1989 and 2021 were included, grouped by pathology. Although ultrasound presents a promising and cost-effective approach to identifying pathology within the residual limb, many gaps remain in the current knowledge, and no specific protocol for a sonographic assessment of the residual limb has ever been proposed. Future studies of diagnostic ultrasound of the residual limb should focus on replicable sonographic techniques and standardized exam protocols.

The Actual Role of Iterative Reconstruction Algorithm Methods in Several Saudi Hospitals As A Tool For Radiation Dose Minimization of Ct Scan Examinations.

BackgroundIterative reconstruction algorithm (IR) techniques were developed to maintain a lower radiation dose for patients as much as possible while achieving the required image quality and medical benefits. The main purpose of the current research was to assess the level and usage extent of IR techniques in computed tomographic (CT) scan exams. Also, the obligation of practitioners in several hospitals in Saudi Arabia to implement IR in CT exams was assessed.Material and MethodologyThe recent research was based on two studies: data collection and a survey study. Data on the CT scan examinations were retrospectively collected from CT scanners. The survey was conducted using a questionnaire to evaluate radiographers’ and radiologists’ perceptions about IR and their practices with IR techniques. The statistical analysis results were performed to measure the usage strength level of IR methods.Results and DiscussionsThe IR strength level of 50% was selected for nearly 80% of different CT examinations and patients of different ages and weights. About 46% of the participants had not learned about IR methods during their college studies, and 54% had not received formal training in applying IR techniques. Only 32% of the participants had adequate experience with IR. Half of the participants were not involved in the updating process of the CT protocol.ConclusionThe results indicate that the majority of radiographer and radiologist at four different hospitals in Saudi Arabia have no explicit or understandable knowledge of selecting IR strength levels during the CT examination of patients. There is a need for more training in IR applications for both radiologists and radiographers. Training sessions were suggested to support radiographers and radiologists to efficiently utilize IR techniques to optimize image quality. Further studies are required to adjust CT exam protocols effectively to utilize the IR technique.

Dose coefficients for organ dosimetry in tomosynthesis imaging of adults and pediatrics across diverse protocols.

The gold-standard method for estimation of patient-specific organ doses in digital tomosynthesis (DT) requires protocol-specific Monte Carlo (MC) simulations of radiation transport in anatomically accurate computational phantoms. Although accurate, MC simulations are computationally expensive, leading to a turnaround time in the order of core hours for simulating a single exam. This limits their clinical utility. The purpose of this study is to overcome this limitation by utilizing patient- and protocol-specific MC simulations to develop a comprehensive database of air-kerma-normalized organ dose coefficients for a virtual population of adult and pediatric patient models over an expanded set of exam protocols in DT for retrospective and prospective estimation of radiation dose in clinical tomosynthesis. A clinically representative virtual population of 14 patient models was used, with pediatric models (M and F) at ages 1, 5, 10, and 15 and adult patient models (M and F) with body mass index (BMIs) at 10th, 50th, and 90th percentiles of the US population. A graphics processing unit (GPU)-based MC simulation framework was used to simulate organ doses in the patient models, incorporating the scanner-specific configuration of a clinical DT system (VolumeRad, GE Healthcare, Waukesha, WI, USA) and an expanded set of exam protocols, including 21 distinct acquisition techniques for imaging a variety of anatomical regions (head and neck, thorax, spine, abdomen, and knee). Organ dose coefficients (hn ) were estimated by normalizing organ dose estimates to air kerma at 70cm (X70cm ) from the source in the scout view. The corresponding coefficients for projection radiography were approximated using organ doses estimated for the scout view. The organ dose coefficients were further used to compute air-kerma-normalized patient-specific effective dose coefficients (Kn ) for all combinations of patients and protocols, and a comparative analysis examining the variation of radiation burden across sex, age, and exam protocols in DT, and with projection radiography was performed. The database of organ dose coefficients (hn ) containing 294 distinct combinations of patients and exam protocols was developed and made publicly available. The values of Kn were observed to produce estimates of effective dose in agreement with prior studies and consistent with magnitudes expected for pediatric and adult patients across the different exam protocols, with head and neck regions exhibiting relatively lower and thorax and C-spine (apsc, apcs) regions relatively higher magnitudes. The ratios (r=Kn /Kn ,rad ) quantifying the differences air-kerma-normalized patient-specific effective doses between DT and projection radiography were centered around 1.0 for all exam protocols, with the exception of protocols covering the knee region (pawk, patk). This study developed a database of organ dose coefficients for a virtual population of 14 adult and pediatric XCAT patient models over a set of 21 exam protocols in DT. Using empirical measurements of air kerma in the clinic, these organ dose coefficients enable practical retrospective and prospective patient-specific radiation dosimetry. The computation of air-kerma-normalized patient-specific effective doses further enables the comparison of radiation burden to the patient populations between protocols and between imaging modalities (e.g., DT and projection radiography), as presented in this study.

A GPU-accelerated framework for individualized estimation of organ doses in digital tomosynthesis.

Estimation of organ doses in digital tomosynthesis (DT) is challenging due to the lack of existing tools that accurately and flexibly model protocol- and view-specific collimations and motion trajectories of the source and detector for a variety of exam protocols, and the computational inefficiencies of conducting MC simulations. The purpose of this study was to overcome these limitations by developing and benchmarking a GPU-accelerated MC simulation framework compatible with patient-specific computational phantoms for individualized estimation of organ doses in DT. The framework for individualized estimation of dose in DT was developed as a two-step workflow: (1) a custom MATLAB code that accepts a patient-specific computational phantom and exam description (organ markers for defining the extremities of the anatomical region of interest, tube voltage, source-to-image distance, angular sweep range, number of projection views, and the pivot point to image distance - PPID) to compute the field of views (FOVs) for a clinical DT system, and (2) a MC tool (developed using MC-GPU) modeling the configuration of a clinical DT system to estimate organ doses based on the computed FOVs. Using this framework, we estimated organ doses for 28 radiosensitive organs in an adult reference patient model (M; 30 years) imaged using a commercial DT system (VolumeRad, GE Healthcare, Waukesha, WI). The estimates were benchmarked against values from a comparable organ dose estimation framework (reference dataset developed by the Advanced Laboratory for Radiation Dosimetry Studies at University of Florida) for a posterior-anterior chest exam. The resulting differences were quantified as percent relative errors and analyzed to identify any potential sources of bias and uncertainties. The timing performance (run duration in seconds) of the framework was also quantified for the same simulation to gauge the feasibility of the workflow for time-constrained clinical applications. The organ dose estimates from the developed framework showed a close agreement with the reference dataset, with percent relative errors ranging from -6.9% to 5.0% and a mean absolute percent difference of 1.7% over all radiosensitive organs, with the exception of testes and eye lens, for which the percent relative errors were higher at -18.9% and -27.6%, respectively, due to their relative positioning outside the primary irradiation field, leading to fewer photons depositing energy and consequently higher errors in estimated organ doses. The run duration for the same simulation was 916.3 s, representing a substantial improvement in performance over existing nonparallelized MC tools. This study successfully developed and benchmarked a GPU-accelerated framework compatible with patient-specific anthropomorphic computational phantoms for accurate individualized estimation of organ doses in DT. By enabling patient-specific estimation of organ doses, this framework can aid clinicians and researchers by providing them with tools essential for tracking the radiation burden to patients for dose monitoring purposes and identifying the trends and relationships in organ doses for a patient population to optimize existing and develop new exam protocols.

"Good practices" in pediatric clinical care for disorders/differences of sex development.

To define, benchmark, and publicize elements of quality care (i.e., "good practices") for pediatric patients with disorders/differences of sex development (DSD). Principles of quality care were identified by literature review; consensus exists for 11 good practices and adherence was evaluated through online survey of 21 North American clinical sites. Strong uptake was observed for many practices, particularly specialty participation (n ≥ 17 of 21 sites for most core specialties); point of contact (n = 18); expertise in gender dysphoria/dissatisfaction (n = 20); and DSD-specific continuing medical education (n = 18). Greater variability was apparent for frequency of peer support referrals (n = 12 universally practiced); standardized questionnaires for routine assessment of psychosocial adaptation (n = 13) and gender development (n = 10); consistently clarifying patient/family values in decision-making (n = 15); genital exam protocols that exclude trainee education as primary reason (n = 15); and internal patient-tracking efforts (n = 5-10 of 20 sites). This study employed a novel approach to designate DSD good practices and identified areas of consistency and variation in these DSD clinical practices. Good practice benchmarking facilitates quality assessment within and across sites, promotes continuous improvement, and empowers stakeholders in locating and delivering high quality care.

Radiation dose optimization in diagnostic and interventional radiology: Current issues and future perspectives.

The medical radiological imaging technological evolution and wide availability has resulted in the exponential increase in utilization. Evidence for a risk of cancer arising from radiation doses of lower than 100mSv is still limited. There is a need for patient dose optimization. A literature review was conducted to identify the reasons why optimization is important and the steps to be followed for a successful optimization process in digital radiology, Computed Tomography, interventional radiology and mammography. Based on recent literature, 5 steps for a dose optimization process are proposed. These steps are: 1) establishment of a quality assurance programme; a mistake, misuse or malfunction of an X-ray machine can potentially affect the health or life of thousands of people, 2) establishment of a dose optimization team consisting of a radiologist, medical physicist and radiation technologist, 3) determination of baseline dose levels and image quality as well as comparisons with benchmarks to decide which exam protocols should be optimized, 4) modification of protocols by the medical physicist and 5) evaluation of the optimization process and its effect on patient dose and image quality. The optimization process should include joint efforts focused on 1) equipment performance 2) exam protocol customization and 3) staff behaviour. Manufacturers should provide detailed descriptions of exam protocols and training on the use of dose reduction features. The diagnostic radiology medical physicist should emerge and take a proactive lead in the everyday clinical routine in order to promote the value of optimization process.

Cardiovascular magnetic resonance in myocardial infarction with non-obstructive coronary arteries patients: A review.

The diagnosis of myocardial infarction with non-obstructive coronary arteries (MINOCA) necessitates documentation of an acute myocardial infarction (AMI), non-obstructive coronary arteries, using invasive coronary angiography or coronary computed tomography angiography and no clinically overt cause for AMI. Historically patients with MINOCA represent a clinical dilemma with subsequent uncertain clinical management. Differential diagnosis is crucial to choose the best therapeutic option for ischemic and non-ischemic MINOCA patients. Cardiovascular magnetic resonance (CMR) is able to analyze cardiac structure and function simultaneously and provides tissue characterization. Moreover, CMR could identify the cause of MINOCA in nearly two-third of patients providing valuable information for clinical decision making. Finally, it allows stratification of patients with worse outcomes which resulted in therapeutic changes in almost half of the patients. In this review we discuss the features of CMR in MINOCA; from exam protocols to imaging findings.

Applications of Rapid MRI, How To Improve Patient Care

Magnetic resonance imaging (MRI) is routinely used in Osteoarthritis (OA) assessment, both clinically and in research studies. Numerous different MRI contrast mechanisms highlight abnormalities or changes over time, with increasing tendency toward quantitative techniques and true 3D imaging. Scan protocols can include multiple contrasts, often resulting in exam protocols of 20-30 minutes for clinical imaging, and even longer for research studies, which can limit utilization or study sizes due to cost.

58. Dosimetric changes with Computed Tomography Automatic Tube Current Modulation techniques

Purpose The objective of the study is the verification of dose changes for a Computed Tomography (CT) Automatic Tube Current Modulation (ATCM) technique. In particular, the work aims to verify that (1) previsions of the CT scanner console (in terms of CTDIvol and DLP) are reflected in the dose distribution within the patient and (2) the experimental results coincide with the predictions of the noise theory on which the technique is based. For this purpose, an anthropomorphic Alderon RANDO (AR) phantom and Gafchromic® XR-QA2 films were used. Methods Radiochromic films were cut to shape the AR phantom in two anatomical regions (shoulders and mid-chest). Since the ATCM algorithm used is based on the Noise Index (NI) parameter, three thorax exam protocols were chosen: reference (NI = 13), lower (NI = 10) and higher (NI = 16) noise. All other acquisition parameters during the three scans were maintained unchanged. CTDIvol and DLP values reported by the CT console were recorded after each exam to compare theoretical and experimental measurements. After dose calibration of the films, dose maps were normalized to the reference map (NI = 13) to obtain percentage variations. Experimental results were compared to the relative variations obtained from CT console and quantum noise theory. Results The results showed that the information reported by the CT console in terms of CTDIvol and DLP variation are in agreement, on average, with experimental measurements. The dose distribution, however, is not uniform and CT console dose reports are purely indicative. Variations, in fact, are calculated by considering a uniform water phantom that does not represent the actual composition of the patient, as shown in Fig. 1. The values reported by the CT console are also in agreement with the prediction by the quantum noise theory. Conclusions The study allowed to verify the dose information reported by the CT scanner console for an ATCM technique. The CTDIvol and DLP values represent, on average, the experimentally measured variation in the AR phantom. Although this evaluation represents an estimate, this method can be a starting point for further studies.

Dosimetric changes with computed tomography automatic tube-current modulation techniques.

The study is aimed at a verification of dose changes for a computed tomography automatic tube-current modulation (ATCM) technique. For this purpose, anthropomorphic phantom and Gafchromic® XR-QA2 films were used. Radiochromic films were cut according to the shape of two thorax regions. The ATCM algorithm is based on noise index (NI) and three exam protocols with different NI were chosen, of which one was a reference. Results were compared with dose values displayed by the console and with Poisson statistics. The information obtained with radiochromic films has been normalized with respect to the NI reference value to compare dose percentage variations. Results showed that, on average, the information reported by the CT console and calculated values coincide with measurements. The study allowed verification of the dose information reported by the CT console for an ATCM technique. Although this evaluation represents an estimate, the method can be a starting point for further studies.

Anatomical Risk Factors for Rupture of the Anterior Cruciate Ligament: Magnetic Resonance Imaging Based Knee Joint Assessment

Anterior cruciate ligament (ACL) rupture is one of the most frequently encountered traumatic ligamentous lesions of the knee. Several intrinsic and extrinsic factors are linked to this lesion. Anatomical factors increase the anterior translation of the knee and thus promote the stretching and rupture of the anterior cruciate ligament. Objectives: To determine the anatomical risk factors favouring ACL rupture by comparing morphometric parameters of patients with knee ACL rupture to patients without ACL rupture, as well as the intercondylar notch index and the tibial slopes of the two groups and describing the ruptured ACLs and associated signs. Materials and Methods: We conducted a case-control descriptive analytical study in imaging centres of the General Henri Mondor of Aurillac Hospital Centre in France (CHM) and the Jordan Medical Centre of Yaounde in Cameroon (CMJ). MRI exam protocols included T1 SE, T2 SE, proton density and Fat Sat sequences, with slices in all three planes. Morphometry knee variables measured in our study were: intercondylar notch index and the tibial slopes. These measurements were obtained from images stored in DICOM format and post processing software OsiriX MD® for CMJ patients and Explore® for CHM patients. Results: The study included 92 individuals, 38 in the case group and 54 in the control group. The mean age was 36.6 years for both groups; 35.5 years for the cases and 37.4 years for the controls. The sex ratio was 1.87 men for 1 woman in both groups; 2.16 men for 1 woman for the case group. 53% of ACL ruptures are partial, with the predominant direct sign being morphologic and signal abnormalities of the ACL. The most significant indirect sign of ACL rupture was mirror-image bone contusion that was observed in 47.3% of cases. In the case group, the mean lateral tibial slope was 4.003°, whereas it was 2.92° in the control group. The comparison of means was estimated at approximately 0.039 (p < 0.05), corresponding to a statistically significant difference. The means of the intercondylar notch indices were: 0.28 for the case group and 0.26 for the control group. The means of the median slopes were 4.93 for the case group and 4.90 for the control group. Conclusion: The increase in the lateral tibial slope was a risk factor for anterior cruciate ligament rupture in our study population. Intercondylar notch index and medial tibial slope did not show any statistical significant difference.

Dual-energy CT workflow: multi-institutional consensus on standardization of abdominopelvic MDCT protocols.

To standardize workflow for dual-energy computed tomography (DECT) involving common abdominopelvic exam protocols. 9 institutions (4 rsDECT, 1 dsDECT, 4 both) with 32 participants [average # years (range) in practice and DECT experience, 12.3 (1-35) and 4.6 (1-14), respectively] filled out a single survey (n=9). A five-point agreement scale (0, 1, 2, 3, 4-contra-, not, mildly, moderately, strongly indicated, respectively) and utilization scale (0-not performing and shouldn't; 1-performing but not clinically useful; 2-performing but not sure if clinically useful; 3-not performing it but would like to; 4-performing and clinically useful) were used. Consensus was considered with a score of ≥2.5. Survey results were discussed over three separate live webinar sessions. 5/9 (56%) institutions exclude large patients from DECT. 2 (40%) use weight, 2 (40%) use transverse dimension, and 1 (20%) uses both. 7/9 (78%) use 50keV for low and 70keV for medium monochromatic reconstructed images. DECT is indicated for dual liver [agreement score (AS) 3.78; utilization score (US) 3.22] and dual pancreas in the arterial phase (AS 3.78; US 3.11), mesenteric ischemia/gastrointestinal bleeding in both the arterial and venous phases (AS 2.89; US 2.79), RCC exams in the arterial phase (AS 3.33; US 2.78), and CT urography in the nephrographic phase (AS 3.11; US 2.89). DECT for renal stone and certain single-phase exams is indicated (AS 3.00). DECT is indicated during the arterial phase for multiphasic abdominal exams, nephrographic phase for CTU, and for certain single-phase and renal stone exams.

The quotidianisation of the war in everyday life at German schools during the First World War

The outbreak of the First World War had a powerful impact on German schools. Undoubtedly, schools were institutions of socialisation that did offer support to the war. Indeed, research has shown that a specific “war pedagogy” made an aggressive propaganda possible in the classroom. This research usually emphasises the enthusiasm for war that swept up teachers and students in schools, as in the rest of the population, in the first few months of the war. However, this emphasis on the war frenzy obscures the fact that schools were not easily transformed into war institutions. Even if schools made a great effort to align themselves with the war effort, they remained independent associations, and soon after 1914, a quotidianisation (akin to routinisation) arose within the schools. To date, source materials that show this lack of influence of wartime propaganda on schools have only been analysed in terms of what they reveal about the deprivations and hardships of schools during the war. However, records from the schools also shed light on the everyday routines that continued during the war, and such evidence calls on scholars to reconsider the conditions in schools in the First World War. This article analyses selected records including school chronicles and exam protocols from the war years and shows that school life was often distinct from war enthusiasm. A more complex view is therefore advocated of the relationship between the First World War and the German school.

Bedside diagnosis of dysphagia: a systematic review.

Dysphagia is associated with aspiration, pneumonia, and malnutrition, but remains challenging to identify at the bedside. A variety of exam protocols and maneuvers are commonly used, but the efficacy of these maneuvers is highly variable. We conducted a comprehensive search of 7 databases, including MEDLINE, Embase, and Scopus, from each database's earliest inception through June 9, 2014. Studies reporting diagnostic performance of a bedside examination maneuver compared to a reference gold standard (videofluoroscopic swallow study or flexible endoscopic evaluation of swallowing with sensory testing) were included for analysis. From each study, data were abstracted based on the type of diagnostic method and reference standard study population and inclusion/exclusion characteristics, design, and prediction of aspiration. The search strategy identified 38 articles meeting inclusion criteria. Overall, most bedside examinations lacked sufficient sensitivity to be used for screening purposes across all patient populations examined. Individual studies found dysphonia assessments, abnormal pharyngeal sensation assessments, dual axis accelerometry, and 1 description of water swallow testing to be sensitive tools, but none were reported as consistently sensitive. A preponderance of identified studies was in poststroke adults, limiting the generalizability of results. No bedside screening protocol has been shown to provide adequate predictive value for presence of aspiration. Several individual exam maneuvers demonstrated reasonable sensitivity, but reproducibility and consistency of these protocols was not established. More research is needed to design an optimal protocol for dysphagia detection.

SU‐E‐I‐62: Dose Reduction to Anterior Surface with Organ‐Based Tube Current Modulation: Evaluation of Performance in a Phantom Study

Purpose: To evaluate in a phantom study image quality and dose reduction to the anterior surface with organ‐based tube current modulation in head and thoracic CT. Methods: Organ‐based tube current modulation is designed to reduce dose to superficial radiosensitive organs such as the lens of the eye, thyroid and breast by decreasing the tube current when the tube passes closest to these organs. Dose and image quality were evaluated in phantoms for clinical head and thorax exam protocols with and without organ‐based tube current modulation. Surface dose reduction as a function of position was measured using a 32‐cm CT Dose Index (CTDI) phantom, an anthropomorphic adult phantom and ion chambers. Surface dose reduction as a function of patient size was investigated using three semi‐ anthropomorphic phantoms with posteroanterior dimensions of 14, 25 and 31 cm. Image noise (the standard deviation of CT numbers in regions of interest) was evaluated for the anthropomorphic and the semi‐ anthropomorphic phantoms. Results: For equivalent scanner output (Volume CTDI), dose to the midline of the anterior surface was reduced by 27–50%, depending on anatomic region (head or thorax) and phantom size; dose to the posterior surface was correspondingly increased. Image noise was not significantly different between scans with and without organ‐based tube current modulation (p=0.35). Conclusions: Organ‐based tube current modulation can reduce dose to the anterior surface of patients, without increasing image noise, by commensurately increasing dose to the posterior surface. This can reduce dose to anterior radiosensitive organs for head and thoracic CT scans.

Assessment of patient doses in CR examinations throughout a large health region.

Optimization and standardization of radiographic procedures in a health region minimizes patient exposure while producing diagnostic images. This report highlights the dose variation in common computed radiography (CR) examinations throughout a large health region. The RadChex cassette was used to measure the radiation exposure at the table or wall bucky in 20 CR rooms, in seven hospitals, using CR technology from two vendors. Exposures were made to simulate patient exposure (21 cm polymethyl methacrylate) under standard conditions for each bucky: 81 kVp at 100 cm for anteroposterior abdomen table bucky exposures (180 cm for posteroanterior chest wall bucky exposures), using the left, the right, or the center automatic exposure control (AEC) cells. Protocol settings were recorded. An average of 37% variation was found between AEC chambers, with a range between 4% and 137%. A 60% difference in dose was discovered between manufacturers, which was the result of the manufacture's image processing algorithm and subsequently corrected via software updates. Finally, standardizing AEC cell selection during common chest examinations could reduce patient dose by up to 30%. In a large health region, variation in exam protocols can occur, leading to unnecessary patient dose from the same type of examination. Quality control programs must monitor exam protocols and AEC chamber calibration in CR to ensure consistent, minimal, patient dose, regardless of hospital or CR vendor. Furthermore, this report highlights the need for communication between radiologists, technologists, medical physicist, service engineers, and manufacturers required to optimize CR protocols.