Scout Radiograph Research Articles

Role of Plain Radiographs in Assessing Appropriate Placement of Orbital Implants for Repair of Floor Fractures.

Intraoperative imaging is becoming increasingly common in repair of facial fractures. Many institutions do not have access to intraoperative advanced 3D imaging but have the capability of obtaining plain radiographs intraoperatively. At institutions where advanced 3D imaging is available, scout radiographs are usually obtained prior to a complete scan. These scout images can provide some information about the placement of radiopaque implants before a complete scan is performed. The aim of this study is to examine the correct anatomic positioning of an orbital floor implant using lateral plain radiographs. Titanium orbital fan implants were molded and secured to orbital floor of 14 adult dry skulls (7 males and 7 females). Lateral radiographs were obtained for both the left and the right orbits individually. The antero-posterior angle of inclination that the implant makes relative to the Frankfort horizontal plane was measured, and results were compared in the male versus female radiographs. The mean angle that the implant made with the Frankfort horizontal plane was 20.1±2.4° in the male orbits (95% CI 18.8-21.5°) and 22.6 ± 2.0° in the female orbits (95% CI, 21.4-23.7°). We found no statistically significant differences between the male and female angles (P-value 0.62). For the combined specimens (i.e., 28 sides in 14 skulls), the overall mean angle was 21.4 ± 2.5° (95% CI, 20.4-22.3°). Based on these findings, the angle that the implant makes with the Frankfort horizontal plane on lateral cross-table plain radiographs can be used intraoperatively to assist the surgeon in confirming the appropriate placement of the implant.

Effects of scout radiographic imaging conditions on tube current modulation in chest computed tomography

For the optimisation of radiation dose in computed tomography (CT), dose reduction is attempted while preserving diagnostic performance. To reduce the overall radiation dose related to CT, the dose from scout radiography may be reduced by decreasing the tube voltage and tube current. We evaluated the effects of scout imaging conditions on CT radiation dose. An anthropomorphic chest phantom was imaged on two CT scanners (scanners A and B) from different vendors, manipulating the scout imaging conditions in terms of imaging direction, tube voltage and tube current, and assessed the tube current modulation in subsequent CT and pixel values in scout radiographs. The direction of the scout radiography influenced the shape of the tube current modulation curve and total radiation dose in subsequent CT. When compared with the use of the lateral projection, use of the posteroanterior or anteroposterior projection alone increased the radiation dose substantially on scanner A, but did not change, or mildly decreased, the dose on scanner B. When imaged using the lateral scout on scanner A, reduction in tube voltage and tube current for scout radiography decreased the CT dose in the cranial part of the scan range and, to a lesser degree, the total radiation dose. On the low-voltage, low-current lateral radiograph, the image contrast was impaired and pixel values were underestimated around the lung apex. Without the use of the lateral radiograph, neither the tube voltage nor tube current for scout radiography influenced the CT dose. On scanner B, reduced tube voltage for scout radiography increased the CT dose. In conclusion, reduced tube voltage and tube current may affect scout radiographs, resulting in alteration of the tube current modulation pattern and total radiation dose in subsequent CT. These effects vary depending on the CT scanners and scout direction.

Anatomic Factors Affecting Size of Suboccipital Decompression

Abstract INTRODUCTION Emergent suboccipital decompressions are not uncommon procedures for the management of cerebellar infarcts and hemorrhages with mass effect. While anatomic landmarks, such as the transverse sinus and foramen magnum, provide clear boundaries to the decompression, there are a multitude of patient-specific anatomic factors that complicate positioning, and make obtaining an adequate decompression challenging. METHODS We reviewed a consecutive series of patients undergoing emergent suboccipital decompressions. Patients in whom a unilateral decompression was performed were excluded from the study. A total of 43 patients met the inclusion criteria, and were further reviewed. The primary outcome was to determine what anatomic factors predicted maximal width and cranial-caudal extent of SOC bone flap. Head CTs, including scout film radiographs, and chest XRs in the pre- and perioperative period were reviewed to measure specific anatomic features. RESULTS The average patient age was 55 (19-85). 34% of patients were female. A bivariate analysis showed that AP diameter correlated to inion-to-foramen magnum distance (P = .001, r2 = 0.501), shoulder width (P = .001, r2 = 0.509), and soft tissue at C1 measured from posterior arch on CT (P = .004, r2 = 0.444). The angle measured from a plumb line through the CT scout radiograph and a line connecting the inion to the spinous process of C2 also correlated to AP diameter (P = .046, r2 = 0.309). The width of decompression also correlated to the cranial-caudal height (P < .001, r2 = 0.522). A linear regression model demonstrated that cranial-caudal height was predicted (F (16,22) = 2.654, P = .017, r2 = 0.659) by age, maximum SOC width, and BMI (ß = -0.421, P = .031, 95% CI = (-1.067, -0.058)). CONCLUSION We demonstrate that a number of anatomic factors affect the ability to achieve optimal SOC size. While these factors are not modifiable, awareness of these factors may help guide positioning and operative planning to achieve maximum cerebellar decompression and help improve patient functional outcomes after emergent suboccipital decompression.

Multi-slice CT examinations of adult patients at Sudanese hospitals: radiation exposure based on size-specific dose estimates (SSDE).

The aim of this study was to update the radiation exposure for adult patients undergoing multi-slice CT (MSCT) examinations using size-specific dose estimates (SSDE). Console, displayed CTDIvol and scan parameters were retrospectively recorded for 423 adult patients in seven Sudanese hospitals. Patient torso diameters were measured using digital calipers on the scanner console. SSDE was determined based on transverse images (SSDEtrans) and scout radiographs (SSDEsco). Size-specific conversion factors were used to translate the recorded CTDIvol into SSDE according to the procedure described in the American Association of Physicists in Medicine (AAPM) Report 204. In chest CT, mean CTDIvol, SSDEtrans and SSDEsco ranged: from 4.3 to 47.5mGy (average: 12.8), 5.5 to 70.3mGy (average: 18.6) and 5.8 to 63.5mGy (average: 18.7), respectively. In abdominal CT, mean CTDIvol, SSDEtrans and SSDEsco ranged: from 4.0 to 74.5mGy (average: 16), 5.5 to 152.8mGy (average: 23.9) and 6.0 to 151.3mGy (average: 25.21), respectively. Our study highlights the relationships between CT dose and patient dimensions measured from scout and transverse CT images. The correlations between the patient size and dose based on scout images were less significant than that based on transverse images. High dose levels and dose variations among hospitals reveal the need for standardization of scanning protocols and staff training on adoption of scanners' dose reduction techniques.

Pre-procedural scout radiographs are unnecessary for routine pediatric fluoroscopic examinations.

Although practice patterns vary, scout radiographs are often routinely performed with pediatric fluoroscopic studies. However few studies have evaluated their utility in routine pediatric fluoroscopy. To evaluate the value of scout abdomen radiographs in routine barium or water-soluble enema, upper gastrointestinal (GI) series, and voiding cystourethrogram pediatric fluoroscopic procedures. We retrospectively evaluated 723 barium or water-soluble enema, upper GI series, and voiding cystourethrogram fluoroscopic procedures performed at our institution. We assessed patient history and demographics, clinical indication for the examination, prior imaging findings and impressions, scout radiograph findings, additional findings provided by the scout radiograph that were previously unknown, and whether the scout radiograph contributed any findings that significantly changed management. We retrospectively evaluated 723 fluoroscopic studies (368 males and 355 females) in pediatric patients. Of these, 700 (96.8%) had a preliminary scout radiograph. Twenty-three (3.2%) had a same-day radiograph substituted as a scout radiograph. Preliminary scout abdomen radiographs/same-day radiographs showed no new significant findings in 719 (99.4%) studies. New but clinically insignificant findings were seen in 4 (0.6%) studies and included umbilical hernia, inguinal hernia and hip dysplasia. No findings were found on the scout radiographs that would either alter the examination performed or change management with regard to the exam. Pre-procedural scout abdomen radiographs are unnecessary in routine barium and water-soluble enema, upper GI series, and voiding cystourethrogram pediatric fluoroscopic procedures and can be substituted with a spot fluoroscopic last-image hold.

Optimizing z-axis coverage of abdominal CT scans of the urinary tract: a proposed alternative proximal landmark for acquisition planning.

To evaluate an alternative method to reduce the acquisition coverage of urinary tract CT. This retrospective study included 365 abdominopelvic CT studies. Three radiographers simulated shortened acquisition coverages using three methods to determine the upper limit of the acquisition: Method 1 used the renal contours; Method 2 used the inferior margin of the 10th thoracic vertebra; and Method 3 used the point of intersection of the left diaphragmatic dome and the anterior margin of the vertebral bodies. Reductions in acquisition coverage and number of CT scans with a portion of the kidney excluded from the simulated reduced acquisition were compared between the three methods. The mean ± standard deviation reduction of acquisition coverage for the three readers with Methods 1, 2 and 3 were 20.5 ± 4.8, 15.1 ± 6.5 and 18.2 ± 5.3%, respectively. Compared with Method 2, Method 3 allowed a mean scan length reduction of 3.6%. The proportions of CT scans with a portion of the kidney excluded from the simulated reduced acquisition with Methods 1, 2 and 3 and averaged over the three readers were 6.7, 0.7 and 1.4%, respectively, with no significant difference between Methods 2 and 3. Interreader and intrareader agreements were excellent with all methods, but interclass correlation coefficients were higher with Method 3. The method using the renal contours should not be used owing to its high proportion of kidneys with a portion excluded from the acquisition. Using the intersection of the left diaphragmatic dome and the anterior margin of the vertebral bodies for proximal landmark for urinary tract CT represents a new alternative method with a better reduction of scan length compared with the method using the inferior margin of T10 and with no significant increase in the number of kidneys with a portion excluded from the reduced acquisition. Advances in knowledge: A new method using the point of intersection of the left diaphragmatic dome and the anterior border of the vertebral bodies on the lateral scout radiograph is introduced to reduce the z-axis coverage of urinary tract CT scans.

Abstract: Posterior Vault Distraction in Multi-Suture Craniosynostosis: A Radiologic Morphometric Assessment

PURPOSE: The first-line treatment of multi-suture syndromic craniosynostosis has shifted to an emphasis on posterior vault distraction (PVD) techniques as a way of increasing intracranial volume. To date, the effect of PVD on craniofacial dysmorphology in these patients has not been well studied. This study was designed to examine the effect of PVD on craniofacial morphology in patients with syndromic multi-suture synostosis using radiologic morphometric analysis. METHODS: With IRB approval, 22 patients (11M, 11F: age 4 to 149 months) with syndromic craniosynostosis (3 Apert, 4 Pfeiffer, 4 Muenke, 3 Crouzon, 2 chromosomal anomaly, 1 craniofrontonasal dysplasia, 5 unknown) underwent PVD for correction of elevated intracranial pressure (n=12) and/or correction of turribrachycephaly (n=16). Morphometric analysis of sequential CT scout radiographs and lateral skull radiographs assessed turricephaly index (TI=cranial length/height), vertical growth index (VGI=cranial base length/height), absolute vertical height (AVH=sella to vertex distance), and occipital inclination angle (OIA). RESULTS: Preoperatively, patients exhibited a mean TI of 1.34 (range=1.02–1.53, SD=0.16), VGI of 0.41 (range=0.26–0.58, SD=0.08), AVH of 107.37mm (range=87.4–149.4, SD=15.38), and OIA of 44.54 degrees (range=12.5–67.2, SD=12.17). PVD (n=18) demonstrated association with increased TI (mean=1.53,p<0.001) and VGI (mean=0.44,p=0.001), while flattening the OIA (mean=37.5,p=0.004). Additional frontal advancement procedures after PVD (n=15) yielded further increase in TI (mean=1.59,p=0.004) and VGI (mean=0.47,p=0.012). AVH did not change significantly once distraction was initiated. CONCLUSIONS: PVD results in significant improvements in craniofacial dysmorphology by increasing calvarial length relative to AVH and flattening occipital inclination, effectively normalizing turricephalic proportions. These results are improved by further frontal advancement surgery. AVH does not appear to increase or decrease after PVD initiation, suggesting aesthetic benefits are due to calvarial length attaining proportion to pre-treatment cranial height.

The prevalence of radiographic signs of pincer type morphology in a population based cohort study of asymptomatic Japanese.

This study was designed to document the prevalence of radiographic findings of pincer-type morphology in an asymptomatic population and determine any relationship to age. A total of 2,104 hips in 1,052 patients (mean age 38.9 years [10-59]), who underwent abdominal/pelvic computed tomography for other conditions, were identified retrospectively. Anteroposterior scout radiographs were used to detect the acetabular crossover sign (COS), prominent ischial spine (PRIS), coxa profunda (CP), and posterior wall sign (PWS). Subgroup analyses of signs were performed by age (group 1: 532 hips in &lt;30-year-old patients; group 2: 1,572 hips in ≥30-year-old patients). COS and PRIS was observed significantly more often in group 1 vs. group 2: COS was 73.1% vs. 29.3% in group 2, p&lt;0.001; PRIS was 23.9% vs.7.4% in group 2, p&lt;0.001. CP and PWS was observed significantly less frequently in group 1 vs. group 2: CP 3.4% vs. 21.2% in group 2, p&lt;0.001; PWS was 4.7% vs. 11.0% in group 2, p&lt;0.001. Radiographic pincer-type findings were common in an asymptomatic population and their prevalence was dependent upon a patient's age, indicating a diagnosis using radiographic parameters should also take into account a patient's age.

Radiation exposure contribution of the scout abdomen radiograph in common pediatric fluoroscopic procedures.

Contrast enema, voiding cystourethrography and upper gastrointestinal studies are the most common fluoroscopic procedures in children. Scout abdomen radiographs have been routinely obtained prior to fluoroscopy and add to the radiation exposure from these procedures. Elimination of unnecessary routine scout radiographs in select studies might significantly reduce radiation exposure to children and improve the overall benefit-to-risk ratio of these fluoroscopic procedures. To determine the radiation exposure contribution of the preliminary/scout abdomen radiographs with respect to the radiation exposure of the total procedure. We retrospectively collected demographic information and radiation exposure values of dose area product (in Gy-cm(2)) and entrance air kerma (in mGy) - initially for the scout abdomen radiographs done prior to fluoroscopy and subsequently the total procedural radiation values (the combined values of the scout radiograph and fluoroscopic radiation exposure) - in children who underwent contrast enemas, voiding cystourethrograms and upper gastrointestinal studies in a 4-month period. The radiation parameters, including fluoroscopy time, dose area product and entrance air kerma, were available in the log book maintained in the fluoroscopy suite. Fluoroscopy procedures were performed on a single fluoroscopy machine using four frames per second pulse rate and other radiation-minimizing techniques. Usage of the grid to obtain scout radiographs was also recorded. The proportion of radiation exposure from the scout radiograph relative to that of the total procedure was calculated by dividing the individual parameters of the scout to the total procedural values and multiplied by 100 to express these values as a percentage. We calculated mean, median and range and performed statistical analysis of the data. A total of 151 procedures performed on 71 males and 80 females qualified for the study. The age range of the patients was 2days to 18years, with a mean of nearly 3.5years (40months) and median of 15months. There were 63 upper gastrointestinal studies, 65 voiding cystourethrography studies and 23 contrast enema studies. The fluoroscopy time for all procedures combined ranged from 0.1min (6s) to 2min, with mean and median values of 0.4min and 0.3min, respectively. The fractional radiation exposure contribution for the dose area product of scout abdomen radiograph to the total procedure ranged from 4% to 98%, with mean and median values of 51% and 49%, respectively. The fractional contribution of the scout radiograph to the total procedure for the entrance air kerma values ranged from 6% to 97%, with mean and median values of 29% and 26%, respectively. There was a significant negative correlation (P<0.001) between fluoroscopy radiation time and the proportion of radiation parameters of scout radiograph to total procedural values. Scout radiographs can contribute a significant proportion (median values of approximately 50% for the dose area product and 26% for the entrance air kerma) of radiation exposure in common fluoroscopy procedures in children.

Does Baseline Radiography of the Kidneys, Ureters, and Bladder Help Facilitate Stone Management in Patients Presenting to the Emergency Department with Renal Colic?

A baseline kidneys, ureters, and bladder (KUB) radiograph, at the time of computed tomography (CT) for ureteral stones, might aid interpretation of future KUBs. The CT scout radiograph might render the baseline KUB redundant, however. We sought to assess the diagnostic utility of baseline KUB for patients with ureteral stones. Patients with ureteral stones were retrospectively identified. All had a baseline KUB in addition to CT and were reassessed after 4 to 60 days with KUB. Each patient's imaging was randomized 1:1 into either "KUB&CT" or "CT" groups. Three urologists independently assessed the imaging: CT (with scout film) and baseline KUB in the KUB&CT group, but only the CT (not KUB) in the CT group. Definitive stone assessment on follow-up KUB was defined as all three reviewers answering either Yes or No (not Indeterminate) to the question of stone passage or migration. Of 154 stones, the mean diameter was 4.8 ± 2.1 mm, density was 914 ± 300 Hounsfield units (HU), with 54.4% in the distal ureter. Stone visibility was 60.4% on KUB vs 43.5% on scout film (P<0.001). Scout film visibility favored the CT group (52.7 vs 35.0%, P = 0.027). After adjusting for body mass index, skin-to-stone distance, size, density, and location, definitive assessment rates were higher in the KUB&CT group (P = 0.047). When reviewers reassessed the CT group using the baseline KUB, they were able to do so definitively in an additional 16 (21.6%, P<0.001). Definitive assessments were associated with higher rates of stone visibility on scout film (86.1 vs 21.1%, P<0.001), KUB (86.1 vs 50.0%, P<0.001), and larger (6.0 vs 3.7 mm, P<0.001), denser stones (1046 vs 802 HU, P<0.001). The addition of a baseline KUB to the CT scout film improves the ability of urologists to determine stone outcome when following patients with KUB imaging and might reduce the subsequent need for additional imaging.

Unenhanced CT in the evaluation of renal/ureteric colic

Unenhanced CT of kidneys, ureters and bladder (CTKUB) is now the recommended imaging modality in the investigation of patients with acute renal or ureteric colic. This review aims to illustrate the normal urinary tract anatomy to assist imaging interpretation, outline the CTKUB imaging technique and image review at the Picture Archiving and Communication System workstation, discuss the pertinent imaging findings such as the direct signs, for example, soft tissue rim sign and comet tail sign, as well as secondary indirect signs such as pale kidney sign, nephromegaly, hydronephrosis, hydroureter and perinephric stranding or edema on the CTKUB for the diagnosis. Imaging pitfalls in the interpretation will be illustrated and discussed, for example in the presence of a ureteral stent and optimal image interpretation with wide windowing on CT. In addition, the discussion will also include the use of scout radiograph, the importance of detecting extraurinary pathology during CTKUB examination and explore Randall...

Organ dose calculation in CT based on scout image data and automatic image registration

Computed tomography (CT) has become the main contributor of the cumulative radiation exposure in radiology. Information on cumulative exposure history of the patient should be available for efficient management of radiation exposures and for radiological justification. To develop and evaluate automatic image registration for organ dose calculation in CT. Planning radiograph (scout) image data describing CT scan ranges from 15 thoracic CT examinations (9 men and 6 women) and 10 abdominal CT examinations (6 men and 4 women) were co-registered with the reference trunk CT scout image. 2-D affine transformation and normalized correlation metric was used for image registration. Longitudinal (z-axis) scan range coordinates on the reference scout image were converted into slice locations on the CT-Expo anthropomorphic male and female models, following organ and effective dose calculations. The average deviation of z-location of studied patient images from the corresponding location in the reference scout image was 6.2 mm. The ranges of organ and effective doses with constant exposure parameters were from 0 to 28.0 mGy and from 7.3 to 14.5 mSv, respectively. The mean deviation of the doses for fully irradiated organs (inside the scan range), partially irradiated organs and non-irradiated organs (outside the scan range) was 1%, 5%, and 22%, respectively, due to image registration. The automated image processing method to registrate individual chest and abdominal CT scout radiograph with the reference scout radiograph is feasible. It can be used to determine the individual scan range coordinates in z-direction to calculate the organ dose values. The presented method could be utilized in automatic organ dose calculation in CT for radiation exposure tracking of the patients.

Evaluation of the sensitivity of scout radiographs on unenhanced helical CT in identifying ureteric calculi: a large UK tertiary referral centre experience

Unenhanced helical CT for kidney, ureter and bladder (CT KUB) has become the standard investigation for renal colic. This study aims to determine the sensitivity of scout radiographs in detecting ureteric calculi using CT KUB as a standard reference. A retrospective review of consecutive patients who presented with acute flank pain and were investigated using CT KUB. 201 patients with positive ureteric calculi were included. Two radiologists independently reviewed the scout radiographs with access to CT KUB images. Each observer recorded the presence or absence of calculi, location, size and mean Hounsfield units of each calculus. 203 ureteric calculi were analysed from 201 patients. The overall sensitivity of scout radiographs for Observer A was 42.3% and for Observer B 52.2%, with an interobserver reliability κ-value of 0.78. The significance of mean Hounsfield units and size between two groups of patients with visible stones and those not visible were tested; the p-value for both variables was <0.0001, which is statistically significant. The study found that calculi in the upper ureter and larger than 4 mm are more likely to be seen on the scout radiograph. Usage of CT scout radiography should be encouraged and reported routinely in conjunction with CT KUB as a baseline for treatment follow-up.

Portal Venous Gas: A Clinical Finding in Obstructed Infracardiac Total Anomalous Pulmonary Venous Connection

Total anomalous pulmonary venous connection is a cyanotic congenital heart defect that presents with a multitude of clinical presentations. We report a case of obstructive total anomalous pulmonary venous connection (TAPVC) which presented in a way that has not previously been described. An infant with mixed type obstructive TAPVC was found to have pulmonary interstitial emphysema and portal venous gas on a scout radiograph obtained prior to computed tomography scan. The presence of portal venous gas indicated a connection between the pulmonary venous system and the portal venous system infradiaphragmatically.

Antiscatter grid use in pediatric digital tomosynthesis imaging

The objective of this study was to assess the effect of antiscatter grid use on tomosynthesis image quality. We performed an observer study that rated the image quality of digital tomosynthesis scout radiographs and slice images of a Leeds TO.20 contrast‐detail test object embedded in acrylic with and without a grid. We considered 10, 15, 20 and 25 cm of acrylic to represent the wide range of patient thicknesses encountered in pediatric imaging. We also acquired and rated images without a grid at an increased patient dose. The readers counted the total number of visible details in each image as a measure of relative image quality. We observed that the antiscatter grid improves tomosynthesis image quality compared to the grid‐out case, which received image quality scores similar to grid‐in radiography. Our results suggest that, in order to achieve the best image quality in exchange for the increase in patient dose, it may often be appropriate to include an antiscatter grid for pediatric tomosynthesis imaging, particularly if the patient thickness is greater than 10 cm.PACS number: 87.57.‐s

Low-dose Unenhanced CT for IV Contrast Bolus Timing:: Is It Reliable to Assess Hepatic Steatosis?

To determine whether an unenhanced low-dose image acquired during automated contrast bolus timing can be used to assess hepatic steatosis. Fifty subjects (29 male, 21 female; 26-92 years; mean body mass index (BMI; 26.9) with abdominal multiphasic computed tomography were included. Abdominal diameters and circumferences were derived from anteroposterior and lateral scout radiographs. Hepatic attenuation (HA) was measured on unenhanced low-dose images (120 kV; 40 mA; 0.5 seconds' rotation time) and corresponding unenhanced standard-dose images (120 kV, z-axis automatic tube current modulation, noise index 11.5). Noise estimates were measured in surrounding air. Pearson correlation was calculated between abdominal circumference and BMI. Mean HA assessed on low-dose images and standard-dose images was compared using a paired Student's t-test and Bland Altman plots. Abdominal circumference (mean, 142.8cm) correlated well with BMI (r = 0.83). No significant difference was found for HA on low-dose images (mean +57.7 HU) compared to HA on standard-dose images (+56.0 HU) (P = .077). Image noise (+11.5 HU) was significantly higher on low-dose images compared to image noise (+8.1 HU) on standard-dose images (P < .05). For HA mean difference comparing low- and standard-dose images was -1.7 HU (limits of agreement: -14.6, 11.2). In all subjects, hepatic attenuation can be correctly assessed on unenhanced low-dose images.

Useful prediction of ureteral calculi visibility on abdominal radiographs based on calculi characteristics on unenhanced helical CT and CT scout radiographs

To determine whether visibility of ureteral calculi on plain radiographs of the kidney, ureter and bladder (KUB) could be predicted based on characteristics on unenhanced helical computed tomography (UHCT) and CT scout radiographs (CTSR). One hundred and twenty-three patients diagnosed with 140 ureteral calculi on UHCT, had undergone both UHCT and KUB within 24 h and before calculus passage or intervention were included. The visibility of ureteral calculi on KUB and CTSR as well as their sizes, locations and densities on UHCT were recorded. The association of CTSR/UHCT characteristics of ureteral calculi and their visibility on KUB were analysed. Multivariate analyses using logistic regression were computed as predictors for visibility on KUB. Of the 140 calculi, 56 (40%) and 98 (70%) were visible on CTSR and KUB respectively. All calculi detectable on CTSR were also visible on KUB. Multivariate analyses of the 84 CTSR undetectable calculi revealed that non-middle ureteral location and higher calculi densities on UHCT were significant predictors of visibility on KUB. All non-middle ureteral calculi with density > 800 Hounsfield units (HU) were visible on KUB. Of 23 calculi in the middle ureter or with density < 200 HU, 17 (74%) were invisible on KUB. Ureteral calculi characteristics on UHCT and CTSR are useful for predicting their visibility on KUB. Patients with visible calculi on CTSR or non-middle ureteral calculi with density > 800 HU are suitable for KUB to follow-up calculi status.

Section Modulus is the Optimum Geometric Predictor for Stress Fractures and Medial Tibial Stress Syndrome in both Male and Female Athletes

Background Various tibial dimensions and geometric parameters have been linked to stress fractures in athletes and military recruits, but many mechanical parameters have still not been investigated. Hypotheses Sedentary people, athletes with medial tibial stress syndrome, and athletes with stress fractures have smaller tibial geometric dimensions and parameters than do uninjured athletes. Study Design Cohort study; Level of evidence, 3. Methods Using a total of 88 subjects, male and female patients with either a tibial stress fracture or medial tibial stress syndrome were compared with both uninjured aerobically active controls and uninjured sedentary controls. Tibial scout radiographs and cross-sectional computed tomography images of all subjects were scanned at the junction of the midthird and distal third of the tibia. Tibial dimensions were measured directly from the films; other parameters were calculated numerically. Results Uninjured exercising men have a greater tibial cortical cross-sectional area than do their sedentary and injured counterparts, resulting in a greater value of some other cross-sectional geometric parameters, particularly the section modulus. However, for women, the cross-sectional areas are either not different or only marginally different, and there are few tibial dimensions or geometric parameters that distinguish the uninjured exercisers from the sedentary and injured subjects. In women, the main difference between the groups was the distribution of cortical bone about the centroid as a result of the different values of section modulus. Last, medial tibial stress syndrome subjects had smaller tibial cross-sectional dimensions than did their uninjured exercising counterparts, suggesting that medial tibial stress syndrome is not just a soft-tissue injury but also a bony injury. Conclusion The results show that in men, the cross-sectional area and the section modulus are the key parameters in the tibia to distinguish exercise and injury status, whereas for women, it is the section modulus only.

Pediatric Chest MDCT Using Tube Current Modulation: Effect on Radiation Dose with Breast Shielding

The purpose of our study was to assess the effect on radiation dose and image noise during pediatric chest 16-MDCT using automatic tube current modulation and bismuth breast shields. Age-based chest 16-MDCT was performed on an anthropomorphic phantom representing a 5-year-old child. Two scans were obtained in each of four sequences: first, without a shield; second, with a 2-ply bismuth shield; third, using automatic tube current modulation with a scout image obtained after placement of the shield; and fourth, using automatic tube current modulation with a scout image obtained before placement of the shield. Metal oxide semiconductor field effect transistor technology was used to measure the radiation dose in 20 organ locations. Effective dose was estimated using the console dose-length product. Noise was measured by recording the SD of Hounsfield units in identical regions of interest. The bismuth breast shield reduced the dose to the breast by 26%. Shielding and automatic tube current modulation reduced the breast dose by 52%. Multiple organ doses were lowest when the shield was placed after the scout radiograph had been obtained. When the shield was placed after the scout image was obtained, the mean noise in the range of shielding increased from 11.4 to 13.1 H (superior mediastinum) and from 10.0 to 12.8 H (heart) (p < 0.01). Increased noise, however, was near the target noise index (measured in SD of Hounsfield units) of 12.0 H (SD). Using automatic tube current modulation, the effective dose was reduced by 35% when the shield was placed after the scout and by 20% when the shield was present in the scout. The greatest dose reduction is achieved by placing the shield after obtaining the scout image to avoid Auto mA compensation due to density of shield. With this technique, image noise increased but remained close to the target noise index.

Patient doses in abdominal aortogram and aorta femoral runoff examinations.

Radiation doses to adult male patients from abdominal aortogram and aorta femoral runoff examinations in a medical center were determined with the help of a dose-area product meter. The abdominal aortogram and aorta femoral runoff examination consisted of scout radiographs, fluoroscopy (to position a catheter near the area of interest), and serial films (to record the flow of contrast media). Measurements were converted to effective doses with the help of published results from Monte Carlo simulation calculations. Data from 19 male adult patients weighing 53 to 86 kg were analyzed. The resulting total effective dose had a value of 14.0 +/- 4A mSv (mean and standard deviation). The percent contribution by fluoroscopy was 18.5 +/- 9.9%. The fluoroscopy effective dose had a stronger correlation with the dose-area product (correlation coefficient of 0.97) than with duration of exposure (correlation coefficient of 0.84). Most of the radiation exposure in the observed abdominal aortogram and aorta femoral runoff examination was attributed to radiography.