Anteroposterior Images Research Articles

Construction and validation of a low cost paediatric pelvis phantom

PurposeImaging phantoms can be cost prohibitive, therefore a need exists to produce low cost alternatives which are fit for purpose. This paper describes the development and validation of a low cost paediatric pelvis phantom based on the anatomy of a 5-year-old child. MethodsTissue equivalent materials representing paediatric bone (Plaster of Paris; PoP) and soft tissue (Poly methyl methacrylate; PMMA) were used. PMMA was machined to match the bony anatomy identified from a CT scan of a 5-year-old child and cavities were created for infusing the PoP. Phantom validation comprised physical and visual measures. Physical included CT density comparison between a CT scan of a 5-year old child and the phantom and Signal to Noise Ratio (SNR) comparative analysis of anteroposterior phantom X-ray images against a commercial anthropomorphic phantom. Visual analysis using a psychometric image quality scale (face validity). ResultsCT density, the percentage difference between cortical bone, soft tissue and their equivalent tissue substitutes were −4.7 to −4.1% and −23.4%, respectively. For SNR, (mAs response) there was a strong positive correlation between the two phantoms (r > 0.95 for all kVps). For kVp response, there was a strong positive correlation between 1 and 8 mAs (r = 0.85), this then decreased as mAs increased (r = −0.21 at 20 mAs). Psychometric scale results produced a Cronbach’s Alpha of almost 0.8. ConclusionsPhysical and visual measures suggest our low-cost phantom has suitable anatomical characteristics for X-ray imaging. Our phantom could have utility in dose and image quality optimisation studies.

Intraoperative Evaluation of the Anatomic Lateral Distal Femoral Angle and Its Variation due to Positioning.

Preoperative evaluation of the contralateral anatomic lateral distal femoral angle (aLDFA) at our institution is used to judge coronal plane alignment. In our study, we investigated 4 different techniques for obtaining an anteroposterior intraoperative fluoroscopic image of the distal femur to determine which technique provides (1) the greatest interobserver reliability; (2) the lowest variability from the previously published population mean; and (3) the lowest side-to-side variability. Inclusion criteria included lower extremity injuries needing fixation that required intraoperative fluoroscopy with an intact femur and an intact extensor mechanism (N = 100). Fluoroscopic images were obtained of the distal femur in 4 positions differentiated by the position of the limb and the orientation of the C-arm beam to the femoral shaft. All measurement techniques resulted in mean measurements within one degree of 81 degrees. Variance between measurements was small among patients with all views, but images that involved a true anteroposterior with the beam perpendicular to the femur had the lowest rate of measurements that were <78 or >84 degrees. Side-to-side differences in patients were <2 degrees on average with every image used. With the best-performing images, 20% of patients had an aLDFA > 3 degrees different from the population mean of 81 degrees and 3% of patients were >5 degrees different. Although restoring aLDFA to 81 degrees will be within 3 degrees of the contralateral side the vast majority of the time, matching the aLDFA to the injured side will be the most accurate reconstruction.

Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P3. Recruitment of mesenchymal stem cells to the intervertebral disc via local chemokine delivery from an injectable hydrogel

BACKGROUND CONTEXT Biologic-based therapies for inhibiting or reversing intervertebral disc (IVD) degeneration have garnered considerable interest, however obtaining a stem cell source remains a resource-intensive hurdle. Strategies to recruit endogenous mesenchymal stem cells (MSCs) to the IVD would assist in circumventing these hurdles. PURPOSE The purpose of this study is to evaluate the ability of three homing chemokines to recruit marrow-derived MSCs to the IVD. METHODS Under IACUC approval, 24 female Lewis rats (n=6/group) underwent anterior, transperitoneal L5/L6 intradiscal injection of hydrogel containing homing chemokine (SDF-1, RANTES, or MCP-1) or hydrogel alone (control). Immediately postop, all rats were administered 1×107 MSCs labeled with CellVue Burgundy, via tail vein injection. In vivo near-infrared (NIR) fluorescence imaging was used to longitudinally track MSC migration to L5/L6 at 1, 2, 7, and 14days postinjection. At each time point, the dorsal lumbar region was shaved to minimize hair-related auto-fluorescence, rats were positioned prone on an imaging bed and NIR fluorescence imaging of the dorsal lumbar region was conducted at 700 nm. Following euthanasia at 14days, the lumbar spine was harvested, dissected, and the anterior aspect was re-imaged using 700 nm NIR. A consistently sized, circular region-of-interest was placed over L5/L6 and mean signal intensity was computed. In vivo and ex vivo imaging were normalized to skin and the L3/L4 disc, respectively, to account for nonspecific signal. Mean signal intensity of chemokine groups was compared to the control group using one-way ANOVA. Post-hoc tests were conducted using the Dunnett correction for multiple comparisons, and all reported P-values are compared to the control group. RESULTS Longitudinal in vivo NIR demonstrates measurable fluorescent signal at L5/L6 at 1day (control: 0.005±0.007, SDF-1: 0.008±0.008, P=0.918; RANTES: 0.017±0.011, P=0.074; MCP-1: 0.007±0.009, P=0.990); however, no significant differences were noted between groups. NIR signal was indistinguishable from skin at 3, 7, and 14day time points for all groups. Ex vivo NIR signal was appreciable at the L5/L6 disc level in all treatment groups, indicating successful migration of tagged MSCs to the target disc. RANTES and MCP-1 treatment groups exhibited significantly higher ex vivo signal compared to control (control: 0.0017±0.0006, SDF-1: 0.0025±0.0003, P=0.054; RANTES: 0.0030±0.0006, P=0.001; MCP-1: 0.0026±0.0006, P=0.017). CONCLUSIONS Following intra-discal injection, in vivo imaging demonstrates early recruitment of labeled MSCs to the L5/L6 IVD, with chemokine groups exhibiting anecdotally higher signal compared to control. Appreciable in vivo signal was only detected at 24hours, suggesting that the highest localization of MSCs to the L5/L6 disc level occurs acutely. Ex vivo imaging, which allows the removal of extraneous tissue and allows antero-posterior image acquisition, revealed notable fluorescent signal at L5/L6, demonstrating retention of labeled MSCs at the L5/L6 IVD at 14days following chemokine injection. Specifically, RANTES was most effective at recruiting MSCs to the IVD compared to control groups and will be used in future studies characterizing therapeutic effects of recruited MSCs in the setting of IVD degeneration. Ongoing histologic analysis will localize tagged cells within specific tissues.

Highly crosslinked polyethylene wear rates and acetabular component orientation: a minimum ten-year follow-up.

The aim of this study was to determine whether there is a difference in the rate of wear between acetabular components positioned within and outside the 'safe zones' of anteversion and inclination angle. We reviewed 100 hips in 94 patients who had undergone primary total hip arthroplasty (THA) at least ten years previously. Patients all had the same type of acetabular component with a bearing couple which consisted of a 28 mm cobalt-chromium head on a highly crosslinked polyethylene (HXLPE) liner. A supine radiostereometric analysis (RSA) examination was carried out which acquired anteroposterior (AP) and lateral paired images. Acetabular component anteversion and inclination angles were measured as well as total femoral head penetration, which was divided by the length of implantation to determine the rate of polyethylene wear. The mean anteversion angle was 19.4° (-15.2° to 48°, sd 11.4°), the mean inclination angle 43.4° (27.3° to 60.5°, sd 6.6°), and the mean wear rate 0.055 mm/year (sd 0.060). Exactly half of the hips were positioned inside the 'safe zone'. There was no difference (median difference, 0.012 mm/year; p = 0.091) in the rate of wear between acetabular components located within or outside the 'safe zone'. When compared to acetabular components located inside the 'safe zone', the wear rate was no different for acetabular components that only achieved the target anteversion angle (median difference, 0.012 mm/year; p = 0.138), target inclination angle (median difference, 0.013 mm/year; p = 0.354), or neither target (median difference, 0.012 mm/year; p = 0.322). Placing the acetabular component within or outside the 'safe zone' did not alter the wear rate of HXLPE at long-term follow-up to a level that risked osteolysis. HXLPE appears to be a forgiving bearing material in terms of articular surface wear, but care must still be taken to position the acetabular component correctly so that the implant is stable. Cite this article: Bone Joint J 2018;100-B:891-7.

3-D Subject-Specific Shape and Density Estimation of the Lumbar Spine From a Single Anteroposterior DXA Image Including Assessment of Cortical and Trabecular Bone.

Dual Energy X-ray Absorptiometry (DXA) is the standard exam for osteoporosis diagnosis and fracture risk evaluation at the spine. However, numerous patients with bone fragility are not diagnosed as such. In fact, standard analysis of DXA images does not differentiate between trabecular and cortical bone; neither specifically assess of the bone density in the vertebral body, which is where most of the osteoporotic fractures occur. Quantitative computed tomography (QCT) is an alternative technique that overcomes limitations of DXA-based diagnosis. However, due to the high cost and radiation dose, QCT is not used for osteoporosis management. We propose a method that provides a 3-D subject-specific shape and density estimation of the lumbar spine from a single anteroposterior (AP) DXA image. A 3-D statistical shape and density model is built, using a training set of QCT scans, and registered onto the AP DXA image so that its projection matches it. Cortical and trabecular bone compartments are segmented using a model-based algorithm. Clinical measurements are performed at different bone compartments. Accuracy was evaluated by comparing DXA-derived to QCT-derived 3-D measurements for a validation set of 180 subjects. The shape accuracy was 1.51 mm at the total vertebra and 0.66 mm at the vertebral body. Correlation coefficients between DXA and QCT-derived measurements ranged from 0.81 to 0.97. The method proposed offers an insightful 3-D analysis of the lumbar spine, which could potentially improve osteoporosis and fracture risk assessment in patients who had an AP DXA scan of the lumbar spine without any additional examination.

Comparison of fluoroscopic techniques for assessment of femoral rotational alignment

Objectives:Anatomic rotational reduction of diaphyseal femur fractures is essential in restoring limb mechanics. Errors in reproducing anteroposterior (AP) or lateral knee reference radiographs of the contralateral limb could result in inaccuracies during rotational reduction. The objective of this study was to examine whether fluoroscopic rotational variation can be observed with the same degree of precision with AP and lateral distal femur projections.Methods:AP and lateral radiographs were obtained from intact knees of 7 cadaveric specimens using fluoroscopy. The lateral condylar width and coronal femoral width from the AP images and the posterior condylar offset and sagittal femoral width from the lateral images were measured by 3 reviewers. Interclass correlation coefficients (ICCs) among the 3 reviewers were calculated. The mean data from all reviewers were plotted against angle of rotation, and the slope (M) and regression of the line were then determined.Results:ICCs were 0.997 (lateral) and 0.994 (AP), demonstrating excellent interobserver agreement. The mean (±SD) M value for lateral images was 0.016 ± 0.001 and for AP images was 0.009 ± 0.001 (P < .0001). The higher lateral M value represents a more appreciable difference in size of the measured segment for the same rotational change.Conclusions:The observed rotational change was 1.76 times greater on lateral images compared to AP images; thus, the lateral images may be more precise as a reference for rotation. The routine use of lateral knee radiographs to guide intraoperative rotational alignment of the femur may therefore be justified.

The greater tuberosity angle: a new predictor for rotator cuff tear

The implication of scapular morphology in rotator cuff tears has been extensively studied. However, the role of the greater tuberosity (GT) should be of equal importance. The aim of this study was to propose a new radiographic marker, the GT angle (GTA), which measures the position of the GT in relation to the center of rotation of the humeral head. The hypothesis was that a higher angle value would be associated with a higher likelihood in detecting a rotator cuff tear. During 1 year, patients were prospectively recruited from a single institution specialized shoulder clinic in 2 different groups. The patient group consisted of individuals with a degenerative rotator cuff tear involving at least the supraspinatus. The control group consisted of individuals with no rotator cuff pathology. Individuals in both groups with congenital, post-traumatic, or degenerative alterations of the proximal humerus were excluded. The GTA was measured on an anteroposterior shoulder x-ray image with the arm in neutral rotation by 3 observers at 2 different times. The study recruited 71 patients (33 patients, 38 controls). Mean GTA value was 72.5° (range, 67.6°-79.2°) in patients and 65.2° (range, 55.8°-70.5°) for controls (P <.001). A value above 70° resulted in 93-fold higher odds of detecting a rotator cuff tear (P <.001). Interobserver and intraobserver reliability were high. GT morphology is implicated in rotator cuff tears. The GTA is a reliable radiographic marker, with more than 70° being highly predictive in detecting such lesions.

A computerized method for evaluating scoliotic deformities using elliptical pattern recognition in X-ray spine images

Several studies have evaluated the reproducibility of the Cobb angle for measuring the degree of scoliotic deformities from X-ray spine images, and proposed different geometric models for describing the spinal curvature. The ellipse was shown to be an adequate geometric form, but was not yet applied for the identification and quantification of scoliotic curvatures. The purpose of this study is therefore to propose and validate a novel computerized methodology for the detection of elliptical patterns from X-ray images to evaluate the extent of the underlying scoliotic deformity. For anteroposterior each X-ray spine image, the spine curve is first reconstructed from vertebral centroids. The ellipse that best fits to the obtained spine curve is the found within a least square and genetic algorithm optimization framework. The geometric parameters of the resulting best fit ellipse are finally used to define an index that quantifies the spinal curvature. The proposed methodology was validated on three synthetic images and then successfully applied to 20 clinical anteroposterior X-ray spine images of patients with a different degree of scoliotic deformity, with the resulting maximal relative error of 3% for the synthetic images and an overall error of 0.5 ± 0.4 mm (mean ± standard deviation) for the clinical cases. The results indicate that the proposed computerized methodology is able to reliably reproduce scoliotic curvatures using the geometric parameters of the underlying ellipses. In comparison to conventional approaches, the proposed methodology potentially produces less errors, requires a relatively low observer interaction, takes into account all vertebrae within the observed scoliotic deformity, and allows for both qualitative and quantitative evaluations that may complement the diagnosis, study and treatment of scoliosis.

Preliminary study on contrast flow analysis of thoracic transforaminal epidural block.

BackgroundThe thoracic transforaminal epidural block (TTFEB) is usually performed to treat herpes zoster or postherpetic neuralgia (PHN). Especially, multiple segmental involvements and approximate contrast medium spread range, according to volume, help to choose the proper drug volume in the transforaminal epidural block. This study investigated the contrast medium spread patterns of 1-ml to 3-ml TTFEBs.MethodsA total of 26 patients with herpes zoster or PHN were enrolled in this study. All participants received 1 ml, 2 ml, or 3 ml of contrast medium. Results were divided into Groups A, B and C based on the volume (1, 2, or 3 ml), with n = 26 for each group. After the injection of contrast medium, the spread levels were estimated in both the lateral and anteroposterior (AP) images using fluoroscopy.ResultsThe cephalad spread of contrast medium in the lateral image as expressed by the median (interquartile range) was 2.00 levels (1.00–2.00) for Group A, 2.50 (2.00–3.00) for Group B, and 3.00 (2.00-4.00) for Group C. The caudal spread level of contrast medium was 1.00 (1.00-2.00) for Group A, 2.00 (2.00–3.00) for Group B, and 2.00 (2.00–3.00) for Group C. There was ventral and dorsal spread of the 3-ml contrast medium injection in 88% (23/26) of cases in the lateral image.ConclusionsInjection of 3 ml of contrast medium through the foramina spread 6 levels in a cephalocaudal direction. Spread patterns revealed a cephalad preference. TTFEB resulted in dorsal and ventral spread in a high percentage of cases. This procedure may be useful for transferring drugs to the dorsal and ventral roots.

Lower limb immobilization device induced small setup errors in the radiotherapy.

The aim of this study was to design a lower limb immobilization device and investigate its clinical application in the radiotherapy of the lower limbs.Around 38 patients who underwent lower limb radiotherapy using the designed immobilization device were included in this study. The setup errors were calculated by comparison of the portal images and the simulator films or digital reconstructed radiographs (DRRs).From all 38 patients accomplished the radiotherapy using this device, 178 anteroposterior portal images and 178 lateral portal images were used for the analysis of the positional accuracy. Significant differences were observed in the setup error of the head–foot direction compared with the left–right direction (t = 3.404, P = .002) and the anterior–posterior directions (t = 3.188, P = .003). No statistical differences were identified in the setup error in the left–right direction and anterior–posterior direction (t = 0.497, P = .622).The use of the in-house designed lower limb immobilization device allowed for relatively small setup errors. Furthermore, it showed satisfactory accuracy and repeatability.

Minimally invasive plate percutaneous osteosynthesis for distal clavicle fractures of Neer type II

Objective To evaluate the clinical and radiologic outcomes of minimally invasive plate percutaneous osteosynthesis (MIPPO) for distal clavicle fractures of Neer type Ⅱ. Methods From May 2015 to May 2016, 13 patients with distal clavicle fracture of Neer type Ⅱ were treated with MIPPO using an anatomic locking plate. Anteroposterior plain X-ray images of the clavicle were taken at intervals until union was observed. Fracture healing time and complications were recorded, and shoulder joint functions evaluated using Constant and University of California at Los Angeles (UCLA) scores. Results The average operating time was 60.9 minutes (range, from 48 to 83 minutes) , average intraoperative blood loss 24.7 mL (range, from 18 to 30 mL) , and average union time for the patients was 13.3 weeks (range, from 11 to 15 weeks) . No delayed union or nonunion occurred.There were no major complications, like infection, plate breakage, or neurovascular injury.Only 2 patients felt local incision numbness.All the patients were satisfactory with their shoulder functions. At the final follow-ups, the mean Constant score was 93.2 points (from 87 to 95 points) and the mean UCLA score 30.6 points (from 28 to 34 points) . Conclusion In the treatment of distal clavicle fractures of Neer type Ⅱ, minimally invasive plate percutaneous osteosynthesis can not only achieve good clinical and radiologic outcomes but also be advantageous over conventional open reduction in aspects of smaller invasion and better cosmetic effect. Key words: Clavicle; Fractures, bone; Fracture fixation, internal; Bone plates

The Use of Fluoroscopy During Direct Anterior Hip Arthroplasty: Powerful or Misleading?

BackgroundDirect anterior approach total hip arthroplasty (THA) with fluoroscopic assistance is growing in popularity. Variables such as pelvic tilt, c-arm technique, and patient positioning can affect the perceived fluoroscopic view. This study evaluates the effect of these variables on the position of the acetabular component. MethodsForty-one hips in 40 patients undergoing direct anterior arthroplasty THA with fluoroscopic assistance underwent routine postoperative radiographs and postoperative pelvic computed tomography scan. The acetabular component position as defined by a 3-dimensional reconstruction was compared to the surgeon's intraoperative perception of the component's position and compared to routine postoperative plain radiograph measurements. ResultsAlthough fluoroscopy was used to create an anteroposterior pelvic radiograph utilizing the coccyx to pubis symphysis distance, a 3D reconstruction created in the same pelvic orientation as the fluoroscopic images confirmed that 39/41 hips were placed with unrecognized excess of anteversion and inclination secondary to imaging the pelvis in extension. ConclusionIntraoperative imaging during supine direct anterior arthroplasty THA confirms appropriate component placement. Pelvic tilt can greatly affect the perceived position of the acetabular component and cannot be accurately compensated for by assessing the relationship between the coccyx and pubic symphysis due to morphologic variation and orientation. We recommend positioning the c-arm so that the size and shape of the obturator foramen matches the standing preoperative anteroposterior pelvis image. This technique allows for the native standing pelvic tilt to be accounted for intraoperatively and will result in the least variation in intraoperative and postoperative standing acetabular component orientation.

Prevalence of hand osteoarthritis and knee osteoarthritis in Kashin-Beck disease endemic areas and non Kashin-Beck disease endemic areas: A status survey.

Osteoarthritis (OA) is a considerable health problem worldwide, and the prevalence of OA varies in different regions. In this study, the prevalence of OA in Kashin-Beck disease (KBD) and non-KBD endemic areas was examined, respectively. According to monitoring data, 4 types of regions (including none, mild, moderate and high KBD endemic areas) in Heilongjiang and Jilin provinces were selected. All local residents were eligible for inclusion criteria have undergone X-ray images of hands and anteroposterior image of knees. A total of 1673 cases were collected, 1446 cases were analyzed after removing the KBD patients (227). The overall hand OA and knee OA detection rates were 33.3% (481/1446) and 56.6% (818/1446), respectively. After being standardized by age, the detection rate of hand OA in the KBD endemic areas was significantly higher than that in the non-endemic endemic areas. Differently, there was no significant difference in the detection rates of knee OA between the KBD endemic areas and the non-endemic area. The correlation coefficient between the severity of OA and the severity of knee OA was 0.358 and 0.197 in the KBD and non-KBD endemic areas, respectively. Where the KBD historical prevalence level was higher, the severity of the residents’ hand OA was more serious. The detection rates of hand OA and knee OA increased with age. The detection rate of knee OA increased with the increase in body mass index. The prevalence of hand OA was closely related to the pathogenic factors of Kashin-Beck disease, and the prevalence of knee OA had no significant correlation with KBD pathogenic factors.

Enchondroma Protuberans of the Transverse Process of D8 Vertebra Extending to the 7th and 8th Ribs: A Rare Case Report.

Enchondroma protuberans (EP) is rare, benign cartilaginous bone tumor arising from the intramedullary cavity of long bones and usually protrudes beyond the cortex with an exophytic growth pattern resembling osteochondroma. This study reports on a rare case of EP arising from the transverse process of the D8 vertebra and extending to the adjacent 7th and 8th ribs and the paraspinal tissues. A 45-year-old female patient came in with complaints of upper back pain radiating up to the left costal margin for the past 6 months. There were no parasthesias, and there was no history of any sensory or motor symptoms. On physical examination there was midline and left paraspinal tenderness over the D6 to D8 region. Anteroposterior and lateral X-ray images revealed a well-defined oval ossific mass lesion over the lateral aspect of the D8 vertebra, extending to the 7th and 8th ribs on the left side, and multiple bridging osteophytes were noted. Computed tomography scan showed an ossific mass lesion arising from the D8 transverse process with extension to the adjacent 7th and 8th ribs; its margins were well defined, with no periosteal reaction. Magnetic resonance imaging showed a well-defined expansile mass lesion arising from the transverse process of the D8 vertebra matrix; it was was isointense with adjacent marrow and had no evidence of calcifications or vascular flow voids and no encroachment into the spinal canal. Complete resection of the mass lesion with the adjacent part of the 7th and 8th ribs and with intramedullary curettage was performed and sent for histopathologic examination. Histopathology showed bony trabeculae with normal mucosal elements, and a mild hypercellularity with binucleation. Chondrocytes in the myxoid matrix located in round lacunae were compatible with enchondroma, with no evidence of atypia. The postoperative period was uneventful, and after 12 months there were no signs of recurrence noted in computed tomography scan. EP is a rare presentation in the dorsal spine; it should be considered in the differential diagnosis of osteochondroma, enchondroma, chondrosarcoma, and periosteal chondroid tumors.

Tip-Apex Distance Is Most Important of Six Predictors of Screw Cutout After Internal Fixation of Intertrochanteric Fractures in Women.

Background:Six risk factors for screw cutout after internal fixation of intertrochanteric fractures have been reported. The purpose of the present study was to evaluate and compare the impact of the 6 risk factors of screw cutout to clarify the most important one.Methods:We enrolled 8 consecutive patients who had screw cutout and 48 random control subjects after internal fixation of intertrochanteric fractures treated with proximal femoral nail antirotation systems at our institution. All of the patients were female. The group that had screw cutout and the control group were retrospectively evaluated and compared with respect to the OTA/AO classification, presence of a posterolateral fragment, types of reduction pattern on anteroposterior and lateral radiographic images, position of the screw, and the presence of a tip-apex distance (TAD) of ≥20 mm. The impact of each factor on screw cutout was assessed using backward stepwise multivariable logistic regression analysis with the Akaike information criterion. Risk stratification was assessed using classification and regression tree (CART) analysis.Results:Among 6 risk factors, only a TAD of ≥20 mm had a significant impact on screw cutout, with an adjusted odds ratio of 12.4 (95% confidence interval, 1.6 to 129.0; p = 0.019). CART analysis also demonstrated that a TAD of ≥20 mm was the most important risk stratification factor (p < 0.001).Conclusions:Among the 6 previously reported screw cutout-related factors, only a TAD of ≥20 mm was associated with screw cutout after internal fixation of intertrochanteric fractures with proximal femoral nail antirotation systems.Level of Evidence:Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Additional Visualization via Smart Glasses Improves Accuracy of Wire Insertion in Fracture Surgery

Smart glasses (SG) are a wearable device consisting of a small computer built into a head-mounted monitor (HMM) that can display various kinds of information. Lateral side visualization is displayed on the HMM of SG so the operator may also see it and the anteroposterior (AP) direction simultaneously. The present pilot study aimed to investigate the usefulness of SG in wire insertion for bone fracture. We marked both the front and lateral sides of the shaft of an artificial femur bone. From the tip of the greater trochanter, we inserted a 2.4-mm Kirschner wire (K-wire) so that it could be directed toward the marks in both planes. Three surgeons enrolled in the study each performed 10 trials, both with SG (SG arm) and without (direct vision arm). We defined the error angle as the angle between the K-wire and the line connecting the marking point from the insertion point in both the front and lateral view images. We also measured the time it took to insert the K-wire in both arms. The SG had a significantly reduced (mean = 3.2°) error angle ( P = .02) when compared to the direct vision group (mean = 4.8°). However, no significant difference was found between direct vision (mean = 17.5 seconds) and SG arms (mean = 14.9 seconds) in the insertion time. While keeping the AP image view in primary focus, simultaneously viewing the lateral side of the surgical field using SG helps achieve more accurate wire insertion in surgery.

An integrated system for clinical treatment verification of HDR prostate brachytherapy combining source tracking with pretreatment imaging

PurposeHigh-dose-rate (HDR) prostate brachytherapy treatment is usually delivered in one or a few large dose fractions. Poor execution of a planned treatment could have significant clinical impact, as high doses are delivered in seconds, and mistakes in an individual fraction cannot be easily rectified. Given that most potential errors in HDR brachytherapy ultimately lead to a geographical miss, a more direct approach to verification of correct treatment delivery is to directly monitor the position of the source throughout the treatment. In this work, we report on the clinical implementation of our treatment verification system that uniquely combines the 2D source-tracking capability with 2D pretreatment imaging, using a single flat panel detector (FPD). Methods and MaterialsThe clinical brachytherapy treatment couch was modified to allow integration of the FPD into the couch. This enabled the patient to be set up in the brachytherapy bunker in a position that closely matched that at treatment planning imaging. An anteroposterior image was acquired of the patient immediately before treatment delivery and was assessed by the Radiation Oncologist online, to reestablish the positions of the catheters relative to the prostate. Assessment of catheter positions was performed in the left-right and superior-inferior directions along the entire catheter length and throughout the treatment volume. Source tracking was then performed during treatment delivery, and the measured position of the source dwells were directly compared to the treatment plan for verification. ResultsThe treatment verification system was integrated into the clinical environment without significant change to workflow. Two patient cases are presented in this work to provide clinical examples of this system, which is now in routine use for all patient treatments in our clinic. The catheter positions were visualized relative to the prostate, immediately before treatment delivery. For one of the patient cases presented in this work, they agreed with the treatment plan on average by 1.5 mm and were identifiable as a predominantly inferior shift. The source tracking was performed during treatment delivery, and for the same case, the mean deviation from the planned dwell positions was 1.9 mm (max = 4.9 mm) for 280 positions across all catheters. ConclusionWe have implemented our noninvasive treatment verification system based on an FPD in the clinical environment. The device is integrated into a patient treatment couch, and the process is now included in the routine clinical treatment procedure with minor impact on workflow. The system which combines both 2D pretreatment imaging and HDR 2D source tracking provides a range of information that can be used for comprehensive treatment verification. The system has the potential to meaningfully improve safety standards by allowing widespread adoption of routine treatment verification in HDR brachytherapy.

Effects of different scout images on radiation dose in CT scanning using automatic tube current modulation

Objective To investigate the influence of different scout image on the radiation dose of head and chest spiral scanning in CT using automatic tube current modulation(ATCM). Methods CT scanning was performed on the head-neck and chest phantom with ATCM.Five different scout images through the five various positions that include anteroposterior(AP),posteroanterior(PA),lateral,AP, lateral,PA and lateral.The phantom was scanned three times for each position.Then each scout image was scanned by spiral technique once more. ROI in orbital center and C5 upper edge level were selected for Head and neck phantom, ROI in the apical and tracheal bifurcation level were selected for chest phantom. The contrast to noise ratio (CNR) was measured and recorded. The organ dose of eye lens and mammary glands were measured by thermoluminescent dosimeters (TLD) in every scanning(the average of 3 measurements), The cumulative value of scout image and spiral scanning were calculated.The volume CT dose index (CTDIvol) of each scan was recorded, and the cumulative value of CTDIvol was calculated. Results In the five scout images of the head-neck phantom mode, the maximum value of accumulated radiation dose of eye lens and CTDIvol appear on PA scout image(18.354 and 26.43 mGy respectively),while the minimum value appear on the lateral scout image(11.847 and 18.20 mGy respectively). In the chest phantom mode, the maximum value of the accumulated radiation dose of the mammary gland and CTDIvol emerge from the AP scout image(6.873 and 9.42 mGy respectively), while the minimum value of the mammary accumulated radiation dose appear on lateral scout image(4.592 mGy), the minimum value of CTDIvol appear on AP plus lateral scout images(3.94 mGy).The accumulated radiation dose of eye lens and CTDIvol value in PA scout image mode were 54.9%(6.507/11.847) and 45.2%(8.23/18.20) higher than those of the lateral scout image mode. The accumulated radiation dose of mammary gland and CTDIvol value in AP scout image mode were 42.5%(2.051/4.822) and 136.7% (5.44/3.98) higher than that of PA plus lateral scout images mode. In the head-neck phantom mode, the CNR value of orbital center and C5 upper edge level were 102.55 to 115.89, 161.01 to 204.52 respectively. In the chest phantom mode, the CNR value of the apical and tracheal bifurcation level were 82.74 to 164.00, 83.12 to 121.49 respectively. Conclusion The choice of the scout image had significant effect on the radiation dose and the sensitive organ dose in CT. Key words: Tomography,X-ray computed; Radiation dosage; Scout image

The clinical value of anteroposterior and lateral scout image combined with Care Dose 4D and Care kV in reducing radiation dose of chest CT scanning

Objective To investigate the feasibility and clinical value of anteroposterior and lateral scout scan combined with Care Dose 4D and Care kV in chest CT scan. Methods A total of 60 patients of clinical diagnosis with lung tumor were enrolled. Those patients were randomly divided into test group and control group. Control group underwent a scan protocol with lateral scout scan combined with Care Dose 4D and Care kV, while anteroposterior and lateral scout scan combined with Care Dose 4D and Care kV were performed in test group. The signal-to-noise ration (SNR) , contrast-to-noise ratio (CNR) , and overall image quality of two groups of images and diseased tissues were analyzed and evaluated by two high-grade radiologists using double-blind method. Effective doses (E) were also calculated. Results All the 60 patients had successfully completed the chest CT scans. Test group overall image quality (4.57±0.45) and control group overall image quality (4.73±0.45) had no statistically significant difference (P>0.05) . The control group image SNR, CNR and diseased tissue SNR, CNR compared with test group had no statistical significance difference (P>0.05) . The difference of the volume CT dose index (CTDIvol) , dose-length product (DLP) and effective dose (E) of test group and control group was statistically significant (t=8.514, 8.464, 8.464, P<0.001) . Compared with control group, the effective dose of test group decreased by 33.3%. Conclusions Compared with lateral scout scan, the technology of anteroposterior and lateral scout scan combined with Care Dose 4D and Care kV can decrease radiation dose without reducing the image quality. This technology can therefore be considered as a regular imaging modality for chest CT scan. Key words: Chest; Radiation dose; Care Dose 4D; Care kV; Scout image

Antero-posterior (AP) pelvis x-ray imaging on a trolley: Impact of trolley design, mattress design and radiographer practice on image quality and radiation dose

IntroductionPhysical and technical differences exist between imaging on an x-ray tabletop and imaging on a trolley. This study evaluates how trolley imaging impacts image quality and radiation dose for an antero-posterior (AP) pelvis projection whilst subsequently exploring means of optimising this imaging examination. MethodsAn anthropomorphic pelvis phantom was imaged on a commercially available trolley under various conditions. Variables explored included two mattresses, two image receptor holder positions, three source to image distances (SIDs) and four mAs values. Image quality was evaluated using relative visual grading analysis with the reference image acquired on the x-ray tabletop. Contrast to noise ratio (CNR) was calculated. Effective dose was established using Monte Carlo simulation. Optimisation scores were derived as a figure of merit by dividing effective dose with visual image quality scores. ResultsVisual image quality reduced significantly (p < 0.05) whilst effective dose increased significantly (p < 0.05) for images acquired on the trolley using identical acquisition parameters to the reference image. The trolley image with the highest optimisation score was acquired using 130 cm SID, 20 mAs, the standard mattress and platform not elevated. A difference of 12.8 mm was found between the image with the lowest and highest magnification factor (18%). ConclusionThe acquisition parameters used for AP pelvis on the x-ray tabletop are not transferable to trolley imaging and should be modified accordingly to compensate for the differences that exist. Exposure charts should be developed for trolley imaging to ensure optimal image quality at lowest possible dose.