Metal Markers Research Articles

The adductor tubercle can be a radiographic landmark for joint line position determination: an anatomic-radiographic correlation study

BackgroundThe adductor tubercle (AT) has been used intraoperatively as a landmark to evaluate the joint line position in knee arthroplasty. The purpose of this study was to determine whether the AT could be clearly identified on radiographic imaging as well as if the AT to joint line distance could be accurately measured for use as a radiographic landmark.MethodsThe distance from the AT to the joint line was measured on each of 78 knees during total knee arthroplasty. Next, the AT was marked with a metal marker for radiographic analysis. On the postoperative radiograph, the location of the AT was determined by tracing the metal marker. Subsequently, the radiographic joint line distance (RJLD) was measured and compared with the intraoperative joint line distance (IJLD) to test the agreement of the measurements.ResultsLocation analysis indicated that the inflection point on the radiographic contour of the distal femur was the predicted location for the AT. The mean IJLD was 45 ± 3 mm and the RJLD was 45 ± 4 mm. The intraclass correlation coefficient was used to evaluate the inter-rater reliability between the two methods; that coefficient was 0.751, indicating good agreement between them. Measurements on the radiograph were comparable to the intraoperative measurements of the operated knees.ConclusionsIn addition to being an intraoperative landmark, the AT may also be an eligible radiographic landmark for analyzing joint line level. The RJLD measurement may be obtained to plan the joint line position in knees with significant bone loss preoperatively and to follow up the results of surgery postoperatively.

Metal Atom Markers for Imaging Epitaxial Molecular Self-Assembly on Graphene by Scanning Transmission Electron Microscopy

Direct imaging of single molecules has to date been primarily achieved using scanning probe microscopy, with limited success using transmission electron microscopy due to electron beam damage and low contrast from the light elements that make up the majority of molecules. Here, we show single complex molecule interactions can be imaged using annular dark field scanning TEM (ADF-STEM) by inserting heavy metal markers of Pt atoms and detecting their positions. Using the high angle ADF-STEM Z1.7 contrast, combined with graphene as an electron transparent support, we track the 2D monolayer self-assembly of solution-deposited individual linear porphyrin hexamer (Pt-L6) molecules and reveal preferential alignment along the graphene zigzag direction. The epitaxial interactions between graphene and Pt-L6 drive a reduction in the interporphyrin distance to allow perfect commensuration with the graphene. These results demonstrate how single metal atom markers in complex molecules can be used to study large scale packing and chain bending at the single molecule level.

Arthroscopic bare spot method underestimates true bone defect in bony Bankart lesion.

The need for precise quantification of the glenoid defect should be emphasized in the choice of surgery for bony Bankart lesion especially in its critical values of 16% to 25. The study aims to verify the validity of bare spot method for arthroscopic quantification of glenoid bone defect using several varieties of posterior portal location. Two intact cadaveric glenoids were prepared for the study. The greatest anteroposterior diameter of the perfect circle concept of the glenoid is identified and center of the circle is marked as glenoid bare spot with metal marker. Sixteen percent and 25% defect were sequentially created using a saw at 0° axis parallel to the longitudinal axis of the glenoid. These were confirmed by 3D CT glenoid scan based on glenoid rim distances. Each glenoids were mounted on Sawbone dome holder model simulating neutral version. Quantification of Glenoid bone defects were sequentially measured by glenoid bare spot method arthroscopically by 5 shoulder arthroscopy trained surgeons in 5 varieties of posterior portals in 5 cycles. Paired sample t test was done for arthroscopic over CT scan method of glenoid bone loss quantification. One way ANOVA for portal location analysis was done. Glenoid bare spot method significantly underestimates 16% and 25% glenoid bone defect to 9% ± 2 (P < 0.001) and 18% ± 2 (P < 0.001), respectively, compared to 3D CT scan method. There was good intra-class correlation coefficient of 0.97 for inter-rater reliability. There was no significant difference in quantification in between five portal sites by one-way ANOVA (P > 0.05). Arthroscopic glenoid bare spot method using the anterior viewing portal significantly underestimates glenoid bone loss in critical margin degrees of decision making in shoulder instability surgery. Minimal variation of posterior portal location for the calibrated probe does not cause significant difference in Glenoid bone loss quantification.

Assessing Agreement of Lateral Leg Muscle and Bone Composition Using Dual X-ray Absorptiometry

Background: Recently, a lateral-view dual X-ray absorptiometry (DXA) scanning method for measuring leg total, lean, and fat masses demonstrated accuracy vs the standard whole-body frontal DXA scanning view on the GE Lunar iDXA. The current study examined the lateral scanning method's agreement using a Hologic Horizon A DXA scanner. Methodology: Thirty healthy college-age participants (16 female; X̅age = 21.5 ± 1.7 yr) received 3 DXA scans (1 whole-body, 2 lateral leg scans) to quantify leg composition in the frontal and lateral plane. To mark regions of interest for postscan analysis, metallic markers were placed at 60% of the length above and below each leg's lateral epicondyle. Using lateral subject positioning, leg composition was measured with participants lying on their right and left sides. Paired t tests examined the lateral DXA scanning method's agreement when quantifying total, fat, and lean masses, bone mineral content, and bone mineral density compared to measurements of equal area in the whole-body frontal scanning view. Results: Comparisons of frontal and lateral view DXA scan measurements for right leg total mass (7.12 ± 0.91kg vs 6.39 ± 0.85kg), fat mass (1.70 ± 0.44kg vs 1.36 ± 0.33kg), lean mass (5.14 ± 1.05kg vs 4.77 ± 0.92kg), bone mineral content (0.28 ± 0.06kg vs 0.23 ± 0.05kg), and bone mineral density (1.39 ± 0.14g/cm2vs 1.36 ± 0.15g/cm2), respectively, were significantly different (p < 0.001–0.028). Similarly, comparisons of frontal and lateral left leg total mass (7.12 ± 0.97kg vs 6.38 ± 0.92kg), fat mass (1.70 ± 0.44kg vs 1.39 ± 0.36kg), lean mass (5.15 ± 1.12kg vs 4.76 ± 0.97kg), bone mineral content (0.28 ± 0.06kg vs 0.24 ± 0.06kg), and bone mineral density (1.39 ± 0.15g/cm2vs 1.36 ± 0.17g/cm2), respectively, were significantly different (p < 0.001–0.046). Conclusion: Unlike a previous study in which agreement of lateral vs frontal leg composition measurements of equal area was reported utilizing the GE Lunar iDXA, agreement was not observed using the Hologic Horizon A DXA scanner. Therefore, lateral view assessment may not be reliably performed on DXA scanner models produced by different manufacturers.

Intraoperative Identification and Guidance of Breast Cancer Microfoci Using Ultrasound and Near-Infrared Fluorescence Dual-Modality Imaging.

The traditional method of labeling the nonpalpable breast cancer is placing a guidewire or metal marker guided by ultrasound or stereographic mammogram prior to surgery. However, the wire localization has a risk of displacement and could be an obstacle in the surgical course. To avoid these issues, we tried to combine the near-infrared (NIR) fluorescence dye dioctadecyltetramethyl indotricarbocyanine iodide (DiR) and microbubbles (MBs) to realize the dual-modality imaging for breast cancer microfoci intraoperative identification and guidance as a more efficient workflow. First, 24 mice were divided into three groups, injected with DiR nanoparticles (NPs), DiR MBs, and DiR MBs + ultrasound (US), and then, in vivo and ex vivo NIR fluorescence imaging was conducted. The distinction of fluorescence imaging intensity at the tumor site among the three groups was statistically significant (P < 0.001). Group 3 (DiR MBs + US) exhibited the highest fluorescence imaging intensity; the distinctions between group 3 and group 1 (DiR NPs) and group 3 and group 2 (DiR MBs) were both statistically significant (P = 0.001, P = 0.003), while the distinction between group 1 and group 2 was not statistically significant (P = 1.0). The results above validated the advantage of fluorescence imaging by using ultrasound-targeted MB destruction. Second, two kinds of subcutaneous breast cancer mice models [4T1-luc(n = 5)/MCF-7(n = 3)] received tumor resection, and NIR fluorescence and bioluminescence images were obtained to detect tumor residuals. We found that the small residual tumor tissues, metastatic lymph nodes, and even the surrounding infiltrated tissue all can be indicated by the fluorescence imaging and verified with bioluminescence and histological examination. In addition, the residual tumor cells appeared as tumor recurrence 22 days post operation and was confirmed with contrast-enhanced ultrasound (CEUS) in vivo. Thereby, ultrasound-targeted DiR MB destruction and then conversion into DiR NPs was feasible for intraoperative identification and guidance of nonpalpable breast cancer foci.

3D Talar Kinematics During External Rotation Stress Testing in Hindfoot Varus and Valgus Using a Model of Syndesmotic and Deep Deltoid Instability.

External rotation stress (ERS) identifies ankle instability after fibular reduction of rotational ankle injuries. Combined hindfoot and ankle motions and an inconsistent starting position could mask differing degrees of instability resulting from syndesmotic and/or deltoid ligament disruption. The goal of this work was to use full 3D talar kinematics to evaluate the effects of hindfoot orientation and foot starting position during ERS on the ability to detect instability caused by ligament disruptions. Six cadaveric ankles with metallic fiducial markers were CT scanned in neutral and 3 stress positions: varus hindfoot internal rotation stress (IRS-var), valgus hindfoot ERS (ERS-val), and varus hindfoot ERS (ERS-var). Scans were obtained in stress positions after transecting the deep deltoid ligament (tDDL) and then the syndesmotic ligaments (tDDL+Syn). Talar rotations and translations were computed in the axial, coronal, and sagittal planes in each stress position. Changes in a fixed center of rotation (CoR) relative to the intact sequence were calculated. Axial plane rotation beginning from IRS-var increased significantly for each level of ligamentous instability (P < .05 for all conditions) (10.9 degrees, intact; 14.1 degrees, tDDL; 22.7 degrees, tDDL+Syn during ERS-val; and 16.4 degrees, intact; 23.1 degrees, tDDL; 29.9 degrees, tDDL+Syn during ERS-var). With ERS-val, the talar CoR moved medially (3.6-5.4 mm) and posteriorly (0.5-5.2 mm); ERS-var moved anterior/laterally or posterior/medially depending on the specific ligamentous instability. With tDDL+Syn the ankle became grossly unstable and there were no clear trends in sagittal/coronal rotation or translation. An ERS test from internal to external rotation consistently differentiates between normal, tDDL, and tDDL+Syn. Talar CoR moved outside the mortise with ligamentous instability. Significant residual deep deltoid instability is likely underrecognized with current practice. The most discriminatory test for detecting such instability in our laboratory was an ERS test performed by internally rotating the foot to a hard, bony endpoint, positioning the hindfoot in varus, and then performing the entire external rotation maneuver while maintaining the varus hindfoot position.

Sentinel lymph node biopsy in N+ breast cancer with conversion into N0 after neoadjuvant chemotherapy

ObjectiveSentinel lymph node biopsy (SLNB) usefulness in breast carcinoma N+ converted to N0 after neoadjuvant chemotherapy (NC). Material and methodsDescriptive study including 16 females with infiltrating carcinoma with lymphatic metastasis confirmed by biopsy, leaving a metallic marker (MM) in pathological lymph nodes (LN). All patients underwent NC reaching a complete radiological response in LN. Lymphoscintigraphy was performed after 99mTc nanocoloid injection, obtaining planar images and SPECT/CT. Lymphatic drainage and concordance of sentinel node (SN) with MM was analyzed. ResultsSN was visualized in lymphoscintigraphy in 93.7% of cases. The SN coincided with the MM in 12/15 cases on SPECT/CT. The SLNB technique was completed on 14/16 patients, intraoperatively locating the GC in all of them. The SN was negative in 10 cases, 3 cases presented macrometastases and 1 micrometastases. Axillary lymphadenectomy (AL) was performed in a case of macrometastasis with >15,000cp/μARNm CK-19, absence of drainage and in one case that showed no coincidence with the MM due different Berg's level location. These last two cases presented lymph node metastasis. In the other two cases with not coincidence between the SN and the MM, a total of 4 lymph nodes were removed, showing no evidence of metastasis. Patients without AL were followed up for an average of 10 months (range 6–17), with no evidence of lymph node involvement. ConclusionSLNB in breast cancer with conversion into N0 after neoadjuvant treatment is a technique with good results and a low false negative rate.

Positioning errors of metal localization devices with motion artifacts on kV and MV cone beam CT.

Objective:To investigate motion artifacts on kV CBCT and MV CBCT images with metal localization devices for image-guided radiation therapy.Methods:The 8 μ pelvis CBCT template for the Siemens Artiste MVision and Pelvis template for the Varian IX on-board Exact Arms kV were used to acquire CBCT images in this study. Images from both CBCT modalities were compared in CNRs, metal landmark absolute positions, and image volume distortion on three different planes of view. The images were taken on a breathing-simulated thoracic phantom in which several typical metal localization devices were implanted, including clips and wires for breast patients, gold seeds for prostate patients, and BBs as skin markers. To magnify the artifacts, a 4 cm diameter metal ball was also implanted into the thoracic phantom to mimic the metal artifacts.Results:For MV CBCT, the CNR at a 4 sec breathing cycle with 1 cm breathing amplitude was 5.0, 3.4 and 4.6 for clips, gold seeds and BBs, respectively while it was 1.5, 2.0 and 1.6 for the kV CBCT. On the images, the kV CBCT showed symmetric streaking artifacts both in the transverse and longitudinal directions relative to the motion direction. The kV CBCT images predicted 89 % of the expected volume, while the MV CBCT images predicted 95 % of the expected volume. The simulated soft tissue observed in the MVCT could not be detected in the kV CBCT.Conclusion:The MV CBCT images showed better volume prediction, less streaking effects and better CNRs of a moving metal target, i.e. clips, BBs, gold seeds and metal balls than on the kV CBCT images. The MV CBCT was more advantageous compared to the kV CBCT with less motion artifacts for metal localization devices.Advances in knowledge:This study would benefit clinicians to prescribe MV CBCT as localization modality for radiation treatment with moving target when metal markers are implanted.

A novel range-verification method using ionoacoustic wave generated from spherical gold markers for particle-beam therapy: a simulation study

This study proposes a novel alternative range-verification method for proton beam with acoustic waves generated from spherical metal markers. When proton beam is incident on metal markers, most of the resulting pressure waves are confined in the markers because of the large difference in acoustic impedance between the metal and tissue. However, acoustic waves with frequency equal to marker’s resonant frequency escape this confinement; the marker briefly acts as an acoustic transmitter. Herein, this phenomenon is exploited to measure the range of the proton beam. We test the proposed strategy in 3-D simulations, combining the dose calculations with modelling of acoustic-wave propagation. A spherical gold marker of 2.0 mm diameter was placed in water with a 60 MeV proton beam incident on it. We investigated the dependence of pressure waves on the width of beam pulse and marker position. At short beam pulse, specific high-frequency acoustic waves of 1.62 MHz originating from the marker were observed in wave simulations, whose amplitude correlated with the distance between the marker and Bragg peak. Results indicate that the Bragg peak position can be estimated by measuring the acoustic wave amplitudes from the marker, using a single detector properly designed for the resonance frequency.

ANATOMICAL DISSECTION AND CT IMAGING OF THE ANTERIOR CRUCIATE AND MEDIAL COLLATERAL LIGAMENT FOOTPRINT ANATOMY IN SKELETALLY IMMATURE CADAVER KNEES

Background: Anterior cruciate ligament (ACL) and medial collateral ligament (MCL) injuries in skeletally immature patients are increasingly recognized and surgically treated. However, the relationship between the footprint anatomy and the physes are not clearly defined. The purpose of this study was to identify the origin and insertion of the ACL and MCL, and define the footprint anatomy in relation to the physes in skeletally immature knees. Methods: Twenty-nine skeletally immature knees from 16 human cadaver specimens were dissected and divided into two groups: Group A (ages 2-5 years), and Group B (ages 7-11 years). Metallic markers were placed to mark the femoral and tibial attachments of the ACL and MCL. CT scans were obtained for each specimen used to measure the distance from the center of the ligament footprints to the respective distal femoral and proximal tibial physes. Results: Median distance from the ACL femoral epiphyseal origin to the distal femoral physis was 0.30 cm (interquartile range, 0.20 cm to 0.50 cm) and 0.70 cm (interquartile range, 0.45 cm to 0.90 cm) for Groups A and B, respectively. The median distance from the ACL epiphyseal tibial insertion to the proximal tibial physis for Groups A and B were 1.50 cm (interquartile range, 1.40 cm to 1.60 cm) and 1.80 cm (interquartile range, 1.60 cm to 1.85 cm), respectively. Median distance from the MCL femoral origin on the epiphysis to the distal femoral physis was 1.20 cm (interquartile range, 1.00 cm to 1.20 cm) and 0.85 cm (interquartile range, 0.63 cm to 1.00 cm) for Groups A and B, respectively. Median distance from the MCL insertion on the tibial metaphysis to the tibial physis was 3.05 cm (interquartile range, 2.63 cm to 3.30 cm) and 4.80 cm (interquartile range, 3.90 cm to 5.10 cm) for Groups A and B, respectively. Conclusion: Surgical reconstruction is a common treatment for ACL injury, and occasionally MCL reconstruction or repair is also required. Cadaveric dissection and CT scanning of exceptionally rare pediatric tissue clearly defines the location of the ACL and MCL with respect to the femoral and tibial physes, and may guide surgeons for physeal respecting procedures for both ACL reconstruction, and ACL repair procedures. Clinical Relevance: In addition to ACL reconstruction, recent basic science and clinical research suggest that ACL repair may be more commonly performed in the future. MCL repair and reconstruction is also occasionally required in skeletally immature patients. This information may be useful to help surgeons avoid or minimize physeal injury during ACL/MCL reconstructions and/or repair in skeletally immature patients. [Figure: see text][Figure: see text][Figure: see text][Figure: see text]

Easy Technique for Radiographic Evaluation of Stump-socket Fit in Below-knee Amputees.

The alignment of a prosthesis affects the way load is transferred to the stump through the socket; this is critically important for its comfort and function. The aim of the study was to assess the value of radiopaque materials in evaluation of stump-socket fit in people with below-knee amputation. Thirty-two amputees (skin breakdown group) had cutaneous lesions in the stump, and another 26 amputees (control group) had no lesion in the stump after training with their prosthesis. Metallic markers were attached to weight-bearing points in the internal socket. X-rays were taken in the antero-posterior and lateral projections. In the antero-posterior view, the weight-bearing points of the stump did not correspond to the metallic markers placed over the patellar tendon and the tibial tuberosity points in the socket in 78.1% of the 32 amputees in the skin breakdown group. This malalignment was present in 42.3% of the 26 amputees in the control group (Pearson Chi-Square, p&lt;0.007). In the lateral view, in 65.6% of the 32, the weight-bearing points of the stump did not correspond to the metallic markers placed over the patellar tendon and the tibial tuberosity points in the socket. This malalignment was noted in 23.1% of the 26 patients in the other group (Pearson Chi-Square, p&lt;0.002). 1. The conflict between the prosthesis and residual limb is the cause of skin disruption at different sites of the stump and can be successfully treated by prosthetic socket modification. 2. Efforts should be made to systematically identify any discrepancies between the stump and the soc-ket. 3. Correct adaptation of the prosthesis to the weight-bearing points of the stump will offer clinicians the possibility of quantification and visualization of this interaction using simple radiographic techniques.

A Novel High-Visibility Radiopaque Tantalum Marker for Biliary Self-Expandable Metal Stents

Background/AimsRadiopaque metal markers are required to improve X-ray absorption by self-expandable metal stents (SEMSs) to enable precise stent placement. A new tantalum radiopaque marker was recently developed using an ultrasonic spray technique. The aim of the present study was to evaluate the safety and visibility of tantalum markers.MethodsA total of three beagle dogs were used for a gastrointestinal tract absorption test. Five tantalum markers were placed in the stomach of each dog endoscopically. Excreted tantalum markers were collected, and their weights were compared to the original weights. In radiopacity tests, marker radiopacities on X-ray images were quantified using ImageJ software and compared with those of commercially available metal markers. Finally, the radiographic images of six patients who underwent biliary SEMS placement using tantalum marker Nitinol SEMSs (n=3) or gold marker Nitinol SEMSs (n=3) were compared with respect to marker brightness on fluoroscopic images.ResultsAbsorption testing showed that the marker structures and weights were unaffected. Radiopacity tests showed that the mean brightness and total brightness scores were greater for tantalum markers (226.22 and 757, respectively) than for gold (A, 209 and 355, respectively; B, 204.96 and 394, respectively; C, 194.34 and 281, respectively) or platinum markers (D, 203.6 and 98, respectively). On fluoroscopic images, tantalum markers had higher brightness and total brightness scores (41.47 and 497.67, respectively) in human bile ducts than gold markers (28.37 and 227, respectively).ConclusionsTantalum markers were found to be more visible than other commercially available markers in X-ray images and to be resistant to gastrointestinal absorption.

A New CT Based Method for Post-operative Motion Analysis of Pelvic Fractures

Conventional X-ray is commonly used for pelvic fracture follow-ups, but has a precision of only ± 5 mm. Implantation of tantalum beads together with RSA has shown high precision but not applicable in clinical practice. CT scan has been shown a suitable substitute for RSA to follow the metal markers. We aimed to assess whether implantation of metal markers could be avoided using CT scan and merging of bone surface anatomy. A human cadaveric pelvis marked with 0.8 mm tantalum beads was fixed over the symphysis and the right SI-joint. Left hemi-pelvis was subsequently distracted using plastic spacers. Sequential CT exams was conducted and data were analyzed using Sectra® (Sectra AB), CTMA package. Examinations were repeated after 2 weeks. Bone registration showed better precision than registration based on tantalum beads. However, only the difference in angular changes was statistically significant (p = 0.008). The confidence interval of the repeatability was ± 0.5 mm for translation and ± 0.5° for rotation. This new non-invasive technique showed good precision and repeatability and might be a future option in clinical practice for post-operative follow-ups of patients with pelvic fractures.

Usability Evaluation of a New Elastic Immobilization with Metal Markers for Image-Guided Radiation Therapy for Breast Cancer

We developed an elastic immobilization based on a commercially available brassier for postoperative radiotherapy for breast cancer. The purpose of this study was to validate the positioning accuracy and the surface doses of image-guided radiotherapy (IGRT) for breast cancer using the immobilization. The elastic immobilization had six small metal markers. We developed the human phantom with a tungsten target in the breast, which had an equivalent form and flexibility to soft tissues of the human body. First, the positioning accuracy of IGRT was evaluated using onboard imaging devices. The immobilization was fixed on the human phantom; the landmarks were drawn on the phantom to indicate positional relationship between the immobilization and body. The setup of the phantom was performed five times, and then several x-ray images were produced. The position verification was performed using the metal markers of the immobilization. The margin of a breast target was estimated using the expanded uncertainty calculated from the displacement between simulated and measured the tungsten target positions. The expanded uncertainty value was obtained by multiplying the combined standard uncertainty value by a coverage factor (k = 2; confidence interval, 95%). Next, the surface doses were measured using the thermoluminescent dosimeters with kV planar imaging at 80 kVp / 100 kVp, 5 mAs, and cone beam computed tomography (CBCT) at 120 kVp, 180 mAs. The measured doses with and without the immobilization were compared. Finally, they were compared with the calculated dose using the EGSnrc Monte Carlo code under the same conditions. The displacement of the tungsten target was 2.31 ± 0.53 mm, -1.21 ± 1.90 mm and -0.11 ± 0.67 mm in the lateral, longitudinal and vertical directions, respectively. The three-dimensional translation vector of variation was 3.28 ± 0.59 mm. The accuracy of IGRT with the elastic immobilization was 3.30 ± 0.53 mm (k = 2). The measured surface doses with and without the immobilization were 0.53 ± 0.28 mGy and 0.97 ± 0.19 mGy in kV planar image pair, 5.50 ± 1.40 mGy and 5.90 ± 1.45 mGy in CBCT, respectively. Similarly, the calculated dose was decreased by using immobilization in CBCT. This study showed a new elastic immobilization with the metal markers could provide positioning accuracy of IGRT for breast cancer with minimum skin markers. Furthermore, the immobilization decreased the surface doses of IGRT.Abstract TU_26_3153; Table 1Uncertainty budget of tungsten target position in IGRT with elastic immobilization (mm).Source of uncertaintyValue (±)Probability distributionDivided factorStandard uncertaintyu1: x-ray correction0.59normal10.26u2: imager position0.12normal10.01uc: combinednormal0.27U: expanded (k = 2)normal0.53 Open table in a new tab

Clinical outcomes of image-guided proton therapy for histologically confirmed stage I non-small cell lung cancer

BackgroundTwo prospective phase II trials were designed to assess the efficacy and safety of image-guided proton therapy (IGPT) for either medically inoperable or operable stage I non-small cell lung cancer (NSCLC). The present study reports the interim results of these trials.MethodsFifty-five patients with histologically confirmed stage I NSCLC (IA in 33 patients and IB in 22 patients; inoperable in 21 patients and operable in 34 patients) who received IGPT between July 2013 and February 2017 were analyzed. The median patient age was 71 years (range: 48–88 years). IGPT with fiducial metallic marker matching was performed for suitable patients, and a respiratory gating method for motion management was used for all treatments. Peripherally located tumors were treated with 66 Gy relative biological effectiveness equivalents (Gy(RBE)) in 10 fractions (n = 49) and centrally located tumors were treated with 72.6 Gy(RBE) in 22 fractions (n = 6). Treatment associated toxicities were evaluated using Common Toxicity Criteria for Adverse Events (v.4.0).ResultsMedian follow-up was 35 months (range: 12–54 months) for survivors. For all patients, the 3-year overall survival, progression-free survival, and local control rates were 87% (95% confidence interval: 73–94%), 74% (58–85%), and 96% (83–99%), respectively. Fiducial marker matching was used in 39 patients (71%). Grade 2 toxicities observed were radiation pneumonitis in 5 patients (9%), rib fracture in 2 (4%), and chest wall pain in 5 (9%). There were no grade 3 or higher acute or late toxicities.ConclusionsIGPT appears to be effective and well tolerated for all patients with stage I NSCLC.Trial registrationLung-001, 13–02-09 (9), registered 11 June 2013 and Lung-002, 13–02-10 (10), registered 11 June 2013.

Gravity-guided Stereotactic Brain Biopsy.

Introduction:This study describes a technique using gravity for guidance in stereotactic brain biopsy. This will be especially useful in hospitals where the stereotactic equipment is unavailable.Objectives:The aim of this study is to describe the technique, develop a formula to define its limits of accuracy, and report on its clinical application.Methods:Using the positioning laser grid lines on the computed tomography scanner, a small metallic marker is placed on the scalp at the intended biopsy site. The distance between the tumor and the inner table of the bone is measured. In the operating theater, the patient is positioned such that the tip and the bridge of the nose are aligned in a horizontal position. The patient's two eyebrows or the orbital canthi are aligned in a vertical line. Simultaneously, the posterior borders of the two pinnae are aligned vertically. Gravity is used to guide the biopsy needle through the marked burr hole into the target. Seven patients had biopsies. One was for targeting the craniopharyngioma cyst to place an Ommaya catheter. The fraction of error or error fraction (EF), was developed for verification of its limits of accuracy.Results:All the biopsies were diagnostic and the Ommaya catheter was correctly sited. The EFs at α = 5° were all predictive of the limits of accuracy of this technique.Conclusion:This is the first reported gravity-guided stereotactic brain surgery. The outcome in all the eight cases showed that it was within the limits of its accuracy. EF can be calculated to ensure accuracy. This technique is helpful if a commercial stereotactic system is not available.

P276] Impact on proton range estimates using a novel mr-based artifact reduction algorithm

Purpose Metal implants lead to streak and cupping artifacts in computed tomography (CT) images, causing erroneous CT number estimates for radiation therapy (RT) planning. We recently introduced kerMAR, a novel Magnetic Resonance (MR)-based CT metal artifact reduction algorithm that combines kernel regression on uncorrupted CT value/MR patch pairs with a forward model of the CT metal artifacts. Here, we compare the impact of kerMAR and the clinical oMAR algorithm (Philips) on the proton range in calculated spot scanning (SS) dose plans for proton RT. Methods We acquired T1w MR and CT image sets of a veal shank phantom with and without metal markers inserted, and applied kerMAR and oMAR to the former. We then created SS plans in Eclipse v. 13.7 (Varian) delivering 150 MeV protons in a 0.55 cm single spot that passed 1) near a metal marker at shallow depth and 2) near two different markers located at shallow (near bone) and deep depths, respectively. Similar images were acquired for 4 head-and-neck (HN) RT patients with dental implants, and plans using the same phantom beam, angled through the artifact corrupted oral cavity, were devised, leading to a configuration most resembling phantom beam 2. We finally recalculated the dose plans for the same beamline settings and monitor units on all CT sets, and compared the proton ranges defined as the depth with 80% of the maximum dose. Results For the phantom plans, the following range deviations relative to the metal-free reference plan (uncorrected CT, oMAR, kerMAR) were observed: Plan 1: (0.6, 0.6, 0.6)%; plan 2: (−4, −1.8, −2.1)%. The patient plans showed the following deviations from the uncorrected CT plan: kerMAR: (10, 8, −7, 11)%; oMAR: (3, 0.1, −10, 0.2)%. Conclusions Proton range calculations on a phantom showed similar improvements compared to the uncorrupted reference with kerMAR and oMAR. Similar calculations on HN patients, however, displayed systematic proton range increases when applying kerMAR as compared to oMAR.

Anatomical relationship of palmar carpal bone landmarks used in locating the lunate and capitate during palpation: A cadaveric investigation

Study DesignDescriptive in situ cadaveric study. IntroductionPerforming accurately directed examination and treatment to the wrist requires clinicians to orient to carpal bone structures. Purpose of the StudyTo examine the anatomical relationships that exist within the wrist–hand complex and identify the accuracy of surface anatomy mapping strategies for localizing anatomical landmarks using a palmar approach. MethodsTwenty-three embalmed cadavers were dissected using standardized procedures. Metal markers were placed in the most prominent palmar landmark of key carpal structures. Relationships between the most prominent palpation landmarks and the carpal bones of interest were visualized using fluoroscopy. ResultsThe most successful methods of palmar capitate localization included the midpoint of a line from trapezium tubercle to pisiform; the midpoint of a line from scaphoid tubercle to hamate hook; or the intersection (cross) of these 2 diagonal lines, with successful capitate identification 100% (23/23) of the time. The most successful method for locating the lunate included the midpoint of a line from the radial styloid process to the ulnar styloid process, which identified the lunate in 100% (23/23) of cases. DiscussionThe results of this cadaveric anatomical relationship study support the use of the midpoint of a line from pisiform to trapezium tubercle, the midpoint of a line from scaphoid tubercle to hamate hook, or a combination (cross) of these lines to locate the capitate from a palmar approach. In addition, the anatomical relationships examined in this study support the use of the midpoint of a line from the radial styloid process to ulnar styloid process to locate the lunate from a palmar approach. Knowledge of these anatomical relationships may improve the clinician’s confidence in locating the capitate and lunate during intercarpal examination, special testing, and treatment. ConclusionResults of this study provide information of the anatomical relationships of the carpal bones from a palmar approach, giving clinicians a foundation for proper orientation to the carpal bones during clinical examination and intervention. Further research is needed to evaluate the reliability and accuracy of these methods for surface palpation on live patients.

Effect of Lateral Column Lengthening Calcaneal Osteotomy on Radiographic Measurements of Foot Alignment

Category: Hindfoot Introduction/Purpose: Lateral column lengthening (LCL) with calcaneal osteotomy has been increasingly used for reconstruction in flexible flat foot reconstruction. The aims of this study were to 1) evaluate the effects of variably sized LCL blocks on the restoration of alignment in an acute flat foot cadaveric model; 2) create a computer algorithm to more objectively measure foot alignment; and 3) develop an acute flat foot model that does not require cyclic loading for creating a type IIB flat foot. Determining if overcorrection with lateral column lengthening can occur would provide guidance surgeons to avoid lateral column overload. A computer guided measurement program could make studies more comparable. An acute flat foot model would clarify the ligament deficiencies necessary to create a type IIB flat foot. Methods: A type IIB flat foot model was used in which the medial and medial-plantar fibers of the calcaneonavicular (CN), the interosseous talo-calcaneal (ITCL) and the cervical (CL) ligaments were transected. Metallic markers were placed in the PF origin. 3D weightbearing CT scans were obtained with the specimens in a custom jig that permitted loading with 100 lbs. (445 N). The jig allowed full pronation under load. Scans were obtained: intact, flat, and with 6, 8 and 10 mm LCL blocks. Simulated AP and lateral radiographs were created using a custom MATLAB program. A custom ImageJ plugin was created which guided measurement of Meary’s angle, naviculo-cuneiform overlap, AP talo-first metatarsal angle, and a novel plantar fascia (PF) distance and PF angle. The program automatically calculated midpoints and perpendicular lines from guided user input. Four observers performed all measurements in blinded and randomized fashion on two occasions greater than 12 weeks apart. Results: The ligament sectioning model reliably produced a type IIB flat foot as noted by talo-navicular sag, increased talar head uncovering (forefoot abduction) and divergence of the talus and calcaneus as seen on the AP weightbearing view (Figure 1). Cyclic loading was not required in any specimens and the remaining medial column ligaments were not sectioned. Intraobserver and interobserver comparisons indicated naviculo-cuneiform overlap and plantar fascia distance had excellent interobserver agreement and Meary’s and plantar fascia angle had good interobserver agreement (Figure 1). Lateral column lengthening trended toward overcorrection at 10 mm suggesting a possible threshold for over-correction. Conclusion: The trend toward overcorrection with 10 mm LCL may indicate a threshold for lateral column overload. Computer guided measurement may improve consistency when comparing studies. The PF measurements are not possible in vivo. The use of a heel centering ring might be a surrogate for the implanted metallic beads. The CL sectioning was essential for creating type IIB flat foot without cyclic loading. The CL has been noted to be a main subtalar stabilizer, but has not entered into mainstream discussions regarding flat foot. Changes that occurred with cyclic loading performed in other flat foot studies have not been defined.

Easy technique for radiographic evaluation of stump-socket fit in below-knee amputees

The critical relationship between accurate fit of a prosthesis and amputee comfort and function constitutes the foundation of prosthetic fitting. Prosthesis alignment affects the way load is transferred to the residual limb through the socket, and this load is critically important for comfort and function. The aim of the study was to assess the value of radiopaque materials in evaluation of stump-socket fit in people with transtibial amputation, and to develop a simple procedure for clinical use in diagnosing skin pressure problems more accurately. Thirty-two amputees (herein: ‘participants’) had one or more cutaneous lesion in the stump, and another 26 amputees (control group) had no lesion in the stump after training with their prosthesis. Radiopaque metallic markers were attached to weight-bearing points in the outer surface of the internal socket. Full weight-bearing X-rays were made in the antero-posterior and lateral projections. In the antero-posterior view, the weight-bearing points of the stump in 78.1% of the participants did not correspond to radiopaque metallic markers placed over the patellar tendon and the tibial tuberosity points in the socket. In the control group, there was non-adaptation in only 42.3% between the up-mentioned anatomical and the metallic (Chi 2 , P < 0.007). In the lateral view X-rays, the weight-bearing points of the stump in 65.6% of the participants did not correspond to radiopaque metallic markers placed over the patellar tendon and over the tibial tuberosity points in the socket. In the control group, there was non-adaptation in only 23.1% between the up-mentioned anatomical and the metallic (Chi 2 , P < 0.002). The conflict between prosthesis and residual limb is the cause of skin disruption in the stump and can be successfully treated by prosthetic socket modification. X-rays should be done to identify if there are discrepancies between the stump and the socket.