High Targeting Accuracy Research Articles

Evaluation of an augmented reality navigational guidance platform for percutaneous procedures in a cadaver model.

The objective of this study is to review the accuracy of an augmented reality navigational guidance system designed to facilitate improved visualization, guidance, and accuracy during percutaneous needle-based procedures including biopsies and ablations. Using the HoloLens 2, the system registers and projects 3D CT-based models of segmented anatomy along with live ultrasound, fused with electromagnetically tracked instruments including ultrasound probes and needles, giving the operator comprehensive stereoscopic visualization for intraoperative planning and navigation during procedures.Tracked needles were guided to targets implanted in a cadaveric model using the system. Image fusion registration error, the multimodality error measured as the post-registration distance between a corresponding point measured in the stereoscopic CT and tracked ultrasound coordinate systems, and target registration error, the Euclidean distance between needle tip and target after needle placement, were measured as registration and targeting accuracy metrics. A t-distribution was used for statistical analysis. Three operators performed 36 total needle passes, 18 to measure image fusion registration error and 18 to measure target registration error on four targets. The average depth of each needle pass was 8.4cm from skin to target center. Mean IFRE was 4.4mm (: , ). Mean TRE was 2.3mm (: , ). The study demonstrated high registration and targeting accuracy of this AR navigational guidance system in percutaneous, needle-based procedures. This suggests the ability to facilitate improved clinical performance in percutaneous procedures such as ablations and biopsies.

Smart Stimuli-Responsive Spherical Nucleic Acids: Cutting-Edge Platforms for Biosensing, Bioimaging, and Therapeutics.

Spherical nucleic acids (SNAs) with exceptional colloidal stability, multiple modularity, and programmability are excellent candidates to address common molecular delivery-related issues. Based on this, the higher targeting accuracy and enhanced controllability of stimuli-responsive SNAs render them precise nanoplatforms with inestimable prospects for diverse biomedical applications. Therefore, tailored diagnosis and treatment with stimuli-responsive SNAs may be a robust strategy to break through the bottlenecks associated with traditional nanocarriers. Various stimuli-responsive SNAs are engineered through the incorporation of multifunctional modifications to meet biomedical demands with the development of nucleic acid functionalization. This review provides a comprehensive overview of prominent research in this area and recent advancements in the utilization of stimuli-responsive SNAs in biosensing, bioimaging, and therapeutics. For each aspect, SNA nanoplatforms that exhibit responsive behavior to both internal stimuli (including sequence, enzyme, redox reactions, and pH) and external stimuli (such as light and temperature) are highlighted. This review is expected to offer inspiration and guidance strategies for the rational design and development of stimuli-responsive SNAs in the field of biomedicine.

Characterization of the Targeting Accuracy of a Neuronavigation-Guided Transcranial FUS System In Vitro, In Vivo, and In Silico.

Focused ultrasound (FUS)-enabled liquid biopsy (sonobiopsy) is an emerging technique for the noninvasive and spatiotemporally controlled diagnosis of brain cancer by inducing blood-brain barrier (BBB) disruption to release brain tumor-specific biomarkers into the blood circulation. The feasibility, safety, and efficacy of sonobiopsy were demonstrated in both small and large animal models using magnetic resonance-guided FUS devices. However, the high cost and complex operation of magnetic resonance-guided FUS devices limit the future broad application of sonobiopsy in the clinic. In this study, a neuronavigation-guided sonobiopsy device is developed and its targeting accuracy is characterized in vitro, in vivo, and in silico. The sonobiopsy device integrated a commercially available neuronavigation system (BrainSight) with a nimble, lightweight FUS transducer. Its targeting accuracy was characterized in vitro in a water tank using a hydrophone. The performance of the device in BBB disruption was verified in vivo using a pig model, and the targeting accuracy was quantified by measuring the offset between the target and the actual locations of BBB opening. The feasibility of the FUS device in targeting glioblastoma (GBM) tumors was evaluated in silico using numerical simulation by the k-Wave toolbox in glioblastoma patients. It was found that the targeting accuracy of the neuronavigation-guided sonobiopsy device was 1.7 ± 0.8 mm as measured in the water tank. The neuronavigation-guided FUS device successfully induced BBB disruption in pigs with a targeting accuracy of 3.3 ± 1.4 mm. The targeting accuracy of the FUS transducer at the GBM tumor was 5.5 ± 4.9 mm. Age, sex, and incident locations were found to be not correlated with the targeting accuracy in GBM patients. This study demonstrated that the developed neuronavigation-guided FUS device could target the brain with a high spatial targeting accuracy, paving the foundation for its application in the clinic.

Advances in PET and MRI imaging of tumor hypoxia.

Tumor hypoxia is a complex and evolving phenomenon both in time and space. Molecular imaging allows to approach these variations, but the tracers used have their own limitations. PET imaging has the disadvantage of low resolution and must take into account molecular biodistribution, but has the advantage of high targeting accuracy. The relationship between the signal in MRI imaging and oxygen is complex but hopefully it would lead to the detection of truly oxygen-depleted tissue. Different ways of imaging hypoxia are discussed in this review, with nuclear medicine tracers such as [18F]-FMISO, [18F]-FAZA, or [64Cu]-ATSM but also with MRI techniques such as perfusion imaging, diffusion MRI or oxygen-enhanced MRI. Hypoxia is a pejorative factor regarding aggressiveness, tumor dissemination and resistance to treatments. Therefore, having accurate tools is particularly important.

Accurate and Early Metastases Diagnosis in Live Animals With Multimodal X-ray and Optical Imaging

In vivo optical imaging systems are essential to track disease progression and evaluate therapeutic efficacy in animal studies. However, current approaches are limited by their inability to accurately capture 3-dimensional (3-D) image information. To overcome this hindrance, we adopted x-ray computed tomography (CT) as a prior for 3-D optical image reconstruction and further challenged the multimodal imaging performance with a metastasis model. The iSMAART system, an integrated small animal research platform, features coregistered high-quality quantitative optical tomography and CT. In the synergistic dual-modality imaging, CT provides both 3-D anatomy information and animal structure mesh for optical tomography reconstruction, which is performed using bioluminescence projections acquired from 4 orthogonal angles. The multimodal imaging system was challenged with a prostate cancer metastasis model, and a double-blind histopathology diagnosis was obtained to validate the imaging results. The iSMAART located, visualized, and quantified early tumor metastases at the millimeter scale, and can accurately track deep tumors as small as 1.5 mm in live animals. Tumors metastasized into the liver, diaphragm, and tibia in 4 mice were all successfully diagnosed by the integrated tomographic imaging. Instead of roughly comparing surface-light intensities, as traditionally performed in 2-dimensional optical imaging, iSMAART provides accurate tumor imaging and quantitative assessment capabilities with integrated CT and optical tomography for cancer metastasis research. With the powerful 3-D optical/CT imaging capability, iSMAART has the potential to tackle more complex research needs with higher targeting accuracy.

Thermal Ablation of Liver Tumors Guided by Augmented Reality: An Initial Clinical Experience.

Simple SummaryWe report the first clinical use of Endosight, a new guidance system for percutaneous interventional procedures based on augmented reality, to guide percutaneous thermal ablations. The new system was demonstrated to be precise and reliable, with a targeting accuracy of 3.4 mm. Clinically acceptable, rapid setup and procedural times can be achieved.Background: Over the last two decades, augmented reality (AR) has been used as a visualization tool in many medical fields in order to increase precision, limit the radiation dose, and decrease the variability among operators. Here, we report the first in vivo study of a novel AR system for the guidance of percutaneous interventional oncology procedures. Methods: Eight patients with 15 liver tumors (0.7–3.0 cm, mean 1.56 + 0.55) underwent percutaneous thermal ablations using AR guidance (i.e., the Endosight system). Prior to the intervention, the patients were evaluated with US and CT. The targeted nodules were segmented and three-dimensionally (3D) reconstructed from CT images, and the probe trajectory to the target was defined. The procedures were guided solely by AR, with the position of the probe tip was subsequently confirmed by conventional imaging. The primary endpoints were the targeting accuracy, the system setup time, and targeting time (i.e., from the target visualization to the correct needle insertion). The technical success was also evaluated and validated by co-registration software. Upon completion, the operators were assessed for cybersickness or other symptoms related to the use of AR. Results: Rapid system setup and procedural targeting times were noted (mean 14.3 min; 12.0–17.2 min; 4.3 min, 3.2–5.7 min, mean, respectively). The high targeting accuracy (3.4 mm; 2.6–4.2 mm, mean) was accompanied by technical success in all 15 lesions (i.e., the complete ablation of the tumor and 13/15 lesions with a >90% 5-mm periablational margin). No intra/periprocedural complications or operator cybersickness were observed. Conclusions: AR guidance is highly accurate, and allows for the confident performance of percutaneous thermal ablations.

Needle Deflection Modeling and Preoperative Trajectory Planning During Insertion Into Multilayered Tissues

Percutaneous needle insertion is a widely used technique in needle-based intervention; however, it is difficult to achieve high targeting accuracy due to needle deflection and the boundary effect in multilayered tissues. This article presents a preoperative needle insertion trajectory planning method that includes needle deflection modeling, insertion angle correction, and needle trajectory optimization. The needle deflection model can predict the needle deflection with preoperatively obtained information, which includes tissue-specific parameters and the geometric/material properties of the needle. An insertion angle shift distribution model is obtained based on experimental data and is used to correct insertion angles at tissue boundaries. The needle trajectory optimization is based on the weighted sum of cost function and balances the assessment criteria, which include the trajectory length, the insertion angle, and the distance to critical structures, and determines the needle trajectory with the best performance. Experiments are conducted to demonstrate that with the proposed preoperative needle insertion trajectory planning method, a needle insertion trajectory with increased accuracy, desired insertion length, and safe distance to critical structures can be obtained.

Gastric artery embolization: studying the\xa0effects of catheter type and injection method on microsphere\xa0distributions within a benchtop arterial model

AimsThe objective of the study is to investigate the effect of catheter type and injection method on microsphere distributions, specifically vessel targeting accuracy.Materials and methodsThe study utilized three catheter types (a standard end-hole micro-catheter, a Surefire anti-reflux catheter, and an Endobar occlusion balloon catheter) and both manual and computer-controlled injection schemes. A closed-loop, dynamically pressurized surrogate arterial system was assembled to replicate arterial flow for bariatric embolization procedures. Four vessel branches immediately distal to the injection site were targeted for embolization. Embolic microspheres were injected into the model using these three catheter types and both manual and computer-controlled injections.ResultsAcross all injection methods, the catheter effect on the proportion of microspheres to target vessels (vs. non-target vessels) was significant (p = 0.005). The catheter effect on the number of non-target vessels embolized was nearly significant (p = 0.059). Across all catheter types, the injection method effect was not statistically significant for either of two outcome measures (percent microspheres to target vessels: p = 0.265, number of non-target vessels embolized: p = 0.148).ConclusionCatheter type had a significant effect on targeting accuracy across all injection methods. The Endobar catheter exhibited a higher targeting accuracy in pairwise comparisons with the other two injection catheters across all injection schemes and when considering the Endobar catheter with the manifold injection method vs. each of the catheters with the manual injection method; the differences were significant in three of four analyses. The injection method effect was not statistically significant across all catheter types and when considering the Endobar catheter/Endobar manifold combination vs. Endobar catheter injections with manual and pressure-replicated methods.

Welfare Measurement and Poverty Targeting Based on Participatory Wealth Rankings

Participatory wealth rankings (PWRs) present an inclusive and inexpensive targeting method to identify poor households. They tend to be well received by participants but point to a systematically different understanding of welfare than implied by consumption-based rankings. This suggests that PWRs could be used as the basis for alternative welfare measures that aim to reflect local perceptions of poverty. This paper demonstrates how such a measure can be constructed, using data from a field experiment on poverty targeting in Indonesia. It then explores the potential impact of using this welfare measure as targeting goal on participants’ and village leaders’ satisfaction. I find that higher targeting accuracy—using the PWR-based measure as benchmark—increases satisfaction with the program. However, after controlling for targeting accuracy, the PWR does not lead to discernibly higher satisfaction than a proxy means targeting mechanism. The PWRs thus seem to be appreciated for their resulting allocations rather than valued intrinsically. I also find that targeting accuracy explains satisfaction outcomes better when it is measured against PWR-based welfare rather than predicted consumption. This holds true even for communities where no actual PWRs had been conducted. The results suggest that the information contained in PWRs can be used as a meaningful basis for targeting and poverty measurement.

Targeting Poor Students With Proxy Means Test

Proxy Means Test (PMT) is one of the most efficient ways to target the poor. The procedure of PMT is using household characteristic variables, which have a relationship with income, as a proxy for poverty. That is, PMT is a measurement of wealth, that is so to say poverty without using income, consumption or expenditure. In this study, we created the PMT poverty scorecard to be used as a tool for targeting poor student in 10 provinces of Thailand, including Mae Hong Son, Nan, Nakhon Ratchasimi, Udon Thani, Nakhon Phanom, Chiang Rai, Trung, Kanchanaburi, Chanthaburi, and Phuket. We estimated the relationship between these household characteristic variables and student’s average monthly household income per capita by using Ordinary Least Square (OLS) regression separately by province to capture any geographical characteristic in each province. We then turned 11 of household characteristic estimated coefficients into PMT poverty scorecard for each province. The result suggests that overall, PMT poverty targeting works well in 10 provinces of Thailand in terms of low undercoverage rate, high targeting accuracy rate in both poverty and total accuracy, except for Phuket which has a huge leakage rate since its geographical characteristics which are quite different comparing to others. This leakage problem, however, needs to be explored more as student maybe, in fact, actually poor as same as PMT poverty targeting suggested. For policy recommendation, we suggested using PMT as the main poverty targeting approach together with an identification survey of student who has been targeted as poor to increase the efficiency of poverty targeting. Also, we suggested the addition of household characteristic variables in survey questionnaire could lead to an increase in efficiency of PMT poverty targeting in statistical term.

Investigation of Optimal Physical Parameters for Precise Proton Irradiation of Orthotopic Tumors in Small Animals

The lack of evidence of biomarkers identifying patients who wouldbenefit from proton therapy has driven the emergence of preclinical proton irradiation platforms using advanced small-animal models to mimic clinical therapeutic conditions. This study aimed to determine the optimal physical parameters of the proton beam with a high radiation targeting accuracy, considering small-animal tumors can reach millimetric dimensions at a maximum depth of about 2cm. Several treatment plans, simulated using Geant4, were generated with different proton beam features to assess the optimal physical parameters for small-volume irradiations. The quality of each treatment plan was estimated by dose-volume histograms and gamma index maps. Because of its low-energy straggling, low-energy proton (<50MeV) single-field irradiation can generate homogeneous spread-out Bragg peaks to deliver a uniform dose in millimeter-sized tumors, while sparing healthy tissues located within or near the target volume. However, multifield irradiation can limit the dose delivered in critical structures surrounding the target for attenuated high-energy beams (E>160MeV). Low-energy proton beam platforms are suitable for precision irradiation for translational radiobiology studies.

Hemorrhage Detection and Incidence during Magnetic Resonance-Guided Deep Brain Stimulator Implantations

Background/Aims: Intraoperative magnetic resonance imaging (iMRI) is increasingly used to implant deep brain stimulator (DBS) electrodes. The approach has the advantages of a high targeting accuracy, minimization of brain penetrations, and allowance of implantation under general anesthesia. The hemorrhagic complications of iMRI-guided DBS implantation have not been studied in a large series. We report on the incidence and characteristics of hemorrhage during these procedures. Methods: Hemorrhage incidence was assessed in a series of 231 iMRI procedures (374 electrodes implanted). All patients had movement disorders and the subthalamic nucleus or the globus pallidus internus was typically targeted. Hemorrhage was detected with intra- or postoperative MRI or postoperative computed tomography. Hemorrhage was classified based on its point of origin and clinical impact. Results: Hemorrhage and symptomatic hemorrhage were detected during 2.4 and 1.1% of electrode implantations, respectively. The hemorrhage origin was subdural/subarachnoid (n = 3), subcortical (n = 5), or deep (n = 1). Factors that contributed to hemorrhage included unintentional crossing of a sulcus and resistance at the pial membrane, which produced cortical depression and a rebound hemorrhage. Delayed hemorrhage occurred in 2 patients and was attributed to premature reintroduction of anticoagulation therapy or air intrusion into the cranial cavity. Conclusions: Hemorrhage was readily apparent on intraoperative imaging, and hemorrhage rates for iMRI-guided DBS implantations were comparable to those for conventional implantation approaches.

Robotic System for MRI-guided Focal Laser Ablation in the Prostate.

MRI-conditional robotic platforms have proved to be an effective approach for image guided interventions. In this study, a computer-assisted, pneumatically-actuated robot was designed, built, and tested for MRI-guided prostate cancer focal laser ablation (FLA). The robotic manipulator provides two active planar degrees of freedom (DoFs) by using a customized CoreXY frame, and one passive rotational DoF. A remote insertion mechanism improves the surgical workflow by keeping the patients inside the scanner during needle insertion. The robotic manipulator was tested in a 3T MR scanner to evaluate its MR compliance, and the results demonstrated that the signal-to-noise ratio (SNR) variation was less than 8%. The in-scanner template positioning accuracy test demonstrated that the manipulator achieves high targeting accuracy with a mean error of 0.46 mm and a standard deviation of 0.25mm. Phantom studies have shown that the needle insertion accuracy of the manipulator is within 2mm (Mean = 1.7mm, StD = 0.2mm).

Three-Dimensional Needle Steering Using Automated Breast Volume Scanner (ABVS)

Robot-assisted and ultrasound-guided needle insertion systems assist in achieving high targeting accuracy for different applications. In this paper, we introduce the use of Automated Breast Volume Scanner (ABVS) for scanning different soft tissue phantoms. The ABVS is a commercial ultrasound transducer used for clinical breast scanning. A preoperative scan is performed for three-dimensional (3D) target localization and shape reconstruction. The ultrasound transducer is also adapted to be used for tracking the needle tip during steering toward the localized targets. The system uses the tracked needle tip position as a feedback to the needle control algorithm. The bevel-tipped flexible needle is steered under ABVS guidance toward a target while avoiding an obstacle embedded in soft tissue phantom. We present experimental results for 3D reconstruction of different convex and non-convex objects with different sizes. Mean Absolute Distance (MAD) and Dice’s coefficient methods are used to evaluate the 3D shape reconstruction algorithm. The results show that the mean MAD values are 0.30[Formula: see text][Formula: see text]0.13[Formula: see text]mm and 0.34[Formula: see text][Formula: see text]0.17[Formula: see text]mm for convex and non-convex shapes, respectively, while mean Dice values are 0.87[Formula: see text]0.06 (convex) and 0.85[Formula: see text]0.06 (non-convex). Three experimental cases are performed to validate the steering system. Mean targeting errors of 0.54[Formula: see text][Formula: see text]0.24, 1.50[Formula: see text][Formula: see text]0.82 and 1.82[Formula: see text][Formula: see text]0.40[Formula: see text]mm are obtained for steering in gelatin phantom, biological tissue and a human breast phantom, respectively. The achieved targeting errors suggest that our approach is sufficient for targeting lesions of 3[Formula: see text]mm radius that can be detected using clinical ultrasound imaging systems.

Online virtual isocenter based radiation field targeting for high performance small animal microirradiation

Advances in precision microirradiators for small animal radiation oncology studies have provided the framework for novel translational radiobiological studies. Such systems target radiation fields at the scale required for small animal investigations, typically through a combination of on-board computed tomography image guidance and fixed, interchangeable collimators. Robust targeting accuracy of these radiation fields remains challenging, particularly at the millimetre scale field sizes achievable by the majority of microirradiators. Consistent and reproducible targeting accuracy is further hindered as collimators are removed and inserted during a typical experimental workflow. This investigation quantified this targeting uncertainty and developed an online method based on a virtual treatment isocenter to actively ensure high performance targeting accuracy for all radiation field sizes. The results indicated that the two-dimensional field placement uncertainty was as high as 1.16 mm at isocenter, with simulations suggesting this error could be reduced to 0.20 mm using the online correction method. End-to-end targeting analysis of a ball bearing target on radiochromic film sections showed an improved targeting accuracy with the three-dimensional vector targeting error across six different collimators reduced from mm (mean ± SD) to mm for an isotropic imaging voxel size of 0.1 mm.

Targeting Accuracy, Procedure Times and User Experience of 240 Experimental MRI Biopsies Guided by a Clinical Add-On Navigation System.

ObjectivesMRI is of great clinical utility for the guidance of special diagnostic and therapeutic interventions. The majority of such procedures are performed iteratively ("in-and-out") in standard, closed-bore MRI systems with control imaging inside the bore and needle adjustments outside the bore. The fundamental limitations of such an approach have led to the development of various assistance techniques, from simple guidance tools to advanced navigation systems. The purpose of this work was to thoroughly assess the targeting accuracy, workflow and usability of a clinical add-on navigation solution on 240 simulated biopsies by different medical operators.MethodsNavigation relied on a virtual 3D MRI scene with real-time overlay of the optically tracked biopsy needle. Smart reference markers on a freely adjustable arm ensured proper registration. Twenty-four operators – attending (AR) and resident radiologists (RR) as well as medical students (MS) – performed well-controlled biopsies of 10 embedded model targets (mean diameter: 8.5 mm, insertion depths: 17-76 mm). Targeting accuracy, procedure times and 13 Likert scores on system performance were determined (strong agreement: 5.0).ResultsDifferences in diagnostic success rates (AR: 93%, RR: 88%, MS: 81%) were not significant. In contrast, between-group differences in biopsy times (AR: 4:15, RR: 4:40, MS: 5:06 min:sec) differed significantly (p<0.01). Mean overall rating was 4.2. The average operator would use the system again (4.8) and stated that the outcome justifies the extra effort (4.4). Lowest agreement was reported for the robustness against external perturbations (2.8).ConclusionsThe described combination of optical tracking technology with an automatic MRI registration appears to be sufficiently accurate for instrument guidance in a standard (closed-bore) MRI environment. High targeting accuracy and usability was demonstrated on a relatively large number of procedures and operators. Between groups with different expertise there were significant differences in experimental procedure times but not in the number of successful biopsies.

New horizons for minimally invasive treatment of acromioklavikular joint injuries

A novel radiation-free electromagnetic navigation system (ENS) method was developed and the feasibility and accuracy for transklavikular-transkorakoid drilling procedures were evaluated in an experimental setting. In this study ten arthroscopically assisted, electromagnetically navigated transkorakoid-transklavikular drilling procedures with subsequent implantation of two TightRope® (Arthrex, Naples, FL.) devices (anatomical reconstruction) were performed on five human cadavers. Postoperative computed tomography (CT) scan analysis was carried out to determine tunnel placement accuracy. All procedures were performed without fluoroscopy. The mean overall operation time was 28.5 ± 6.6min. Successful anatomical tunnel placement was achieved in 98.8 %. During the navigated drilling procedure no misguidance of the drill requiring directional readjustments or restarts occurred. No cortical breaches, fractures or complications occurred. The electromagnetically navigated transkorakoid-transklavikular drilling procedure used in this study demonstrated high targeting accuracy, required no intraoperative x-ray radiation and was associated with no complications.

Development of optimal and robust predictive guidance technique for Mars aerocapture

The paper discusses a predictive guidance technique for the optimal aerocapture maneuver accomplished by a high-mass Mars orbiter to achieve the targeted circular parking orbit with minimal fuel consumption. Unlike the majority of investigated algorithms of the “predictor–corrector” family with a time-invariant control, the guidance algorithm considered in the paper computes a time-dependent control function which, being a reference profile of the angle of attack, provides a minimum to the post-aerocapture propulsive ΔV at the apoapsis of a transfer ellipse. Initially, the two-parametric bounded linear control function has been used, and the algorithm developed found an optimal solution directly by “descending” in a control parameters space. The simulation has shown that an optimum is achieved when the slope of the linear function tends to infinity, i.e., the bounded linear control is being transformed into a one-parametric step function. Such a result proved to be in conformity with the earlier “indirect” optimal solution, namely, derived from Pontryaginʼs maximum principle for a slightly simplified motion model. Thus, the final version of algorithm providing “direct” optimization by solving a nonlinear eigenvalue problem needs to determine only one parameter – switching time of angle of attack. The solution obtained satisfies the terminal condition – a target apoapsis, as well as it is close to optimum. Another issue the paper focuses on is an improvement of robustness of the algorithm under unpredictable model disturbances, especially variations of atmospheric density. The new model adaptation algorithm is developed, which estimates density errors and updates the density profile during the descent phase to be used for control corrections in the ascent phase. Testing the example simulation model with angular motion has shown the runtime effectiveness and high targeting accuracy provided by the proposed predictive technique.

Electromagnetic navigation provides high accuracy for transcoracoid-transclavicular drilling

A novel radiation-free electromagnetic navigation system (ENS)-based method was developed, and its feasibility and accuracy for transclavicular-transcoracoid drilling procedures were evaluated in an experimental setting. Sixteen arthroscopically assisted electromagnetic navigated transcoracoid-transclavicular drilling procedures with subsequent TightRope device implantation were performed on eight human cadavers. Post-operative fluoroscopy and CT-scan analysis were acquired to determine tunnel placement accuracy. Optimal tunnel placement was defined as both the coracoid entry and exit point of the tunnel localized in the centre position of the coracoid base without cortical breach or fracture. Successful tunnel placement was accomplished in all 16 cases. The mean overall operation time was 30.3 ± 5.0 min. Regarding the coracoid exit point, 15 of 16 tunnels (93.8%) were localized in the desired base-centre position. During the navigated drilling procedure, no misguidance of the drill requiring directional readjustments or restarts occurred. No cortical breach, no fractures and no complications occurred. The electromagnetically navigated transcoracoid-transclavicular drilling procedure used in this study demonstrated high targeting accuracy, required no intraoperative radiographs, was associated with no complications and provided user-friendliness.

Emission guided radiation therapy for lung and prostate cancers: a feasibility study on a digital patient.

Accurate tumor tracking remains a challenge in current radiation therapy. Many strategies including image guided radiation therapy alleviate the problem to certain extents. The authors propose a new modality called emission guided radiation therapy (EGRT) to accurately and directly track the tumor based on its biological signature. This work is to demonstrate the feasibility of EGRT under two clinical scenarios using a 4D digital patient model. EGRT uses lines of response (LOR's) from positron emission events to direct beamlets of therapeutic radiation through the emission sites inside a tumor. This is accomplished by a radiation delivery system consisting of a Linac and positron emission tomography (PET) detectors on a fast rotating closed-ring gantry. During the treatment of radiotracer-administrated cancer patients, PET detectors collect LOR's from tumor uptake sites and the Linac responds in nearly real-time with beamlets of radiation along the same LOR paths. Moving tumors are therefore treated with a high targeting accuracy. Based on the EGRT concept, the authors design a treatment method with additional modulation algorithms including attenuation correction and an integrated boost scheme. Performance is evaluated using simulations of a lung tumor case with 3D motion and a prostate tumor case with setup errors. The emission process is simulated by Geant4 Application for Tomographic Emission package (GATE) and Linac dose delivery is simulated using a voxel-based Monte Carlo algorithm (VMC++). In the lung case with attenuation correction, compared to a conventional helical treatment, EGRT achieves a 41% relative increase in dose to 95% of the gross tumor volume (GTV) and a 55% increase to 50% of the GTV. All dose distributions are normalized for the same dose to the lung. In the prostate case with the integrated boost and no setup error, EGRT yields a 19% and 55% relative dose increase to 95% and 50% of the GTV, respectively, when all methods are normalized for the same dose to the rectum. In the prostate case with integrated boost where setup error is present, EGRT contributes a 21% and 52% relative dose increase to 95% and 50% of the GTV, respectively. As a new radiation therapy modality with inherent tumor tracking, EGRT has the potential to substantially improve targeting in radiation therapy in the presence of intrafractional and interfractional motion.