X-ray Navigation Research Articles

Clinical application of neodymium magnetic instruments for the removal of foreign bodies in blind wounds

A feature of modern military conflicts is the high frequency of shrapnel wounds. The search for foreign bodies, even under X-ray navigation, can be technically difficult, lengthy and not always successful. Most injuring objects have ferromagnetic properties.
 AIM: The Military Medical Academy, Saint Petersburg purpose of the study: to evaluate the effectiveness of removing ferromagnetic foreign bodies from blind wounds using neodymium magnetic instruments.
 MATERIALS AND METHODS: Instruments based on a neodymium magnet for removing foreign bodies and a technique for their use have been developed. An analysis was made of 45 operations where traditional instruments were used and 75 operations using original magnetic instruments. Of these, in 40 cases of blind wounds, foreign bodies were removed from the soft tissues of various areas, and in 35 cases, foreign bodies were removed during videothoracoscopy operations for blind penetrating chest wounds. The criteria for evaluating the effectiveness of the method were the duration of the operation, the duration of work with the X-ray unit and the number of detected and removed foreign bodies in a fixed period of time.
 CONCLUSION: High efficiency, simplicity, accessibility, minimally invasiveness of the developed instruments have been proven. Neodymium magnets made it possible to reduce the time of radiation exposure and the duration of the operation, to increase the efficiency of removing ferromagnetic foreign bodies. The use of original instruments makes it possible to detect 80% of foreign bodies in 10 minutes, and within 30 minutes to remove 90% of foreign bodies from the soft tissues of the wounded. With videothoracoscopy, the time of fluoroscopy was halved, and the total duration of the surgical intervention was reduced by 40%.

HEX: a safe research framework for hybrid EMT X-ray navigation

PurposeNavigating with continuous X-ray provides visual guidance, but exposes both surgeon and patient to ionizing radiation, which is associated with serious health risks. Interleaving fluoro snapshots with electromagnetic tracking (EMT) potentially minimizes radiation.MethodsWe propose hybrid EMT + X-ray (HEX), a research framework for navigation with an emphasis on safe experimentation. HEX is based on several hardware and software components that are orchestrated to allow for safe and efficient data acquisition.ResultsIn our study, hybrid navigation reduces radiation by 71% with cubic, and by 40% with linear error compensation while achieving submillimeter accuracy. Training points for compensation can be reduced by half while keeping a similar accuracy–radiation trade-off.ConclusionThe HEX framework allows to safely and efficiently evaluate the hybrid navigation approach in simulated procedures. Complementing intraoperative X-ray with EMT significantly reduces radiation in the OR, increasing the safety of patients and surgeons.

Сomparative effectiveness of various methods of epidural administration of glucocorticosteroids in treating root pain syndromes

This review aimed to compare the effectiveness of different methods of epidural glucocorticosteroid (GCS) use in the treatment of root syndrome pain according to literature over the past 20 years. A literary search was conducted in the databases of PubMed, MEDLINE, EMBASE, Cochrane Library, and Google Scholar, as well as a manual search of bibliographies of famous primary and review articles and abstracts of scientific meetings between 2000 and 2020. During the search, 637 studies were identified, of which 615 were excluded, as they did not correspond to the topic of the article. The remaining 22 studies were included in this review.
 Scientific papers describe three ways to deliver glucocorticosteroids, namely, epiduralinterlaminar injection, transforaminal injection, sacralepidural injection.
 For sciatica, 5 out of 8 comparative randomized controlled trials found the transforaminal route of administration to be superior to the sacroepidural or interlaminar route of administration. In a number of studies, the sacroepidural route of administration was comparable in efficiency with transfor-real with low herniated discs.
 In cases of cervicobrachialgia, the transforaminal route of administration is recognized by most authors as unsafe, with risks of accidental intravascular injection. In this regard, at the cervical level, interlaminar access is considered preferable. In addition, the differences between the epidural use of water-soluble and dispersed (not approved for use in the Russian Federation) glucocorticosteroids are described.
 The review describes the techniques of various approaches to the epidural space with their advantages and disadvantages.
 Different methods require different material equipment of clinics. Sacral access, with relatively high efficiency, allows for blind use, in contrast to transforaminal access at the lumbar level and interlaminar access at the cervical level, which require X-ray navigation.

Comparison of Deep Space Navigation Using Optical Imaging, Pulsar Time-of-Arrival Tracking, and/or Radiometric Tracking

Recent advances with space navigation technologies developed by NASA in space-based atomic clocks and pulsar X-ray navigation, combined with past successes in autonomous navigation using optical imaging, brings to the forefront the need to compare space navigation using optical, radiometric, and pulsar-based measurements using a common set of assumptions and techniques. This review article examines these navigation data types in two different ways. First, a simplified deep space orbit determination problem is posed that captures key features of the dynamics and geometry, and then each data type is characterized for its ability to solve for the orbit. The data types are compared and contrasted using a semi-analytical approach with geometric dilution of precision techniques. The results provide useful parametric insights into the strengths of each data type. In the second part of the paper, a high-fidelity, Monte Carlo simulation of a Mars cruise, approach, and entry navigation problem is studied. The results found complement the semi-analytic results in the first part, and illustrate specific issues such as each data type’s quantitative impact on solution accuracy and their ability to support autonomous delivery to a planet.

Super-selective prostatic arteries embolization in patients with benign prostate hyperplasia: prevention and treatment of complications

Introduction. Super-selective prostatic arteries embolization (PAE) is a modern minimally invasive surgical method for the treatment of benign prostatic hyperplasia (BPH). PAE is included in the Russian clinical guidelines for the BPH treatment and approved for use in the United States and European countries.Purpose of the study. To analyze the most common PAE-associated complications and to develop preventive arrangements.Materials and methods. During the period from 2013 to 2020, PAE as the main method of BPH treatment was used in 168 patients with an average age of 69.3 ± 8.1 (53-82) years. All patients underwent two-day antibiotic prophylaxis before the operation and lasted 7-10 days. For catheterization of the prostatic arteries, 2.0-2.8 Fr microcatheters and 4-5 Fr microconductors were used. For embolization, hydrogel microspheres with a diameter of 100-300 µm and 300-500 µm were used, as well as poly polyvinyl alcohol (PVA) microparticles with a diameter of 100-500 µm.Results. Bilateral PAE was successfully performed in 146 cases; unilateral PAE was performed in 22 patients due to anatomical features. Seventeen (10.1%) PAE from the orifice, super-selective PAE was performed in 67 (39.9%) cases, the PErFecTED embolization was performed in 84 (50.0%) patients. The most common complication was acute urinary retention (AUR) in 28 (16.6%) patients: trocar cystostomy was required in 11 (6.5%) patients, AUR was resolved using conservative therapy in 17 (10.2%) patients. In 23 (14.2%) cases, complications associated with unintentional embolization of the anastomoses of the prostate arteries were identified: rectal pain and/or the appearance of blood in the stool in 19 (11.3%) patients, the appearance of trophic ulcers on the glans penis in 5 (2.8%) patients. In addition, several adverse events that were not complications were noted: postembolization syndrome in 50 (29.7%) patients, and worsening of LUTS in 41 (24.4%) patients. Seven (4.1%) patients had acute epididymitis; 4 (2.4%) patients had a hematoma at the puncture site.Conclusion. PAE can cause a limited number of complications. It is necessary to unify the system for reporting PAE complications. Antibiotic prophylaxis is recommended. The use of visualization and X-ray navigation methods make it possible to make the PAE safer. The PErFecTED technique in combination with small particle sizes increases the risk of complications. The surgeon's experience and proficiency in special surgical techniques are essential. The transradial approach is promising, but further observation and an increase in patient samples are required. The question of choosing the optimal embolization drug continues to be relevant.

Применение ультразвуковой визуализации при минимально инвазивной перкутанной нефролитотрипсии. Нужно ли полностью отказаться от рентгеноскопии?

AIM To determine the possibility of performing minimally invasive percutaneous nephrolithotomy (PCNL) under ultrasound guidance with the use of X-ray during the access tract formation. MATERIALS AND METHODS The results of 102 mini-PNL procedures, performed by a single surgeon during the period 2018-2019, were analyzed retrospectively. In the beginning, ureteral catheter Ch5 was put into an ipsilateral ureter. Further, a puncture of the collecting system was performed with an advancement of the guidewire. At the next stage, a dilation of tract was done using X-ray guidance for the safe formation of the working channel, followed by holmium lithotripsy. At the end a nephrostomy or JJ-stent was left. RESULTS The mean age of the patients was 53.13+/-12.9, while average BMI was 29.3+/-6.5. In total, there were 44.1% of women. The average stone size was 20.7+/-10.9 mm; 45.1% of stones were left-sided. Staghorn stones accounted for 15.7% of cases and hydronephrosis was found in 18.6% of patients. The time for creating renal access, dilation of the nephrostomy tract, total operative time and fluoroscopy time were: 19.6+/-13.1, 7.7+/-4.2, 107.7+/-49.9, 57.1+/-41.2 minutes, respectively. In the Group I there were 32 (31.4%) patients undergoing to PCNL under X-ray guidance, while in Group II (n=70, 68.6%) combined US+/-X-ray control was used. The patients age (52.2+/-12.6 vs 53.6+/-13.2, p<0.05) and the stone size (20.6+/-8.9 vs 20.7+/-10.4, p=0.30) were comparable in both groups. There were slightly shorter access time and the total operative time in group II compared with group I (20.6+/-12.3 vs 19.2+/-13.5, p=0.27; 108.1+/-43.3 vs 106.9+/-53.2, p=0.25 respectively). In total, hematocrit level decreased by 4.5% and blood transfusions was done in 3 patients. Postoperative complications developed in 9 cases in both groups (according to the Clavien-Dindo classification, all complications were grade I-II). The stone-free rate (SFR) was 87.2%, and a second-stage was required in 2 cases. DISCUSSION The use of ultrasound guidance improves visualization of the collecting system and contributes to the creation of an optimal renal access. It significantly reduces the radiation exposure to the patient and the operating team. We were able to puncture the collecting system in all cases. SFR after PCNL under ultrasound guidance was 88.6%, which is comparable to the results of conventional PCNL with X-ray navigation. CONCLUSION PCNL can be performed effectively and safely under ultrasound guidance, which reduces the number of renal punctures and lowers the complication rate. However, this technique also has disadvantages, including longer puncture time in morbidly obese patients without hydronephrosis. With growing experience, the number of unsuccessful kidney punctures decreases, as well as operative time. The use of fluoroscopy during dilatation of the nephrostomy tract allows for preventing additional injuries of the collecting system.

3D-XGuide: open-source X-ray navigation guidance system

PurposeWith the growing availability and variety of imaging modalities, new methods of intraoperative support have become available for all kinds of interventions. The basic principles of image fusion and image guidance have been widely adopted and are commercialized through a number of platforms. Although multimodal systems have been found to be useful for guiding interventional procedures, they all have their limitations. The integration of more advanced guidance techniques into the product functionality is, however, not easy due to the proprietary solutions of the vendors. Therefore, the purpose of this work is to introduce a software system for image fusion, real-time navigation, and working points documentation during transcatheter interventions performed under X-ray (XR) guidance.MethodsAn interactive software system for cross-modal registration and image fusion of XR fluoroscopy with CT or MRI-derived anatomic 3D models is implemented using Qt application framework and VTK visualization pipeline. DICOM data can be imported in retrospective mode. Live XR data input is realized by a video capture card application interface.ResultsThe actual software release offers a graphical user interface with basic functionality including data import and handling, calculation of projection geometry and transformations between related coordinate systems, rigid 3D-3D registration, and template matching-based tracking and motion compensation algorithms in 2D and 3D. The link to the actual software release on GitHub including source code and executable is provided to support independent research and development in the field of intervention guidance.ConclusionThe introduced system provides a common foundation for the rapid prototyping of new approaches in the field of XR fluoroscopic guidance. As a pure software solution, the developed system is potentially vendor-independent and can be easily extended to be used with the XR systems of different manufacturers.

Sensor Configuration Trade Study for Navigation in Near Rectilinear Halo Orbits

Deep Space Gateway is a NASA program planned to support deep space human exploration and prove new technologies needed to achieve it. One Gateway requirement is the ability to operate in the absence of communications with the Deep Space Network (DSN) for a period of at least three weeks. In this paper, three types of onboard sensors (a camera for optical navigation, a GPS receiver, and X-ray navigation) are considered to enhance its autonomy and reduce the reliance on DSN. A trade study is conducted to explore alternatives on how to achieve autonomy and how to reduce DSN dependency while satisfying navigation performance requirements. Using linear covariance analysis, error budgets, and sensitivity analysis, the performance of navigation systems using combinations of DSN with the aforementioned onboard sensors is shown.

An X-ray frequency modulation method and its application in X-ray communication

X-ray communication (XCOM) is a novel space communication method with great potential. X-rays have much shorter wavelengths than both infrared and radio. In principle, XCOM can send more data for the same amount of transmission power, which could permit more efficient gigabits-per-second data rates for deep space missions. Besides, X-rays can pierce the hot plasma sheath that builds up as spacecraft hurdle through Earth’s atmosphere at hypersonic speeds. However, some current technical limitations have made X-ray communication unable to fully release its theoretical advantages in space communications. Among them, the modulation of X-ray emission impacts significantly. For the requirements of high-flux, collimation, quasi-monochromatic X-ray emissions, as well as the exploration of X-ray frequency modulation, we propose an X-ray frequency modulation method for generating different energy X-rays by controlling the electron beam deflection based on an external electrostatic field. Different from all traditional on-off control methods, this scheme uses two specific X-ray energies indicate the digital signal 0 and 1, which makes X-ray frequency modulation possible. Based on this, we simulated the emission flux and energy distribution of two different targets. Simulation results indicate that this X-ray modulation method produce X-rays with up to 50 GHz modulation frequency, 1014 cps X-ray emission flux, 99% monochrome, and 1.5 mrad divergence angle. Through this modulator, not only the communication distance and communication speed experience significant increases, but also the concept of X-ray communication, X-ray ranging and X-ray navigation can be realized as a three-in-one mission.

Surgical Stereo X-Ray Navigation

Hardware and software for surgical instrument navigation using stereo X-ray imaging were developed. The developed surgical stereo X-ray navigation system provides 3D imaging in the process of surgery or during diagnostic examination of deep-lying abnormal foci or structural abnormalities of organs and tissues. Application of the developed system makes it possible to reduce considerably the duration of surgery. The obtained 3D X-ray images are automatically processed to provide accurate real-time guidance of the medical instrument (i.e., adjustment of the penetration depth, position, and orientation of the instrument). The developed technique of stereo X-ray navigation can be used for purposes of upgrading medical X-ray equipment, such as C-arch (Arcoscope) surgical X-ray devices.

An Automatic Personalized Internal Fixation Plate Modeling Framework for Minimally Invasive Curved Bone Fracture Surgery Based on Preregistration With Capsule Projection Model

In this paper, a framework to visualize and model internal fixation plates is presented for computer-aided personalized and minimally invasive curved bone fracture surgery. We focus on personalized reverse reconstruction of the bone fracture plate based on three-dimensional (3-D) mesh models obtained from a 3-D optical scanner. The steps of the method are as follows. First, principal component analysis and the K-means method are used to reconstruct a Bezier curve (ridge line) of broken bones. Second, based on the geometric shape of the curved broken bones, a capsule projection model of the broken bones is proposed to obtain the feature information of the broken bone sections. Third, the ordering points to identify the clustering structure (OPTICS) method is utilized for preregistration (rough registration). Fourth, a regional self-growth strategy is designed to extract the cross-section points. Fifth, the iterative closest point method is applied for the accurate registration of the fracture surface models. Finally, a personalized internal fixation plate model is reconstructed based on several user points. The internal fixation plate model can be reconstructed according to the patient's bone parameters. Clinicians can use this framework to obtain personalized and accurate internal fixation plate models that effectively represent the broken bones of patients. Via X-ray navigation, the personalized forged plate can be fixed on the target area through a small incision. This framework provides a reasonable and practicable technical approach for computer-aided minimally invasive curved bone fracture surgery.

Pose Estimation of Periacetabular Osteotomy Fragments With Intraoperative X-Ray Navigation.

State-of-the-art navigation systems for pelvic osteotomies use optical systems with external fiducials. In this paper, we propose the use of X-ray navigation for pose estimation of periacetabular fragments without fiducials. A two-dimensional/three-dimensional (2-D/3-D) registration pipeline was developed to recover fragment pose. This pipeline was tested through an extensive simulation study and six cadaveric surgeries. Using osteotomy boundaries in the fluoroscopic images, the preoperative plan was refined to more accurately match the intraoperative shape. In simulation, average fragment pose errors were 1.3 ° /1.7mm when the planned fragment matched the intraoperative fragment, 2.2 ° /2.1mm when the plan was not updated to match the true shape, and 1.9 ° /2.0mm when the fragment shape was intraoperatively estimated. In cadaver experiments, the average pose errors were 2.2 ° /2.2mm, 3.8 ° /2.5mm, and 3.5 ° /2.2mm when registering with the actual fragment shape, a preoperative plan, and an intraoperatively refined plan, respectively. Average errors of the lateral center edge angle were less than 2 ° for all fragment shapes in simulation and cadaver experiments. The proposed pipeline is capable of accurately reporting femoral head coverage within a range clinically identified for long-term joint survivability. Human interpretation of fragment pose is challenging and usually restricted to rotation about a single anatomical axis. The proposed pipeline provides an intraoperative estimate of rigid pose with respect to all anatomical axes, is compatible with minimally invasive incisions, and has no dependence on external fiducials.

Kalman Filter Analysis for Orbit Estimation using Pulsars for Interplanetary Missions

Abstract Autonomous Navigation in Interplanetary Missions is the main challenge due to lack of dense ground tracking network measurements. This paper presents a novel technique for determining spacecraft position and velocity using celestial X-ray sources, such as pulsars. It portrays the formulation of the pulsar measurements and describes the development of a noise model for X-ray Navigation and brings out the cumulative efforts in this developing field. In addition to that, it also covers the blending of the pulsar-derived measurements with a Kalman filter for continuous determination of position and velocity of an Earth orbiting spacecraft. Several sampling analysis are presented to establish the expected performance using measurements obtained from models of pulsed X-ray signals. This is the first step and future efforts shall make the orbit estimation more sophisticated.

Validation of Pulsar Phase Tracking for Spacecraft Navigation

Previous theoretical work has shown that pulsars have fascinating potential as aids for autonomous, deep space navigation. In this paper, phase tracking is investigated as a technique to measure the distance traveled by a spacecraft over an observation interval. Phase tracking was experimentally validated using photons emitted by a modulated x-ray source and detected by a silicon-drift detector using the NASA Goddard X-Ray Navigation Laboratory Testbed. Models of the Crab pulsar and PSR B1821-24 were used. Three simulated, one-dimensional trajectories were considered: one stationary, one with constant velocity, and one with constant acceleration. For constant signal frequency, a maximum-likelihood phase estimator was used. Otherwise, the observation window was broken into smaller blocks over which maximum-likelihood phase estimates were looped through a digital phase-locked loop to reduce errors and estimate the Doppler frequency. The maximum-likelihood phase estimator tracked the initial phase within 0.15% for the simulations and 2.5% in the experiments. The maximum-likelihood phase estimator–digital phase-locked loop cascade tracked the phase and frequency in both the simulations and experiments. The phase error and Doppler frequency error tended toward zero in under 250 and 100 s, respectively, with the Crab pulsar.

Morphologic study of foramen oval region on surgery approach for trigeminal neuralgia.

Trigeminal neuralgia is a complex refractory neurologic disease. The foramen ovale puncture performs an important role in nerve anesthesia, balloon compression, focal gamma radiation, microvascular decompression, and radiofrequency nerve rhizotomy when the drug does not work. In this study, we provide some information about foramen oval region. Measuring the point at the distance of 2 cm beneath the zygomaxillare, which is close to the percutaneous insertion point and the center of foramen ovale and foramen spinosum separately, hoping to provide relatively accurate data for clinical treatment and avoiding some side injury of the puncture with computed tomography or x-ray navigation.

The accuracy analysis of the spacecraft autonomous navigation system based on X-ray pulsars

An autonomous and secure navigation system is needed for the spacecraft in future deep space missions. X-ray pulsar offers the possibility of autonomous navigation anywhere in the solar system. This article introduces an analysis of the spacecraft autonomous navigation system accuracy, utilizing signals emitted from the X-ray pulsars. Based on the principle of the X-ray navigation, visibility of X-ray pulsar on L1 sun-observation orbit was simulated. The influence of the geometry distribution and the pulsar angle position error was analyzed. Error sources of the navigation system were listed, including the measurement error of the X-ray detector, transformation error of time-of-arrival (TOA), and the navigation calculation error, and the simulations of their parts were shown.

Respiratory motion compensation by model-based catheter tracking during EP procedures

In many cases, radio-frequency catheter ablation of the pulmonary veins attached to the left atrium still involves fluoroscopic image guidance. Two-dimensional X-ray navigation may also take advantage of overlay images derived from static pre-operative 3D volumetric data to add anatomical details otherwise not visible under X-ray. Unfortunately, respiratory motion may impair the utility of static overlay images for catheter navigation. We developed a novel approach for image-based 3D motion estimation and compensation as a solution to this problem. It is based on 3D catheter tracking which, in turn, relies on 2D/3D registration. To this end, a bi-plane C-arm system is used to take X-ray images of a special circumferential mapping catheter from two directions. In the first step of the method, a 3D model of the device is reconstructed. Three-dimensional respiratory motion at the site of ablation is then estimated by tracking the reconstructed catheter model in 3D based on bi-plane fluoroscopy. Phantom data and clinical data were used to assess model-based catheter tracking. Our phantom experiments yielded an average 2D tracking error of 1.4mm and an average 3D tracking error of 1.1mm. Our evaluation of clinical data sets comprised 469 bi-plane fluoroscopy frames (938 monoplane fluoroscopy frames). We observed an average 2D tracking error of 1.0 + or - 0.4mm and an average 3D tracking error of 0.8 + or - 0.5mm. These results demonstrate that model-based motion-compensation based on 2D/3D registration is both feasible and accurate.

Silicon Carbide Power Diodes as Radiation Detectors

We have tested the radiation detection performance of Silicon Carbide (SiC) PIN diodes originally developed as high power diodes. These devices consist of 100 micron thick SiC grown epitaxially on SiC substrates. The size and thickness of the devices make them appropriate for a number of radiation detection applications. We tested 0.25 cm2 and 0.5 cm2 devices and obtained X-ray spectra under illumination with an Am-241 radioactive source. The spectra showed an energy resolution that was consistent with the resolution expected for the large capacitance of the device. Smaller devices with a diameter of 1 mm were also tested and produced spectra with a room temperature energy resolution of ~550 eV, which is consistent with the electronics limit for the capacitance of the small device. We measured the absolute charge generated by X-rays per KeV in SiC by comparing the charge generation with similar silicon devices and determined the energy required per electron hole pair in SiC to be 8.4 eV. We also performed radiation damage tests on these devices and found no significant loss in charge collection up to a photon dose of 100 MRad. Applications for these devices can be found in the fields of particle physics, nuclear physics, nuclear medicine, X-ray fluorescence, X-ray astronomy and X-ray navigation.

Three-Dimensional Rotational X-Ray Navigation for Needle Guidance in Percutaneous Vertebroplasty: An Accuracy Study

The position of a needle tip displayed on a navigation system after transpedicular introduction into a vertebral body is compared with the real position of the needle tip when using a direct navigation coupling between a three-dimensional rotational X-ray (3DRX) system and a navigation system. To assess whether the needle tip position displayed by the navigation system corresponds to the real needle position and to quantitatively determine needle navigation accuracy in a clinically relevant setting. Image-guided navigation has reportedly increased the accuracy and safety of pedicle screw insertion and decreased complication rates. In former studies, the result of image-guided navigation was mainly compared qualitatively with the result of conventional fluoroscopy-guided procedures. Previously, a direct navigation coupling between a 3DRX system and a standard navigation system was introduced that bypasses the need for explicit patient-to-image registration necessary for image-guided orthopedic surgery. In a phantom experiment, the reported accuracy of navigation with the coupling to a 3DRX system was approximately 1 mm. However, in a clinical setting, additional errors can be introduced. Twenty-three needles were placed transpedicularly into vertebral bodies of embalmed human trunks using 3DRX-guided navigation. The navigated needle tip positions were compared with the real needle tip positions manually extracted from 3DRX volumes acquired after completion of the introduction. The average distance between the navigated needle tip and the real position of the needle tip extracted from a postprocedure 3DRX volume was 2.5 +/- 1.5 mm. Accuracy of 3DRX-guided navigation is 2.5 +/- 1.5 mm in a clinically relevant setting, which is less than the accuracy determined in phantom experiments.

Robotic System Based on X-Ray Navigation for Assistance in Orthopaedic Surgery

The treatment of femoral shaft fractures typically involves the surgical insertion of a metallic fixation device (intramedullary nail) into the marrow cavity of the femur. Depending upon the severity of the fracture, interlocking screws may then be inserted through the lower (distal) end of the nail/femur. Unfortunately, the pilot holes for these distal interlocking screws can only be drilled under fluoroscopic guidance. As a consequence, distal interlocking is a technically demanding process, which inevitably leads to irradiation of the surgeon. A custom-built robotic-assisted surgery system has therefore been developed with a view to providing a “remote” surgical drilling capability. This paper describes the digital X-ray photogrammetry based registration and trajectory planning techniques employed by the robotic system.