Accurate Needle Placement Research Articles

Preliminary Study of a Modular MR-Compatible Robot for Image-Guided Insertion of Multiple Needles.

Percutaneous needle-based interventions such as transperineal prostate brachytherapy require the accurate placement of multiple needles to treat cancerous lesions within the target organ. To guide needle placement, magnetic resonance imaging (MRI) offers excellent visualization of the target lesion without the need for ionizing radiation. To date, multi-needle insertion relies on a grid template, which limits the ability to steer individual needles. This work describes an MR-compatible robot designed for the sequential insertion of multiple non-parallel needles under MR guidance. The 6-DOF system is designed with an articulated arm to extend the reach of the robot. This strategy presents a novel approach enabling the robot to maneuver around existing needles while minimizing the footprint of the robot. Forward kinematics as well as optimization-based inverse kinematics are presented. The impact of the robot on image quality was tested for four sequences (T1w-TSE, T2w-TSE, THRIVE and EPI) on a 3T Philips Achieva system. Quantification of the signal-to-noise ratio showed a 46% signal loss in a gelatin phantom when the system was powered on but no further adverse effects when the robot was moving. Joint level testing showed a maximum error of 2.10 ± 0.72°s for revolute joints and 0.31 ± 0.60 mm for prismatic joints. The theoretical workspace spans the proposed clinical target surface of 10 x 10 cm. Lastly, the feasibility of multi-needle insertion was demonstrated with four needles inserted under real-time MR-guidance with no visible loss in image quality.

Starting CT-guided robotic interventional oncology at a UK centre.

A commercially available CT-guided robot offers enhanced abilities in planning, targeting, and confirming accurate needle placement. In this short communication, we describe our first UK experience of robotic interventional oncology procedures. We describe the device, discuss installation, operation, and report upon needle insertion success, accuracy (path deviation; PD and tip deviation; TD), number of adjustments, complications, and procedural success. Nine patients (seven males), median age 66 years (range 43-79) were consented for biopsy or ablation between March and April 2021. Needle placement in biopsy was more accurate than ablation (median 1 vs 11 mm PD and 1 vs 20 mm TD) and required fewer adjustments (median 0 vs 5). No complications arose, and all procedures were successful (diagnostic material obtained or complete ablation at follow-up). Short procedure times and very high levels of accuracy were readily achieved with biopsy procedures, although tumour ablation was less accurate which likely reflects higher procedural complexity. Achieving highly accurate robotic biopsy with is feasible within a very short time span. Further work is required to maximise the potential of robotic guidance in tumour ablation procedures, which is likely due to higher complexity giving a longer learning curve.

Ultrasound-guided interventions in rheumatology.

Over the last few years, percutaneous procedures have undergone great advances, thanks to the ultrasound (US) guidance, due to the technical improvements in the US field, combined with the greater availability, good portability, and reduced cost of US devices. The direct target visualization and the real-time imaging performance enabled by US-guidance account for an improved accuracy in needle placement in several rheumatology interventions. So, ultrasound-guided procedures contribute to several diagnostic or therapeutic procedures such as fluid aspiration or treatment instillations of common joints, tendons, and bursas. In clinical practice, this fact is especially important in the case of depth areas like the hip, small anatomical structures as tendon sheaths or nerves in tenosynovitis or nervous blocks, or complex anatomical structures like the spine's facet joints. The US-guide is an essential tool for performing diagnostic procedures as synovial biopsy. US can also be combined with other imaging techniques, like the establishment portal arthroscopy for instance. Compared to older blind procedures, US-guided injections are more accurate and safer, and they result in better clinical outcomes in terms of joints improvement in function and decreased risk of damages caused by needle misplacement. With the ultrasound guided treatment, we can avoid the instillation of therapeutic products outside the predetermined target, which may be sometimes potentially harmful. The aim of this article is to describe the main generalities of ultrasound-guided procedures in rheumatology, their main advantages and disadvantages, and their particularities in joints where they are most frequently used, such as the shoulder, hip, and knee.

Robotic assistance for percutaneous needle insertion in the kidney: preclinical proof on a swine animal model

BackgroundWe evaluated the accuracy, safety, and feasibility of a computed tomography (CT)-guided robotic assistance system for percutaneous needle placement in the kidney.MethodsFiducials surgically implanted into the kidneys of two pigs were used as targets for subsequent robotically-assisted needle insertion. Robotically-assisted needle insertions and CT acquisitions were coordinated using respiratory monitoring. An initial scan volume data set was used for needle insertion planning defining skin entry and target point. Then, needle insertion was performed according to robot positioning. The accuracy of needle placement was evaluated upon the distance between the needle tip and the predefined target on a post needle insertion scan. A delayed contrast-enhanced CT scan was acquired to assess safety.ResultsEight needle trajectories were performed with a median procedural time measured from turning on the robotic system to post needle insertion CT scan of 21 min (interquartile range 15.5−26.5 min). Blind review of needle placement accuracy was 2.3 ± 1.2 mm (mean ± standard deviation) in lateral deviation, 0.7 ± 1.7 mm in depth deviation, and 2.8 ± 1.3 mm in three-dimensional Euclidian deviation. All needles were inserted on the first attempt, which determined 100% feasibility, without needle readjustment. The angulation and length of the trajectory did not impact on the needle placement accuracy. Two minor procedure-related complications were encountered: 2 subcapsular haematomas (13 × 6 mm and 35 × 6 mm) in the same animal.ConclusionsRobotically-assisted needle insertion was shown feasible, safe and accurate in a swine kidney model. Further larger studies are needed.

Review of Sacroiliac Joint Injection Techniques.

The purpose of the review is to evaluate the current evidence on techniques for sacroiliac joint (SIJ) injections using landmark, ultrasound, fluoroscopy, and computed tomography (CT) guidance. A literature search was performed to find all relevant retrospective, prospective, and randomized controlled (RCT) studies where SIJ injections were performed under ultrasound, fluoroscopy, and CT guidance. A total of eight studies were identified with suitable data for inclusion. There were two RCTs, four prospective, and two retrospective studies included. Case reports or case series were excluded. A total of 420 patients were enrolled across all eight studies. CT guidance provided the most accurate needle placement in the SIJ injections followed by fluoroscopy, which was more accurate than ultrasound. Landmark-guided injections were not accurate. Accurate needle placement in SIJ confirms SIJ-mediated pain and injection of corticosteroids leads to improvement in pain and/or disability outcome measures regardless of guidance technique. Diagnostic CT-guided SIJ injections should be performed prior to consideration of SIJ fusion.

Robotic Tissue Sampling for Safe Post-Mortem Biopsy in Infectious Corpses.

In pathology and legal medicine, the histopathological and microbiological analysis of tissue samples from infected deceased is a valuable information for developing treatment strategies during a pandemic such as COVID-19. However, a conventional autopsy carries the risk of disease transmission and may be rejected by relatives. We propose minimally invasive biopsy with robot assistance under CT guidance to minimize the risk of disease transmission during tissue sampling and to improve accuracy. A flexible robotic system for biopsy sampling is presented, which is applied to human corpses placed inside protective body bags. An automatic planning and decision system estimates optimal insertion point. Heat maps projected onto the segmented skin visualize the distance and angle of insertions and estimate the minimum cost of a puncture while avoiding bone collisions. Further, we test multiple insertion paths concerning feasibility and collisions. A custom end effector is designed for inserting needles and extracting tissue samples under robotic guidance. Our robotic post-mortem biopsy (RPMB) system is evaluated in a study during the COVID-19 pandemic on 20 corpses and 10 tissue targets, 5 of them being infected with SARS-CoV-2. The mean planning time including robot path planning is 5.72±167s. Mean needle placement accuracy is 7.19± 422mm.

Ultrasonographic Validation for Needle Placement in the Tibialis Posterior Muscle.

BackgroundThe tibialis posterior (TP) muscle plays an important role in normal foot function. Safe, efficacious therapeutic approaches addressing this muscle are necessary; however, the location of the muscle in the deep posterior compartment can create challenges.PurposeThe purpose of this study was to assess the accuracy of needle placement in the TP muscle and determine the needle placement in relation to the neurovascular structures located within the deep compartment.DesignCross Sectional Study.MethodsNeedle placement and ultrasound imaging were performed on 20 healthy individuals. A 50 mm or 60 mm needle was inserted between 30 - 50% of the tibial length measured from the medial tibiofemoral joint. The needle was inserted in a medial to lateral direction into the right extremity with the patient in right side lying. Placement of the needle into the TP muscle was verified with ultrasound imaging, and the shortest distance from the needle to the posterior tibial artery and tibial nerve was measured. The depth from the skin to the superficial border of the TP muscle was also measured.ResultsUltrasonography confirmed the needle filament was inserted into the TP muscle in all 20 individuals and did not penetrate the neurovascular bundle in any individual. The mean distance from the needle to the tibial nerve and posterior tibial artery was 10.0 + 4.7 mm and 10.2 + 4.7 mm respectively. The superficial border of the TP muscle from the skin was at a mean depth of 25.8 + 4.9 mm.ConclusionThis ultrasound imaging needle placement study supports placement of a solid filament needle into the TP muscle with avoidance of the neurovascular structures of the deep posterior compartment when placed from a medial to lateral direction at 30-50% of the tibial length.Level of Evidence2b

Irreversible electroporation for pancreatic cancer using intraprocedural cone-beam computed tomography fusion navigation: a case report

BackgroundPatients diagnosed with locally advanced pancreatic cancer are usually not eligible for surgical resection because of significant vascular involvement. Stereotactic body radiation therapy and chemotherapy are the treatments recommended by the National Comprehensive Cancer Network criteria. For patients who do not respond to or tolerate stereotactic body radiation therapy and/or chemotherapy, a new option is irreversible electroporation. Irreversible electroporation is a nonthermal minimally invasive ablation technique that uses electrical pulses to induce apoptosis of tumor cells without damage to the extracellular matrix, thus preserving ducts and vessels. Irreversible electroporation requires very precise needle placement, which has limited its ubiquitous use. Intraprocedural cone-beam computed tomography with navigation can be fused with previous imaging to provide real-time tumor navigation capabilities during the procedure to allow for more accurate needle placement and treatment. Here, we present a patient who underwent percutaneous irreversible electroporation with intraprocedural cone-beam computed tomography fusion guidance to treat his pancreatic cancer.Case presentationThe patient, an 88-year-old White male, initially presented with abdominal pain, and was ultimately diagnosed with locally advanced pancreatic cancer. He has an excellent performance status and no other comorbidities. He was started on chemotherapy and radiation therapy, with good response. However, continued vascular involvement of the tumors precluded him from safe surgical resection. The patient underwent irreversible electroporation with intraprocedural cone-beam computed tomography fusion navigation. The primary lesion demonstrates no residual tumor, and the soft tissue involvement of the adjacent vasculature has stabilized.ConclusionsAlthough not curative on its own, irreversible electroporation holds promise as a treatment option for patients with locally advanced pancreatic cancer to increase downsizing to curative surgery or increase quality of life. Cone-beam computed tomography navigation can improve irreversible electroporation by providing guidance during needle guidance. Image fusion with previous advanced imaging can improve lesion visualization and targeting, thereby improving the effectiveness of irreversible electroporation.

Robotic Cytology using Extra-Fine Needles : -Proposal of Puncture Control Strategy for Increasing Collection Amount.

Fine needle aspiration cytology requires accurate needle insertion into a tumor and sufficient amount collection of samples, which highly depends on the skill of the physician. The advantage of the diagnosis is to minimize the tissue damage with the fine needle, while, when the amount of the sample sucked from the lesion is not enough for the definite diagnosis, the procedure has to be repeated until satisfying them. Although numerous research reported a robot-assisted insertion method to improve the accuracy of needle placement with fine needles, there was less research to address the efficient tissue collection. Ideally, the amount of the samples can be satisfied for the diagnosis even if an extra-fine needle (e.g. 25-gauge) is used. This paper proposes a novel needle insertion method for increasing the amount of the tissue sample with the extra-fine needle. The proposed insertion method comprises the round-trip insertion motion and trajectory rerouting with the nature of the bevel-tipped needle. The phantom study's result showed the equivalency of the aspiration amount between a physician's manual procedure with a 22-gauge needle and the proposed method with a 25-gauge needle (4.5 ± 1.0 mg vs 5.1 ± 0.7 mg). The results suggested that the proposed robotic aspiration method can increase the sampling amount with the extra-fine needle in the fine needle aspiration cytology.

Online Needle-Tissue Interaction Model Identification for Force Feedback Enhancement in Robot-Assisted Interventional Procedures

Many interventional procedures, e.g., biopsies and tumor ablation, imply the insertion of a needle into soft tissues. The interaction force at the needle tip can convey information important for the accuracy of needle placement and the patient’s safety. This information is essential when feedback from an imaging system is missing or only available at a low rate. To isolate the force exchanged at the needle tip during the insertion, it is necessary to remove other components from the needle-tissue interaction force. In particular, the friction along the needle shaft becomes more and more relevant as the needle penetrates deeper into the tissues. In this paper, we propose a method for the identification of the friction component during needle penetration into a multi-layered target. The proposed online identification procedure allows, at the transition from one tissue layer to the next, to subtract the friction contribution from the previous layers and isolate the force relative to the layer where the needle tip is currently located. We call this an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">enhanced</i> force signal because it improves the ratio of the useful information about the force at the needle tip to the total force rendered. This result can be used in teleoperated needle insertion schemes, or other robot-assisted architectures, with the aim of facilitating the user perception of variations in tissue properties. In the proposed implementation, the force at the base of the needle can either be measured or estimated by using a model-based approach. An originally developed simulation framework provides a tool for procedure planning and online monitoring.

Concept for parallel placement of flexible needles for Irreversible Electroporation

Abstract Irreversible Electroporation (IRE) is a non-thermal tumor ablation treatment applicable for prostate cancer. IRE uses ultra-short but strong electrical pulses to destroy cancer cells nonthermally [1]. Clinically available IRE therapy requires two or more needle electrodes placed around the target tissue to apply the electric fields. A pre-requirement to achieve successful and effective ablation is an accurate and parallel needle placement to cover the tumor zone. Differences in tissue density, organ surface curvature as well as organ and patient motion in combination with long and highly flexible needle electrodes causes’ difficulties to achieve the desired target accuracy during needle placement process. We propose a concept of a shooting mechanism in combination with a grid template support to improve the parallel needle placement process for prostate cancer treatment. Instead of conventionally inserting the needle in the body by hand, it can be placed with high speed using a shooting device setup, that works similar like a biopsy gun.

State of the art: percutaneous tracheostomy in the intensive care unit.

Percutaneous tracheostomy is a commonly performed procedure for patients in the intensive care unit (ICU) and offers many benefits, including decreasing ICU length of stay and need for sedation while improving patient comfort, effective communication, and airway clearance. However, there is no consensus on the optimal timing of tracheostomy in ICU patients. Ultrasound (US) and bronchoscopy are useful adjunct tools to optimize procedural performance. US can be used pre-procedurally to identify vascular structures and to select the optimal puncture site, intra-procedurally to assist with accurate placement of the introducer needle, and post-procedurally to evaluate for a pneumothorax. Bronchoscopy provides real-time visual guidance from within the tracheal lumen and can reduce complications, such as paratracheal puncture and injury to the posterior tracheal wall. A step-by-step detailed procedural guide, including preparation and procedural technique, is provided with a team-based approach. Technical aspects, such as recommended equipment and selection of appropriate tracheostomy tube type and size, are discussed. Certain procedural considerations to minimize the risk of complications should be given in circumstances of patient obesity, coagulopathy, or neurologic illness. Herein, we provide a practical state of the art review of percutaneous tracheostomy in ICU patients. Specifically, we will address pre-procedural preparation, procedural technique, and post-tracheostomy management.

Matrix 3D ultrasound-assisted thyroid nodule volume estimation and radiofrequency ablation: a phantom study

BackgroundTwo-dimensional (2D) ultrasound is well established for thyroid nodule assessment and treatment guidance. However, it is hampered by a limited field of view and observer variability that may lead to inaccurate nodule classification and treatment. To cope with these limitations, we investigated the use of real-time three-dimensional (3D) ultrasound to improve the accuracy of volume estimation and needle placement during radiofrequency ablation. We assess a new 3D matrix transducer for nodule volume estimation and image-guided radiofrequency ablation.MethodsThirty thyroid nodule phantoms with thermochromic dye underwent volume estimation and ablation guided by a 2D linear and 3D mechanically-swept array and a 3D matrix transducer.ResultsThe 3D matrix nodule volume estimations had a lower median difference with the ground truth (0.4 mL) compared to the standard 2D approach (2.2 mL, p < 0.001) and mechanically swept 3D transducer (2.0 mL, p = 0.016). The 3D matrix-guided ablation resulted in a similar nodule ablation coverage when compared to 2D-guidance (76.7% versus 80.8%, p = 0.542). The 3D mechanically swept transducer performed worse (60.1%, p = 0.015). However, 3D matrix and 2D guidance ablations lead to a larger ablated volume outside the nodule than 3D mechanically swept (5.1 mL, 4.2 mL (p = 0.274), 0.5 mL (p < 0.001), respectively). The 3D matrix and mechanically swept approaches were faster with 80 and 72.5 s/mL ablated than 2D with 105.5 s/mL ablated.ConclusionsThe 3D matrix transducer estimates volumes more accurately and can facilitate accurate needle placement while reducing procedure time.

The accuracy of needle electrode placement by trainees in selected forearm muscles using verification by neuromuscular ultrasound

IntroductionAnatomic landmarks alone may not always be sufficient to accurately guide electromyography (EMG) electrode needle placement. MethodsSenior residents and fellows (n = 11) targeted 4 forearm muscles with anatomic landmarks alone versus with audiovisual EMG feedback. Accuracy of EMG needle placement was verified using neuromuscular ultrasound imaging. ResultsWhile relatively large and superficial FCR muscle was sampled at a rate of 100% with and without audiovisual EMG feedback, accuracy of deeper and/or smaller forearm muscles (FPL, EIP, and SUP) diminished significantly without audiovisual EMG feedback. DiscussionOur study suggests that in clinical scenarios in which an electrodiagnostician relies on anatomic landmarks alone to target small and deep muscles, the risk of misplacement of needle electrode is increased. Consideration for neuromuscular ultrasound to augment training and/or real time guidance in EMG practice may be appropriate.

CLINICAL OUTCOME OF BLIND VERSUS SONOGRAPHIC GUIDED INFILTRATION OF CORTICO STEROID FOR PAINFUL SHOULDER CONDITIONS IN ADULTS – A COMPARATIVE STUDY

Background: Painful shoulder is one of the commonest ailmaent encountered in the outpatient department of orthopedica now a days. One of the ways to get relief from the pain is to instill intraarticular corticosteroids. Corticosteroid injections can be performed blind or with image guidance. The objective of this study was to compare the accuracy and efcacy of image guided intraarticular corticosteroid injections in shoulder pain versus blind, with specic reference to pain relief as per VAS and functional improvement as per constant score. Objective : To compare the efcacy of image guided intra-articular corticosteroid injection in shoulder pain versus blind method of inltration, with specic reference to 1. pain relief as per visual analogue score. 2. To compare post inltration functional improvement of as per constant score with these two methods. Methods: The present Study included 50 adults with a history of pain around the shoulder of three or more than three months duration and were divided into two groups of 25 patients each by simple computer based allocation. Results: Both groups showed improvement as per CONSTANT SCORE, (26.64 to 72.00, an improvement of 45.36 in USG group and 27.48 to 58.60, an improvement of 31.12 in blind group with significant p value of 0.001). Conclusion: USG inltration of corticosteroids in shoulder pain is a superior method compared to blind inltration as clearly established by signicant improvement in pain and range of motion (ROM) of shoulder joint (more in ultrasonic group compared to blind group) probably due to accurate needle placement and proper dosage of drug is delivered at the required site.

Development and Validation of a Three-Dimensional Printed Training Model to Teach Ultrasound-Guided Injections of the Cervical Articular Process Joints in Horses.

Intra-articular injections are routinely performed to alleviate pain and inflammation associated with osteoarthritis in horses. Intra-articular injections require accurate needle placement to optimize clinical outcomes and minimize complications. This study's objectives were to develop and validate a three-dimensional (3D) printed model of an equine cervical articular process joint to teach ultrasound-guided injections. Five identical models of an equine cervical articular process joint were 3D printed and embedded in 10% ballistic gelatin. Experts' and novices' ability to successfully insert a needle into the joint space of the model using ultrasound guidance was assessed and graded using an objective structured clinical examination (OSCE). Scores from experts and novices were compared to evaluate the construct validity of the model. Participants also answered a survey assessing the face and content validity of the model. Experts required less time (22.51 seconds) for correct needle placement into the model joint space than novices (35.96 seconds); however, this difference was not significant (p = .53). Experts' median total OSCE score (14) was significantly higher (p = .03) than novices' (12), supporting the model's construct validity. Participants agreed on the face and content validity of the model by grading all survey questions greater than 7 on a 10-point Likert-type scale. In summary, we successfully developed a 3D printed model of an equine cervical articular process joint, partially demonstrated the construct validity of the model, and proved the face and content validity of this new training tool.

Body-Mounted Robotic System for MRI-Guided Shoulder Arthrography: Cadaver and Clinical Workflow Studies.

This paper presents an intraoperative MRI-guided, patient-mounted robotic system for shoulder arthrography procedures in pediatric patients. The robot is designed to be compact and lightweight and is constructed with nonmagnetic materials for MRI safety. Our goal is to transform the current two-step arthrography procedure (CT/x-ray-guided needle insertion followed by diagnostic MRI) into a streamlined single-step ionizing radiation-free procedure under MRI guidance. The MR-conditional robot was evaluated in a Thiel embalmed cadaver study and healthy volunteer studies. The robot was attached to the shoulder using straps and ten locations in the shoulder joint space were selected as targets. For the first target, contrast agent (saline) was injected to complete the clinical workflow. After each targeting attempt, a confirmation scan was acquired to analyze the needle placement accuracy. During the volunteer studies, a more comfortable and ergonomic shoulder brace was used, and the complete clinical workflow was followed to measure the total procedure time. In the cadaver study, the needle was successfully placed in the shoulder joint space in all the targeting attempts with translational and rotational accuracy of 2.07 ± 1.22 mm and 1.46 ± 1.06 degrees, respectively. The total time for the entire procedure was 94 min and the average time for each targeting attempt was 20 min in the cadaver study, while the average time for the entire workflow for the volunteer studies was 36 min. No image quality degradation due to the presence of the robot was detected. This Thiel-embalmed cadaver study along with the clinical workflow studies on human volunteers demonstrated the feasibility of using an MR-conditional, patient-mounted robotic system for MRI-guided shoulder arthrography procedure. Future work will be focused on moving the technology to clinical practice.

Feasibility and accuracy of 3D printed patient-specific skull contoured brain biopsy guides.

ObjectiveDesign 3D printed skull contoured brain biopsy guides (3D‐SCGs) from computed tomography (CT) or T1‐weighted magnetic resonance imaging (T1W MRI).Study DesignFeasibility study.Sample PopulationFive beagle dog cadavers and two client‐owned dogs with brain tumors.MethodsHelical CT and T1W MRI were performed on cadavers. Planned target point was the head of the caudate nucleus. Three‐dimensional‐SCGs were created from CT and MRI using commercially available open‐source software. Using 3D‐SCGs, biopsy needles were placed into the caudate nucleus in cadavers, and CT was performed to assess needle placement accuracy, followed by histopathology. Three‐dimensional‐SCGs were then created and used to perform in vivo brain tumor biopsies.ResultsNo statistical difference was found between the planned target point and needle placement. Median needle placement error for all planned target points was 2.7 mm (range: 0.86–4.5 mm). No difference in accuracy was detected between MRI and CT‐designed 3D‐SCGs. Median needle placement error for the CT was 2.8 mm (range: 0.86–4.5 mm), and 2.2 mm (range: 1.7–2.7 mm) for MRI. Biopsy needles were successfully placed into the target in the two dogs with brain tumors and biopsy was successfully acquired in one dog.ConclusionThree‐dimensional‐SCGs designed from CT or T1W MRI allowed needle placement within 4.5 mm of the intended target in all procedures, resulting in successful biopsy in one of two live dogs.Clinical SignificanceThis feasibility study justifies further evaluation of 3D‐SCGs as alternatives in facilities that do not have access to stereotactic brain biopsy.

A novel multi-DoF surgical robotic system for brachytherapy on liver tumor: Design and control

PurposeRadioactive seed implantation is an effective invasive treatment method for malignant liver tumors in hepatocellular carcinomas. However, challenges of the manual procedure may degrade the efficacy of the technique, such as the high accuracy requirement and radiation exposure to the surgeons. This paper aims to develop a robotic system and its control methods for assisting surgeons on the treatment.MethodWe present an interventional robotic system, which consists of a 5 Degree-of-Freedom (DoF) positioning robotic arm (a 3-DoF translational joint and a 2-DoF revolute joint) and a needle actuator used for needle insertion and radioactive seeds implantation. Control strategy is designed for the system to ensure the safety of the motion. In the designed framework, an artificial potential field (APF)-based motion planning and an ultrasound (US) image-based contacting methods are proposed for the control.ResultExperiments were performed to evaluate position and orientation accuracy as well as validate the motion planning procedure of the system. The mean and standard deviation of targeting error is 0.69 mm and 0.33 mm, respectively. Needle placement accuracy is 1.10 mm by mean. The feasibility of the control strategy, including path planning and the contacting methods, is demonstrated by simulation and experiments based on an abdominal phantom.ConclusionThis paper presents a robotic system with force and US image feedback in assisting surgeons performing brachytherapy on liver tumors. The proposed robotic system is capable of executing an accurate needle insertion task with by optical tracking. The proposed methods improve the safety of the robot’s motion and automate the process of US probe contacting under the feedback of US-image.

PO38: Commissioning and Workflow Development for a Real-Time, Ultrasound-Guided Prostate HDR Brachytherapy Program

Purpose: This work presents the commissioning of a real-time, ultrasound (US)-guided HDR brachytherapy system (Elekta AB, Inc.), including the hardware, US imaging system, treatment planning system (TPS) (Oncentra Prostate), and the developed workflow.Materials and Methods: Commissioning tasks were separated into (1) US imaging, (2) stepper mechanicals, and (3) treatment planning aspects. Quality assurance US imaging measurements consisted of benchmarking the spatial resolution, accuracy, and low-contrast detectability. Mechanical tests were first performed to validate the electronic encoders used within the stepper and were later expanded to evaluate the needle free length calculation accuracy. Several system-integrated measurements were performed to verify needle positioning accuracy and imaging origin coincidence measurements using the needle free length measurement as a surrogate marker, as this remains one of the largest potential sources of error. The workflow was developed through a multi-disciplinary team, including physicians, radiation-therapists, nurses, physicists, administration staff, sterilization and anesthesia staff and included multi-dry-runs of the full procedure. A detailed description of each party's role was also developed, including checklists for the planning physicist, a secondary check physicist, and a radiation therapist.Results: Needle placement accuracy was verified to within 1 mm for both sagittal and transverse imaging planes. Needle reconstruction accuracy was also rigorously evaluated. The source strength was also calibrated with the interstitial needle and was found to be 1.14% lower than when measured in a plastic needle. The calibration length of each probe was redundantly check between the calculated and measured needle free length, which was found to be within 1 mm for a variety of scenarios. Dose calculations in the TPS and secondary dose calculation software were benchmarked against manual TG-43 calculations, which were within 1% for all calculated points. Source positioning and dummy coincidence was also verified. The US-guided HDR prostate procedure consisted of six primary components: (1) the delineation of personnel and their roles, (2) HDR suite preparation prior to the treatment day, (3) day of treatment preparations, (4) patient setup, (4) pre-needle insertion plan, (5) initial insertion and live reconstruction, and (6) final imaging and planning. A set of plan evaluation metrics were established based on the currently available guidelines (ABS, ESTRO, and RTOG) and the culmination of clinical experiences across multiple institutions.Conclusions: The commissioning of real-time, US-guided HDR prostate systems requires careful consideration among several facets including the image quality, dosimetric and mechanical accuracy. The TPS relies on each of these components to develop and administer a treatment plan, and as such, should be carefully examined.