Search

Background: The steep radiation dose gradients in cervical cancer brachytherapy (BT) necessitate a thorough understanding of the behavior of afterloader source cables or needles in the curved channels of (patient-tailored) applicators. Purpose: The purpose of this study is to develop and validate computer models to simulate: (1) BT source positions, and (2) insertion forces of needles in curved applicator channels. The methodology presented can be used to improve the knowledge of instrument behavior in current applicators and aid the development of novel (3D-printed) BT applicators. Methods: For the computer models, BT instruments were discretized in finite elements. Simulations were performed in SPACAR by formulating nodal contact force and motion input models and specifying the instruments’ kinematic and dynamic properties. To evaluate the source cable model, simulated source paths in ring applicators were compared with manufacturer-measured source paths. The impact of discrepancies on the dosimetry was estimated for standard plans. To validate needle models, simulated needle insertion forces in curved channels with varying curvature, torsion, and clearance, were compared with force measurements in dedicated 3D-printed templates. Results: Comparison of simulated with manufacturer-measured source positions showed 0.5–1.2 mm median and <2.0 mm maximum differences, in all but one applicator geometry. The resulting maximum relative dose differences at the lateral surface and at 5 mm depth were 5.5% and 4.7%, respectively. Simulated insertion forces for BT needles in curved channels accurately resembled the forces experimentally obtained by including experimental uncertainties in the simulation. Conclusion: The models developed can accurately predict source positions and insertion forces in BT applicators. Insights from these models can aid novel applicator design with improved motion and force transmission of BT instruments, and contribute to the estimation of o, Medical Instruments & Bio-Inspired Technology, Mechatronic Systems Design

Conformity of tumour volumes and dose plans in prostate brachytherapy (BT) can be constrained by unwanted needle deflections, needle access restrictions and visualisation limitations. This work validates the feasibility of teleoperated robotic control of an active steerable needle using magnetic resonance (MR) for guidance. With this system, perturbations can be counteracted and critical structures can be circumvented to access currently inaccessible areas. The system comprises of (1) a novel steerable needle, (2) the minimally invasive robotics in an MR environment (MIRIAM) system, and (3) the daVinci Research Kit (dVRK). MR scans provide visual feedback to the operator controlling the dVRK. Needle steering is performed along curved trajectories to avoid the urethra towards targets (representing tumour tissue) in a prostate phantom with a targeting error of 1.2 ± 1.0 mm. This work shows the potential clinical applicability of active needle steering for prostate BT with a teleoperated robotic system in an MR environment., Medical Instruments & Bio-Inspired Technology

Patients treated for vulvar carcinoma may experience losses in mobility and physical activity. In this study, we assess the prevalence and severity of mobility problems using patient-reported outcomes of three questionnaires: EQ-5D-5L to estimate QoL and perceived health; SQUASH to estimate habitual physical activity; and a problem-specific questionnaire on bicycling. Patients treated for vulvar carcinoma between 2018 and 2021 were recruited, and 84 (62.7%) responded. The mean age was 68 ± 12 years (mean ± standard deviation). Self-reported QoL and perceived health were 0.832 ± 0.224 and 75.6 ± 20.0, respectively. Dutch physical activity guidelines were met by 34.2% of participants. Compared to baseline values, the times spent walking, bicycling, and participating in sports were all reduced. During bicycling, patients experienced moderate or severe pain in the skin of the vulva (24.5%), pain in the sit bones (23.2%), chafing (25.5%), or itching (8.9%). Overall, 40.3% experienced moderate or severe bicycling problems or could not bicycle, 34.9% felt that their vulva impeded bicycling, and 57.1% wished to make more or longer bicycling journeys. To conclude, vulvar carcinoma and its treatment reduce self-reported health, mobility, and physical activity. This motivates us to investigate ways to reduce discomfort during physical activities, and help women regain their mobility and self-reliance., Medical Instruments & Bio-Inspired Technology

Medical use of (non-)thermal plasmas is an emerging field in gynaecology. However, data on plasma energy dispersion remain limited. This systematic review presents an overview of plasma devices, fields of effective application, and impact of use factors and device settings on tissues in the female pelvis, including the uterus, ovaries, cervix, vagina, vulva, colon, omentum, mesenterium, and peritoneum. A search of the literature was performed on 4 January 2023 in the Medline Ovid, Embase, Cochrane, Web of Science, and Google Scholar databases. Devices were classified as plasma-assisted electrosurgery (ES) using electrothermal energy, neutral argon plasma (NAP) using kinetic particle energy, or cold atmospheric plasma (CAP) using non-thermal biochemical reactions. In total, 8958 articles were identified, of which 310 were scanned, and 14 were included due to containing quantitative data on depths or volumes of tissues reached. Plasma-assisted ES devices produce a thermal effects depth of <2.4 mm. In turn, NAP effects remained superficial, <1.0 mm. So far, the depth and uniformity of CAP effects are insufficiently understood. These data are crucial to achieve complete treatment, reduce recurrence, and limit damage to healthy tissues (e.g., prevent perforations or preserve parenchyma). Upcoming and potentially high-gain applications are discussed, and deficits in current evidence are identified., Medical Instruments & Bio-Inspired Technology

The most important prognostic factor for the survival of advanced-stage epithelial ovarian cancer (EOC) is the completeness of cytoreductive surgery (CRS). Therefore, an intraoperative technique to detect microscopic tumors would be of great value. The aim of this pilot study is to assess the feasibility of near-infrared hyperspectral imaging (HSI) for EOC detection in ex vivo tissue samples. Images were collected during CRS in 11 patients in the wavelength range of 665–975 nm, and processed by calibration, normalization, and noise filtering. A linear support vector machine (SVM) was employed to classify healthy and tumorous tissue (defined as >50% tumor cells). Classifier performance was evaluated using leave-one-out cross-validation. Images of 26 tissue samples from 10 patients were included, containing 26,446 data points that were matched to histopathology. Tumorous tissue could be classified with an area under the curve of 0.83, a sensitivity of 0.81, a specificity of 0.70, and Matthew’s correlation coefficient of 0.41. This study paves the way to in vivo and intraoperative use of HSI during CRS. Hyperspectral imaging can scan a whole tissue surface in a fast and non-contact way. Our pilot study demonstrates that HSI and SVM learning can be used to discriminate EOC from surrounding tissue., Medical Instruments & Bio-Inspired Technology

Background: The aim of surgery for advanced-stage ovarian cancer is a complete cytoreduction, because this is the most important independent prognostic factor for prolonged survival. Yet this can be difficult to achieve when there are micrometastases on the intestinal mesentery or intestines. The PlasmaJet device is an instrument to remove these micrometastases, but little is known about the depth of damage in human tissue compared to electrocoagulation devices. Methods: A prospective study was performed for the ex-vivo comparison of the histological depth of thermal damage of neutral argon plasma (PlasmaJet®) and electrocoagulation devices, in a series of 106 histological slides of 17 advanced-stage ovarian cancer patients. Depending on the tissue types resected during complete cytoreductive surgery, samples were collected from reproductive organs (uterus, ovaries), intestines (ileum, colon, rectum) and omentum, intestinal mesentery and peritoneum. Results: Average thermal damage depth was 0.15 mm (range 0.03–0.60 mm) after use of neutral argon plasma and 0.33 mm (range 0.08–1.80 mm) after use of electrocoagulation (p < 0.001). Greater disruption of the tissue surface was often observed after electrocoagulation. Conclusion: Our case series suggests that the use of neutral argon plasma during cytoreductive surgery produces significantly less thermal damage than electrocoagulation treatment. It is therefore considered a thermally safe alternative, aiding in the achievement of cytoreductive surgery., Medical Instruments & Bio-Inspired Technology

The most important prognostic factor for the survival of advanced-stage epithelial ovarian cancer (EOC) is the completeness of cytoreductive surgery (CRS). Therefore, an intraoperative technique to detect microscopic tumors would be of great value. The aim of this pilot study is to assess the feasibility of near-infrared hyperspectral imaging (HSI) for EOC detection in ex vivo tissue samples. Images were collected during CRS in 11 patients in the wavelength range of 665–975 nm, and processed by calibration, normalization, and noise filtering. A linear support vector machine (SVM) was employed to classify healthy and tumorous tissue (defined as >50% tumor cells). Classifier performance was evaluated using leave-one-out cross-validation. Images of 26 tissue samples from 10 patients were included, containing 26,446 data points that were matched to histopathology. Tumorous tissue could be classified with an area under the curve of 0.83, a sensitivity of 0.81, a specificity of 0.70, and Matthew’s correlation coefficient of 0.41. This study paves the way to in vivo and intraoperative use of HSI during CRS. Hyperspectral imaging can scan a whole tissue surface in a fast and non-contact way. Our pilot study demonstrates that HSI and SVM learning can be used to discriminate EOC from surrounding tissue., Medical Instruments & Bio-Inspired Technology

Purpose: To present a novel methodical approach to compare visibility of percutaneous needles in ultrasound images. Methods: A motor-driven rotation platform was used to gradually change the needle angle while capturing image data. Data analysis was automated using block-matching-based registration, with a tracking and refinement step. Every 25 frames, a Hough transform was used to improve needle alignments after large rotations. The method was demonstrated by comparing three commercial needles (14G radiofrequency ablation, RFA; 18G Trocar; 22G Chiba) and six prototype needles with different sizes, materials, and surface conditions (polished, sand-blasted, and kerfed), within polyvinyl alcohol phantom tissue and ex vivo bovine liver models. For each needle and angle, a contrast-to-noise ratio (CNR) was determined to quantify visibility. CNR values are presented as a function of needle type and insertion angle. In addition, the normalized area under the (CNR-angle) curve was used as a summary metric to compare needles. Results: In phantom tissue, the first kerfed needle design had the largest normalized area of visibility and the polished 1 mm diameter stainless steel needle the smallest (0.704 ± 0.199 vs. 0.154 ± 0.027, p < 0.01). In the ex vivo model, the second kerfed needle design had the largest normalized area of visibility, and the sand-blasted stainless steel needle the smallest (0.470 ± 0.190 vs. 0.127 ± 0.047, p < 0.001). As expected, the analysis showed needle visibility peaks at orthogonal insertion angles. For acute or obtuse angles, needle visibility was similar or reduced. Overall, the variability in needle visibility was considerably higher in livers. Conclusion: The best overall visibility was found with kerfed needles and the commercial RFA needle. The presented methodical approach to quantify ultrasound visibility allows comparisons of (echogenic) needles, as well as other technological innovations aiming to improve ultrasound visibility o, Medical Instruments & Bio-Inspired Technology

Brachytherapy is a common treatment in cervical, uterine and vaginal cancer management. The technique is characterised by rapid developments in the fields of medical imaging, dosimetry planning and personalised medical device design. To reduce unnecessary burden on patients, assessments and training of these technologies should preferable be done using high-fidelity physical phantoms. In this study, anthropomorphic deformable phantoms of the vaginal wall and cavity were developed for image-guided adaptive brachytherapy, in which vaginal wall biomechanics were mimicked. Phantoms were produced from both silicone and polyvinyl alcohol materials. Material characterisations were performed with uniaxial tensile tests, via which Young’s moduli and toughness were quantified. In addition, the contrast between adjacent phantom layers was quantified in magnetic resonance images. The results showed that stress-strain curves of the silicone phantoms were within the range of those found in healthy human vaginal wall tissues. Sample preconditioning had a large effect on Young’s moduli, which ranged between 2.13 and 6.94 MPa in silicone. Toughness was a more robust and accurate metric for biomechanical matching, and ranged between 0.23 and 0.28 ·106 J·m-3 as a result of preconditioning. The polyvinyl alcohol phantoms were not stiff or tough enough, with a Young’s modulus of 0.16 MPa and toughness of 0.02 ·106 J·m-3. All materials used could be clearly delineated in magnetic resonance images, although the MRI sequence did affect layer contrast. In conclusion, we developed anthropomorphic deformable phantoms that mimic vaginal wall tissue and are well visible in magnetic resonance images. These phantoms will be used to evaluate the properties and to optimise the development and use of personalised brachytherapy applicators., Engineering Thermodynamics, Medical Instruments & Bio-Inspired Technology

Accurate needle placement in deep-seated liver tumours can be difficult. In this work, we disclose two new manually controlled steerable needles for 17G radio-frequency ablation probe placement. The needles contain stylets with embedded compliant joints for active tip articulations, and concentric tubes for (curved-path) guidance. Needle steering was evaluated sequentially by intended users and in intended-use tissue types. Six interventional radiologists evaluated the needle in repeated ultrasound-guided steering tasks in liver-mimicking phantoms. Targets were located at a 100 mm depth and 20 mm lateral offset from the initial insertion line. The resulting mean absolute tip placement error was 1.0 ± 1.0 mm. Subsequently, steering-induced tissue damage was evaluated in fresh cirrhotic human liver explants. The surface area of puncture holes was estimated in scanned histology slides, using a connected-components analysis. The mean surface area was 0.26 ± 0.16 mm2 after steering with a median radius of curvature of 0.7 × 103 mm, versus 0.35 ± 0.15 mm2 after straight-path insertions with the steerable needle and 0.15 ± 0.09 mm2 after straight-path RFA probe insertions. The steering mechanisms proposed enable clinically relevant path corrections for 17G needles. Radiologists were quickly adept in curved-path RFA probe placement and the evaluation of histological tissue damage demonstrated a potentially safe use during liver interventions., Medical Instruments & Bio-Inspired Technology

Purpose: To present a novel methodical approach to compare visibility of percutaneous needles in ultrasound images. Methods: A motor-driven rotation platform was used to gradually change the needle angle while capturing image data. Data analysis was automated using block-matching-based registration, with a tracking and refinement step. Every 25 frames, a Hough transform was used to improve needle alignments after large rotations. The method was demonstrated by comparing three commercial needles (14G radiofrequency ablation, RFA; 18G Trocar; 22G Chiba) and six prototype needles with different sizes, materials, and surface conditions (polished, sand-blasted, and kerfed), within polyvinyl alcohol phantom tissue and ex vivo bovine liver models. For each needle and angle, a contrast-to-noise ratio (CNR) was determined to quantify visibility. CNR values are presented as a function of needle type and insertion angle. In addition, the normalized area under the (CNR-angle) curve was used as a summary metric to compare needles. Results: In phantom tissue, the first kerfed needle design had the largest normalized area of visibility and the polished 1 mm diameter stainless steel needle the smallest (0.704 ± 0.199 vs. 0.154 ± 0.027, p < 0.01). In the ex vivo model, the second kerfed needle design had the largest normalized area of visibility, and the sand-blasted stainless steel needle the smallest (0.470 ± 0.190 vs. 0.127 ± 0.047, p < 0.001). As expected, the analysis showed needle visibility peaks at orthogonal insertion angles. For acute or obtuse angles, needle visibility was similar or reduced. Overall, the variability in needle visibility was considerably higher in livers. Conclusion: The best overall visibility was found with kerfed needles and the commercial RFA needle. The presented methodical approach to quantify ultrasound visibility allows comparisons of (echogenic) needles, as well as other technological innovations aiming to improve ultrasound visibility o, Medical Instruments & Bio-Inspired Technology

Brachytherapy is a common treatment in cervical, uterine and vaginal cancer management. The technique is characterised by rapid developments in the fields of medical imaging, dosimetry planning and personalised medical device design. To reduce unnecessary burden on patients, assessments and training of these technologies should preferable be done using high-fidelity physical phantoms. In this study, anthropomorphic deformable phantoms of the vaginal wall and cavity were developed for image-guided adaptive brachytherapy, in which vaginal wall biomechanics were mimicked. Phantoms were produced from both silicone and polyvinyl alcohol materials. Material characterisations were performed with uniaxial tensile tests, via which Young’s moduli and toughness were quantified. In addition, the contrast between adjacent phantom layers was quantified in magnetic resonance images. The results showed that stress-strain curves of the silicone phantoms were within the range of those found in healthy human vaginal wall tissues. Sample preconditioning had a large effect on Young’s moduli, which ranged between 2.13 and 6.94 MPa in silicone. Toughness was a more robust and accurate metric for biomechanical matching, and ranged between 0.23 and 0.28 ·106 J·m-3 as a result of preconditioning. The polyvinyl alcohol phantoms were not stiff or tough enough, with a Young’s modulus of 0.16 MPa and toughness of 0.02 ·106 J·m-3. All materials used could be clearly delineated in magnetic resonance images, although the MRI sequence did affect layer contrast. In conclusion, we developed anthropomorphic deformable phantoms that mimic vaginal wall tissue and are well visible in magnetic resonance images. These phantoms will be used to evaluate the properties and to optimise the development and use of personalised brachytherapy applicators., Engineering Thermodynamics, Medical Instruments & Bio-Inspired Technology

Accurate needle placement in deep-seated liver tumours can be difficult. In this work, we disclose two new manually controlled steerable needles for 17G radio-frequency ablation probe placement. The needles contain stylets with embedded compliant joints for active tip articulations, and concentric tubes for (curved-path) guidance. Needle steering was evaluated sequentially by intended users and in intended-use tissue types. Six interventional radiologists evaluated the needle in repeated ultrasound-guided steering tasks in liver-mimicking phantoms. Targets were located at a 100 mm depth and 20 mm lateral offset from the initial insertion line. The resulting mean absolute tip placement error was 1.0 ± 1.0 mm. Subsequently, steering-induced tissue damage was evaluated in fresh cirrhotic human liver explants. The surface area of puncture holes was estimated in scanned histology slides, using a connected-components analysis. The mean surface area was 0.26 ± 0.16 mm2 after steering with a median radius of curvature of 0.7 × 103 mm, versus 0.35 ± 0.15 mm2 after straight-path insertions with the steerable needle and 0.15 ± 0.09 mm2 after straight-path RFA probe insertions. The steering mechanisms proposed enable clinically relevant path corrections for 17G needles. Radiologists were quickly adept in curved-path RFA probe placement and the evaluation of histological tissue damage demonstrated a potentially safe use during liver interventions., Medical Instruments & Bio-Inspired Technology

This literature review was conducted to evaluate liver biopsy adequacy, including total core length (TCL), number of portal tracts (PT), fragmentation, and complication rates, as a function of needle type and gauge. A systematic electronic search was performed in the Web of Science and Google Scholar databases, according to the PRISMA statement. Eligible data, describing in vivo percutaneous ultrasound-guided human liver biopsy quality outcomes, were compared to adequacy criteria of the American Association for the Study of Liver Diseases (AASLD, TCL ≥ 20 mm, PT ≥ 11). An adequate mean number of PTs was found in 83% of biopsy needles assessed between 2012 and 2019, compared to 0% between 1998 and 2004. For TCL, this was 44% and 33%, respectively. Increasing the needle diameter enhanced TCL (result in 50% of included studies) and PT count (100%), and reduced fragmentation rates (75%), whereas no effect on pain or complications was found (83%). In total, five needle types achieved adequate PT counts, using 16 G (3×), 17 G (1×), or 18 G (1×) needles. Adequacy was reached using either a core needle biopsy (CNB, 3×) approach with one pass, or a fine needle aspiration (FNA, 2×) approach with two passes. The recommendations for biopsy adequacy can be met using 16/17 G FNA or 16/18 G CNB needles. Currently, many publications still present substandard liver biopsy quality outcomes. Although minimizing biopsy invasiveness is desirable, a decreased diameter or number of passes is ill-judged when reliability of biopsy outcomes is at stake., Medical Instruments & Bio-Inspired Technology

Purpose: Smothering to death is most often done with a soft cover, such as a pillow. This is one of the hardest to diagnose causes of death. Knowing more about how people perform such an act and whether there is any correlation between perpetrator characteristics and smothering approaches may help in solving criminal cases involving smothering. Methods: A total of 181 visitors of a music festival were asked to smother a dummy with a pillow. Each participant provided their age, gender, dominant hand, length, weight, alcohol use (last 24 h) and drug use (last 24 h) in a questionnaire. Forces applied by the participant on the dummy head with the pillow were continuously measured and the smothering modus operandi (described by aspects such as the placement of the hands, feet and body weight) was obtained from video recordings. Results: Participants with high alcohol consumption provided higher smothering forces. Increases were also found for taller participants and those who had used drugs. Smothering seemed most effective when placing both hands on the pillow on the head and when placing the center of mass as much directly above the dummy head as possible. A stable, central stance also benefitted smothering effectiveness. Conclusion: Forensic case work may potentially benefit from these results in the future by linking the current results to the location of hand and finger marks on a pillow., Medical Instruments & Bio-Inspired Technology

This literature review was conducted to evaluate liver biopsy adequacy, including total core length (TCL), number of portal tracts (PT), fragmentation, and complication rates, as a function of needle type and gauge. A systematic electronic search was performed in the Web of Science and Google Scholar databases, according to the PRISMA statement. Eligible data, describing in vivo percutaneous ultrasound-guided human liver biopsy quality outcomes, were compared to adequacy criteria of the American Association for the Study of Liver Diseases (AASLD, TCL ≥ 20 mm, PT ≥ 11). An adequate mean number of PTs was found in 83% of biopsy needles assessed between 2012 and 2019, compared to 0% between 1998 and 2004. For TCL, this was 44% and 33%, respectively. Increasing the needle diameter enhanced TCL (result in 50% of included studies) and PT count (100%), and reduced fragmentation rates (75%), whereas no effect on pain or complications was found (83%). In total, five needle types achieved adequate PT counts, using 16 G (3×), 17 G (1×), or 18 G (1×) needles. Adequacy was reached using either a core needle biopsy (CNB, 3×) approach with one pass, or a fine needle aspiration (FNA, 2×) approach with two passes. The recommendations for biopsy adequacy can be met using 16/17 G FNA or 16/18 G CNB needles. Currently, many publications still present substandard liver biopsy quality outcomes. Although minimizing biopsy invasiveness is desirable, a decreased diameter or number of passes is ill-judged when reliability of biopsy outcomes is at stake., Medical Instruments & Bio-Inspired Technology

Purpose: Smothering to death is most often done with a soft cover, such as a pillow. This is one of the hardest to diagnose causes of death. Knowing more about how people perform such an act and whether there is any correlation between perpetrator characteristics and smothering approaches may help in solving criminal cases involving smothering. Methods: A total of 181 visitors of a music festival were asked to smother a dummy with a pillow. Each participant provided their age, gender, dominant hand, length, weight, alcohol use (last 24 h) and drug use (last 24 h) in a questionnaire. Forces applied by the participant on the dummy head with the pillow were continuously measured and the smothering modus operandi (described by aspects such as the placement of the hands, feet and body weight) was obtained from video recordings. Results: Participants with high alcohol consumption provided higher smothering forces. Increases were also found for taller participants and those who had used drugs. Smothering seemed most effective when placing both hands on the pillow on the head and when placing the center of mass as much directly above the dummy head as possible. A stable, central stance also benefitted smothering effectiveness. Conclusion: Forensic case work may potentially benefit from these results in the future by linking the current results to the location of hand and finger marks on a pillow., Medical Instruments & Bio-Inspired Technology

Background: Brachytherapy involves placement of radioactive sources inside or near the tumour. For gynaecological cancer, recent developments, including 3D imaging and image-guided adaptive brachytherapy, have improved treatment quality and outcomes. However, for large or complex tumours, target coverage and local control with commercially available applicators remain suboptimal. Moreover, side effects are frequent and impact on quality of life. This signifies that brachytherapy treatment conformity can improve. Therefore, the aim of this study is to develop 3D printed personalised brachytherapy applicators with a custom vaginal topography and guided needle source channels, based on the patients’ anatomy. - Methods: Customised applicators were derived from MRI data of two gynaecological cancer patients. Needle channels were planned by the Radiation Oncologist during image segmentation. Applicators contained multi-curved channels for 6F needles (ProGuide, Elekta) and were manufactured using a digital light processing-based 3D printer. Needle channel radius constraints were measured by analysing needle insertion forces in a 3D printed template, and imposed on the designs. - Results: Two customised needle applicators are presented. Interstitial needle channels have tapered ends to increase needle protrusion angle accuracy. Additional structures were included to serve as anchor points in MR images for applicator and needle modelling and reconstruction during treatment planning. An insertion force analysis yielded a radius constraint of 35 mm to minimise the risk on needle jamming or buckling. For radii larger than 50 mm, no differences in insertion forces were found. - Conclusion: A novel method to design and produce vaginal topography-based 3D prints for personalised brachytherapy applicators, derived from patient MRI data, is presented. The applicators include curved needle channels that can be used for intracavitary, Medical Instruments & Bio-Inspired Technology

During ultrasound-guided percutaneous interventions, needle localization can be a challenge. To increase needle visibility, enhancements of both the imaging methods and the needle surface properties have been investigated. However, a methodical approach to compare potential solutions is currently unavailable. The work described here involves automated image acquisition, analysis and reporting techniques to collect large amounts of data efficiently, delineate relevant factors and communicate effects. Data processing included filtering, line fitting and image intensity analysis steps. Foreground and background image samples were used to compute a contrast-to-noise ratio or a signal ratio. The approach was evaluated in a comparative study of commercially available and custom-made needles. Varied parameters included needle material, diameter and surface roughness. The shafts with kerfed patterns and the trocar and chiba tips performed best. The approach enabled an intuitive polar depiction of needle visibility in ultrasound images for a large range of insertion angles., Medical Instruments & Bio-Inspired Technology

Background: Brachytherapy involves placement of radioactive sources inside or near the tumour. For gynaecological cancer, recent developments, including 3D imaging and image-guided adaptive brachytherapy, have improved treatment quality and outcomes. However, for large or complex tumours, target coverage and local control with commercially available applicators remain suboptimal. Moreover, side effects are frequent and impact on quality of life. This signifies that brachytherapy treatment conformity can improve. Therefore, the aim of this study is to develop 3D printed personalised brachytherapy applicators with a custom vaginal topography and guided needle source channels, based on the patients’ anatomy. - Methods: Customised applicators were derived from MRI data of two gynaecological cancer patients. Needle channels were planned by the Radiation Oncologist during image segmentation. Applicators contained multi-curved channels for 6F needles (ProGuide, Elekta) and were manufactured using a digital light processing-based 3D printer. Needle channel radius constraints were measured by analysing needle insertion forces in a 3D printed template, and imposed on the designs. - Results: Two customised needle applicators are presented. Interstitial needle channels have tapered ends to increase needle protrusion angle accuracy. Additional structures were included to serve as anchor points in MR images for applicator and needle modelling and reconstruction during treatment planning. An insertion force analysis yielded a radius constraint of 35 mm to minimise the risk on needle jamming or buckling. For radii larger than 50 mm, no differences in insertion forces were found. - Conclusion: A novel method to design and produce vaginal topography-based 3D prints for personalised brachytherapy applicators, derived from patient MRI data, is presented. The applicators include curved needle channels that can be used for intracavitary, Medical Instruments & Bio-Inspired Technology

During ultrasound-guided percutaneous interventions, needle localization can be a challenge. To increase needle visibility, enhancements of both the imaging methods and the needle surface properties have been investigated. However, a methodical approach to compare potential solutions is currently unavailable. The work described here involves automated image acquisition, analysis and reporting techniques to collect large amounts of data efficiently, delineate relevant factors and communicate effects. Data processing included filtering, line fitting and image intensity analysis steps. Foreground and background image samples were used to compute a contrast-to-noise ratio or a signal ratio. The approach was evaluated in a comparative study of commercially available and custom-made needles. Varied parameters included needle material, diameter and surface roughness. The shafts with kerfed patterns and the trocar and chiba tips performed best. The approach enabled an intuitive polar depiction of needle visibility in ultrasound images for a large range of insertion angles., Medical Instruments & Bio-Inspired Technology

Purpose: Accurate and precise needle placement is of utmost importance in interventional radiology. However, targeting can be challenging due to, eg, tissue motion and deformation. Steerable needles are a possible solution to overcome these challenges. The present work studied the clinical need for steerable needles. We aimed to answer three subquestions: 1) What are the current challenges in needle placement? 2) What are allowable needle placement errors? and 3) Do current needles need improvement and would steerable needles add clinical value? Methods: A questionnaire was administered at the Annual Meeting of ­Cardiovascular and Interventional Radiology Society of Europe in 2016. In total, 153 respondents volunteered to fill out the survey, among them 125 (interventional) radiologists with experience in needle placement. Results: 1) Current challenges in needle placement include patient-specific and technical factors. Movement of the target due to breathing makes it most difficult to place a needle (90%). 2) The mean maximal allowable needle placement error in targeted lesions is 2.7 mm. A majority of the respondents (85%) encounter unwanted needle bending upon insertion. The mean maximal encountered unwanted needle bending is 5.3 mm. 3) Needles in interventional radiology need improvement, eg, improved needle visibility and manipulability, according to 95% of the respondents. Added value for steerable needles in current interventions is seen by 93% of the respondents. Conclusion: Steerable needles have the potential to add clinical value to radiologic interventions. The current data can be used as input for defining clinical design requirements for technical tools, such as steerable needles and navigation models, with the aim to improve needle placement in interventional radiology., Medical Instruments & Bio-Inspired Technology

Radio frequency ablation is commonly used in the treatment of hepatocellular carcinoma. Clinicians rely on imaging techniques, such as medical ultrasound, to confirm an accurate needle placement. This accuracy may improve by means of active needle steering techniques, which are currently in development. Needle steering will likely increase the clinician’s reliance on imaging techniques. This has motivated the study of the echogenicity of steerable needle joint structures. Two needles were manufactured with arrays of kerfs, similar to the compliant joint structures found in steerable needles. The needle visibility was compared to a smooth surface needle and a commercially available RFA needle. The visibility was quantified for both the shaft and tip, by means of a contrast-to-noise ratio (CNR). CNR data were obtained for three insertion angles. The results show that the CNRs of the compliant joint structures were consistently higher than those of the smooth surface needle, whereas they were either higher than or comparable to those of the RFA needle. For acute insertion angles, the bevel tip of the RFA needle had a higher CNR than the conical tip of the kerfed needles, motivating the extension of this visibility study to the full needle design., Medical Instruments & Bio-Inspired Technology

Radio frequency ablation is commonly used in the treatment of hepatocellular carcinoma. Clinicians rely on imaging techniques, such as medical ultrasound, to confirm an accurate needle placement. This accuracy may improve by means of active needle steering techniques, which are currently in development. Needle steering will likely increase the clinician’s reliance on imaging techniques. This has motivated the study of the echogenicity of steerable needle joint structures. Two needles were manufactured with arrays of kerfs, similar to the compliant joint structures found in steerable needles. The needle visibility was compared to a smooth surface needle and a commercially available RFA needle. The visibility was quantified for both the shaft and tip, by means of a contrast-to-noise ratio (CNR). CNR data were obtained for three insertion angles. The results show that the CNRs of the compliant joint structures were consistently higher than those of the smooth surface needle, whereas they were either higher than or comparable to those of the RFA needle. For acute insertion angles, the bevel tip of the RFA needle had a higher CNR than the conical tip of the kerfed needles, motivating the extension of this visibility study to the full needle design., Medical Instruments & Bio-Inspired Technology

Purpose: Accurate and precise needle placement is of utmost importance in interventional radiology. However, targeting can be challenging due to, eg, tissue motion and deformation. Steerable needles are a possible solution to overcome these challenges. The present work studied the clinical need for steerable needles. We aimed to answer three subquestions: 1) What are the current challenges in needle placement? 2) What are allowable needle placement errors? and 3) Do current needles need improvement and would steerable needles add clinical value? Methods: A questionnaire was administered at the Annual Meeting of ­Cardiovascular and Interventional Radiology Society of Europe in 2016. In total, 153 respondents volunteered to fill out the survey, among them 125 (interventional) radiologists with experience in needle placement. Results: 1) Current challenges in needle placement include patient-specific and technical factors. Movement of the target due to breathing makes it most difficult to place a needle (90%). 2) The mean maximal allowable needle placement error in targeted lesions is 2.7 mm. A majority of the respondents (85%) encounter unwanted needle bending upon insertion. The mean maximal encountered unwanted needle bending is 5.3 mm. 3) Needles in interventional radiology need improvement, eg, improved needle visibility and manipulability, according to 95% of the respondents. Added value for steerable needles in current interventions is seen by 93% of the respondents. Conclusion: Steerable needles have the potential to add clinical value to radiologic interventions. The current data can be used as input for defining clinical design requirements for technical tools, such as steerable needles and navigation models, with the aim to improve needle placement in interventional radiology., Medical Instruments & Bio-Inspired Technology

Purpose To study the ability of a human operator to manually correct for errors in the needle insertion path without partial withdrawal of the needle by means of an active, tip-articulated steerable needle. Materials and Methods The needle is composed of a 1.32-mm outer-diameter cannula, with a flexure joint near the tip, and a retractable stylet. The bending stiffness of the needle resembles that of a 20-gauge hypodermic needle. The needle functionality was evaluated in manual insertions by steering to predefined targets and a lateral displacement of 20 mm from the straight insertion line. Steering tasks were conducted in 5 directions and 2 tissue simulants under image guidance from a camera. The repeatability in instrument actuations was assessed during 100 mm deep automated insertions with a linear motor. In addition to tip position, tip angles were tracked during the insertions. Results The targeting error (mean absolute error ± standard deviation) during manual steering to 5 different targets in stiff tissue was 0.5 mm ± 1.1. This variability in manual tip placement (1.1 mm) was less than the variability among automated insertions (1.4 mm) in the same tissue type. An increased tissue stiffness resulted in an increased lateral tip displacement. The tip angle was directly controlled by the user interface, and remained unaffected by the tissue stiffness. Conclusions This study demonstrates the ability to manually steer needles to predefined target locations under image guidance., Medical Instruments & Bio-Inspired Technology

Purpose To study the ability of a human operator to manually correct for errors in the needle insertion path without partial withdrawal of the needle by means of an active, tip-articulated steerable needle. Materials and Methods The needle is composed of a 1.32-mm outer-diameter cannula, with a flexure joint near the tip, and a retractable stylet. The bending stiffness of the needle resembles that of a 20-gauge hypodermic needle. The needle functionality was evaluated in manual insertions by steering to predefined targets and a lateral displacement of 20 mm from the straight insertion line. Steering tasks were conducted in 5 directions and 2 tissue simulants under image guidance from a camera. The repeatability in instrument actuations was assessed during 100 mm deep automated insertions with a linear motor. In addition to tip position, tip angles were tracked during the insertions. Results The targeting error (mean absolute error ± standard deviation) during manual steering to 5 different targets in stiff tissue was 0.5 mm ± 1.1. This variability in manual tip placement (1.1 mm) was less than the variability among automated insertions (1.4 mm) in the same tissue type. An increased tissue stiffness resulted in an increased lateral tip displacement. The tip angle was directly controlled by the user interface, and remained unaffected by the tissue stiffness. Conclusions This study demonstrates the ability to manually steer needles to predefined target locations under image guidance., Medical Instruments & Bio-Inspired Technology

Steering of needles involves the planning and timely modifying of instrument-tissue force interactions to allow for controlled deflections during the insertion in tissue. In this work, the effect of tip shape on these forces was studied using 10 mm diameter needle tips. Six different tips were selected, including beveled and conical versions, with or without pre-bend or pre-curve. A six-degree-of-freedom force/torque sensor measured the loads during indentations in tissue simulants. The increased insertion (axial) and bending (radial) forces with insertion depth-the force-displacement slopes-were analyzed. Results showed that the ratio between radial and axial forces was not always proportional. This means that the tip load does not have a constant orientation, as is often assumed in mechanics-based steering models. For all tip types, the tip-load assumed a more radial orientation with increased axial load. This effect was larger for straight tips than for pre-bent or pre-curved tips. In addition, the force-displacement slopes were consistently higher for (1) increased tip angles, and for (2) beveled tips compared to conical tips. Needles with a bent or curved tip allow for an increased bending force and a decreased variability of the tip load vector orientation., Medical Instruments & Bio-Inspired Technology

Needle interventions play an important role both during the diagnosis and treatment of liver cancer. However, due to intermediate anatomical structures, such as the ribs and lungs, deep seated lesions are not always directly accessible. In addition, instrument-tissue interaction forces may cause needles to deflect during insertion. This leads to placement errors and possibly faulty diagnostic or therapeutic results. In literature, discussed methods to increase the reachability of deep seated lesions and decrease the chance on placement errors, include improvements of the medical imaging quality and of the initial needle-target alignment. In addition, the option to steer needles is actively being investigated. Needle steering involves the planning and timely modifying of instrument-tissue interaction forces in order to control the deflections in tissue. Currently investigated steering methods employ needle base manipulations, bevel-tip needles, pre-curved stylets, active cannulas, programmable bevel-tip needles, and articulated-tip needles. The technique proposed in this work employs an actively articulated needle tip. The aim of this research is to enhance our understanding of where needle-tissue interaction forces originate and how they can be effectively modified to steer needles. This is done by means of force measurements and device functionality evaluations during needle insertions in tissue simulants. The influence of tip shape on the formation of bending forces during needle insertion was studied in a fundamental and macroscopic experiment (Chapter 3). It was found that articulated bevel-tip needles are more efficient in building up bending force than matched conical-tip needles. However, increasing the tip articulation angle has a larger positive effect on bending force. Furthermore, it was found that the resultant force orientation depends on the insertion force and that the size of this vector rotation varies per tip shape. In general, the ra, Medical Instruments & Bio-Inspired Technology

Needle interventions play an important role both during the diagnosis and treatment of liver cancer. However, due to intermediate anatomical structures, such as the ribs and lungs, deep seated lesions are not always directly accessible. In addition, instrument-tissue interaction forces may cause needles to deflect during insertion. This leads to placement errors and possibly faulty diagnostic or therapeutic results. In literature, discussed methods to increase the reachability of deep seated lesions and decrease the chance on placement errors, include improvements of the medical imaging quality and of the initial needle-target alignment. In addition, the option to steer needles is actively being investigated. Needle steering involves the planning and timely modifying of instrument-tissue interaction forces in order to control the deflections in tissue. Currently investigated steering methods employ needle base manipulations, bevel-tip needles, pre-curved stylets, active cannulas, programmable bevel-tip needles, and articulated-tip needles. The technique proposed in this work employs an actively articulated needle tip. The aim of this research is to enhance our understanding of where needle-tissue interaction forces originate and how they can be effectively modified to steer needles. This is done by means of force measurements and device functionality evaluations during needle insertions in tissue simulants. The influence of tip shape on the formation of bending forces during needle insertion was studied in a fundamental and macroscopic experiment (Chapter 3). It was found that articulated bevel-tip needles are more efficient in building up bending force than matched conical-tip needles. However, increasing the tip articulation angle has a larger positive effect on bending force. Furthermore, it was found that the resultant force orientation depends on the insertion force and that the size of this vector rotation varies per tip shape. In general, the ra, Medical Instruments & Bio-Inspired Technology

Needle insertion procedures are commonly performed in current clinical practice for diagnostic and therapeutic purposes. Although prevailing technology allows accurate localization of lesions, they cannot yet be precisely targeted. Needle steering is a promising technique to overcome this challenge. In this paper, we describe the development of a novel steering system for an actuated-tip flexible needle. Strain measurements from an array of Fiber Bragg Grating (FBG) sensors are used for online reconstruction of the needle shape in 3D-space. FBG-sensor data is then fused with ultrasound images obtained from a clinically-approved Automated Breast Volume Scanner (ABVS) using an unscented Kalman filter. A new ultrasound-based tracking algorithm is developed for the robust tracking of the needle in biological tissue. Two experimental cases are presented to evaluate the proposed steering system. In the first case, the needle shape is reconstructed using the tracked tip position in ultrasound images and FBG-sensor measurements, separately. The reconstructed shape is then compared with the actual 3D needle shape obtained from the ABVS. In the second case, two steering experiments are performed to evaluate the overall system by fusing the FBG-sensor data and ultrasound images. Average targeting errors are 1.29±0.41 mm and 1.42±0.72 mm in gelatin phantom and biological tissue, respectively., Accepted Author Manuscript, Medical Instruments & Bio-Inspired Technology

Thermal spread is the extend of lateral damage resulting from soft tissue dissection by means of an energetic surgical instrument. Both a true definition of this factor, and a consistent means to quantify it, are still lacking. This study attempts to standardize thermal spread by 1) listing the relevant medical, technical, and statistical parameters, 2) selecting a soft tissue substitute to reduce biological influences, and 3) testing the protocol by determining the thermal spread of the Lotus grasper. Thermal spread was measured in a meat replacement product (quorn) by means of eight thermocouples. Spread of heat was determined as the distance between the instrument shaft and the 7:5_C isotherm. It was measured at 5 mm depth in the left (3:09 _ 0:637 mm), and right flank (2:70 _ 0:966 mm). In addition, two more depth levels were measured in the left flank, 2:5 mm (2:11_ 0:732 mm), and 7:5 mm (2:95_0:959 mm). The thermal distribution of the Lotus obtained by this measuring technique was comprehensible and educative. The use of thermocouples seemed adequate, as spread could be measured in the deep direction, and sufficiently precise. The selected test material (quorn) was sub- optimal from a mechanical viewpoint. This may have led to experimental uncertainties and an increased measurement variance., BME, BioMechanical Engineering, Mechanical, Maritime and Materials Engineering

Thermal spread is the extend of lateral damage resulting from soft tissue dissection by means of an energetic surgical instrument. Both a true definition of this factor, and a consistent means to quantify it, are still lacking. This study attempts to standardize thermal spread by 1) listing the relevant medical, technical, and statistical parameters, 2) selecting a soft tissue substitute to reduce biological influences, and 3) testing the protocol by determining the thermal spread of the Lotus grasper. Thermal spread was measured in a meat replacement product (quorn) by means of eight thermocouples. Spread of heat was determined as the distance between the instrument shaft and the 7:5_C isotherm. It was measured at 5 mm depth in the left (3:09 _ 0:637 mm), and right flank (2:70 _ 0:966 mm). In addition, two more depth levels were measured in the left flank, 2:5 mm (2:11_ 0:732 mm), and 7:5 mm (2:95_0:959 mm). The thermal distribution of the Lotus obtained by this measuring technique was comprehensible and educative. The use of thermocouples seemed adequate, as spread could be measured in the deep direction, and sufficiently precise. The selected test material (quorn) was sub- optimal from a mechanical viewpoint. This may have led to experimental uncertainties and an increased measurement variance., BME, BioMechanical Engineering, Mechanical, Maritime and Materials Engineering