Design of a seed implantation robot with counterbalance and soft tissue stabilization mechanism for prostate cancer brachytherapy

This article focuses on the topic of the structural design of surgical radioactive surgery robot for prostate cancer. To improve the weight-to-payload ratio of surgery robot end-effector, the energy consumption and stability of robot joint drive and reducing the displacement and deformation of needle insertion in soft tissue. This article discusses the new static torque balancing method and multi-needle insertion soft tissue stabilization mechanisms that may be used in previously articulated seed implantation robots. Compared with the existing balancing system schemes, we adopt the idea of mutual conversion of gravitational potential energy and elastic potential energy and establish a static balancing model. With preloaded displacement parameter of the spring α, the variable gravity torque balance of robot arm can be achieved. Torque and equivalent gravity balancing distribution with the spring balance system and the quantitative evaluation experiment were performed, and experiment results provide evidence that these spring balance devices can basically compensate the gravity torque of the robot arm. In addition, we used nonlinear spring–damper model to establish multi-needles insertion soft tissue force model. Then, a variable multi-needle insertion soft tissue stabilization device is designed with six working modes. The innovative design of this device is the use of the first four needles that are introduced simultaneously on either side of the midline. Initially completed displacement simulation of different numbers of needle insertion prostate tissue, experiment results indicate that multi-needle puncture mechanism could reduce prostate displacement in the y- or z-direction. By this method, the prostate may be fixed, thus this mechanism maybe reduces rotation of the prostate and enabling subsequent needles to be inserted accurately.

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Effect of Point-Spread Function Reconstruction for Indeterminate PSMA-RADS-3A Lesions on PSMA-Targeted PET Imaging of Men with Prostate Cancer

Diagnostics ◽

10.3390/diagnostics11040665 ◽

2021 ◽

Vol 11 (4) ◽

pp. 665

Author(s):

Wajahat Khatri ◽

Hyun Woo Chung ◽

Rudolf A. Werner ◽

Jeffrey P. Leal ◽

Kenneth J. Pienta ◽

...

Keyword(s):

Prostate Cancer ◽

Soft Tissue ◽

Point Spread Function ◽

Prospective Trial ◽

Blood Pool ◽

True Positive ◽

Point Spread ◽

Standardized Uptake Values ◽

Spread Function

Purpose: Prostate-specific membrane antigen (PSMA) positron emission tomography (PET) is emerging as an important modality for imaging patients with prostate cancer (PCa). As with any imaging modality, indeterminate findings will arise. The PSMA reporting and data system (PSMA-RADS) version 1.0 codifies indeterminate soft tissue findings with the PSMA-RADS-3A moniker. We investigated the role of point-spread function (PSF) reconstructions on categorization of PSMA-RADS-3A lesions. Methods: This was a post hoc analysis of an institutional review board approved prospective trial. Around 60 min after the administration of 333 MBq (9 mCi) of PSMA-targeted 18F-DCFPyL, patients underwent PET/computed tomography (CT) acquisitions from the mid-thighs to the skull vertex. The PET data were reconstructed with and without PSF. Scans were categorized according to PSMA-RADS version 1.0, and all PSMA-RADS-3A lesions on non-PSF images were re-evaluated to determine if any could be re-categorized as PSMA-RADS-4. The maximum standardized uptake values (SUVs) of the lesions, mean SUVs of blood pool, and the ratios of those values were determined. Results: A total of 171 PSMA-RADS-3A lesions were identified in 30 patients for whom both PSF reconstructions and cross-sectional imaging follow-up were available. A total of 13/171 (7.6%) were re-categorized as PSMA-RADS-4 lesions with PSF reconstructions. A total of 112/171 (65.5%) were found on follow-up to be true positive for PCa, with all 13 of the re-categorized lesions being true positive on follow-up. The lesions that were re-categorized trended towards having higher SUVmax-lesion and SUVmax-lesion/SUVmean-blood-pool metrics, although these relationships were not statistically significant. Conclusions: The use of PSF reconstructions for 18F-DCFPyL PET can allow the appropriate re-categorization of a small number of indeterminate PSMA-RADS-3A soft tissue lesions as more definitive PSMA-RADS-4 lesions. The routine use of PSF reconstructions for PSMA-targeted PET may be of value at those sites that utilize this technology.

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Mechanics-Based Interactive Modeling for Medical Flexible Needle Insertion in Consideration of Nonlinear Factors

Journal of Computational and Nonlinear Dynamics ◽

10.1115/1.4030747 ◽

2016 ◽

Vol 11 (1) ◽

Cited By ~ 5

Author(s):

Shan Jiang ◽

Xingji Wang

Keyword(s):

Soft Tissue ◽

Kinematic Model ◽

Needle Insertion ◽

Winkler Foundation ◽

Nonlinear Characteristics ◽

Deformation Control ◽

Needle Deflection ◽

Iteration Cycle ◽

Foundation Model ◽

Sensitivity Studies

A mechanics-based model of flexible needle insertion into soft tissue is presented in this paper. Different from the existing kinematic model, a new model has been established based on the quasi-static principle, which also incorporates the dynamics of needle motions. In order to increase the accuracy of the model, nonlinear characteristics of the flexible needle and the soft tissue are both taken into account. The nonlinear Winkler foundation model and the modified Euler–Bernoulli theory are applied in this study, providing a theoretical framework to study insertion and deformation of needles. Galerkin method and iteration cycle analysis are applied in solving a series of deformation control equations to obtain the needle deflection. The parameters used in the mechanics-based model are obtained from the needle force and needle insertion experiment. Sensitivity studies show that the model can respond reasonably to changes in response to variations in different parameters. A 50 mm needle insertion simulation and a 50 mm corresponding needle insertion experiment are conducted to prove the validity of the model. At last, a study on different needle tip bevel demonstrates that the mechanics-based model can precisely predict the needle deflection when more than one parameter is changed. The solution can also be used in optimizing trajectory of the needle tip, enabling the needle to reach the target without touching important physiological structures such as blood vessels with the help of dynamic trajectory planning.

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Mechanics-based modeling of needle insertion into soft tissue

2013 IEEE/ASME International Conference on Advanced Intelligent Mechatronics ◽

10.1109/aim.2013.6584065 ◽

2013 ◽

Author(s):

Jianjun Wang ◽

Xiangpeng Li ◽

Jinjin Zheng ◽

Dong Sun

Keyword(s):

Soft Tissue ◽

Needle Insertion

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Gravitational potential energy and active deformation in the Apennines

Earth and Planetary Science Letters ◽

10.1016/j.epsl.2014.04.013 ◽

2014 ◽

Vol 397 ◽

pp. 121-132 ◽

Cited By ~ 20

Author(s):

N. D'Agostino ◽

P. England ◽

I. Hunstad ◽

G. Selvaggi

Keyword(s):

Potential Energy ◽

Gravitational Potential ◽

Gravitational Potential Energy ◽

Active Deformation

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Transperineal Permanent Seed Implantation of “Low-Risk” Prostate Cancer

Strahlentherapie und Onkologie ◽

10.1007/s00066-006-1570-4 ◽

2006 ◽

Vol 182 (11) ◽

pp. 666-671 ◽

Cited By ~ 7

Author(s):

Thomas Block ◽

Heinz Czempiel ◽

Frank Zimmermann

Keyword(s):

Prostate Cancer ◽

Low Risk ◽

Seed Implantation ◽

Risk Prostate Cancer ◽

Low Risk Prostate Cancer

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Tracker-assisted modelling: simultaneous validation of the conservation law of energy and the work-energy theorem

Physics Education ◽

10.1088/1361-6552/ac36a9 ◽

2021 ◽

Vol 57 (1) ◽

pp. 015012

Author(s):

Unofre B Pili ◽

Renante R Violanda

Keyword(s):

Kinetic Energy ◽

Potential Energy ◽

Gravitational Potential ◽

Conservation Law ◽

Gravitational Potential Energy ◽

Time Data ◽

Home Based ◽

Basic Physics ◽

Free Falling ◽

Work Done

Abstract The video of a free-falling object was analysed in Tracker in order to extract the position and time data. On the basis of these data, the velocity, gravitational potential energy, kinetic energy, and the work done by gravity were obtained. These led to a rather simultaneous validation of the conservation law of energy and the work–energy theorem. The superimposed plots of the kinetic energy, gravitational potential energy, and the total energy as respective functions of time and position demonstrate energy conservation quite well. The same results were observed from the plots of the potential energy against the kinetic energy. On the other hand, the work–energy theorem has emerged from the plot of the total work-done against the change in kinetic energy. Because of the accessibility of the setup, the current work is seen as suitable for a home-based activity, during these times of the pandemic in particular in which online learning has remained to be the format in some countries. With the guidance of a teacher, online or face-to-face, students in their junior or senior high school—as well as for those who are enrolled in basic physics in college—will be able to benefit from this work.

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Walking in simulated reduced gravity: mechanical energy fluctuations and exchange

Journal of Applied Physiology ◽

10.1152/jappl.1999.86.1.383 ◽

1999 ◽

Vol 86 (1) ◽

pp. 383-390 ◽

Cited By ~ 55

Author(s):

Timothy M. Griffin ◽

Neil A. Tolani ◽

Rodger Kram

Keyword(s):

Kinetic Energy ◽

Potential Energy ◽

Gravitational Potential ◽

Inverted Pendulum ◽

Mechanical Energy ◽

Center Of Mass ◽

Metabolic Cost ◽

Metabolic Energy ◽

Gravitational Potential Energy ◽

Reduced Gravity

Walking humans conserve mechanical and, presumably, metabolic energy with an inverted pendulum-like exchange of gravitational potential energy and horizontal kinetic energy. Walking in simulated reduced gravity involves a relatively high metabolic cost, suggesting that the inverted-pendulum mechanism is disrupted because of a mismatch of potential and kinetic energy. We tested this hypothesis by measuring the fluctuations and exchange of mechanical energy of the center of mass at different combinations of velocity and simulated reduced gravity. Subjects walked with smaller fluctuations in horizontal velocity in lower gravity, such that the ratio of horizontal kinetic to gravitational potential energy fluctuations remained constant over a fourfold change in gravity. The amount of exchange, or percent recovery, at 1.00 m/s was not significantly different at 1.00, 0.75, and 0.50 G (average 64.4%), although it decreased to 48% at 0.25 G. As a result, the amount of work performed on the center of mass does not explain the relatively high metabolic cost of walking in simulated reduced gravity.

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Comparison of PSMA PET/CT With Fluoride PET/CT for Detection of Bone Metastatic Disease in Prostate Cancer

10.21203/rs.3.rs-776117/v2 ◽

2021 ◽

Author(s):

Naresh Kumar Regula ◽

Vasileios Kostaras ◽

Silvia Johansson ◽

Carlos Trampal ◽

Elin Lindström ◽

...

Keyword(s):

Prostate Cancer ◽

Lymph Node ◽

Bone Metastasis ◽

Soft Tissue ◽

Diagnostic Performance ◽

Bone Lesions ◽

Soft Tissue Lesions ◽

Contrast Enhanced Ct ◽

Psma Pet ◽

Pet Ct

Abstract 18F-NaF positron emission tomography/computed tomography (fluoride PET/CT) is considered the most sensitive technique to detect bone metastasis in prostate cancer (PCa). 68Ga-PSMA-11 (PSMA) PET/CT is increasingly used for staging of PCa. This study primarily aimed to compare the diagnostic performance of fluoride PET/CT and Gallium based PSMA PET/CT in identifying bone metastasis followed by a comparison of PSMA PET/CT with contrast-enhanced CT (CE-CT) in identifying soft tissue lesions as a secondary objective. Methods: Twenty-eight PCa patients with high suspicion of disseminated disease following curative treatment were prospectively evaluated. PET/CT examinations using fluoride and PSMA were performed. All suspicious bone lesions were counted, and the tracer uptake was measured as standardized uptake values (SUV) for both tracers. In patients with multiple findings, ten bone lesions with highest SUVmax were selected from which identical lesions from both scans were considered for direct comparison of SUVmax. Soft tissue findings of local and lymph node lesions from CE-CT were compared with PSMA PET/CT. Results: Both scans were negative for bone lesions in 7 patients (25%). Of 699 lesions consistent with skeletal metastasis in 21 patients on fluoride PET/CT, PSMA PET/CT identified 579 lesions (83%). In 69 identical bone lesions fluoride PET/CT showed significantly higher uptake (mean SUVmax: 73.1±36.8) compared to PSMA PET/CT (34.5±31.4; p<0.001). Compared to CE-CT, PSMA PET/CT showed better diagnostic performance in locating local (96% vs 61%, p=0.004) and lymph node (94% vs 46%, p<0.001) metastasis. Conclusion: In this prospective comparative study PSMA PET/CT detected the majority of bone lesions that were positive on fluoride PET/CT. Further, this study indicates better diagnostic performance of PSMA PET/CT to locate soft tissue lesions compared to CE-CT.

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