Development of a pneumatic robot for MRI-guided transperineal prostate biopsy and brachytherapy: New approaches

Song, Sang-Eun; Cho, Nathan B.; Fischer, Gregory S.; Hata, N.; Tempany, Clare M.; Fichtinger, Gabor; Iordachita, Iulian

doi:10.1109/robot.2010.5509710

Cited by 47 publications

(9 citation statements)

References 25 publications

(24 reference statements)

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“…However, hydraulic actuators are rarely used because of their high risk of leakage in cases in which sterility is critical, and also because of their inherent controllability issues [ 6 ]. Pneumatic motors also suffer from issues of stability, controllability in motion, and high complexity, while requiring tightly geared break mechanisms to lock the system in a malfunction case [ 7 , 8 ]. Ultrasonic motors (USMs) have the advantages of high accuracy, high torque/size ratio, compactness, and non-back-drivability (i.e., they cannot move when turned off).…”

Section: Introductionmentioning

confidence: 99%

Signal-to-noise ratio evaluation of magnetic resonance images in the presence of an ultrasonic motor

2017

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BackgroundSafe robot-assisted intervention using magnetic resonance imaging (MRI) guidance requires the precise control of assistive devices, and most currently available tools are rarely MRI-compatible. To obtain high precision, it is necessary to characterize and develop existing MRI-safe actuators for use in a high magnetic field (≥3 T). Although an ultrasonic motor (USM) is considered to be an MRI-safe actuator, and can be used in the vicinity of a high field scanner, its presence interferes with MR images. Although an MR image provides valuable information regarding the pathology of a patient’s body, noise, generally of a granular type, decreases the quality of the image and jeopardizes the true evaluation of any existing pathological issues. An eddy current induced in the conductor material of the motor structure can be a source of noise when the motor is close to the isocenter of the image. We aimed to assess the effects of a USM on the signal-to-noise ratio (SNR) of MR images in a 3-T scanner. The SNR was compared for four image sequences in transverse directions for three orientations of the motor (x, y, and z) when the motor was in the “off” state. The SNR was evaluated to assess three artifact reduction methods used to minimize the motor-induced artifacts.ResultsThe SNR had a range of 5–10 dB for slices close to the motor in the x and y orientations, and increased to 15–20 dB for slices far from the motor. Averaging the SNR for slices in all cases gave an SNR loss of about 10 dB. The maximum SNR was measured in the z orientation. In this case, the SNR loss was almost the same as that of other motor orientations, approximately 10 dB, but with a higher range, approximately 20–40 dB.ConclusionsThe selection of certain scanning parameters is necessary for reducing motor-generated artifacts. These parameters include slice selection and bandwidth. In developing any MRI-compatible assisted device actuated by a USM, this study recommends the use of an approximately 3-mm slice thickness with minimum bandwidth to achieve optimized SNR values when a USM is operating close to (within approximately 40 mm) the region being imaged. The SNR can be further enhanced by increasing the number of signal averages, but this is achieved only at the cost of increased scan duration.

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Section: Introductionmentioning

confidence: 99%

Signal-to-noise ratio evaluation of magnetic resonance images in the presence of an ultrasonic motor

2017

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“…Even for robots equipped with needle insertion and tissue sampling or seed deployment mechanisms for a fully automated process, it is crucial to secure safe access to the patient in the bore. To address these issues, we have been developing an MRI-compatible pneumatic robot for needle placement with a four degrees-of-freedom (4-DOF) parallel kinematic structure that effectively utilizes the space under the legs of the patient in the lithotomy position [29,30]. The robot is designed to guide a needle towards a lesion so that a radiologist can manually insert it in the bore.…”

Section: Introductionmentioning

confidence: 99%

“…Although the kinematic structure was designed for an angulated insertion, it has never been validated with an MRI scanner in our past studies [30,29,31] due to the lack of a practical user interface to plan an angulated needle insertion intuitively. The user interface was integrated with our navigation software, 3D Slicer with ProstateNav software plug-in module, which has been used in our ongoing clinical trial of MRI-guided manual prostate biopsy using a template [23].…”

Section: Introductionmentioning

confidence: 99%

Preclinical evaluation of an MRI-compatible pneumatic robot for angulated needle placement in transperineal prostate interventions

et al. 2012

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Purpose To evaluate the targeting accuracy of a small profile MRI-compatible pneumatic robot for needle placement that can angulate a needle insertion path into a large accessible target volume. Methods We extended our MRI-compatible pneumatic robot for needle placement to utilize its four degrees-of-freedom (4-DOF) mechanism with two parallel triangular structures and support transperineal prostate biopsies in a closed-bore magnetic resonance imaging (MRI) scanner. The robot is designed to guide a needle towards a lesion so that a radiologist can manually insert it in the bore. The robot is integrated with navigation software that allows an operator to plan angulated needle insertion by selecting a target and an entry point. The targeting error was evaluated while the angle between the needle insertion path and the static magnetic field was between −5.7° and 5.7° horizontally and between −5.7° and 4.3° vertically in the MRI scanner after sterilizing and draping the device. Results The robot positioned the needle for angulated insertion as specified on the navigation software with overall targeting error of 0.8 ± 0.5 mm along the horizontal axis and 0.8 ± 0.8 mm along the vertical axis. The two-dimensional root-mean-square targeting error on the axial slices as containing the targets was 1.4 mm. Conclusions Our preclinical evaluation demonstrated that the MRI-compatible pneumatic robot for needle placement with the capability to angulate the needle insertion path provides targeting accuracy feasible for clinical MRI-guided prostate interventions. The clinical feasibility has to be established in a clinical study.

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“…Several of these systems can accommodate various needle drivers for different percutaneous interventions such as biopsy, thermal ablation, or brachytherapy. Some have novel features such as compatibility with an MRI environment [ 10 – 12 , 30 , 31 ]. Similarly, robots are also being developed for brachytherapy in other sites such as lung [ 32 , 33 ].…”

Section: Discussionmentioning

confidence: 99%

Reduced dose to urethra and rectum with the use of variable needle spacing in prostate brachytherapy: a potential role for robotic technology

Vyas¹,

Le²,

Zhang³

et al. 2015

jcb

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PurposeSeveral robotic delivery systems for prostate brachytherapy are under development or in pre-clinical testing. One of the features of robotic brachytherapy is the ability to vary spacing of needles at non-fixed intervals. This feature may play an important role in prostate brachytherapy, which is traditionally template-based with fixed needle spacing of 0.5 cm. We sought to quantify potential reductions in the dose to urethra and rectum by utilizing variable needle spacing, as compared to fixed needle spacing.Material and methodsTransrectal ultrasound images from 10 patients were used by 3 experienced planners to create 120 treatment plans. Each planner created 4 plan variations per patient with respect to needle positions: 125I fixed spacing, 125I variable spacing, 103Pd fixed spacing, and 103Pd variable spacing. The primary planning objective was to achieve a prostate V100 of 100% while minimizing dose to urethra and rectum.ResultsAll plans met the objective of achieving prostate V100 of 100%. Combined results for all plans show statistically significant improvements in all assessed dosimetric variables for urethra (Umax, Umean, D30, D5) and rectum (Rmax, Rmean, RV100) when using variable spacing. The dose reductions for mean and maximum urethra dose using variable spacing had p values of 0.011 and 0.024 with 103Pd, and 0.007 and 0.029 with 125I plans. Similarly dose reductions for mean and maximum rectal dose using variable spacing had p values of 0.007 and 0.052 with 103Pd, and 0.012 and 0.037 with 125I plans.ConclusionsThe variable needle spacing achievable by the use of robotics in prostate brachytherapy allows for reductions in both urethral and rectal planned doses while maintaining prostate dose coverage. Such dosimetric advantages have the potential in translating to significant clinical benefits with the use of robotic brachytherapy.

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Development of a pneumatic robot for MRI-guided transperineal prostate biopsy and brachytherapy: New approaches

Cited by 47 publications

References 25 publications

Signal-to-noise ratio evaluation of magnetic resonance images in the presence of an ultrasonic motor

Signal-to-noise ratio evaluation of magnetic resonance images in the presence of an ultrasonic motor

Preclinical evaluation of an MRI-compatible pneumatic robot for angulated needle placement in transperineal prostate interventions

Reduced dose to urethra and rectum with the use of variable needle spacing in prostate brachytherapy: a potential role for robotic technology

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