D. Fuller

In vivo motion and force measurement of surgical needle intervention during prostate brachytherapy

In this paper, we present needle insertion forces and motion trajectories measured during actual brachytherapy needle insertion while implanting radioactive seeds in the prostate glands of 20 different patients. The needle motion was captured using ultrasound images and a 6 degree-of-freedom electromagnetic-based position sensor. Needle velocity was computed from the position information and the corresponding time stamps. From in vivo data we found the maximum needle insertion forces to be about 15.6 and 8.9N for 17gauge (1.47mm) and 18gauge (1.27mm) needles, respectively. Part of this difference in insertion forces is due to the needle size difference (17G and 18G) and the other part is due to the difference in tissue properties that are specific to the individual patient. Some transverse forces were observed, which are attributed to several factors such as tissue heterogeneity, organ movement, human factors in surgery, and the interaction between the template and the needle. However, theses insertion forces are significantly responsible for needle deviation from the desired trajectory and target movement. Therefore, a proper selection of needle and modulated velocity (translational and rotational) may reduce the tissue deformation and target movement by reducing insertion forces and thereby improve the seed delivery accuracy. The knowledge gleaned from this study promises to be useful for not only designing mechanical/robotic systems but also developing a predictive deformation model of the prostate and real-time adaptive controlling of the needle.

Robot-Assisted prostate brachytherapy

In contemporary brachytherapy procedures, needle placement at the desired target is challenging due to a variety of reasons. A robot-assisted brachytherapy system can improve the needle placement and seed delivery resulting in enhanced patient care. In this paper we present a 16 DOF (degrees-of-freedom) robotic system (9DOF positioning module and 7 DOF surgery module) developed and fabricated for prostate brachytherapy. Techniques to reduce needle deflection and target movement have been incorporated after verifying with extensive experiments. Provisions for needle motion and force feedback have been included into the system for improving the robot control and seed delivery. Preliminary experimental results reveal that the prototype system is quite accurate (sub-millimeter) in placing brachytherapy needles.

Effects of Velocity Modulation during Surgical Needle Insertion

Precise interstitial intervention is essential for many medical diagnostic and therapeutic procedures. But accurate insertion and placement of surgical needle in soft tissue is quite challenging. The understanding of the interaction between surgical needle and soft tissue is very important to develop new devices and systems to achieve better accuracy and to deliver quality treatment. In this paper we present the effects of velocity (linear, rotational, and oscillatory) modulation on needle force and target deflection. We have experimentally verified our hypothesis that needle insertion with continuous rotation reduces target movement and needle force significantly. We have observed little changes in force and target deflection in rotational oscillation (at least at lower frequency) of the needle

Robotic system for prostate brachytherapy.

In contemporary brachytherapy procedures, needle placement at the desired target is challenging for a variety of reasons. A robot-assisted brachytherapy system can potentially improve needle placement and seed delivery, resulting in enhanced therapeutic outcome. In this paper we present a robotic system with 16 degrees of freedom (DOF) (9 DOF for the positioning module and 7 DOF for the surgery module) that has been developed and fabricated for prostate brachytherapy. Strategies to reduce needle deflection and target movement were incorporated after extensive experimental validation. Provision for needle motion and force feedback was included in the system to improve robot control and seed delivery. Preliminary experimental results reveal that the prototype system is sufficiently accurate in placing brachytherapy needles.

Needle insertion force estimation model using procedure-specific and patient-specific criteria.

Placement accuracy of different types of surgical needles in soft biological tissues depends on a variety of factors. The needles used for prostate brachytherapy procedures are typically about 200 mm in length and 1.27-1.47 mm in diameter. These needles are prone to deflection and thereby depositing the seeds at a location other than the planned one. Thus tumorous tissues may not receive the planned dose whereas the critical organs may be over-dosed. A significant amount of needle deflection and target movement is related to some procedure-specific criteria and some patient-specific criteria. In this paper we have developed needle insertion force models taking both procedure-specific criteria and patient-specific criteria. These statistical models can be used to estimate the force that the needle will experience during insertion and thereby control the needle to reduce the needle deflection and enhance seed delivery accuracy

In-vivo Measurement of Surgical Needle Intervention Parameters: A Pilot Study

Percutaneous intervention is essential in numerous medical diagnostic and therapeutic procedures. In these procedures, accurate insertion of the surgical needle is very important. But precise interstitial intervention is quite challenging. Robot-assisted needle intervention can significantly improve accuracy and consistency of various medical procedures. To design and control any robotic system, the design and control engineers must know the forces that will be encountered by the system and the motion trajectories that the needling mechanism will have to follow. Several researchers have reported needle insertion forces encountered while steering through soft tissue and soft material phantoms, but hardly any in-vivo force measurement data is available in the literature. In this paper, we present needle insertion forces and motion trajectories measured during actual brachytherapy needle insertion while implanting radioactive seeds in the prostate glands of twenty five patients

Semi-automated Needling and Seed Delivery Device for Prostate Brachytherapy

In this paper we present a semi-automated device designed and developed to deliver radio-active seeds for treating prostate cancer. In the brachytherapy procedure a slander needle is inserted through the perineum and passed through different types of tissues. Thus, the needle experiences significant amount of force which may cause it to buckle and bend. In our design, we have considered the buckling force and insertion force on needle by collecting in-vivo data from real patient and performing in-vitro experiments. Techniques to reduce force and organ/tissue deformation have been implemented into this new design. To track the axial force on the needle for detecting pubic arch interference and to improve robotic control, we have incorporated three force sensors. Rigidity and factor of safety of the device has been analyzed using finite element method which was very useful for iterative design process

A method to minimize puncturing force and organ deformation

A robotic system providing force feedback and automation for minimally invasive heart surgery H. Mayer Æ I. Nagy Æ A. Knoll Æ E.U. Schirmbeck Æ R. Bauernschmitt Robotics and Embedded Systems Lab, Technical University Munich, Germnay Department of Cardiovascular Surgery, German Heart Center Munich, Germany Abstract We have developed an experimental system for robotic heart surgery, which provides force feedback and full Cartesian control on each of the four end effectors Currently the system is used to determine the degree of automation that can be included into surgical procedures. Therefore we have included an optical system with thread recognition and we provide assistance to the surgeon via automated knot-tying.

Efficacy of Prostate Stabilizing Techniques during Brachytherapy Procedure

During the prostate brachytherapy procedure, multiple needles are inserted into the prostate and radioactive seeds are deposited. Stabilizing needles are first inserted to provide some rigidity and support to the prostate, ideally this will provide better seed placement and an overall improved treatment. However, there is much speculation regarding the effectiveness of using regular brachytherapy needles as stabilizers. In this study, we explored the efficacy of (1) two types of needles -18 gauge brachytherapy needle vs. 18 gauge hooked needle; and (2) parallel vs. angulated needle configurations to stabilize the prostate. Prostate phantom movement and needle insertion progression were imaged using ultrasound (US). The recorded images were analyzed and prostate displacement was computed from images using implanted artifacts. Experimentation allowed us to further understand the mechanics behind prostate stabilization. We observed superior stabilization by the hooked needles compared to the regular brachytherapy needles (more than 40% for parallel stabilization). Prostate movement was also reduced significantly when regular brachytherapy needles were in an angulated configuration as compared to the parallel configuration (approximately 40%). When the hooked needles were angled for stabilization, further improvement in decreased displacement was observed. In general, for convenience of dosimetric planning, all needles are desired to be in parallel and in this case, hooked needles are better suited to improve stabilization of the prostate. On the other hand, both regular and hooked needles appear to be equally effective in reducing prostate movement when they are in angulated configurations, which will be useful in robotic permanent seed implantation (PSI)

Robot-Assisted Platform for Intratumoral Delivery (RAPID)

In prostate brachytherapy, radioactive seeds are permanently implanted in the prostate for delivering a tumorocidal dose to the cancerous tissues. These seeds provide a significant radiation dose to a relatively small volume, requiring that the seeds be placed accurately to ensure complete treatment. Sensitivity of the urethra and rectal mucosa to radiation are other factors that heighten the need for careful placement of the seeds. In currently practiced manual procedures, the needles are inserted into the patient through fixed holes of a physical template where the maneuverability of the needle is extremely difficult. In contrast, a robotic system can not only provide flexibility in positioning and orientating along with improved consistency and accuracy of needle insertion and seed deposition but may also assist less skillful/inexperienced clinicians to treat patients with higher quality. Thus, it is important to develop an automated (or a semiautomated) seed delivery device which can provide enhanced consistency, accuracy and efficiency.