Sanjeev Soni

Investigation on nanoparticle distribution for thermal ablation of a tumour subjected to nanoparticle assisted thermal therapy

This study investigates the effect of the distribution of nanoparticles delivered to a skin tumour for the thermal ablation conditions attained during thermal therapy. Ultimate aim is to define a distribution of nanoparticles as well as a combination of other therapeutic parameters to attain thermal ablation temperatures (50-60 °C) within whole of the tumour region. Three different cases of nanoparticle distributions are analysed under controlled conditions for all other parameters viz. irradiation intensity and duration, and volume fraction of nanoparticles. Results show that distribution of nanoparticles into only the periphery of tumour resulted in desired thermal ablation temperature in whole of tumour. For the tumour size considered in this study, an irradiation intensity of 1.25 W/cm(2) for duration of 300 s and a nanoparticle volume fraction of 0.001% was optimal to attain a temperature of ≥53 °C within the whole tumour region. It is concluded that distribution of nanoparticles in peripheral region of tumour, along with a controlled combination of other parameters, seems favourable and provides a promising pathway for thermal ablation of a tumour subjected to nanoparticle assisted thermal therapy.

Role of optical coefficients and healthy tissue-sparing characteristics in gold nanorod-assisted thermal therapy.

Purpose: This study seeks to define parameters for gold nanorod assisted thermal therapy, to achieve the thermal ablation temperature (50–60°C) in the tumour region and spare healthy tissue surrounding the tumour. Also, a criterion for size selection of gold nanorods is described based on the role of optical coefficients. Theory and methods: In this study a tissue domain (comprising a 3 mm tumour and 7 mm of surrounding healthy tissue) embedded with gold nanorods is irradiated with electromagnetic radiation within the therapeutic wavelength band. Optical interaction is captured using light scattering theory (Mie-electrostatic approach). The resulting temperature field is evaluated using Pennes bioheat model. The effect of key parameters, namely irradiation intensity, irradiation duration and volume fraction, on tissue temperature is also modelled numerically. Results: With increasing nanorod diameter – from 5 nm to 15 nm – the scattering coefficient increases ∼76 times as compared to a 1.7-fold increase in absorption coefficient. Scattering is considerably minimised by having smaller gold nanorods of 5 nm diameter. For this study, gold nanorods of 5 nm diameter and volume fraction 0.001%, irradiated with 50 W/m2-nm for 250 s ablated the tumour as well as spare healthy tissue 2 mm beyond the tumour region. Conclusion: Overall it may be concluded that tumour ablation as well as surrounding healthy tissue-sparing (within millimetres immediately adjacent to the tumour) can be achieved through a combination of specified parameters, namely diameter and volume fraction of gold nanorods, irradiation intensity and duration.

Extension of D-H parameter method to hybrid manipulators used in robot-assisted surgery

The main focus of this work is to extend the applicability of D-H parameter method to develop a kinematic model of a hybrid manipulator. A hybrid manipulator is a combination of open- and closed-loop chains and contains planar and spatial links. It has been found in the literature that D-H parameter method leads to ambiguities, when dealing with closed-loop chains. In this work, it has been observed that the D-H parameter method, when applied to a hybrid manipulator, results in an orientational inconsistency, because of which the method cannot be used to develop the kinematic model. In this article, the concept of dummy frames is proposed to resolve the orientational inconsistency and to develop the kinematic model of a hybrid manipulator. Moreover, the prototype of 7-degree-of-freedom hybrid manipulator, known as a surgeon-side manipulator to assist the surgeon during a medical surgery, is also developed to validate the kinematic model derived in this work.

The influence of tumour blood perfusion variability on thermal damage during nanoparticle-assisted thermal therapy

Abstract Purpose: This study investigates the influence of blood perfusion variability within a tumour and the surrounding healthy tissue during nanoparticle-assisted thermal therapy. It seeks to define ideal therapeutic parameters for a wide range of perfusion rates to attain the desired thermal damage. Material and methods: Pennes’ bioheat model and the Arrhenius model are used to evaluate the thermal damage for a two-dimensional tumour surrounded by healthy tissue. A wide range of tumour perfusion rates were modelled, ranging from moderate to high perfusion in both a homogenously and a heterogeneously perfused tumour. Results: For low perfusion rates, a temporal variation in blood perfusion does not critically influence the thermal damage. For moderately and highly perfused tumours, temporal variation in blood perfusion extends the thermal damage zone by 25–52% compared to a constant perfusion rate. For the tumour size and perfusion conditions under consideration, the ideal therapeutic parameters were found to be irradiation intensity of 1 W/cm2, and irradiation duration of 105–150 s, for a nanoparticle volume fraction of 0.001%. Conclusions: It is concluded for low perfusion rates that due to shorter therapeutic duration, nanoparticle-assisted thermal therapy is relatively insensitive to changes in the perfusion rate during the therapy. For moderately and highly perfused tumours, a constant perfusion under-predicts the real thermal damage zone. This study concludes that for moderately and highly perfused tumours the spatial as well as temporal blood perfusion dynamics should be carefully accounted for to get a realistic estimate of thermal damage zone.

D-H parameters augmented with dummy frames for serial manipulators containing spatial links

Conventional kinematic studies of serial manipulators involve the proper selection of coordinate frames of reference at appropriate positions. The standard practice, being used in the past, is the use of Denavit-Hartenberg (D-H) algorithm for assigning coordinate frames. However, it has been observed that when an open kinematic chain contains a spatial link with two consecutive joint axes at right angle to each other, the forward kinematics derived with D-H algorithm comes geometrically inconsistent. A typical spatial link involves more than one non-zero link/joint parameters, which are not being accounted for, in the corresponding D-H parameter table. Forward kinematic study of manipulators involving spatial links with two consecutive joint axes at right angles to each other leads to recognizable deficiency of the D-H algorithm, as one of its practical limitation. In the present work, the concept of dummy frames is proposed to eliminate this deficiency. The proposed concept is demonstrated successfully for the case study of a Manipulator for Medical Application (MMA), which is a seven degrees-of-freedom (DOF) manipulator containing spatial links. Both geometrical and physical validation is performed to ensure the efficacy of the proposed concept.

Exoskeleton Device for Rehabilitation of Stroke Patients Using SEMG during Isometric Contraction

Robots are becoming more interactive and assisting to human beings day by day. They are serving humanity in the fields of industry, defense and medicine. Exoskeletons are also devices that reside in category of wearable robotics. An exoskeleton is an external structural mechanism with joints and links corresponding to those of the human body. With applications in rehabilitation medicine and virtual reality simulation, exoskeletons offer benefits for both disabled and healthy populations. Exoskeletons can be used as a capability magnifier or assisting device. This paper presents a proposed design for smart active exoskeleton for lower limbs. This proposed exoskeleton design not only assist a person but also tries to improve its GAIT. The twin wearable legs are powered by Actuators, all controlled by a microprocessor. The simulation results of the control mechanism shows its smart capabilities. In addition, the processor based control produces a more natural muscle like activity and as such can be considered a soft and bio-mimetic actuation system. This capacity to “replicate” the function of natural muscle and inherent safety is extremely important when working in close proximity to humans. The integration of the components sections and testing of the performance will also be considered to show how the structure and actuators can be combined to produce the various systems needed for a highly flexible/low weight clinically viable rehabilitation exoskeleton.

Kinematic modeling of a 7-degree of freedom spatial hybrid manipulator for medical surgery:

The prime objective of this work is to deal with the kinematics of spatial hybrid manipulators. In this direction, in 1955, Denavit and Hartenberg proposed a consistent and concise method, known as D-H parameters method, to deal with kinematics of open serial chains. From literature review, it is found that D-H parameter method is widely used to model manipulators consisting of lower pairs. However, the method leads to ambiguities when applied to closed-loop, tree-like and hybrid manipulators. Furthermore, in the dearth of any direct method to model closed-loop, tree-like and hybrid manipulators, revisions of this method have been proposed from time-to-time by different researchers. One such kind of revision using the concept of dummy frames has successfully been proposed and implemented by the authors on spatial hybrid manipulators. In that work, authors have addressed the orientational inconsistency of the D-H parameter method, restricted to body-attached frames only. In the current work, the condition of body-attached frames is relaxed and spatial frame attachment is considered to derive the kinematic model of a 7-degree of freedom spatial hybrid robotic arm, along with the development of closed-loop constraints. The validation of the new kinematic model has been performed with the help of a prototype of this 7-degree of freedom arm, which is being developed at Council of Scientific & Industrial Research–Central Scientific Instruments Organisation Chandigarh to aid the surgeon during a medical surgical task. Furthermore, the developed kinematic model is used to develop the first column of the Jacobian matrix, which helps in providing the estimate of the tip velocity of the 7-degree of freedom manipulator when the first joint velocity is known.

Adaptive neuro-fuzzy inference system–based path planning of 5-degrees-of-freedom spatial manipulator for medical applications:

Over the last few decades, medical-assisted robots have been considered by many researchers, within the research domain of robotics. In this article, a 5-degrees-of-freedom spatial medical manipulator is analyzed for path planning, based on inverse kinematic solutions. Analytical methods have generally employed for finding the inverse kinematic solutions in earlier studies. However, this method is only appreciable in case of closed-form solutions. The unusual joint configurations of considered manipulator result in more complexity to attain the closed-form solutions, analytically. To overcome with shortcomings of analytical method, a non-traditional approach named adaptive neuro-fuzzy inference system is proposed under the class of artificial intelligent techniques. This article presents this neuro-fuzzy approach for desired path generation by 5-degrees-of-freedom manipulator. The estimation of percentage error between actual path and adaptive neuro-fuzzy inference system–generated path is done with respect to x, y, and z directions, respectively. Furthermore, the error between actual and predicted values regarding joint parameters is calculated for a certain arm matrix. The prototype of 5-degrees-of-freedom medical-assisted manipulator is developed at CSIR-CSIO Laboratory Chandigarh, which is also termed as patient-side manipulator to be utilized in robot-assisted surgery. Through the simulation runs, in this work, it is found that the results from adaptive neuro-fuzzy inference system approach are quite satisfactory and acceptable.

Effect of Nanoparticle Concentration on Thermal Damage in Nanoparticle-Assisted Thermal Therapy

Photothermal therapy involving nanoparticles is evolving as a promising targeted treatment for cancer. This paper presents the results for the effect of nanoparticle concentration, within a tumor, to control the thermal damage during nanoparticle assisted thermal therapy.A surface tumor embedded with gold nanoparticles (distributed uniformly) is considered. The thermal damage is evaluated for various nanoparticle concentrations (within the tumor) to identify an optimal concentration of the nanoparticles so as to achieve spatial confinement of the damage to the tumor region. Optical interaction is coupled to the biological heat transfer through Pennes’ bioheat model and Beer’s law. Spatiotemporal thermal damage is simulated through the Arrhenius method. The finite difference implicit method is used to solve the coupled phenomenon.Results show that there is a specific value of nanoparticle concentration at which it is possible to confine thermal damage to the tumor within a spatial scale of less than 1 mm. This way the healthy tissues surrounding a tumor are safe. This optimum value of nanoparticle concentration (irrespective of tumor diameters) is 0.00001%. This concentration along with irradiation intensity of 1 W/cm2 for irradiation duration of 110 seconds is sufficient to thermally ablate the considered tumors. Novelty of this study is that it presents a combination of the controlling parameters for achieving a high (<1 mm) spatial confinement of the thermal damage. This finding is very much significant from clinical point of view. Clinically it is always desired to attain the therapeutic efficacy with minimal delivery of external agents (nanoparticles in this case) to a patient.Copyright

Spatiotemporal Temperature in a Tumor During Nanorod Assisted Thermal Therapy

Gold nanoparticles, especially nanorods, are emerging as a promising future material to achieve targeted thermal treatment for cancer. The treatment involves nanoparticle-radiation interaction phenomenon to generate the heat confined to a specific region. Obtaining effective treatments requires a more detailed theoretical understanding of this phenomenon. This study evaluates the temperature field in a tumor tissue embedded with gold nanorods, considering a two dimensional domain representing a skin tumor, irradiated with near infrared radiation. The results indicate that it is possible to localize the heat damage to the tumor region while surrounding healthy tissues are spared. The developed numerical model predicts the temperature through various input of the involved process parameters like size, concentration and irradiation intensity.Copyright