Dr. Sergio Curto Profile

Dr. Sergio Curto

at Kansas State Univ

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Publications (3)

Proceedings Article | 12 March 2015 Paper

Multiple-antenna microwave ablation: analysis of non-parallel antenna implants

Souvick Mukherjee, Sergio Curto, Nathan Albin, Bala Natarajan, Punit Prakash

Proceedings Volume 9326, 93260U (2015) https://doi.org/10.1117/12.2080349

KEYWORDS: Antennas, Tissues, Microwave radiation, Electromagnetism, 3D modeling, Tumors, Laser ablation, Cancer, Oncology, Numerical modeling

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Proceedings Article | 12 March 2015 Paper

Development of a fast 3D treatment planning platform for clinical interstitial microwave hyperthermia within free-hand obliquely implanted HDR catheters

Serena Scott, Vasant Salgaonkar, Punit Prakash, Sergio Curto, I-Chow Hsu, Chris Diederich

Proceedings Volume 9326, 93260X (2015) https://doi.org/10.1117/12.2079701

KEYWORDS: Antennas, Tissues, 3D modeling, Superposition, Microwave radiation, Liquid crystals, High dynamic range imaging, Dielectrics, Blood, Distance measurement

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A treatment planning platform for interstitial microwave hyperthermia was developed for practical, free-hand clinical implants. Such implants, consisting of non-parallel, moderately curved antennas with varying insertion depths, are used in HDR brachytherapy for treating locally advanced cancer.

Numerical models for commercially available MA251 antennas (915 MHz, BSD Medical) were developed in COMSOL Multiphysics, a finite element analysis software package. To expedite treatment planning, electric fields, power deposition and temperature rises were computed for a single straight antenna in 2D axisymmetric geometry. A precomputed library of electric field and temperature solutions was created for a range of insertion depths (5-12 cm) and blood perfusion rates (0.5-5 kg/m³/s). 3D models of multiple antennas and benchtop phantoms experiments using temperature-sensitive liquid crystal paper to monitor heating by curved antennas were performed for comparative evaluation of the treatment planning platform.

A patient-customizable hyperthermia treatment planning software package was developed in MATLAB with capabilities to interface with a commercial radiation therapy planning platform (Oncentra, Nucleotron), import patient and multicatheter implant geometries, calculate insertion depths, and perform hyperthermia planning with antennas operating in asynchronous or synchronous mode. During asynchronous operation, the net power deposition and temperature rises were approximated as a superposition sum of the respective quantities for one single antenna. During synchronous excitation, a superposition of complex electrical fields was performed with appropriate phasing to compute power deposition. Electric fields and temperatures from the pre-computed single-antenna library were utilized following appropriate non-rigid coordinate transformations. Comparison to 3D models indicated that superposition of electric fields around parallel antennas is valid when they are at least 15 mm apart. Phantom experiments with curved antennas produced temperature profiles quite similar to those created using the planning system.

The hyperthermia planning software allowed users to select power and phasing, assess the corresponding 3D contours of energy and temperature, and optimize treatment parameters through gradient search techniques. The system produces fairly accurate temperature distributions in cases when the antennas are at least 15 mm apart.

Proceedings Article | 12 March 2015 Paper

Design and analysis of a conformal patch antenna for a wearable breast hyperthermia treatment system

Sergio Curto, Manoshika Ramasamy, Minyoung Suh, Punit Prakash

Proceedings Volume 9326, 93260I (2015) https://doi.org/10.1117/12.2079718

KEYWORDS: Antennas, Tissues, Breast, Skin, Printing, Prototyping, Silver, Microwave radiation, Tumors, Dielectrics

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To overcome the limitations of currently available clinical hyperthermia systems which are based on rigid waveguide antennas, a wearable microwave hyperthermia system is presented. A light wearable system can improve patient comfort and be located in close proximity to the breast, thereby enhancing energy deposition and reducing power requirements. The objective of this work was to design and assess the feasibility of a conformal patch antenna element of an array system to be integrated into a wearable hyperthermia bra. The feasibility of implementing antennas with silver printed ink technology on flexible substrates was evaluated. A coupled electromagnetic-bioheat transfer solver and a hemispheric heterogeneous numerical breast phantom were used to design and optimize a 915 MHz patch antenna. The optimization goals were device miniaturization, operating bandwidth, enhanced energy deposition pattern in targets, and reduced Efield back radiation. The antenna performance was evaluated for devices incorporating a hemispheric conformal groundplane and a rectangular groundplane configuration. Simulated results indicated a stable -10 dB return loss bandwidth of 88 MHz for both the conformal and rectangular groundplane configurations. Considering applied power levels restricted to 15 W, treatment volumes (T>41⁰C) and depth from the skin surface were 11.32 cm³ and 27.94 mm, respectively, for the conformal groundplane configuration, and 2.79 cm³ and 19.72 mm, respectively, for the rectangular groundplane configuration. E-field back-radiation reduced by 85.06% for the conformal groundplane compared to the rectangular groundplane configuration. A prototype antenna with rectangular groundplane was fabricatd and experimentally evaluated. The groundplane was created by printing silver ink (Metalon JS-B25P) on polyethylene terephthalate (PET) film surface. Experiments revealed stable antenna performance for power levels up to 15.3 W. In conclusion, the proposed patch antenna with conformal groundplane and prined ink technology shows promising performance to be integrated in a clinical array system.

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