Shiva Kumar Das

Journal article Semin Radiat Oncol · April 2006 Featured Publication Oligometastases refer to metastases that are limited in number and location and are amenable to regional treatment. The majority of these metastases appear in the brain, lung, liver, and bone. Although the focus of interest in the past within radiation onc ... Full text Link to item Cite

Improved magnetic resonance thermal imaging by combining proton resonance frequency shift (PRFS) and apparent diffusion coefficient (ADC) data.

Journal article Int J Hyperthermia · November 2005 Featured Publication Effective thermal therapy for cancer is dependent on adequate tumor heating. Adequate heating, in turn, is dependent on reliable volumetric measurement of temperature to guide heating. Proton resonance frequency shift (PRFS) magnetic resonance imaging is f ... Full text Link to item Cite

Predicting radiotherapy-induced cardiac perfusion defects.

Journal article Med Phys · January 2005 Featured Publication The purpose of this work is to compare the efficacy of mathematical models in predicting the occurrence of radiotherapy-induced left ventricular perfusion defects assessed using single-photon emission computed tomography (SPECT). The basis of this study is ... Full text Link to item Cite

Relationship between the generalized equivalent uniform dose formulation and the Poisson statistics-based tumor control probability model.

Journal article Med Phys · September 2004 Featured Publication The generalized equivalent uniform dose (GEUD) model uses a power-law formalism, where the outcome is related to the dose via a power law. We herein investigate the mathematical compatibility between this GEUD model and the Poisson statistics based tumor c ... Full text Link to item Cite

Penalized likelihood fluence optimization with evolutionary components for intensity modulated radiation therapy treatment planning.

Journal article Med Phys · August 2004 Featured Publication A novel iterative penalized likelihood algorithm with evolutionary components for the optimization of beamlet fluences for intensity modulated radiation therapy (IMRT) is presented. This algorithm is designed to be flexible in terms of the objective functi ... Full text Link to item Cite

A preliminary study of the role of modulated electron beams in intensity modulated radiotherapy, using automated beam orientation and modality selection.

Journal article Int J Radiat Oncol Biol Phys · June 1, 2004 Featured Publication PURPOSE: To develop an algorithm for optimal beam arrangement selection in intensity-modulated radiotherapy (IMRT) of mixed photon and electron beams. To apply this algorithm to study the utility of modulated electron beams in the context of IMRT planning. ... Full text Link to item Cite

Feasibility of optimizing the dose distribution in lung tumors using fluorine-18-fluorodeoxyglucose positron emission tomography and single photon emission computed tomography guided dose prescriptions.

Journal article Med Phys · June 2004 Featured Publication The information provided by functional images may be used to guide radiotherapy planning by identifying regions that require higher radiation dose. In this work we investigate the dosimetric feasibility of delivering dose to lung tumors in proportion to th ... Full text Link to item Cite

Incorporation of functional imaging data in the evaluation of dose distributions using the generalized concept of equivalent uniform dose.

Journal article Phys Med Biol · May 7, 2004 Featured Publication Advances in the fields of IMRT and functional imaging have greatly increased the prospect of escalating the dose to highly active or hypoxic tumour sub-volumes and steering the dose away from highly functional critical structure regions. However, current c ... Full text Link to item Cite

A dose-volume-based tool for evaluating and ranking IMRT treatment plans.

Journal article J Appl Clin Med Phys · 2004 Featured Publication External beam radiotherapy is commonly used for patients with cancer. While tumor shrinkage and palliation are frequently achieved, local control and cure remain elusive for many cancers. With regard to local control, the fundamental problem is that radiot ... Full text Link to item Cite

Beam orientation selection for intensity-modulated radiation therapy based on target equivalent uniform dose maximization.

Journal article Int J Radiat Oncol Biol Phys · January 1, 2003 Featured Publication PURPOSE: To develop an automated beam-orientation selection procedure for intensity-modulated radiotherapy (IMRT), and to determine if a small number of beams picked by this automated procedure can yield results comparable to a large number of manually pla ... Full text Link to item Cite

Optimization of a 90Sr/90Y radiation source train stepping for intravascular brachytherapy.

Journal article Med Phys · December 2002 Featured Publication A steepest-descent gradient algorithm is developed to optimize the stepping of a 90Sr/90Y radiation source train (RST) for intravascular brachytherapy (IVB). The objective function is to deliver a uniform dose in a coronary target vessel and minimize the d ... Full text Link to item Cite

Radiation-induced pulmonary toxicity: a dose-volume histogram analysis in 201 patients with lung cancer.

Journal article Int J Radiat Oncol Biol Phys · November 1, 2001 Featured Publication PURPOSE: To relate lung dose-volume histogram-based factors to symptomatic radiation pneumonitis (RP) in patients with lung cancer undergoing 3-dimensional (3D) radiotherapy planning. METHODS AND MATERIALS: Between 1991 and 1999, 318 patients with lung can ... Full text Link to item Cite

Discretizing large traceable vessels and using DE-MRI perfusion maps yields numerical temperature contours that match the MR noninvasive measurements.

Journal article Med Phys · November 2001 Featured Publication The success of hyperthermia treatments is dependent on thermal dose distribution. However, the three-dimensional temperature distribution remains largely unknown. Without this knowledge, the relationship between thermal dose and outcome is noisy, and thera ... Full text Link to item Cite

Acute urinary toxicity following transperineal prostate brachytherapy using a modified Quimby loading method.

Journal article Int J Radiat Oncol Biol Phys · July 15, 2001 Featured Publication PURPOSE: To examine the acute urinary toxicity following transperineal prostate implant using a modified Quimby loading method with regard to time course, severity, and factors that may be associated with a higher incidence of morbidity. METHODS AND MATERI ... Full text Link to item Cite

Three-dimensional tumor perfusion reconstruction using fractal interpolation functions.

Journal article IEEE Trans Biomed Eng · April 2001 Featured Publication It has been shown that the perfusion of blood in tumor tissue can be approximated using the relative perfusion index determined from dynamic contrast-enhanced magnetic resonance imaging (DE-MRI) of the tumor blood pool. Also, it was concluded in a previous ... Full text Link to item Cite

A method of MRI-based thermal modelling for a RF phased array.

Journal article Int J Hyperthermia · 2001 Featured Publication Magnetic Resonance Imaging (MRI) is an attractive method of temperature monitoring in vivo due to its non-invasive nature. The natural extension of this temperature monitoring is to implement temperature control. This work outlines a method of MRI-based th ... Full text Link to item Cite

3D numerical reconstruction of the hyperthermia induced temperature distribution in human sarcomas using DE-MRI measured tissue perfusion: validation against non-invasive MR temperature measurements.

Journal article Int J Hyperthermia · 2001 Featured Publication Essential to the success of optimized thermal treatment during hyperthermia is accurate modelling. Advection of energy due to blood perfusion significantly affects the temperature. Without accurate estimates of the magnitude of the local tissue blood perfu ... Full text Link to item Cite

Dynamic contrast-enhanced MRI and fractal characteristics of percolation clusters in two-dimensional tumor blood perfusion.

Journal article J Biomech Eng · October 1999 Featured Publication Dynamic contrast-enhanced magnetic resonance imaging (DE-MRI) of the tumor blood pool is used to study tumor tissue perfusion. The results are then analyzed using percolation models. Percolation cluster geometry is depicted using the wash-in component of M ... Full text Link to item Cite

Computational techniques for fast hyperthermia temperature optimization.

Journal article Med Phys · February 1999 Featured Publication Hyperthermia temperature optimization involves arriving at a temperature distribution which minimizes a stated goal function, the goal function having a biological basis in maximizing tumor cell kill while not exceeding normal tissue toxicity. This involve ... Full text Link to item Cite

Electromagnetic thermal therapy power optimization for multiple source applicators.

Journal article Int J Hyperthermia · 1999 Featured Publication The optimization of power deposition for electromagnetic (EM) thermal therapy is investigated. Several goal or objective functions are examined using a generalized mathematical formulation. These include maximization of: (1) target power absorption, (2) th ... Full text Link to item Cite

Selection of coplanar or noncoplanar beams using three-dimensional optimization based on maximum beam separation and minimized nontarget irradiation.

Journal article Int J Radiat Oncol Biol Phys · June 1, 1997 Featured Publication PURPOSE: The design of an appropriate set of multiple fixed fields to achieve a steep dose gradient at the tumor edge, with minimal normal tissue exposure, is a very difficult problem, since a virtually infinite number of possible beam orientations exists. ... Full text Link to item Cite

Hyperthermia treatment planning and temperature distribution reconstruction: a case study.

Journal article Int J Hyperthermia · 1996 Featured Publication While a great deal of effort has been applied toward solving the technical problems associated with modelling clinical hyperthermia treatments, much of that effort has focused on only estimating the power deposition. Little effort has been applied toward u ... Full text Link to item Cite

Verification of a hyperthermia model method using MR thermometry.

Journal article Int J Hyperthermia · 1995 Featured Publication Simulation of hyperthermia induced power and temperature distributions is becoming generally accepted and finding its way into clinical hyperthermia treatments. Such simulations provide a means for understanding the complete three-dimensional temperature d ... Full text Link to item Cite

Simulation of electromagnetically induced hyperthermia: a finite element gridding method.

Journal article Int J Hyperthermia · 1995 Featured Publication A finite element gridding method for simulating electromagnetically (EM) induced hyperthermia is presented. The method uses patient CT data as its primary input, with critical structures manually outlined (on a graphics workstation) for explicit demarcatio ... Full text Link to item Cite