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Biomedical subjects

Michael Lamba

Publications and source records attributed to Michael Lamba.

2 recordsLinked to original sources

An improved methodology for modeling neurobehavioral late-effects of radiotherapy in pediatric brain tumors.

BACKGROUND: Technical advances in radiation oncology provide new opportunities to study neurobehavioral outcomes of radiation therapy (RT) in children treated for brain tumors. METHODS: In this study, we describe an approach to modeling late-effects using integral biologically effective dose (IBED) combined with improved measurement of critical neuropsychological functions. RESULTS: IBED was found to provide more differentiated information about dose distribution than prescribed dose in five subjects treated for brain tumors. Furthermore, IBED was more closely related than was prescribed dose to specific changes in Attention 2-3 years post-RT. CONCLUSIONS: Results support the feasibility of this methodology as well as promising preliminary evidence of the relationship of IBED to the construct of Attention. Improved modeling could lead to more refined radiation therapy protocols that preserve critical neuropsychological functions and also provide new insights into the treatment of neurobehavioral sequelae.

Attention↗

Fast high-resolution 3D segmented echo planar imaging for dose mapping using a superheated emulsion chamber.

The superheated emulsion chamber (SEC) consists of superheated droplets of halocarbons in an aqueous gel. The gel resides in a pressure chamber. Brachytherapy sources can be implanted in the SEC for radiation dosimetry studies. Upon irradiation by ionizing radiation, the metastable droplets vaporize to form microbubbles. MRI can be used to determine the distribution of bubbles following irradiation of the SEC. In order to generate sufficient statistical accuracy in the determination of dose distributions around brachytherapy sources, it is necessary to use hundreds of irradiation cycles. Susceptibility-weighted images provide contrast between the gel and the vapor microbubbles. This article describes a 3D, blipped, double-sampled, segmented echo-planar imaging technique for rapidly imaging the SEC at 650 microm isotropic 3D resolution in about 2 min. This method was used with a pressure cycling SEC to acquire hundreds of images in several hours. Results are presented showing the 2D dose distribution generated by an (125)I source as measured in the SEC using this new imaging method.

Brachytherapy↗