Ashok Tiwari

Postdoctoral Research Associate

Dr. Ashok Tiwari is a Postdoctoral Research Associate in the Computational Sciences and Engineering Division at Oak Ridge National Laboratory (ORNL). He primarily focuses on Monte Carlo simulations incorporating dosimetry and radiation biology. Before joining ORNL, he worked as a graduate research assistant in the Department of Radiology and Physics at the University of Iowa. His Ph.D. research encompassed radiopharmaceutical therapy dosimetry and quantitative imaging in nuclear medicine. He explored (1) the dosimetry of β- and α-emitting radionuclides using Monte Carlo simulations and (2) simulations of a clinical PET scanner along with validation. For his outstanding contributions, Dr. Tiwari's Ph.D. thesis garnered the esteemed Ballard and Seashore Dissertation Fellowship. His research interests continue to revolve around radiation physics, radiopharmaceutical therapy, and the utilization of Monte Carlo simulations in solving medical physics problems.

Tiwari A., Merrick M., Graves S., and Sunderland J. J. Monte Carlo evaluation of hypothetical long axial field-of-view PET scanner using GE Discovery MI PET front-end architecture, Med Phys, 49:1139-1152, 2022.

Tiwari A., Sunderland J., Graves S., Strand S., and Flynn R. Absorbed dose distributions from beta-decaying radionuclides: experimental validation of Monte Carlo tools for radiopharmaceutical dosimetry. Med Phys, 47(11):5779-5790, 2020.

Graves S., Martin M., Tiwari A., Merrick M., and Sunderland J. J. SIR-Spheres® activity measurements reveal systematic miscalibration, J Nucl Med 2022; 63:1131-1135, DOI: 10.2967/jnumed.121.262650.

Tiwari A., Graves S., and Sunderland J. The Impact of Tissue Type and Density on Dose Point Kernels for Patient-Specific Voxel-Wise Dosimetry: A Monte Carlo Investigation. Radiat Res, 193 (6): 531-542, 2020.

Merrick M. J., Rotsch D. A., Tiwari A., Nolen J., Brossard T., Song J., Wadas T. J., Sunderland J. J., and Graves S. A. Half-Life of 67Cu, J. Phys. Commun. 5 085007, 2021.

Merrick M. J., Rotsch D. A., Tiwari A., Nolen J., Brossard T., Song J., Wadas T. J., Sunderland J. J., and Graves S. A. Imaging and Dosimetric Characteristics of 67Cu. Phys Med Biol 66, 035002, 2021.

Tiwari A., Zhang C., Mei D.-M., and Cushman P. Observation of annual modulation induced by γ rays from (α, γ) reactions at the Soudan Underground Laboratory, Phys Rev C, Vol. 96, No. 4, 2017.

Zhang C., Mei D.-M., Tiwari A., and Cushman P. Reply to “Comment of ‘Observation of annual modulation induced by γ rays from (α, γ) reactions at the Soudan Underground Laboratory’”, Phys Rev C 101, 049802, 2020.

Tiwari A., and Khanal U., Gravitational radiation from a particle in bound orbit around the black hole; relativistic correction, J. Phys.: Conf. Ser. 716, 012024, 2016.