I am a Postdoctoral Research Associate in the Computational Sciences and Engineering Division at Oak Ridge National Laboratory. My primary research focuses on radiation physics, radiopharmaceutical dosimetry, and Monte Carlo simulations. I specialize in Monte Carlo simulations to address radiation physics challenges, encompassing dosimetry and radiation biology. A distinguishing aspect of my research is the tight-knit collaborations with experts in radiopharmaceutical therapy dosimetry, molecular imaging, and radiation transport simulations.
My doctoral thesis (download) encompassed radiopharmaceutical therapy dosimetry and quantitative imaging in nuclear medicine. Specifically, I delved into two key areas: (1) dosimetry of β- and α-emitting radionuclides and (2) Monte Carlo simulation of PET scanner, bolstered by subsequent validation.
Short Bio:
I originate from the charming northwestern region of Gorkha, Nepal, where I cherished my formative years. I received my B.Sc. and M.Sc. degrees from Tribhuvan University in 2008 and 2012, respectively. Subsequently, I did my second master’s at the University of South Dakota (2017) and a Ph.D. in physics from the University of Iowa (2022).
On a personal note, I find solace in cycling and relish the serenity of natural surroundings. My literary interests span both fiction and non-fiction genres. I also enjoy various gaming formats, such as Carrom board, cards, and culinary arts.
Certificate in Medical Physics, 2023
Wake Forest University, Winston-Salem, NC, USA
PhD in Physics, 2022
University of Iowa, Iowa City, IA, USA
MS in Physics, 2017
University of South Dakota, Vermillion, SD, USA
MSc in Physics, 2012
Tribhuvan University, Kathmandu, Nepal
BSc in Physics, 2008
Tribhuvan University, Kathmandu, Nepal
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The aim of this project is to experimentally validate the Monte Carlo generated absorbed doses from the beta particles emitted by 90Y and 177Lu using radiochromic EBT3 film‐based dosimetry.
Line sources of 90Y and 177Lu were inserted longitudinally through blocks of low‐density polyethylene and tissue‐equivalent slabs of cortical bone and lung equivalent plastics. Radiochromic film (Gafchromic EBT3) was laser cut to accommodate orthogonal line sources of radioactivity, and the film was sandwiched intimately between the rectangular blocks to achieve charged particle equilibrium. Line sources consisted of plastic capillary tube of length (13 ± 0.1) cm, with 0.42‐mm inner diameter and a wall thickness of 0.21 mm. 90Y line sources were prepared from a solution of dissolved 90Y resin microspheres. 177Lu line sources were prepared from an aliquot of 177Lu‐DOTATATE. Film exposures were conducted for durations ranging from 10 min to 38 h. Radiochromic film calibration was performed by irradiation with 6‐MV‐bremsstrahlung x rays from a calibrated linear accelerator, in accordance with literature recommendations. Experimental geometries were precisely simulated within the GATE Monte Carlo toolkit, which has previously been used for the generation of dose point kernels.
The mean percentage difference between measured and simulated absorbed doses were 5.04% and 7.21% for 90Y and 177Lu beta absorbed dose in the range of (0.1–10) Gy. Additionally, 1D gamma analysis using a local 10%/1 mm gamma criterion was performed to compare the absorbed dose distributions. The percentage of measurement points passing the gamma criterion, averaged over all tests, was 93.5%. We report the experimental validation of Monte Carlo derived beta absorbed dose distributions for 90Y and 177Lu, solidifying the validity of using Monte Carlo‐based methods for estimating absorbed dose from beta emitters.
Overall, excellent agreement was observed between the experimental beta absorbed doses in the linear region of the radiochromic film and the GATE Monte Carlo simulations demonstrating that radiochromic film dosimetry has sufficient sensitivity and spatial resolution to be used as a tool for measuring beta decay absorbed dose distributions.