Title:

Spatiotemporal dosimetry and oximetry for FLASH radiotherapy

Speaker:

Dr. Rongxiao Zhang

Affiliation:

Dartmouth-Hitchcock Health

When:

Thursday, September 24, 2020 at 11:00:00 AM   Add to Calendar

Where:

Room https://bluejeans.com/726425108

Host:

Dr. Chaitanya S Deo
cdeo3@gatech.edu
3139712314

Abstract

Radiation therapy is an essential component of cancer care and over 14 million people a year, that is 50 percent 60 percent of total cancer patients, receive radiation therapy. The capabilities available for clinicians to localize and deliver precise amounts of radiation to specific anatomies have improved dramatically over recent years, due to advances in imaging guidance, treatment planning and dose delivery technologies. However, we are now facing a long lasting bottleneck to further improve the therapeutic ratio, i.e. tumor control vs. normal tissue toxicity. Recent advances in ultra high dose radiotherapy, abbreviated as FLASH, have shown the potential for reduction in healthy tissue damage while preserving tumor control. FLASH therapy relies on very high dose rate of 40Gy sec with sub second temporal beam modulation, taking a seemingly opposite direction from the conventional paradigm of fractionated therapy. With this, FLASH brings unique challenges to its dosimetry. While spatial dose conformity delivered to a target volume has been pushed to its practical limits with advanced treatment planning and delivery, FLASH RT necessitates novel spatiotemporal dosimetry techniques. The FLASH effect has been reported mainly based upon phenomenological observations with tissue function assays, rather than mechanistic in situ measurements. There are several radiobiological hypotheses around the mechanisms for less damage, however to date none are directly proven, and indeed the data supporting any mechanism is glaringly absent. The central feature dominating most proposed mechanisms is linked to the fact that oxygen depletion, which is expected to occur rapidly at FLASH dose rates, via oxygen radical production with consumption from oxidation reactions. In this seminar, I am going to go over recent progresses on MeV electron FLASH RT at Dartmouth, focusing on the newly developed eFLASH irradiation platform, optical imaging based spatiotemporal dosimetry quantification as well as in vivo oximetry based on radioluminescence lifetime imaging.

Biography

I completed my PhD in physics from Dartmouth, focused around imaging the first veterinary and human images of Cherenkov in external beam radiation therapy and going on to show how to achieve chemical sensing. From this, I was admitted to the Harvard Medical Physics Residency Program 2015 2018, where I received training in all aspects of radiation therapy, including proton therapy. In 2018, I was recruited to the Department of Radiation Oncology, Emory University School of Medicine as a proton therapy medical physicist, where I joined the acceptance of the proton center, lead on the commissioning of an individual gantry treatment room and the commissioning of all the imaging modalities. I was recently recruited to be a faculty clinical physicist II at Dartmouth Medical School and Dartmouth Hitchcock Health to focus on the MRI guided radiation therapy and medical physics residency program. I have strong interests in innovative imaging guidance, molecular imaging, radiation transport modeling, novel treatment planning, dose delivery technologies and adaptive radiation therapy. I currently conduct research on optical based dose measurement and quality assurance, beam modeling with Monte Carlo methods, machine learning for medical image processing and translational studies on FLASH therapy and photon dynamic protected radiation therapy. Our work has been presented in 80 national international conference abstracts, published in 50 peer reviewed journal papers, led to SBIR grant funded and commercialized products. In the long term, I am committed to be a medical physicist who leads on clinical and translational research and eventually implement scientific discovery in clinical practice to ensure and continuously improve the quality of radiation therapy.