04/15/2021
By Erica Freund

The Kennedy College of Science, Department of Physics, invites you to attend a doctoral dissertation defense by Erica Freund entitled “Novel Ta2O5 Thin-Film Sensors for Applications in Diagnostic Imaging and Radiotherapy.”

The defense will be held on April 26 at 5 p.m. via Zoom. Please contact Erica Freund for meeting information if you are interested in attending. The committee will be composed of Erno Sajo (chair), Piotr Zygmanski, and James Egan. A brief abstract is provided below.

Abstract:

Fundamental limitations in the operating principles of existing radiation detectors underscores the need for innovations which more comprehensively address the current trends in healthcare technology. Modern detectors must be cost and energy efficient, versatile, and provide real-time user-specific information in a secure manner. Hight Energy Current (HEC) technology exploits radiation interactions with the surfaces of thin films to produce and collect electrical signal proportional to incident radiation. Radiation sensors that operate on the HEC principle are inherently self- or low-powered and designed with inexpensive raw materials.

The design, fabrication and characterization of a novel solid state HEC sensor prototype called Anodox is the subject of this work. A scalable and inexpensive benchtop method to produce Anodox prototypes is described. The prototypes have a nominal thickness of 50 µm, are flexible and produce real-time electrical signal measurable with generic commercial electronics without amplification and less than 5 V external bias. These unique features have powerful implications to improve dosimetry, quality assurance and/or radiation safety practices across clinical radiation modalities.

Anodox sensors are characterized in electronic kV x-ray fields emblematic of those used in medical diagnostic imaging. Energy response and favorable angular sensitivity in the kV photon range indicate Anodox detectors can provide real-time information during CT scans to address the shortcomings of current dosimetry and QA techniques for comprehensive stochastic risk estimates. Anodox sensors are also effectively detect MV gamma emitting radioisotopes Cs-137, Co-60 and Ir-192. These radioisotopes are clinically relevant in nuclear medicine and radiotherapy and are also used in other industries. Experiments with radionuclides demonstrate Anodox detectors are uniquely resilient and do not saturate under extreme radiation fields (up to 4 Gy/s tested). Dose rate effects in the detector at the highest exposures also further illuminate aspects of radiation-induced charge generation in the dielectric layer of Anodox type HEC sensors. The advancements outlined in this research address key limitations in medical radiation techniques and enable new applications for radiation detection and characterization in other industries that utilize kV-MV ionizing radiation.

All interested students and faculty members are invited to attend.