Online Ph.D. Defense: “Considerations on Two Types of Solid-Sate Dosimeters for Ionization Radiation” — April 13, 2020 at 1 PM
Mr. Ren Tong
Mentor: J. Daniel Bourland
Department of Physics
Wake Forest University
Tuesday, April 13, 2020 at 1:00 pm – 3:00 pm
(Private defense will follow public presentation)
Via Video Conference (contact wfuphys@wfu.edu for link information)
ABSTRACT
Radiation therapy is a common type of treatment for cancer. Being able to measure the ionization radiation dose distribution with high resolution is of great importance for characterizing radiation devices and for quality assurance of patient radiation procedures. Two solid-state devices have been studied for their radiation dosimetric properties, to bring potential improvements for their use as dosimeters.
First, radiochromic film is a robust two-dimensional dosimeter with high resolution measurement capability. When digitized on a flatbed photo scanner, the fidelity of radiochromic film dosimetry is primarily affected by film active layer non-uniformity and the lateral artifact. The fist focus of this work is to develop a novel and efficient lateral artifact correction method as well as a channel weighted analytical method for radiochromic film dosimetry. This channel weighted approach accounts for the physical phenomenon that red, green and blue light with the same intensity are attenuated differently by the same attenuator. This phenomenon is characterized by the channel specific Napierian attenuation coefficient. The new channel weighted method mitigates more effectively the lateral artifact/parabola effect and better compensates for radiochromic film active layer non-uniformity than the channel-independent analytical algorithm. The channel weighted approach for radiochromic film dosimetry demonstrates improvement without pre-irradiation scans and is compatible with the existing, efficient one-scan protocol. The lateral artifact correction method utilizes fully exposed radiochromic film strips and corrects the lateral artifact in the dose domain of multichannel dosimetry. And it compensates non-uniform off-axis output from open fields of a linear accelerator and the film active layer non-uniformity. This unique layout is symmetric about the scanner central-axis and covers the sufficient lateral space of a flatbed scanner. Radiation treatment plans validated with the new channel weighted and lateral artifact correction methods show improvements in passing rates, when quantitatively analyzed using gamma criteria for the agreement of dose and distance parameters.
The metal–oxide–semiconductor field-effect transistor dosimeter can be used for in-vivo dose monitoring in external beam dosimetry for radiation therapy and radiosurgery. In this study, the response of an organic thin-film device to megavoltage X-rays is characterized. The device is based on organic field-effect transistor.
PUBLICATIONS
Manuscripts in Preparation, Under Review and Published
1. Ren T, and Bourland JD, An efficient single-scan lateral artifact correction method combined
with dose calibration for multichannel radiochromic film dosimetry, J. of Appl. Clin. Med. Phys.
(2021) [ready to submit]
2. Ren T, Dezarn WA, Hinson WH, McKee MM, Ververs JD, Black PJ, Parker SA, Zeidell AM,
Bourland JD, A channel weighted method for radiochromic film dosimetry, Med. Phys. 2020
[submitted, under peer-review]
3. Zeidell AM, Ren T, Filston DS, Iqbal HF, Holland E, Bourland JD, Anthony JE, Jurchescu OD,
Organic field‐effect transistors as flexible, tissue‐equivalent radiation dosimeters in medical
applications. Adv. Sci. (2020), 2001522.
4. Ren T, and Zeidell AM, et al. Dose linearization and calibration of an, organic field-effect
transistor dosimeter for megavoltage X-ray, Med. Phys. 2022 [In preparation]
5. Ren T, McKee MM, Dezarn WA, Parker SA, Black PJ, Ververs JD, Hinson WH, Bourland JD, A
fiducial-mark free triple-channel dose space registration technique for IMRT/VMAT QA with
radiochromic film dosimetry, J. Appl. Clin. Med. Phys. 2021 [in preparation]
Conference Proceeding
6. McKee, M., Ren, T., Bourland, J., “Gamma Knife relative output factor measurements with
multichannel radiochromic film dosimetry.” Radiother. Oncol. (2020), 152, S691-S692
7. Ren, T., Prajapati, S., Dorand, J., Bourland, J.D., “Source characteristics and loading pattern
for a unique beta irradiation device for preclinical research of cutaneous radiation injury.”
Med. Phys. (2020) Vol. 47. No.6
8. Zeidell, A., Ren, T., Filson D., Haneef, H., Bourland, J., Anthony, J., Jurchescu, O., “Device
fabrication and characterization of OFET-RAD for dosimetric response of Megavoltage X-
ray.” Med. Phys. (2020) Vol. 47. No.6, pp. e810-810
9. Ren, T., and J. Bourland. ” Triple-channel dosimetry with the channel weighted perturbation
method.” Med. Phys. (2019) Vol. 46. No. 6，pp. e320-e320.
10. Ren, T., and J. Bourland. ” An Improved sensitometric calibration function for radiochromic
film dosimetry.” Med. Phys. (2019) Vol. 46. No. 6，pp. e608-e608.
11. Ren, T., and Bourland, J., An efficient automatic dose-space registration technique for
clinical IMRT/VMAT quality Assurance with radiochromic film dosimetry, J. Appl. Clin. Med.
Phys. (2019) May 16;20(5):159–159.
12. Ren, T., and J. Bourland. “Efficient method for combining flatbed scanner calibration and
lateral response correction in a single scan for radiochromic film dosimetry.” Med. Phys.
(2018) Vol. 45. No. 6，pp. e608-e608.
13. Ren, T., and J. Bourland. “Temperature effect during radiation exposure period for
radiochromic film dosimetry using flatbed scanner densitometer.” Med. Phys. (2018) Vol.
45. No. 6，pp. e607-e607.
