Prog Med Phys.  2020 Jun;31(2):9-19. 10.14316/pmp.2020.31.2.9.

Development of a Wide Dose-Rate Range Electron Beam Irradiation System for Pre-Clinical Studies and Multi-Purpose Applications Using a Research Linear Accelerator

Affiliations
  • 1Research Center, Dongnam Institute of Radiological and Medical Sciences, Korea
  • 2Department of Radiation Oncology, Dongnam Institute of Radiological and Medical Sciences, Busan, Korea

Abstract

Purpose
This study aims to develop a multi-purpose electron beam irradiation device for preclinical research and material testing using the research electron linear accelerator installed at the Dongnam Institute of Radiological and Medical Sciences.
Methods
The fabricated irradiation device comprises a dual scattering foil and collimator. The correct scattering foil thickness, in terms of the energy loss and beam profile uniformity, was determined using Monte Carlo calculations. The ion-chamber and radiochromic films were used to determine the reference dose-rate (Gy/s) and beam profiles as functions of the source to surface distance (SSD) and pulse frequency.
Results
The dose-rates for the electron beams were evaluated for the range from 59.16 Gy/s to 5.22 cGy/s at SSDs of 40一120 cm, by controlling the pulse frequency. Furthermore, uniform dose distributions in the electron fields were achieved up to approximately 10 cm in diameter. An empirical formula for the systematic dose-rate calculation for the irradiation system was established using the measured data.
Conclusions
A wide dose-rate range electron beam irradiation device was successfully developed in this study. The pre-clinical studies relating to FLASH radiotherapy to the conventional level were made available. Additionally, material studies were made available using a quantified irradiation system. Future studies are required to improve the energy, dose-rate, and field uniformity of the irradiation system.

Keyword

Electron irradiation system; Scattering foil; High dose-rate; Monte Carlo calculation; Research linear accelerator

Figure

  • Fig. 1 Design of irradiation device. (a) Side view, (b) front view, (c) 3D view. a1, scattering foil diameter; a2, collimated field size; l, length.

  • Fig. 2 Calculated and measured percentage depth doses for the determination of incident electron beam energy.

  • Fig. 3 Monte Carlo calculation geometry. SSD, source to surface distance.

  • Fig. 4 Calculated percentage depth doses (a) and beam profiles (b) for foil thickness.

  • Fig. 5 (a) Mean energy at the phantom surface and (b) field diameters (90% and 95% maximum) for foil thickness.

  • Fig. 6 Calculated beam profiles for single and dual foils. SSD, source to surface distance.

  • Fig. 7 Experimental setup using DIRAMS LINAC. (a) Reference dosimetry in water using the ionization chamber, (b) film dosimetry. LINAC, linear accelerator; DIRAMS, Dongnam Institute of Radiological and Medical Sciences.

  • Fig. 8 Measured percentage depth dose for electron irradiator using dual foil system.

  • Fig. 9 Measured relative dose and linear fit with logarithmic axis at the source to surface distance from 40 to 100 cm.

  • Fig. 10 Relative dose rate as a function of pulse frequency in DIRAMS LINAC (Dongnam Institute of Radiological and Medical Sciences linear accelerator) and a fit line separated into two functions.

  • Fig. 11 Determined dose rate (Gy/s) at the depth of dose maxi­mum in water for the electron irradiator system in DIRAMS (Dongnam Institute of Radiological and Medical Sciences). SSD, source to surface distance.

  • Fig. 12 Measured beam profiles at the SSDs of 40, 50, 60, 80, 100 cm. (a) Normalized dose, (b) relative dose. SSD, source to surface distance.


Cited by  1 articles

High-Dose-Rate Electron-Beam Dosimetry Using an Advanced Markus Chamber with Improved Ion-Recombination Corrections
Dong Hyeok Jeong, Manwoo Lee, Heuijin Lim, Sang Koo Kang, Kyoung Won Jang
Prog Med Phys. 2020;31(4):145-152.    doi: 10.14316/pmp.2020.31.4.145.


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