• The Journal of Korean Society for Radiation Therapy
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• v.1 no.1
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• pp.63-69
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• 1985

High energy electron beams took effect for tumor radio-therapy, however, had a lot of problems in clinical application because of various conversion factors and complication of physical reactions. Therefore, we had experimentally studied the important properties of high energy electron beams from the linear accelerator, LMR-13, installed in Yonsei Cancer Center. The results of experimental studies on the problems in the 8, 10, 12 Mev electron beam therapy were reported as following. 1. On the measurements of the outputs and absorbed does, the ionization type dosimeters that had calibrated by $^{90}Sr$ standard source were suitable as under $3\%$ errors for high energy electrons to measure, but measuring doses in small field sizes and the regions of rapid fall off dose with ionization chambers were difficult. 2. The electron energy were measured precisely with energy spectrometer consisted of magnet analyzer and tele-control detector and the practical electron energy was calculated under $5\%$ errors by maximum range of high energy electron beam in the water. 3. The correcting factors of perturbated dose distributions owing to radiation field, energy and material of the treatment cone were checked and described systematically and variation of dose distributions due to inhomogeneous tissues and sloping skin surfaces were completely compensated. 4. The electron beams, using the scatters; i.e., gold, tin, copper, lead, aluminium foils, were adequately diffused and minimizing the bremsstrahlung X-ray induced by the electron energy, irradiation field size and material of scatterers, respectively. 5. Inproving of the dose distribution from the methods of pendulum, slit, grid and focusing irradiations, the therapeutic capacity with limited electron energy could be extended.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.161-163
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• 1997

In this paper, a two-dimensional electron beam dose calculational algorithm implented for use in a two-dimensional radiation therapy planning system is described. The 2-D electron beam calculations have been in use clinically for a few decades. Our algorithm uses Age-diffusion model based int the Boltzman Transport Equation. Our implementation provides convenient user interface associated with electron beam therapy planning and displays radiation dose distribution according to different electron energy on patient images.

• Nuclear Engineering and Technology
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• v.54 no.6
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• pp.2213-2220
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• 2022

The maximum dose delivery at the end of the beam range provides the main advantage of using proton therapy. The range of the proton beam, however, is subject to uncertainties, which limit the clinical benefits of proton therapy and, therefore, accurate in vivo verification of the beam range is desirable. For the beam range verification in spot scanning proton therapy, a prompt gamma detection system, called as gamma electron vertex imaging (GEVI) system, is under development and, in the present study, the performance of the GEVI system in spot scanning proton therapy was predicted with Geant4 Monte Carlo simulations in terms of shift detection sensitivity, accuracy and precision. The simulation results indicated that the GEVI system can detect the interfractional range shifts down to 1 mm shift for the cases considered in the present study. The results also showed that both the evaluated accuracy and precision were less than 1-2 mm, except for the scenarios where we consider all spots in the energy layer for a local shifting. It was very encouraging results that the accuracy and precision satisfied the smallest distal safety margin of the investigated beam energy (i.e., 4.88 mm for 134.9 MeV).

• Nuclear Engineering and Technology
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• v.54 no.3
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• pp.1016-1023
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• 2022

In proton therapy, a highly conformal proton dose can be delivered to the tumor by means of the steep distal dose penumbra at the end of the beam range. The proton beam range, however, is highly sensitive to range uncertainty, which makes accurately locating the proton range in the patient difficult. In-vivo range verification is a method to manage range uncertainty, one of the promising techniques being prompt gamma imaging (PGI). In earlier studies, we proposed gamma electron vertex imaging (GEVI), and constructed a proof-of-principle system. The system successfully demonstrated the GEVI imaging principle for therapeutic proton pencil beams without scanning, but showed some limitations under clinical conditions, particularly for pencil beam scanning proton therapy. In the present study, we upgraded the GEVI system in several aspects and tested the performance improvements such as for range-shift verification in the context of line scanning proton treatment. Specifically, the system showed better performance in obtaining accurate prompt gamma (PG) distributions in the clinical environment. Furthermore, high shift-detection sensitivity and accuracy were shown under various range-shift conditions using line scanning proton beams.

• The Journal of Korean Society for Radiation Therapy
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• v.5 no.1
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• pp.74-78
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• 1992

• The Journal of Korean Society for Radiation Therapy
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• v.11 no.1
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• pp.79-83
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• 1999

• Progress in Medical Physics
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• v.21 no.1
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• pp.60-69
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• 2010

For treatment of Total Skin Electron beam Therapy (TSET), measurement of dose at various conditions is need on the contrary to usual radiotherapy. When treating TSET with modified Stanford technique based on linear accelerator, the energy of treatment electron beam, the spatial dose distribution and the actual doses deposited on the surface of the patient were measured by using EBT2. The measured energy of the electron beam was agreed with the value that measured by ionization chamber, and the spatial dose distribution at the patient position and the doses at several point on the patient's skin could be easily measured by EBT2 film. The dose on the patient that was measured by EBT2 film showed good agreement with the data measured simultaneously by TLD. With the results of this study, it was proven that the EBT2 film can be one of the useful dosimeter for TSET.

• The Journal of Korean Society for Radiation Therapy
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• v.8 no.1
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• pp.29-35
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• 1996

We are often faced with the clinical situations that is inevitably extended SSD for electron beam therapy due to anatomical restriction or applicator structure. But there are some difficulties in accurately predicting output and properties. In electron beam treatment , unlike photon beam the decrease in output for extended SSD does not follow inverse-square law accurately because of a loss of side scatter equilibrium, which is particularly significant for small cone size and low energies. The purpose of our study is to analyze the output in changing with the energy, cone size, air gap beyond the standard SSD and to compare inverse-square law factor derived from calculated effective SSD, mominal SSD with measured output factor. In addition, we have analyzed the change of PDD for several cones with different SSDs which range from 100cm to 120cm with 5cm step and with different energies(6MeV, 9MeV, 12MeV, 16MeV, 20MeV). In accordance with our study, an extended SSD produces a significant change in beam output, negligible change in depth dose which range from 100cm to 120cm SSDs. In order to deliver the more accurate dose to the neoplastic tissue, first of all we recommend inverse-square law using the table of effective SSDs with cone sizes and energies respectively or simply to create a table of extended SSD air gap correction factor. The second we need to have an insight into some change of dose distribution including PPD, penumbra caused by extended SSD for electron beam therapy.

• The Journal of Korean Society for Radiation Therapy
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• v.12 no.1
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• pp.85-90
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• 2000

• The Journal of Korean Society for Radiation Therapy
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• v.12 no.1
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• pp.140-143
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• 2000