• Progress in Medical Physics
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• v.34 no.4
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• pp.48-54
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• 2023

Purpose: In this study, the dosimetric characteristics of lung stereotactic body radiotherapy (SBRT) plans using the new Halcyon system were analyzed to assess its suitability. Methods: We compared the key dosimetric parameters calculated for the Halcyon SBRT plans with those of a conventional C-arm linear accelerator (LINAC) equipped with a high-definition multileaf collimator (HD-MLC)-Trilogy Tx. A total of 10 patients with non-small-cell lung cancer were selected, and all SBRT plans were generated using the RapidArc technique. Results: Trilogy Tx exhibited significant superiority over Halcyon in terms of target dose coverage (conformity index, homogeneity index, D_{0.1 cc}, and D_95%) and dose spillage (gradient). Trilogy Tx was more efficient than Halcyon in the lung SBRT beam delivery process in terms of the total number of monitor units, modulation factor, and beam-on time. However, it was feasible to achieve a dose distribution that met SBRT plan requirements using Halcyon, with no significant differences in satisfying organs at risk dose constraints between both plans. Conclusions: Results confirm that Halcyon is a viable alternative for performing lung SBRT in the absence of a LINAC equipped with HD-MLC. However, extra consideration should be taken in determining whether to use Halcyon when the planning target volume setting is enormous, as in the case of significant tumor motions.

• Radiation Oncology Journal
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• v.1 no.1
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• pp.41-45
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• 1983

To obtain 7 MeV electron beam which is suitable for treatment of the chest wall after radical of modified radical mastectomy, the authors reduced the energy of electron beam by means by Lucite plate inserted in the beam. To determine the proper thickness of the Lucite plate necessary to reduce the energy of 9 MeV electron beam to 6 MeV, dosimetry was made by using a parallel plate ionization chamber in polystyrene phantom. Separation between two adjacent fields, 7 MeV for chest wall and 12 MeV for internal mammary region, was studied by means of film dosimetry in both polytyrene phantom and Humanoid phantom. The results were as follows. 1. The average energy of 9 MeV electron beam transmitted through the Lucite plate was reduced. Reduction was proportional to the thickness of the Lucite plate in the rate of 1.7 MeV/cm. 2. The proper thickness of the Lucite plate necessary to obtain 6 MeV electron beam from 9 MeV was 1.2 cm. 3. 7 MeV electron beam, 80% dose at 2cm depth, is adequate for treatment of the chest wall. 4. Proper separation between two adjacent electron fields, 7 MeV and 12 MeV, was 5mm on both flat surface and sloping surface to produce uniform dose distribution.

• Journal of the korean academy of Pediatric Dentistry
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• v.39 no.3
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• pp.273-279
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• 2012

Purpose : This study was aimed to calculate effective dose from cone beam CT and compare effective dose from periapical and panoramic radiography for mesiodens. Materials and Methods : Upper anteiror periapical, panoramic radiography and cone-beam CT were taken for diagnosis of mesiodens. The effective dose were calculated by using an anthropomorphic phantom loaded with thermoluminescent dosimeters at the 23 sites related to sensitive organs. Results : The highest absorbed doses were received by the mandibular body, parotid gland and cheek from periapical, panoramic and cone-beam CT, respectively. The effective doses for periapical, panoramic radiography and cone-beam CT measured 2, 18 and 48 ${\mu}Sv$. Conclusion : Cone-beam CT, although providing additional diagnostic benefits, exposes patients to higher levels of radiation than conventional periapical and panoramic radiography.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2004.11a
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• pp.69-71
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• 2004

The proton therapy of radiation therapy methods using Bragg Peak which is proton beam's characteristic dose distribution can give a normal tissue lower dose than cancer, comparing with the former existing radiation therapy methods. For exact treatment and patient' safety, we need to know proton beam's position in body, but a proton beam completely stops at treatment region and proton beam's range is uncertainly made by the variety of organs having each different density, so we aren't able to find a proton beam' position by suitable methods yet. With Monte Carlo Computing Method, as a result that we had simulated prompt gamma detection system using correlation of proton beam's absorbed dose distribution about water and prompt gamma distribution by nuclear interaction occurred by collisions of proton and water's hydrogen atoms, we could confirm that a proton beam's position was able to detect by using simulated prompt gamma detection system in body on the real-time

• Progress in Medical Physics
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• v.30 no.4
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• pp.112-119
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• 2019

Purpose: The advantages of ocular proton therapy are that it spares the optic nerve and delivers the minimal dose to normal surrounding tissues. In this study, it developed a solid eye phantom that enabled us to perform quality assurance (QA) to verify the dose and beam range for passive single scattering proton therapy using a single phantom. For this purpose, a new solid eye phantom with a polymethyl-methacrylate (PMMA) wedge was developed using film dosimetry and an ionization chamber. Methods: The typical beam shape used for eye treatment is approximately 3 cm in diameter and the beam range is below 5 cm. Since proton therapy has a problem with beam range uncertainty due to differences in the stopping power of normal tissue, bone, air, etc, the beam range should be confirmed before treatment. A film can be placed on the slope of the phantom to evaluate the Spread-out Bragg Peak based on the water equivalent thickness value of PMMA on the film. In addition, an ionization chamber (Pin-point, PTW 31014) can be inserted into a hole in the phantom to measure the absolute dose. Results: The eye phantom was used for independent patient-specific QA. The differences in the output and beam range between the measurement and the planned treatment were less than 1.5% and 0.1 cm, respectively. Conclusions: An eye phantom was developed and the performance was successfully validated. The phantom can be employed to verify the output and beam range for ocular proton therapy.

• Journal of IKEEE
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• v.24 no.2
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• pp.626-631
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• 2020

In this paper, a study on beam synthesis technique of conformal array was performed. It is applied to various radar systems that can perform beam steering without deterioration of performance due to beam steering in a general linear arrangement. Unlike the beam synthesis technique in the planar linear array, the conformal array has a radiation element located on a curved surface, so it is necessary to compensate for a difference in length from the radaation element to the wave front surface. In addition, by calculating the offset angle for each radiation element and applying it during actual synthesis, it was possible to predict an accurate beam pattern. In this paper, length compensation and offset angle were calculated and applied to beam pattern synthesis to perform beam pattern comparison, and performance was compared through mathematical analysis.

• Food Science of Animal Resources
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• v.30 no.4
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• pp.603-608
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• 2010

This study investigated the effects of electron beam irradiation on pathogens, quality, and functional properties of shell eggs during storage. A 1st grade 1-d-old egg was subjected to electron beam irradiation at 0, 1, 2, and 3 kGy, after which the number of total aerobic bacteria, reduction of inoculated Escherichia coli and Salmonella Typhimurium, egg quality, and functional properties were measured. Electron beam irradiation at 2 kGy reduced the number of E. coli and S. Typhimurium cells to a level below the detection limit (<$10^2$ CFU/g) after 7 and 14 d of storage. Egg freshness as measured by albumen height and the number of Haugh units was significantly reduced by 1-kGy irradiation. The viscosity of irradiated egg white was also significantly decreased by increased irradiation, whereas its foaming ability was increased. Electron beam irradiation also increased lipid oxidation in egg yolks. These results suggest that electron beam irradiation reduces the freshness of shell eggs while increasing the oxidation of egg yolk and improving important functional properties such as foaming capacity. Electron beam irradiation can also be applied to the egg breaking process since the irradiation reduces the viscosity of egg white, which can allow egg whites and yolks to be separated with greater efficiency.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.5
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• pp.68-73
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• 2015

Electron beam irradiation is also an eco-friendly treatment compared to other physical and chemical treatments. In this study, we attempted to evaluate the possibilities of energy savings by applying electron beam irradiation to the refining process. After softwood unbleached kraft pulp (UKP) was irradiated with electron beams at 50 and 100 kGy, it was beaten in a laboratory beater, and then its freeness and fiber properties were analyzed. The physical properties of their fiber handsheet were also and measured. As the irradiation dose of the electron beam and the beating time increased, lower freeness and fiber lengths of the UKP were observed. Handsheets made from UKP that was irradiated by electron beam and beaten showed a reciprocal relationship with the irradiation dose of the electron beam, in particular, the strength of the handsheets decreased dramatically at 100 kGy of irradiation. Therefore, it was confirmed that electron beam irradiation is effective in reducing the beating time or beating energy. But the irradiation dose must be controlled under 50 kGy to minimize the loss of paper strength.

• Progress in Medical Physics
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• v.33 no.4
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• pp.108-113
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• 2022

Purpose: Proton therapy has been used for optimal cancer treatment by adapting its Bragg-peak characteristics. Recently, a tissue-sparing effect was introduced in ultrahigh-dose-rate (FLASH) radiation; the high-energy transmission proton beam is considered in proton FLASH therapy. In measuring high-energy/ultrahigh-dose-rate proton beam, Faraday Cup is considered as a dose-rate-independent measurement device, which has been widely studied. In this paper, the feasibility of the simply designed Faraday Cup (Poor Man's Faraday Cup, PMFC) for transmission proton FLASH therapy is investigated. Methods: In general, Faraday cups were used in the measurement of charged particles. The simply designed Faraday Cup and Advanced Markus ion chamber were used for high-energy proton beam measurement in this study. Results: The PMFC shows an acceptable performance, including accuracy in general dosimetric tests. The PMFC has a linear response to the dose and dose rate. The proton fluence was decreased with the increase of depth until the depth was near the proton beam range. Regarding secondary particles backscatter from PMFC, the effect was negligible. Conclusions: In this study, we performed an experiment to investigate the feasibility of PMFC for measuring high-energy proton beams. The PMFC can be used as a beam stopper and secondary monitoring system for transmission proton beam FLASH therapy.

• 대한방사선방어학회:학술대회논문집
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• 2011.11a
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• pp.196-197
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• 2011