• Progress in Medical Physics
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• v.30 no.1
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• pp.14-21
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• 2019

Purpose: To report the initial experience of patient-specific quality assurance (pQA) for the wobbling and line-scanning proton therapy at Samsung Medical Center. Materials and Methods: The pQA results of 89 wobbling treatments with 227 fields and 44 line-scanning treatments with 118 fields were analyzed from December 2015 to June 2016. For the wobbling method, proton range and spread-out Bragg peak (SOBP) width were verified. For the line-scanning method, output and two-dimensional dose distribution at multiple depths were verified by gamma analysis with 3%/3 mm criterion. Results: The average range difference was -0.44 mm with a standard deviation (SD) of 1.64 mm and 0.1 mm with an SD of 0.53 mm for the small and middle wobbling radii, respectively. For the line-scanning method, the output difference was within ${\pm}3%$. The gamma passing rates were over 95% with 3%/3 mm criterion for all depths. Conclusions: For the wobbling method, proton range and SOBP width were within the tolerance levels. For the line-scanning method, the output and two-dimensional dose distribution showed excellent agreement with the treatment plans.

• Journal of Plant Biotechnology
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• v.30 no.3
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• pp.227-232
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• 2003

Radiation technique has been used to develope mutant rice. Suwon 345 rice seeds were irradiated with 250 Gy gamma ray. Morphological characteristics of the variants in M$_{8}$ generation were observed and random amplified polymorphic DNA(RAPD) analysis was carried out. Plant height, panicle length, 1,000 grain weight and lodging were very different in mutants compared with donor cultivar. RAPD analysis showed that polymorphic bands were presented in several primers of the mutants. In comparison with original variety, variants were classified into four group through UPGMA analysis. A group has mutation trait in panicle length, B group in plant height and C group in 1,000 grain weight. Among mutants, no. 46 and 147 was ranked as salt tolerance and the malonaldehyde content of these mutants was more increased than that of original variety. Valuable mutants obtained will be useful for developing new cultivars and for studing gene function in molecular level.l.

• Radiation Oncology Journal
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• v.6 no.1
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• pp.75-80
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• 1988

Twenty seven lesions of 25 patients with locally advanced malignant tumors were treated with combined hyperthermia introduced by microwave and ultrasound and radiotherapy. Most of all patients were failed with previous conventional therapeutic trial. Hyperthermia had been done immediately after radiotherapy, twice a week, $43^{\circ}C$ for one hour and radiotherapy had been done 5 fractions per week with fraction size of 2Gy upto 30 to 60Gy. Conclusions are as follows. 1. Total response rate (PR+PR) to thermoradiotherapy with microwave and ultrasound was $81\%$. 2. Tumor depth, minimum temperature of tumor center, number of heat fraction and radiation dose were statistically significant factors affecting response. 3. Hyperthermia with microwave and ultrasound can be used efficiently to control locally advanced malignant disease whether previously received near tolerance dose of radiotherapy or not.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.2
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• pp.969-975
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• 2013

Aim: The aim of this study was to determine the impact of age on the occurrence, severity, and timing of acute side effects related to radiotherapy. Materials and Methods: We analysed the data of 423 patients. Results: Of the patients, 295 (70%) were under the age of 65 (group 1) and 128 (30%) were over the age of 65 (group 2). The frequencies of radiotherapy-induced side effects were 89% in group 1 and 87% in group 2 (p=0.286). The mean times to occurrence were $2.5{\pm}0.1$ weeks in group 1 and $2.2{\pm}0.1$ weeks in group 2 (p=0.013). Treatment was ended in 2% of patients in group 1 and 6% of those in group 2 (p=0.062). Treatment interruption was identified in 18% of patients in group 1 and 23% in group 2 (p=0.142). Changes in performance status were greater in older patients (p=0.013). There were no significant differences according to the frequency or severity of side effects, except skin and genitourinary complications, between the groups. Conclusions: Early normal tissue reactions were not higher in older versus younger patients, though there was a tendency towards an earlier appearance.

• Radiation Oncology Journal
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• v.11 no.1
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• pp.183-191
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• 1993

The homogeneous dose planning is one of the most important roles in radiation therapy. But, it is not easy to obtain a homogeneous dose to paranasal sinus region including the ethmoidal sinus with conventional irradiation techniques. In this experimental study, the authors tried to get a homogeneous dose at PNS region, but the nasal cartirage does not exceed the tolerance dose, with anterior-posterior beam and two both lateral wedged beams. Used three fields were shielded with full thickness of blocks to preserve the eye-balls and with blocks of one half value layer to create a homogeneous dose at the whole treatment volume. The dose computations are based on the three dimensonal structure with modified scatter contributions of partial shielders and attenuated beams in 6 MV photon beams. The dose distributions of mid-plane is examined with Kodak verification films and teflon-embedded TLD rod (1 mm diameter and 6 mm length) to confirm the computed dose. In our study, the whole PNS regions have shown within $85{\%}$ of the resultant isodose curves with relatively homogeneous dose distribution. The results of dose computation and measurements are agree well within $5{\%}$ uncertainties.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.7
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• pp.3643-3646
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• 2016

Management of eyelid cancers is based on surgery and/or radiotherapy (RT). The treatment objective is to control tumors with acceptable functional and esthetic outcomes. The aim of this study was to evaluate the results of radiation therapy in management of epithelial eyelid cancers, reviewing retrospectively the clinical records of patients treated in our institution from January 1989 to December 2013. We focused on clinical and histological features, treatment characteristics, tolerance and disease control. One hundred and eight patients (62 men and 46 women) were enrolled, with a mean age of 61 years [ranges 15-87]. The most frequent tumor location was the inner canthus (42.6%). Median tumor size was 21 mm [ranges 4-70]. Histological type was basal cell carcinoma in 88 cases (81.5%), squamous cell carcinoma in 16 (14.8%) and sebaceous carcinoma in 4 (3.7%). Radiation therapy was exclusive in 67 cases (62%) and post-operative for positive or close margins in the remaining cases. Kilovoltage external beam radiotherapy (KVRT) was used in 63 patients (58.3%) and low-dose-rate interstitial brachytherapy in 37 (34.3%). Eight (7.4%) were treated with cobalt or with a combination of KVRT-cobalt, KVRT-electron beams, KVRT-brachytherapy or cobalt-electron beams. The total delivered radiation doses were 70 Gy (2 Gy/fraction) in 62 patients (57.4%), 66 Gy (2 Gy/fraction) in 37 (34.3%) and 61.2 Gy (3.4Gy/fraction) in 9 (8.3%). After a median follow-up of 64 months, we noted 10 cases of local recurrences(9.2%): 7 after exclusive and 3 after post-operative RT. No local recurrence occurred in patients treated with brachytherapy. Actuarial 5-year local recurrence-free rate, disease-free survival and overall survival were respectively 90%, 90% and 97%. T-stage was found to be a significant factor for recurrence (p=0.047). All acute radiation-related reactions were scored grade I or II. Delayed effects were eye watering in 24 cases (22.2%), eye dryness in 19 (17.6%), unilateral cataract in 7 (6.4%) and ectropion in 4 (3.7%). Radiation therapy and especially brachytherapy is an efficient treatment of eyelid cancers, allowing eye conservation and functional preservation with good local control rates and acceptable toxicity.

• Korean Journal of Optics and Photonics
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• v.24 no.1
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• pp.29-38
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• 2013

In this paper, the illumination performances of three freeform lenses optimally designed for a point source were investigated for several LEDs with different source sizes, and also the tolerance characteristics of the lenses were analyzed. For comparison, two lenses with different sizes were designed with a divergent illumination model, and the last one was done with an overlapped illumination model. As the LED source size increased, the illuminance uniformity decreased more strongly, and the influence of a source misalignment on illumination performance became insignificant. However, the variation of LED radiation characteristics had strong effect on the illumination performance, irrespective of LED source size. Even though the lens based on a divergent illumination model showed superior performance compared to the lens based on an overlapped illumination model, the latter was less sensitive to the variation of LED radiation characteristics.

• Journal of Radiation Protection and Research
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• v.19 no.3
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• pp.189-198
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• 1994

An angular dependence experiment was made and a performance test of the Teledyne dosimetry system was done in accordance with the ANSI N13.11-1992. The angular dependence experiment was performed with $^{137}Cs$ and low energy X-ray beam. Teledyne dosimetry system performed well at the $0^{\circ}$ angle of incidence for all dosimeters in both vertical and horizontal irradiations. It would have easily passed the 0.5 tolerance limit. But the dosimetry system was not performed well at the ${\pm}60^{\circ}$ angle of incidence for low energy X-ray beam. The accuracy for $^{137}Cs$ beam at all angles of incidence was within the 0.5 tolerance limit. Therefore performance of the dosimetry system could be considered acceptable in case that the dosimeter is irradiated to $^{137}Cs$ beam. However, it could not be acceptable for the dosimeter irradiated to low energy X-ray, especially at more than ${\pm}40^{\circ}$

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.12
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• pp.5019-5024
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• 2015

Background: The purpose of this study was to assess the dosimetric and clinical feasibility of volumetric modulated arc based hypofractionated stereotactic radiotherapy (RapidArc) treatment for large acoustic schwannoma (AS >10cc). Materials and Methods: Ten AS patients were immobilized using BrainLab mask. They were subject to multimodality imaging (magnetic resonance and computed tomography) to contour target and organs at risk (brainstem and cochlea). Volumetric modulated arc therapy (VMAT) based stereotactic plans were optimized in Eclipse (V11) treatment planning system (TPS) using progressive resolution optimizer-III and final dose calculations were performed using analytical anisotropic algorithm with 1.5 mm grid resolution. All AS presented in this study were treated with VMAT based HSRT to a total dose of 25Gy in 5 fractions (5fractions/week). VMAT plan contains 2-4 non-coplanar arcs. Treatment planning was performed to achieve at least 99% of PTV volume (D99) receives 100% of prescription dose (25Gy), while dose to OAR's were kept below the tolerance limits. Dose-volume histograms (DVH) were analyzed to assess plan quality. Treatments were delivered using upgraded 6 MV un-flattened photon beam (FFF) from Clinac-iX machine. Extensive pretreatment quality assurance measurements were carried out to report on quality of delivery. Point dosimetry was performed using three different detectors, which includes CC13 ion-chamber, Exradin A14 ion-chamber and Exradin W1 plastic scintillator detector (PSD) which have measuring volume of $0.13cm^3$, $0.009cm^3$ and $0.002cm^3$ respectively. Results: Average PTV volume of AS was 11.3cc (${\pm}4.8$), and located in eloquent areas. VMAT plans provided complete PTV coverage with average conformity index of 1.06 (${\pm}0.05$). OAR's dose were kept below tolerance limit recommend by American Association of Physicist in Medicine task group-101(brainstem $V_{0.5cc}$ < 23Gy, cochlea maximum < 25Gy and Optic pathway <25Gy). PSD resulted in superior dosimetric accuracy compared with other two detectors (p=0.021 for PSD.

• Journal of Radiation Protection and Research
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• v.20 no.1
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• pp.37-44
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• 1995

Since provisions on the technical criteria for personnel dosimetry was amended three years ago, several improvements in the technique of monitoring personnel doses by TLD have taken place, but for the photograpfic film as a personnel monitor, additional investigations should be carried out for its accuracy of dose estimates because of its wide use in the radiation involved industries. So, this paper describes the methods to develope dose evaluation algorithm for photographic film using ISO reference radiations by i) empirical formula, ii) degree-of-fit method, and iii) matrix approximation. These methods show a good agreement between irradiated and calculated dose within tolerance level represented in ANSI N13. 11, and can be used for the dose evaluation of X, ${\gamma}$ and/or radiation fields.