• Radiation Oncology Journal
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• v.7 no.1
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• pp.93-100
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• 1989

Several combinations of measuring devices and phantoms were studied to measure electron beams. Silicon Pmt junction diode was used to find the dependence of depth dose profile on field size on axis of electron beam Depths of 50, 80 and $90\%$ doses increased with the field size for small fields. For some larger fields, they were nearly constant. The smallest of field sizes over which the parameters were constant was enlarged with increase of the energy of electron beams. Depth dose distributions on axis of electron beam of $10\times10cm^2$ field were studied with several combinations of measuring devices and phantoms. Cylindrical ion chamber could not be used for measurement of surface dose, and was not convenient for measurement of near surface region of 6MeV electron. With some exceptions, parameters agreed well with those studied by different devices and phantoms. Surface dose in some energies showed $4\%$ difference between maximum and minimum. For 18MeV, depths of 80 and $90\%$ doses were considerably shallower by film than by others. Parallel-plate ion chamber with polystyrene phamtom and silicon PN junction would be recommended for measurement of central axis depth dose of electron beams with considerably large field size. It is desirable not to use cylindrical ion chamber for the purpose of measurement of surface dose or near surface region for lower energy electron beam. It is questionable that film would be recommended for measurement of dose distribution of electron with high energy like as 18MeV.

• Journal of Physiology & Pathology in Korean Medicine
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• v.24 no.1
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• pp.134-142
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• 2010

Although BinSo-San(BSS), a mixed herbal formula consisted of 11 types of medicinal herbs and have been used as anti-inflammatory agent, In the present study, the acute toxicity (single oral dose toxicity) of lyophilized BSS aqueous extracts was monitored in male and female mice after oral administration according to Korea Food and Drug Administration (KFDA) Guidelines (2005-60, 2005). In order to observe the 50% lethal dose ($LD_{50}$), approximate lethal dosage (ALD), maximum tolerance dosage (MTD) and target organs, test articles were once orally administered to female and male ICR mice at dose levels of 2000, 1000, 500, 250 and 0 (control) mg/kg (body wt.) according to the recommendation of KFDA Guidelines (2005-60, 2005). The mortality and changes on body weight, clinical signs and gross observation were monitored during 14 days after dosing according to KFDA Guidelines (2005-60, 2005) with organ weight and histopathology of 12 types of principle organs. We could not find any mortality, clinical signs and changes in the body weights except for dose-independent increases of body weight and gains restricted in 1000 mg/kg of BSS extracts-dosing female group. Hypertrophic changes of lymphoid organs.thymus, spleen and popliteal lymph nodes were detectedat postmortem observation with BSS extracts dose-dependent increases of lymphoid organ weights, and hyperplasia of lymphoid cells in these all three lymphoid organs at histopathological observations. These changes are considered as results of pharmacological effects of BSS extracts or their components, immunomodulating effects, not toxicological signs. In addition, some sporadic accidental findings such as congestion spots, cyst formation in kidney, atrophy of thymus and spleen with depletion of lymphoid cells, and edematous changes of uterus with desquamation of uterus mucosa as estrus cycles were detected throughout the whole experimental groups including both male and female vehicle controls. The significant (p<0.01) increases of absolute weights of kidney and pancreas detected in BSS extracts 1000 mg/kg-treated female group are considered as secondary changes from increases of body weights. The results obtained in this study suggest that the BSS extract is non-toxic in mice and is therefore likely to be safe for clinical use. The LD50 and ALD of BSS aqueous extracts in both female and male mice were considered as over 2000 mg/kg because no mortalities were detected upto 2000 mg/kg that was the highest dose recommended by KFDA and OECD. In addition, the MTD of BSS extracts was also considered as over 2000 mg/kg because no BSS extracts-treatment related toxicological signs were detected at histopathological observation except for BSS or their component-related pharmacological effects, the immunomodulating effects detected in the present study.

• Journal of Radiation Protection and Research
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• v.29 no.2
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• pp.105-115
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• 2004

The Monte Carlo simulation requires very much time to obtain a result of acceptable accuracy. Therefore we should know the optimum number of history not to sacrifice time as well as the accuracy. In this study, we have investigated the effects of statistical uncertainties of the photon dose calculation. BEAMnrc and DOSXYZnrc systems were used for the Monte Carlo dose calculation and the case of mediastinum was simulated. The several dose calculation result from various number of histories had been obtained and analyzed using the criteria of isodose curve comparison, dose volume histogram comparison(DVH) and root mean-square differences(RMSD). Statistical uncertainties were observed most evidently in isodose curve comparison and RMSD while DVHs were less sensitive. The acceptable uncertainties $(\bar{{\Delta}D})$ of the Monte Carlo photon dose calculation for the radiation therapy were estimated within total 9% error or 1% error for over than $D_{max}/2$ voxels or voxels at maximum dose.

• Progress in Medical Physics
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• v.25 no.4
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• pp.288-297
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• 2014

Dynamic conformal arc therapy (DCAT) and flattening-filter-free (FFF) beams are commonly adopted for efficient conformal dose delivery in stereotactic body radiation therapy (SBRT). Off-axis geometry (OAG) may be necessary to obtain full gantry rotation without collision, which has been shown to be beneficial for peripheral targets using flattened beams. In this study dose distributions in OAG using FFF were evaluated and the effect of mechanical rotation induced uncertainty was investigated. For the lateral target, OAG evaluation, sphere targets (2, 4, and 6 cm diameter) were placed at three locations (central axis, 3 cm off-axis, and 6 cm off-axis) in a representative patient CT set. For each target, DCAT plans under the same objective were obtained for 6X, 6FFF, 10X, and 10FFF. The parameters used to evaluate the quality of the plans were homogeneity index (HI), conformality indices (CI), and beam on time (BOT). Next, the mechanical rotation induced uncertainty was evaluated using five SBRT patient plans that were randomly selected from a group of patients with laterally located tumors. For each of the five cases, a plan was generated using OAG and CAG with the same prescription and coverage. Each was replanned to account for one degree collimator/couch rotation errors during delivery. Prescription isodose coverage, CI, and lung dose were evaluated. HI and CI values for the lateral target, OAG evaluation were similar for flattened and unflattened beams; however, 6FFF provided slightly better values than 10FFF in OAG. For all plans the HI and CI were acceptable with the maximum difference between flattened and unflattend beams being 0.1. FFF beams showed better conformality than flattened beams for low doses and small targets. Variation due to rotational error for isodose coverage, CI, and lung dose was generally smaller for CAG compared to OAG, with some of these comparisons reaching statistical significance. However, the variations in dose distributions for either treatment technique were small and may not be clinically significant. FFF beams showed acceptable dose distributions in OAG. Although 10FFF provides more dramatic BOT reduction, it generally provides less favorable dosimetric indices compared to 6FFF in OAG. Mechanical uncertainty in collimator and couch rotation had an increased effect for OAG compared to CAG; however, the variations in dose distributions for either treatment technique were minimal.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.1
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• pp.107-120
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• 2019

The decommissioning of one nuclear power plant in a multi-unit nuclear power plant (multi-unit NPP) site may pose radiation exposure risk to decommissioning workers. Thus, it is essentially required to evaluate the exposure dose of decommissioning workers of operating multi-unit NPPs nearby. The ENDOS program is a dose evaluation code developed by the Korea Atomic Energy Research Institute (KAERI). As two sub-programs of ENDOS, ENDOS-ATM to anticipate atmospheric transport and ENDOS-G to calculate exposure dose by gaseous radioactive effluents are used in this study. As a result, the annual maximum individual dose for decommissioning workers is estimated to be $2.31{\times}10^{-3}mSv{\cdot}y^{-1}$, which is insignificant compared with the effective dose limit of $1mSv{\cdot}y^{-1}$ for the public. Although it is revealed that the exposure dose of operating multi-unit NPPs does not result in a significant impact on decommissioning workers, closer examination of the effect of additional exposure due to actual demolition work is required. The calculation method of this study is expected to be utilized in the future for planned decommissioning projects in Korea. Because domestic NPPs are located in multi-unit sites, similar situations may occur.

• Progress in Medical Physics
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• v.19 no.1
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• pp.80-88
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• 2008

Recent radiotherapy dose planning system (RTPS) generally adapted the kernel beam using the convolution method for computation of tissue dose. To get a depth and profile dose in a given depth concerened a given photon beam, the energy spectrum was reconstructed from the attenuation dose of transmission of filter through iterative numerical analysis. The experiments were performed with 15 MV X rays (Oncor, Siemens) and ionization chamber (0.125 cc, PTW) for measurements of filter transmitted dose. The energy spectrum of 15MV X-rays was determined from attenuated dose of lead filter transmission from 0.51 cm to 8.04 cm with energy interval 0.25 MeV. In the results, the peak flux revealed at 3.75 MeV and mean energy of 15 MV X rays was 4.639 MeV in this experiments. The results of transmitted dose of lead filter showed within 0.6% in average but maximum 2.5% discrepancy in a 5 cm thickness of lead filter. Since the tissue dose is highly depend on the its energy, the lateral dose are delivered from the lateral spread of energy fluence through flattening filter shape as tangent 0.075 and 0.125 which showed 4.211 MeV and 3.906 MeV. In this experiments, analyzed the energy spectrum has applied to obtain the percent depth dose of RTPS (XiO, Version 4.3.1, CMS). The generated percent depth dose from $6{\times}6cm^2$ of field to $30{\times}30cm^2$ showed very close to that of experimental measurement within 1 % discrepancy in average. The computed dose profile were within 1% discrepancy to measurement in field size $10{\times}10cm$, however, the large field sizes were obtained within 2% uncertainty. The resulting algorithm produced x-ray spectrum that match both quality and quantity with small discrepancy in this experiments.

• Radiation Oncology Journal
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• v.20 no.1
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• pp.24-33
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• 2002

Purpose : In order to improve dose homogeneity and to reduce acute toxicity in tangential whole breast radiotherapy, we evaluated two treatment techniques using multiple static fields or universal compensators. Materials and Methods : 1) Multistatic field technique : Using a three dimensional radiation treatment planning system, Adac Pinnacle 4.0, we accomplished a conventional wedged tangential plan. Examining the isodose distributions, a third field which blocked overdose regions was designed and an opposing field was created by using an automatic function of RTPS. Weighting of the beams was tuned until an ideal dose distribution was obtained. Another pair of beams were added when the dose homogeneity was not satisfactory. 2) Universal compensator technique : The breast shapes and sizes were obtained from the CT images of 20 patients who received whole breast radiation therapy at our institution. The data obtained were averaged and a pair of universal physical compensators were designed for the averaged data. DII (Dose Inhomogeneity Index : percentage volume of PTV outside $95\~105\%$ of the prescribed dose) $D_{max}$ (the maximum point dose in the PTV) and isodose distributions for each technique were compared. Results : The multistatic field technique was found to be superior to the conventional technique, reducing the mean value of DII by $14.6\%$ (p value<0.000) and the $D_{max}$ by $4.7\%$ (p value<0.000). The universal compensator was not significantly superior to the conventional technique since it decreased $D_{max}$ by $0.3\%$ (p value=0.867) and reduced DII by $3.7\%$ (p value=0.260). However, it decreased the value of DII by maximum $18\%$ when patients' breast shapes fitted in with the compensator geometry. Conclusion : The multistatic field technique is effective for improving dose homogeneity for whole breast radiation therapy and is applicable to all patients, whereas the use of universal compensators is effective only in patients whose breast shapes fit inwith the universal compensator geometry, and thus has limited applicability.

• The Plant Pathology Journal
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• v.22 no.4
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• pp.339-347
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• 2006

Riboflavin caused induction of systemic resistance in chickpea against Fusarium wilt and charcoal rot diseases. The dose effect of 0.01 to 20 mM riboflavin showed that 1.0 mM concentration was sufficient for maximum induction of resistance; higher concentration did not increase the effect. At this concentration, riboflavin neither caused cell death of the host plant nor directly affected the pathogen's growth. In time course observation, it was observed that riboflavin treated chickpea plants were inducing resistance 2 days after treatment and reached its maximum level from 5 to 7 days and then decreased. Riboflavin had no effect on salicylic acid(SA) levels in chickpea, however, riboflavin induced plants found accumulation of phenols and a greater activities of phenylalanine ammonia lyase(PAL) and pathogenesis related(PR) protein, peroxidase was observed in induced plant than the control. Riboflavin pre-treated plants challenged with the pathogens exhibited maximum activity of the peroxidases 4 days after treatment. Molecular weight of the purified peroxidase was 42 kDa. From these studies we demonstrated that riboflavin induced resistance is PR-protein mediated but is independent of salicylic acid.

• Structural Engineering and Mechanics
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• v.90 no.2
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• pp.107-116
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• 2024

This study examined the changes in the mechanical properties of coral concrete under different coconut fiber admixtures. To accomplish this goal, the compressive strength, splitting tensile strength, flexural strength and elastic modulus properties of coral concrete blocks reinforced with coconut fibers were measured. The results showed that the addition of coconut fiber had little effect on the cube and axial compressive strengths. With increasing coconut fiber content, the flexural strength and splitting tensile strength of the concrete changed substantially, first by increasing and then by decreasing, with maximum increases of 36.0% and 12.8%, respectively; additionally, the addition of coconut fibers resulted in a failure type with some ductility. When the coconut fiber-reinforced coral concrete was 7 days old, it reached approximately 74% of its maximum strength. The addition of coconut fiber did not affect the early strength of the coral concrete mixed with seawater. When the amount of coconut fiber was no more than 3 kg/m3, the resulting concrete elastic modulus decreased only slightly from that of a similar concrete without coconut fiber, and the maximum decrease was 5.4%. The optimal dose of coconut fiber was 3 kg/m3 in this study.

• Radiation Oncology Journal
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• v.27 no.2
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• pp.103-110
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• 2009

Purpose: To investigate the feasibility of helical tomotherapy on a wide curved area of the skin, and its accuracy in calculating the absorbed dose in the superficial region. Materials and Methods: Two types of treatment plans were made with the cylinder-shaped 'cheese phantom'. In the first trial, 2 Gy was prescribed to a 1-cm depth from the surface. For the other trial, 2 Gy was prescribed to a 1-cm depth from the external side of the surface by 5 mm. The inner part of the phantom was completely blocked. To measure the surface dose and the depth dose profile, an EDR2 film was inserted into the phantom, while 6 TLD chips were attached to the surface. Results: The film indicated that the surface dose of the former case was 118.7 cGy and the latter case was 130.9 cGy. The TLD chips indicated that the surface dose was higher than these, but it was due to the finite thickness of the TLD chips. In the former case, 95% of the prescribed dose was obtained at a 2.1 mm depth, while the prescribed does was at 2.2 mm in the latter case. The maximum dose was about 110% of the prescribed dose. As the depth became deeper, the dose decreased rapidly. Accordingly, at a 2-cm depth, the dose was 20 % of the prescribed dose. Conclusion: Helical tomotherapy could be a useful application in the treatment of a wide area of the skin with curvature. However, for depths up to 2 mm, the planning system overestimated the superficial dose. For shallower targets, the use of a compensator such as a bolus is required.