• Radiation Oncology Journal
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• v.10 no.1
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• pp.85-93
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• 1992

We have studied the dosimetric properties of electron beam using Lyon intraoperative device for intraoperative radiation therapy. The dosimetry data had compiled in such a way that a quick and correct decision regarding the cone shape, energy, and accurate calculations could be made. Using 3 dimensional water phantom, we have got the following data: cone output ratios, surface dose, $d_{max}$, $d_{90}$, flatness, symmetry, beam profiles, isodose curve, and SSD correction factors. The cone output ratios were measured with straight and bevelled cone, respectively. As the cone size and the energy were reduced, the cone output ratios decreased rapidly. With the flattening filter, the surface dose increased by electron beam to $85.3\%$, $89.2\%$, and $93.4\%$, for 6 MeV, 9 MeV, and 12 MeV, respectively. It is important to increase the surface dose to $90\%$ or more. Inspite of diminishing dose rate and beam penetration, this flattening filter increases the treatment volume significantly. With the combination of the three levels collimation and the flattening filter, we achieved good homogeneity of the beam and better flatness and the diameter of the 90$\%$ isodose curve was increased. It is important to increase the area that is included in the $90\%$ isodose level. The value of measured and calculated SSD correction factors did not agree over the clinically important range from 100 cm to 110 cm.

• Journal of radiological science and technology
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• v.39 no.2
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• pp.177-184
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• 2016

Recently linear accelerator of radiation therapy intensity modulated radiation therapy, stereotactic radiation therapy are widely used. Such radiation treatment techniques are generally difficult to exclude the small field by using the inverse treatment plan. It is necessary to dose an accurate measurement of characteristics of the small field. Thus, using different detectors to measure the volume of the effective percentage depth dose, beam profile, and the output factor of the small field was to evaluate the dose characteristics of each detector. Experimental results for the X-ray beam 6 MV energy beam quality($PDD_{20}/PDD_{10}$) is $10{\times}10cm^2$ Diode detector is as high as 2.4% compared to Pinpoint detector. All field size to lesser effective volume of Diode detector shows that it is far better than other detectors by more than 50% of small penumbra, therefore spatial resolution far excellent. In field size $2{\times}2cm^2$ Semiflex detector was measured about 2% less than the other detector. Field size $1{\times}1cm^2$ is that there is no judgment about the validity show the difference between 20%. Field size $1{\times}1cm^2$ from the measured values of the Diode detector and Pinpoint detector showed a 13% difference. Less than field size $3{\times}3cm^2$ the feed to the difference between the output factor of the effective volume of the detector to be used for the effective volume available to the detector.

• Radiation Oncology Journal
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• v.12 no.2
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• pp.225-232
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• 1994

Purpose : This study was to obtain the basic dosimetric data using the 10 MV X-ray for the total body irradiation. Materials and Methods : A linear accelerator photon beam is planned to be used as a radiation source for total body irradiation (TBI) in Chonnam University Hospital. The planned distance from the target to the midplane of a patient is 360cm and the maximum geometric field size is 144cm x 144cm. Polystyrene phantom sized $30{\times}30{\times}30.2cm^3$ and consisted of several sheets with various thickness, and a parallel plate ionization chamber were used to measure surface dose and percent depth dose (PDD) at 345cm SSD, and dose profiles. To evaluate whether a beam modifier is necessary for TBI, dosimetry in build up region was made first with no modifier and next with an 1cm thick acryl plate 20cm far from the polystyrene phantom surface. For a fixed sourec-chamber distance, output factors were measured for various depth. Results : As any beam modifier was not on the way of radiation of 10MV X-ray, the $d_{max}$ and surface dose was 1.8cm and $61\%$, respectively, for 345cm SSD. When an 1cm thick acryl plate was put 20cm far from polystyrene phantom for the SSD, the $d_{max}$ and surface dose were 0.8cm and $94\%$, respectively. With acryl as a beam spoiler, the PDD at 10cm depth was $78.4\%$ and exit dose was a little higher than expected dose at interface of exit surface. For two-opposing fields for a 30cm phantom thick phantom, the surface dose and maximum dose relative to mid-depth dose in our experiments were $102.5\%$ and $106.3\%$, respectively. The off-axis distance of that point of $95\%$ of beam axis dose were 70cm on principal axis and 80cm on diagonal axis. Conclusion: 1. To increase surface dose for TBI by 10MV X-ray at 360cm SAD, 1cm thick acrylic spoiler was sufficient when distance from phantom surface to spoiler was 20cm. 2. At 345cm SSD, 10MV X-ray beam of full field produced a satisfiable dose uniformity for TBI within $7\%$ in the phantom of 30cm thickness by two-opposing irradiation technique. 3. The uniform dose distribution region was 67cm on principal axis of the beam and 80cm on diagonal axis from beam axis. 4. The output factors at mid-point of various thickness revealed linear relation with depth, and it could be applicable to practical TBI.

• The Korean Journal of Physiology
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• v.20 no.2
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• pp.249-256
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• 1986

The present study was performed to investigate a possible influence of the adrenergic nervous system on pancreatic exocrine secretion stimulated by intraduodenal acid perfusion. Pancreatic secretion was collected in rats anesthetized with urethane after 24 hours fasting. The duodenal lumen was perfused (0.2 ml/min) with HCI solution in a concentration of 0.005, 0.01, 0.02, 0.05 or 0.1 N When the volume of panceratic juice secreted for IS min became constant phentolamine (1 mg/kg), $noradrenaline\;(10\;{\mu}g/kg),\;Propranolol\;(1\;mg/kg),\;and \;isoproterenol\;(1\;{\mu}g/kg)$ were administered through the jugular vein in bolus. The secretory volume and protein output were measured in the pancreatic juice collected for 15 min. 1) HCI, perfused intraduodenally in graded concentrations from 0.005 N to 0.1 N, increased the pancreatic secretory volume and protein output dose-dependently. 2) In the basal state as well as in the stimulated state by the duodenal acid perfusion, phentolamine increased the pancreatic secretory volume and protein output while propranolol inhibited the volume and protein output. 3) In the basal state, noradrenaline did not change the pancreatic secretory volume but increased the protein output while isoproterenol increased both of the secretory volume and the protein output. These results strongly suggest that ${\alpha}-adrenoceptors$ in the rat pancreas exert an inhibitory influence on the pancreatic exocrine secretion including volume and protein output in the basal state as well as in the stimulated state by the intraduodenal acid perfusion while ${\beta}-adrenoceptors$ play a stimulatory role in the pancreatic exocrine secretion. However, in the physiological situation, adrenergic excitation may stimulate the protein output through ${\beta}-adrenoceptors$ without change in the secretory volume in the rat pancreas.

• Radiation Oncology Journal
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• v.4 no.2
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• pp.165-172
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• 1986

In electron therapy, lead cutout or low-melting alloy block is used for shaping the field. Material for shaping electron field affects the output factor as wet 1 as the collimation system. The authors measured the output factors of electron beams for shaped fields from Clinac-18 using ionization chamber of Farmer type in polystyrene phantom. They analyzed the parameters that affect the output factors. The output factors of electron beams depend on the incident energy, collimation system and size of shaped field. For shaped field the variation of output factor for the field size (A/P) has appearence of a smooth curve for all energy and all applicator collimator combination. The output factors for open field deviate from the curves for shaped fields. An output factor for a given field can be calculated by equivalent field method such as A/P method, if a combination of applicator and collimator is fixed.

• Progress in Medical Physics
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• v.29 no.1
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• pp.16-22
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• 2018

Current dosimetry protocols recommend the use of parallel-plate chambers in electron dosimetry because the electron fluence perturbation can be effectively minimized. However, substitutable methods to calibrate and measure the electron output and energy with the widely used cylindrical chamber should be developed in case a parallel-plate chamber is unavailable. In this study, we measured the correction factors and absolute dose-to-water of electrons with energies of 4, 6, 9, 12, 16, and 20 MeV using Farmer-type and Roos chambers by varying the dose rates according to the AAPM TG-51 protocol. The ion recombination factor and absolute dose were found to be varied across the chamber types, energy, and dose rate, and these phenomena were remarkable at a low energy (4 MeV), which was in good agreement with literature. While the ion recombination factor showed a difference across chamber types of less than 0.4%, the absolute dose differences between them were largest at 4 MeV at approximately 1.5%. We therefore found that the absolute dose with respect to the dose rate was strongly influenced by ion-collection efficiency. Although more rigorous validation with other types of chambers and protocols should be performed, the outcome of the study shows the feasibility of replacing the parallel-plate chamber with the cylindrical chamber in electron dosimetry.

• YAKHAK HOEJI
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• v.49 no.3
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• pp.237-243
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• 2005

Present study was performed for the development of a new supplementary product with gastroprotective effect. The preliminary screening were conducted for the effects of HCl-ethanol-induced gastric lesions in rats. Samples were aloe gel, active hexose correlated compound (AHCC) mentioned that have GI protective property and pulmuone healthy aloe gel (PHAG) that mixture of natural products from Pulmuone company. Aloe gel significantly inhibited HCl-ethanol-induced gastric lesions at the oral dose of 5 ml/kg. AHCC showed the strongest effectiveness at the oral dose of 1,200 mg/kg. PHAG also showed the significant effects at the oral dose of 10, 20 g/kg. In pylorus ligated rats, the treatments of aloe gel, AHCC and PHAG showed decrease in the volume of gastric secretion and acid output. And aloe gel, AHCC and PHAG significantly suppressed the aspirin-induced ulcer and chronic ulcer in pylorus ligated rats. The treatments of aloe gel and PHAG significantly reduced acetic acid-induced ulcer at the oral dose of 5 ml/kg and 10 g/kg for 12 days. In this study; we have found that PHAG had significant improvement in acute gastritis and ulcer at the dose of 20 g/kg and in chronic gastritis and ulcer at the dose of 10 g/kg. Also we evaluated the anti-bacterial activity against H. pylori treated with aloe gel, AHCC and PHAG. PHAG had a equivalent anti bacterial activity with ampicillin against H. pylori at the dose of 1 g/kg.

• Progress in Medical Physics
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• v.25 no.1
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• pp.15-22
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• 2014

The IMRT is proper implement to get high dose deliver to tumor as its shape and selective approach in radiation therapy. Since the IMRT is performed as modulated the radiation fluence by the MLC created the open shapes and its irradiation time, the dose of segment of radiation field effects on the cumulated portal dose. The accurate output factor of small and step shape of segment is important to improve the determination of deliver tumor dose as it is directly proportional to dose. This experiment performed with the 6 MV photon beam of Clinac Ex(Varian) from $3{\times}3cm^2$ to $0.5{\times}0.5cm^2$ small field size for collimator jaw in MLC free and/or for MLC open field in fixed collimator jaw $10{\times}10cm^2$ using the CC01 ion chamber, SFD diode, diamond detector and X-Omat film dosimetry. As results of normalized to the reference field of $10{\times}10cm^2$ of MLC, the output factor of $3{\times}3cm^2$ showed $0.899{\pm}0.0106$, $0.855{\pm}0.0106$ for $2{\times}2cm^2$, $0.764{\pm}0.0082$ for $1{\times}1cm^2$ and $0.602{\pm}0.0399$ for $0.5{\times}0.5cm^2$. The output factor of MLC open field has shown a maximum 3.8% higher than that of the collimator jaw open field.

• Proceedings of the Korean Society of Food Science and Nutrition Conference
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• 2004.11a
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• pp.47-52
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• 2004

This study was conducted to determine the effects of egg phospholipids [(Phosphatidylcholine (PC) and sphingomyelin (SM)] on intestinal absorption of cholesterol and other lipids. Each rat with Iymph cannula was infused via a duodenal catheter at 3.0 mL/h for 8 h with a lipid emulsion containing triolein, cholesterol and PC in 24 mL PBS. The PC in the lipid emulsion was egg PC (EPC), hydrogenated egg PC (HPC), or soy PC (SPC). The EPC in the lipid emulsion markedly lowered the Iymphatic absorption of cholesterol, compared with SPC and a lipid emulsion containing no PC. The HPC further lowered the absorption of cholesterol. The phospholipid output was not affected by the source of PC infused. The total Iymphatic output of oleic acid (18: 1), the major fatty acid infused in the form of triolein, did not differ among the NPC, SPC and EPC groups, but was significantly lower in the HPC group. The findings provide the first evidence that EPC markedly lowers the Iymphatic absorption of cholesterol under in vivo conditions. The inhibitory effect of EPC appears to be due to the higher degree of saturation of its acyl groups relative to SPC, suggesting that the intestinal absorption of egg cholesterol may be reduced by the presence of PC in e99 yolk. Experiment 2 was designed to determine whether egg SM, structurally similar to PC, also inhibits the Iymphatic absorption of cholesterol. Egg SM lowered the Lymphatic absorption of cholesterol in a dose dependent manner. Likewise, SM lowered the Iymphatic absorption of oleic acid, whereas it had no effect on retinol absorption. SM at a high dose lowered the Iymphatic outputs of both PC and SM, whereas there was no such effect at a lower dose. These results also indicate that luminal egg SM has an inhibitory effect on the intestinal absorption of cholesterol and other lipids of relatively high hydrophobicity.

• The Journal of Korean Society for Radiation Therapy
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• v.11 no.1
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• pp.6-10
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• 1999

The field size can be beam output, therefore MonitorUnit can be varied due to field size dependence The purpose of this study is to evaluate and compare the dose variation according to exchange of collimator The measurements were perfomed with Wellhofer dosimetry system(water phantom. ion chamber. electrometer. system controller. build up cap. etc)and two types of linear accerlerator (Mevatron KD, MevatronMX) Scatter can be affected to field size dependence and scatter correction is separated into collimator and phantom components, scatter components can affect by exchanging of collimator Measurements of collimator scatter factor(Sc) was done in air with build up cap. 1)Square field (5cm2 to 40cm2) was measured 2)and then keeping the upper jaw constant at loom and varing lower jaw from 5cm to 40cm, 3)keeping the lower jaw constant at 10cm and varing upper jaw from 5cm to 40cm Measurements of total scatter factor(Scp) was done in water at Dmax as the procedure of collimator scatter factor measurements in water Dmax The total scatter factors were obtained to the following equation(Sp=Scp/Sc) The measured data is normalized to the data of reference field size($10{\times}10$), rectangular field is inverted to equivalent field to compare three field size data As the collimator setting is varied, the output was changed In conclusion, the error was obtained small but it must be eliminated if we intend to reach the common stated goal of $5\%$ overall uncertainty in dose determination