• Journal of radiological science and technology
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• v.38 no.4
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• pp.337-345
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• 2015

After the Fukushima nuclear accident in 2011, concerns about radiation by people are increasing rapidly. If people could know how much they will be exposed by radiation, it may help them avoiding it and understand what exactly radiation is. By doing this, we were helping to reduce the anxiety of radiation contamination. In this study, we have researched figures of radioactivity with 'Captus-3000 thyroid uptake measurement systems' in well counter detector system. The materials were measured with Briquette, Shiitake, Pollock, Button type battery, Alkaline battery, Topsoil, Asphalt, Gasoline, Milk powder, Pine, Basalt stone, Pencil lead, Wasabi, Coarse salt, Tuna(can) Cigar, Beer, and then we categorized those samples into Land resources, Water resources, Foodstuff and Etc (Beer classified as a water resources has been categorized into Foodstuff). Also, we selected the standard radiation source linear 137Cs to measure the sensitivity of well counter detector. After that, we took cpm(counter per minute) for the well counter detector of thyroid uptake system's sensitivity. Then we compared the results of each material's cpm and converted those results to Bq/kg unit. There were a little limitation with the measurement equipment because it has less sensitivity than other professional equipment like 'High purity germanium radiation detector'. Moreover, We didn't have many choices to decide the materials. As a result, there are macroscopic differences among the rates of material's spectrum. Therefore, it had meaningful results that showed how much each material had emitted radiation. To compare the material's cpm with BKG, we've compounded their spectrums. By doing that, we were able to detect some differences among the spectrums at specific peak section. Lastly, Button type battery, Alkaline Battery, Briquette, Asphalt and Topsoil showed high value. There were classified emitting high radiation Group A and emitted lower radiation Group B. The Group A, alkaline battery showed higher rate of radiation by 7.67 %, and Button type battery was yield 4.65 % higher rate than BKG. Additionally, Asphalt (8.03 %), Topsoil (3.76 %), Briquette (7.46 %) were yield for higher values. Several samples of the daily supplies were yield little higher, but it seems safe to use in daily lives. In the case of the 'Foodstuff', all of the samples were safe and they were under the radiation limits of the Ministry of Food and Drug Safety for Food; thus, we highly recommend this study to you as a reference of common daily routine.

• The Journal of Korean Society for Radiation Therapy
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• v.16 no.1
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• pp.91-99
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• 2004

Purpose : For the head and neck radiotherapy, abutting photon field with electron field is frequently used for the irradiation of posterior neck when tolerable dose on spinal cord has been reached. Materials and methods : Using 6 MV X-ray and 9 MeV electron beams of Clinac1800(Varian, USA) linear accelerator, we performed film dosimetry by the X-OMAT V film of Kodak in solid water phantom according to depths(0 cm, 1.5 cm, 3 cm, 5 cm). 6 MV X-ray and 9 MeV electron(1Gy) were exposes to 8cm depth and surface(SSD 100cm) of phantom. The dose distribution to the junction line between photon($10cm{\times}10cm$ field with block) and electron($15cm{\times}15cm$ field with block) fields was also measured according to depths(0 cm, 0.5 1.5 cm, 3 cm, 5 cm). Results : At the junction line between photon and electron fields, the hot spot was developed on the side of the photon field and a cold spot was developed on that of the electron field. The hot spot in the photon side was developed at depth 1.5 cm with 7 mm width. The maximum dose of hot spot was increased to $6\%$ of reference doses in the photon field. The cold spot in the electron side was developed at all measured depths(0.5 cm-3 cm) with 1-12.5 mm widths. The decreased dose in the cold spot was $4.5-30\%$ of reference dose in the electron field. Conclusion : When we make use of abutting photon field with electron field for the treatment of head and neck cancer we should consider the hot and cold dose area in the junction of photon and electron field according to location of tumor.

• Journal of radiological science and technology
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• v.33 no.3
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• pp.261-268
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• 2010

This study is compared that the dose distribution by experimentation and radiation therapy planning (RTP) when the air cavity region was treated high energy photon. The dose measurements were performed with a 6 MV photon beam of linear accelerator. The polystyrene and self made acyl phantom were similar to tissue density of the human body. A parallel plate chamber was connected to an electrometer. The measurement setup was SCD (Source Chamber Distance) 100 cm and the distance of surface from air cavity was 3 cm. Absorbed dose of interface were measured by area and height. The percent depth dose were measured presence and absence of air cavity, depth according to a ratio of field size and air cavity size. The dose distribution on planning was expressed to do the inhomogeneity correction. As the area of air cavity was increased, the absorbed dose were gradually reduced. It was slightly increased, when the height of air cavity was changed from 0 cm to 0.5 cm. After the point, dose was decreased. In case of presence of air cavity, dose after distal air cavity interface was more great than absence of air cavity. The rebuild up by field size and area of air cavity occurred for field size, $4{\times}4\;cm^2$, $5{\times}5\;cm^2$ and $6{\times}6\;cm^2$, with fixed on area of air cavity, $5{\times}5\;cm^2$. But it didn't occur at $10{\times}10\;cm^2$ field size. On the contrary, the field size was fixed on $5{\times}5\;cm^2$, rebuild up occurred in area of air cavity, $4{\times}4\;cm^2$, $5{\times}5\;cm^2$. but, it did not occur for air cavity, $2{\times}2\;cm^2$, $3{\times}3\;cm^2$. All of the radiation therapy planning were not occurred rebuild up. It was required to pay attention to treat tumor in air cavity because the dose distribution of planning was different from the dose distribution of patient.

• Radiation Oncology Journal
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• v.16 no.1
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• pp.71-79
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• 1998

Purpose : The objective of this study is to introduce our installation of a non-commercial 3D Planning system, Plunc and confirm it's clinical applicability in various treatment situations. Materials and Methods : We obtained source codes of Plunc, offered by University of North Carolina and installed them on a Pentium Pro 200MHz (128MB RAM, Millenium VGA) with Linux operating system. To examine accuracy of dose distributions calculated by Plunc, we input beam data of 6MV Photon of our linear accelerator(Siemens MXE 6740) including tissue-maximum ratio, scatter-maximum ratio, attenuation coefficients and shapes of wedge filters. After then, we compared values of dose distributions(Percent depth dose; PDD, dose profiles with and without wedge filters, oblique incident beam, and dose distributions under air-gap) calculated by Plunc with measured values. Results : Plunc operated in almost real time except spending about 10 seconds in full volume dose distribution and dose-volume histogram(DVH) on the PC described above. As compared with measurements for irradiations of 90-cm 550 and 10-cm depth isocenter, the PDD curves calculated by Plunc did not exceed $1\%$ of inaccuracies except buildup region. For dose profiles with and without wedge filter, the calculated ones are accurate within $2\%$ except low-dose region outside irradiations where Plunc showed $5\%$ of dose reduction. For the oblique incident beam, it showed a good agreement except low dose region below $30\%$ of isocenter dose. In the case of dose distribution under air-gap, there was $5\%$ errors of the central-axis dose. Conclusion : By comparing photon dose calculations using the Plunc with measurements, we confirmed that Plunc showed acceptable accuracies about $2-5\%$ in typical treatment situations which was comparable to commercial planning systems using correction-based a1gorithms. Plunc does not have a function for electron beam planning up to the present. However, it is possible to implement electron dose calculation modules or more accurate photon dose calculation into the Plunc system. Plunc is shown to be useful to clear many limitations of 2D planning systems in clinics where a commercial 3D planning system is not available.

• Journal of Wetlands Research
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• v.21 no.2
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• pp.102-113
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• 2019

Slack-tide sampling was carried out at 6 stations at high and low tide for a tidal cycle during spring tide of the early summer (June) and summer (July, August) of 2016 to determine the difference of water quality according to tide in Masan Bay, Korea. The mixing regime of all the water quality components investigated was well explained through the correlation with SAL. In the early summer and summer, TURB, DSi and NNN which mainly flow into the bay from the streams and SS, COD, AMN and $H_2S$ which mainly indicate the internal sink and source materials have a property of conservative mixing and non-conservative mixing, respectively. The conservative mixing showed a good linear relationship of the water quality between high and low tide, and the non-conservative mixing showed a variation of different pattern each other. Factor analysis performed on the concentration difference data sets between high and low tide helped in identifying the principal latent variables for them. In early summer, multiple effects (tidal action, natural influx and internal sinks and sources etc.) acted in combination for the differences to be distributed evenly in four factors (VF1~4), since there were few allochthonous inputs as a low-water season. On the contrary, in summer, the parameters showing large concentration difference at ST-1 affected by stream water were concentrated in one factor (VF1) and clearly distinguished from the parameters affected by the internal sinks and sources. In fact, there is no estuary (bay) that always maintains steady state flow conditions. The mixing regime of an estuary might be changed at any time due to the change of flushing time, and furthermore the change of end-member conditions due to the internal sinks and sources makes the occurrence of concentration difference inevitable. Therefore, when investigating the water quality of the estuary, it is necessary to take a sampling method considering the tide to obtain average water quality data.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.1
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• pp.1-9
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• 2022

The effect of sediments in a waste dumping area on marine organisms was evaluated using sediment toxicity tests with a benthic amphipod (Monocorophium acherusicum) and bioluminescent bacterium (Vibrio fischeri) in accordance with the Korean Standard Method for Marine Wastes (KSMMW). Nine sites in the East Sea-Byeong, East Sea-Jeong, and Yellow Sea-Byeong areas were sampled from 2016 to 2019. The test results showed that the relative average survival rate (benthic amphipods) and relative luminescence inhibition rate (luminescent bacteria) were below 30%, which were judged to be "non-toxic." However, in the t-test, a total of 12 benthic amphipod samples (6, 1, 1, and 4 in 2016, 2017, 2018, and 2019, respectively) were significantly different (p<0.05) from the control samples. To identify the source of toxicity on benthic amphipods, a simple linear regression analysis was performed between the levels of eight heavy metals (Cr, As, Ni, Cd, Cu, Pb, Zn, and Hg) in sediments and the relative average survival rate. The results indicated that Cr had the highest contribution to the toxicity of benthic amphipods (p = 0.000, R2 = 0.355). In addition, Cr was detected at the highest concentration at the DB-85 station and exceeded the Marine Environment Standards every year. Although the sediments were determined as "not toxic" according to the ecotoxicity criteria of the KSMMW, the results of the statistical significance tests and toxicity identification evaluation indicated that the toxic effect was not acceptable. Therefore, revising the criteria for determining the toxic effect by deriving a reference value through quantitative risk assessment using species sensitivity distribution curves is necessary in the future.

• Journal of the Korean Society of Radiology
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• v.17 no.1
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• pp.149-156
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• 2023

The purpose of this study is to compare of growth and chlorophyl between old-barley seed (OBS, 2019) and New-barley seed (NBS, 2020) exposed by X-ray. After germination the OBS and NBS, experimental group was exposed by 30 Gy X-ray using linear accelerator (Clinac IS, VERIAN, USA), by 6 MV X-ray, SSD 100 cm, 18 × 10 cm², 600 MU/min. Length was measured every day until 9th day, and chlorophyl was analyzed using spectrophotometer(uv-1800, shimadzu, japan) after measuring weight in 9th day. Data analysis was performed the Independent T-test using SPSS ver 26.0(Chicago, IL, USA). NBS grow more faster than OBS in control group, but OBS grow more faster than NBS in experimental group. Length of control group was longer significantly every day than that of experimental group in OBS. NBS weighted more than OBS in control group, but OBS weighted more than NBS in experimental group. In comparing chlorophyl density, NBS high more than OBS in control group as well as experimental group. Growth and weight of OBS was effected more those than NBS by X-ray, but NBS in chlorophyl by X-ray. It is expected to be used as basic data for future X-ray research in barley seed.

• Journal of the Korean Society of Radiology
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• v.17 no.7
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• pp.1171-1178
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• 2023

In study, we investigated changes on growth and chlorophyll concentration on sprouted barley by fractionated X-ray irradiation (FXI). Group was divided into the control group (CG), 1-time irradiation group (30 Gy once), 2-time irradiation group (15 Gy 2 times), and 3-time irradiation group (10 Gy 3 times), and 20 grains were used per group. Experimental group (EG) was exposed by using linear accelerator (Clinac IS, VERIAN, USA), by 6 MV X-ray, SSD 100 cm, 18×10 cm², 600 MU/min. Length was measured every day until 9th day, and chlorophyl was analyzed using spectrophotometer(uv-1800, shimadzu, japan) in 9th day. Data analysis was performed the One-way ANOVA using SPSS ver 26.0(Chicago, IL, USA). In the pre-germination irradiation group (Pre-GIG), the CG had greater length than the EG on all measurement days, and as the number of FXI increased, the length became shorter. In the post-germination irradiation group (Post-GIG), the length of the CG was statistically significantly greater than that of the EG on all measurement days, and as the number of FXI increased, the length also became longer. The chlorophyll concentration was higher in the Post-GIG than in the Pre-GIG, and chlorophyll concentrations of EG was higher in the Pre-GIG than in the CG, as well as and Post-GIG. In addition, the smaller the number of FXI, the higher the chlorophyll concentration in both groups. FXI was found to affect the growth and chlorophyll concentration of sprouted barley.