• The Journal of Korean Society for Radiation Therapy
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• v.21 no.1
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• pp.17-23
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• 2009

Purpose: In treating head and neck cancer, it is very important to irradiate uniform dose on the junction of the bilateral irradiation field of the upper head and neck and the anterior irradiation field of the lower neck. In order to improve dose distribution on the junction, this study attempted to correct non uniform dose resulting from under dose and over dose using the field-in-field technique in treating the anterior irradiation field of the lower neck and to apply the technique to the treatment of head and neck cancer through comparison with conventional treatment. Materials and Methods: In order to examine dose difference between the entry point and the exit point where beam diffusion happens in bilateral irradiation on the upper head and neck, we used an anthropomorphic phantom. Computer Tomography was applied to the anthropomorphic phantom, the dose of interest points was compared in radiation treatment planning, and it was corrected by calculating the dose ratio at the junction of the lower neck. Dose distribution on the junction of the irradiated field was determined by placing low-sensitivity film on the junction of the lower neck and measuring dose distribution on the conventional bilateral irradiation of the upper head and neck and on the anterior irradiation of the lower neck. In addition, using the field-in-field technique, which takes into account beam diffusion resulting from the bilateral irradiation of the upper head and neck, we measured difference in dose distribution on the junction in the anterior irradiation of the lower neck. In order to examine the dose at interest points on the junction, we compared and analyzed the change of dose at the interest points on the anthropomorphic phantom using a thermoluminescence dosimeter. Results: In case of dose sum with the bilateral irradiation of the upper head and neck when the field-in-field technique is applied to the junction of the lower neck in radiation treatment planning, The dose of under dose areas increased by 4.7~8.65%. The dose of over dose areas also decreased by 2.75~10.45%. Moreover, in the measurement using low-sensitivity film, the dose of under dose areas increased by 11.3%, and that of over dose areas decreased by 5.3%. In the measurement of interest point dose using a thermoluminescence dosimeter, the application of the field-in-field technique corrected under dose by minimum 7.5% and maximum 17.6%. Thus, with the technique, we could improve non.uniform dose distribution. Conclusion: By applying the field-in-field technique, which takes into account beam divergence in radiation treatment planning, we could reduce cold spots and hot spots through the correction of dose on the junction and, in particular, we could correct under dose at the entry point resulting from beam divergence. This study suggests that the clinical application of the field-in-field technique may reduce the risk of lymph node metastasis caused by under dose on the cervical lymph node.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.7
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• pp.1108-1113
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• 2003

We performed this study to determine the effect of green tea on jejunal crypt survival, endogenous spleen colony formation, and apoptosis in jejunal crypt cells of mice irradiated with high and low dose of gammairradiation. The radioprotective effect of green tea was compared with the effect of diethyldithiocarbamate (DDC). Jejunal crypts were protected by pretreatment of green tea (p<0.01). Green tea administration before irradiation resulted in an increase of the formation of endogenous spleen colony (p<0.05). The frequency of radiation-induced apoptosis in intestinal crypt cells was also reduced by pretreatment of green tea (p<0.05). The radioprotective effect on jejunal crypts and apoptosis in the DDC treated group appeared similar to those in the green tea treated groups. Treatment with DDC showed no significant modifying effects on the formation of endogenous spleen colony. These results indicated that green tea might be a useful radioprotector, especially since it is a relatively nontoxic natural product. Further studies are needed to characterize better the promotion nature of green tea and its components.

• Korean Journal of Environmental Agriculture
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• v.17 no.3
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• pp.274-278
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• 1998

To observe the stimulating effects of low-dose ${\gamma}-radiation$ on the Chinese cabbage, $1{\sim}5$ years old seeds were cultivated in the green house and the experimental field after irradiation of $0.5Gy{\sim}30.0Gy$ and the growth characters of them were investigated. The germination rates and the seedling heights of old seeds increased positively in the green house, but different from each other depending on their period of storage. Those of 3-, 4-, and 5-year old seeds increased remarkably at the 4.0Gy-, 1.0Gy-, and 0.5Gy-irradiation group respectively. However, in the case of 1-year and 2-year old seeds, there were not significant effects of irradiation except the increase of seedling height. There were significant increasing effects of radiation on the plant height, fresh weight, and diameter of all seeds grown in the experimental field of 4.0Gy- and 8.0Gy-irradiation group, including the corresponding effects of 1-year and 2-year old seeds in 20.0Gy- and 30.0Gy-irradiation group.

• Journal of Radiation Protection and Research
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• v.26 no.1
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• pp.7-12
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• 2001

Sintered LiF:Mg,Cu,Na,Si thermoluminescence (TL) pellets were developed for application in radiation dosimetry. In the present study, the TL dosimetric properties of LiF:Mg,Cu,Na,Si TL pellets have been investigated for emission spectrum, dose response, energy response, and fading characteristics. LiF:Mg,Cu,Na,Si TL pellets were made by using a sintering process, that is, pressing and heat treatment from TL powders. Photon irradiations for the experiments were carried out using X-ray beams and a $^{137}Cs$ gamma source at the Korea Atomic Energy Research Institute (KAERI). The average energies and the dose were in the range of 20-662 keV and $10^{-6}-10^{-2}\;Gy$, respectively. The glow curves were measured with a manual type TLD reader(System 310, Teledyne) at a constant nitrogen flux and a linear heating rate. For a constant heating rate of $5^{\circ}C\;s^{-1}$, the main dosimetric peak of glow curve appeared at $234^{\circ}C$, the activation energy was 2.34 eV and frequency factor was $1.00{\times}10^{23}$. TL emission spectrum is appeared at the blue region centered at 410 nm. A linearity of photon dose response was maintained up to 100 Gy. The photon energy responses relative to $^{137}Cs$ response were within ${\pm}20%$ at overall photon energy region. The fading of TL sensitivity of the pellets stored at the room temperature was not found for one year.

• 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 the Korean Society of Food Science and Nutrition
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• v.44 no.3
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• pp.455-463
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• 2015

This study investigated the effects of low-dose electron beam irradiation treatment on the physicochemical and sensorial properties of imported navel oranges during storage at $20^{\circ}C$ for 12 days. The samples were irradiated at doses of 0.2, 0.4, 0.6, 0.8, and 1.0 kGy, after which changes in color value, hardness, Brix/acid ratio, total sugar contents, reducing sugar contents, vitamin C contents, and sensory evaluation were investigated. There were no significant differences between non-irradiated and irradiated samples in terms of color value, Brix/acid ratio, total sugar contents, total reducing sugar contents, and vitamin C contents. Hardness of irradiated samples significantly decreased in the early storage period in an irradiation dose-independent manner, and the difference between non-irradiated and irradiated samples decreased again at the end of storage. For the sensory evaluation, there was no significant difference between non-irradiated and irradiated samples up to 0.6 kGy, and all sensory item scores decreased at the end of the storage period regardless of irradiation. These results suggest that electron beam irradiation below 0.6 kGy does not affect physicochemical and sensory properties during storage at $20^{\circ}C$. Thus, electron beam irradiation up to 0.6 kGy applied to imported navel oranges is the optimum dose for minimizing quality changes and disinfestation treatment.

• Radiation Oncology Journal
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• v.15 no.4
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• pp.393-402
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• 1997

Purpose : When an x-ray beam of small field size is irradiated to target area containing an air cavity, such as larynx, the underdosing effect is observed in the region near the interfaces of air and soft tissue. With a larynx model, air cavity embedded in tissue-equivalent material, this study is intonded for examining Parameters, such as beam quality, field size, and cavity size, to affect the dose distribution near the air cavity. Materials and Methods : Three x-rar beams, 4-, 6- and 10-MV, were employed to Perform a measurement using a 2cm $(width){\times}L$ (length in cm, one side of x-ray field used 2cm (height) air cavity in the simulated larynx. A thin window parallel-plate chamber connected to an electrometer was used for a dosimetry system. A ratio of the dose at various distances from the cavity-tissue interface to the dose at the same points in a homogeneous Phantom (ebservedlexpected ratio, O/E) normalized buildup curves, and ratio of distal surface dose to dose at the maximum buildup depth were examined for various field sizes. Measurement for cavity size effect was performed by varying the height (Z) of the air cavity with the width kept constant for several field sizes. Results : No underdosing effect for 4-MV beam for fields larger than $5cm\times5cm$ was found For both 6- and 10-MV beams, the underdosing portion of the larynx at the distal surface was seen to occur for small fields, $4cm\times4cm\;and\;5cm\times5cm$. The underdosed tissue was increased in its volume with beam energy even for similar surface doses. The relative distal surface dose to maximum dose was changed to 0.99 from 0.95, 0.92, and 0.91 for 4-, 6-, and 10-MV, respectively, with increasing field size, $4cm\times4cm\;to\;8cm\times8cm$, For 6- and 10-MV beams, the dose at the surface of the cavity is measured less than the predicted by about two and three percent. respectively. but decrease was found for 4-MV beam for $5cm\times5cm$ field. For the $4cm\timesL\timesZ$ (height in cm). varying depth from 0.0 to 4.8cm, cavity, O/E> 1.0 was observed regardless of the cavity size for any field larger than about $8cm\times8cm$. Conclusion : The magnitude of underdosing depends on beam energy, field size. and cavity size for the larynx model. Based on the result of the study. caution must be used when a small field of a high quality x-ray beam is irradiated to regions including air cavities. and especially the region where the tumor extends to the surface. Low quality beam. such as. 4-MV x-ray, and larger fields can be used preferably to reduce the risk of underdosing, local failure. In the case of high quality beams such as 6- and 10-MV x-rays, however. an additional boost field is recommended to add for the compensation of the underdosing region when a typically used treatment field. $8cm\times8cm$, is employed.

• Journal of radiological science and technology
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• v.40 no.4
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• pp.557-565
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• 2017

This study was conducted to investigate the radiation protection, awareness, and attitude of radiological technologists in the mammography room due to the low energy use of breast imaging. Data collection was performed by 222 independent radiological technologists in the breast and breast clinic of six hospitals except Jeju Island. The independent sample t-test and oneway variance analysis were performed. As a result, it was found that the lower the number of men(p<0.05), the age of 30s(p<0.05), the marriage(p<0.05), the work experience of more than 10 years(p<0.05), the working hours of 8 hours(p<0.01), the less the impact of radiation(p<0.01), the more important it was to radiation defense. appear. This is thought to be influenced by the work specificity and work environment of the mammography room, and it will be used as a basic data to raise awareness and act on the exposure through analysis with other factors.

• Journal of Radiation Protection and Research
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• v.28 no.2
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• pp.117-125
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• 2003

It was reported that radiopharamaceuticals induced radiation adaptive response (RAR) in patients undergoing nuclear medicine imaging studies. Individual variations of RAR were not studied well. The purpose of this study was to evaluate individual variation of RAR in patients undergoing nuclear medicine imaging studies. Peripheral lymphocytes were collected from 23 patients undergoing $^{99m}Tc-diethylenetriamine$ pentaacetic acid $(^{99m}Tc-DTPA)$ renal scintigraphy, 18 patients undergoing $^{99m}Tc-methylene$ diphosphonate $(^{99m}Tc-MDP)$ bone scintigraphy and 21 patients undergoing $^{99m}Tc-tetrofosmin\;(^{99m}Tc-TF)$ scintigraphy were collected before and 4 hours after injection of radiopharmaceuticals. The lymphocytes were exposed to challenge dose of 2 Gy gamma rays using a cell irradiator. Numbers of ring-form (R) and dicentric (D) chromosomes were counted under the light microscope. and used to calculate the frequency of chromosomal aberration [Ydr=(D+R)/total number of counted lymphocytes]. Adaptation index (k) was defined 3s ratio of Ydr in conditioned lymphocytes over Ydr in unconditioned lymphocytes. Coefficients of variance of k in $^{99m}Tc-DTPA,\;^{99m}Tc-MDP\;and\;^{99m}Tc-TF$ were 35%, 34% and 21%, respectively k was not dependent upon age, sex, and underlying diseases. There was a wide variation of RAR induced by radiopharmaceuticals among patients undergoing nuclear medicine procedures. It remains to be determined for causes of such variation.

• Radiation Oncology Journal
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• v.20 no.1
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• pp.34-40
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• 2002

Purpose : This study was undertaken to retrospectively evaluate white blood ceil kinetics, especially lymphocyte depression after different treatments, and to find the correlation between immunosuppression and large blood volume and dynamic blood flow within the mediastinal radiotherapy (RT) field in lung cancer. Materials and Methods : Thirty-four patients with lung cancer were retrospectively evaluated; 10 patients had only radiotherapy (RT group), 8 had chemotherapy (CT group) and 16 fad chemotherapy and radio-therapy (RT/CT group). The mean follow-up periods of the RT-including groups (RT group and RT/CT group) and the RT-excluding group (CT group) were 6 and 8 months, respectively. Complete blood cell counts including lymphocyte percentage $(\%)$ were checked weekly during RT but less frequently during CT and after RT and after RT. Results : Changes in total white blood cell counts were not significantly different among the three groups. The lymphocyte count and lymphocyte $\%$ were much lower in the RT-including groups than in the RT-excluding group. The difference between pre-treatment and final lymphocyte count and the difference between pre-treatment and final lymphocyte $\%$ were significant (p=0.044 and p=0.037) between the RT-including groups and the RT-excluding group. Conclusion : lymphopenia was more marked after treatment containing RT than CT only. Lymphopenia may be one cause of a compromised immune system after mediastinal irradiation in lung cancer. We suggest cautiously that previous studies showing evidence of lymphocyte apoptosis after low-dose irradiation and large blood volume and dynamic blood flow within the RT fields could be somewhat related to lymphopenia after mediastinal irradiation.