• Radiation Oncology Journal
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• v.20 no.2
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• pp.172-178
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• 2002

Purpose : X-ray film over responds to low-energy photons in relative photon beam dosimetry because its sensor is based on silver bromide crystals, which are high-Z molecules. This over-response becomes a significant problem in clinical photon beam dosimetry particularly in regions outside the penumbra. In intensity modulated radiation therapy (IMRT), the radiation field is characterized by multiple small fields and their outside-penumbra regions. Therefore, in order to use film dosimetry for IMRT, the nature the source of the over-response in its radiation field need to be known. This study is aimed to verify and possibly improve film dosimetry for IMRT. Materials and Method : Modulated beams were constructed by a combination of five or seven different static radiation fields using 6 MeV X-rays. In order to verify film dosimetry, we used X-ray film and an ion chamber were used to measure the dose profiles at various depths in a phantom. In addition, in order to reduce the over-response, 0.01 inch thick lead filters were placed on both sides of the film. Results : The measured dose profiles showed a film over-response at the outside-penumbra and low dose regions. The error increased with depths and approached 15% at a maximum for the field size of $15{\times}15cm^2$ at 10 cm depth. The use of filters reduced the error to 3%, but caused an under-response of the dose in a perpendicular set-up. Conclusion : This study demonstrated that film dosimetry for IMRT involves sources of error due to its over-response to low-energy Photons. The use of filers can enhance the accuracy in film dosimetry for IMRT. In this regard, the use of optimal filter conditions is recommended.

• Journal of Radiation Protection and Research
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• v.31 no.2
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• pp.53-63
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• 2006

The increased risk of cancer with exposure to low-dose radiation was estimated through longitudinal study for radiation workers at the nuclear power plants in Korea. The radiation dose data were collected from the Radiation Safety Management System(RSMS) of the Korea Hydro & Nuclear Power Co., Ltd(KHNP). The cancer risks with radiation exposure were evaluated in terms of relative mortality ratios(RMR) and relative incidence ratios(RIR) to the unexposed employees at the nuclear power plants, and of the standardized mortality ratios(SMR) and standardized incidence ratios(SIR). There were no significant increases of canters of all sites in the exposed group either in RIR[1.08, 95% confidence interval(CI) 0.74-1.58] or in RMR[1.21, CI 0.70-2.08]. Neither SIR[0.81, CI 0.28-0.96] nor SMR[0.86, CI 0.66-1.10] significantly deviated from 1.0 for cancers of all sites. The trend analysis did not identify evident dose-response relationship due to insufficient numbers of the cases. Consequently, it is concluded that increases in cancer risks in the radiation worker group exposed to low doses at the nuclear power plants in Korea are not identified at this time.

• Journal of Korean Society for Atmospheric Environment
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• v.8 no.1
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• pp.29-37
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• 1992

The risk of benzo(a)pyrene for cancer in the ambient air of Seoul was assessed by using the extrapolation methods. The average daily lifetime exposure of benzo(a)pyrene in the ambient air of Seoul was calculated at 6.97-24.30ng/$m^2$/day, which was based on the occurrence analysis of benzo(a)pyrene in the residential(Bull Kwang Dong) and traffic areas(Shin Chon) of Seoul. Using the dose scaling based on body surface area in comparisons of toxicity for extrapolation from animal to human and mathematical models from the high dose region, the low-dose risk was estimated. The response probabilities were estimated by the tolerance distribution models; Probit, Logit and Weibull model. They were consistent with the observed ones at experimental dose region. The unit risk estimates of these models were too low to be used. One-hit and multistage model to prove more conservative risk was selected. As a redult, the lifetime unit risk of benzo(a)pyrene for cancer and virtually safe dose were calculated; One-hit model provided the risk 2.8 $\times 10^{-7}$ and 3.4ng/$m^3$, respectively and multistage model provided 5.2 $\times 10^{-7}$ and 1.9ng/$m^3$ as the more conservatives. The lifetime excess risk estimates of benzo(a)pyrene for cancer were calculated at 0.37-1.30 persons/million persons by one-hit model and 0.69-2.41 persons/million persons by multistage model, which was considered in without virtual risk.

• The Korean Journal of Pain
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• v.14 no.2
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• pp.186-192
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• 2001

Background: Epidural test doses containing epinephrine are an incomplete marker for the detection of inadvertent intravascular injection. Therefore, many investigators have attempted to find a more reliable marker as an alternative to epinephrine in adult patients anesthetized with enflurane. The present study was designed to test whether two different simulated intravenous test doses of isoproterenol could be used as a reliable marker for the detection of inadvertent intravascular injection in adult patients anesthetized with $O_2-N_2O$-enflurane. Methods: Forty healthy adult patients were anesthetized with 1% end-tidal enflurane and nitrous oxide after endotracheal intubation and were randomized to one of two groups according to the dose of isoproterenol. Group 1 and 2 (n = 20 each) received 3 ml of 1.5% lidocaine with 3 and 5 g isoproterenol intravenously, respectively, to simulate an intravascularly administered test dose. Heart rate (HR) and systolic blood pressure (SBP) were measured at 20-second intervals for 4 min after injection. Results: Mean maximal HR increases were $24{\pm}17$, $35{\pm}11$ bpm (P < 0.05), mean maximal SBP increases were $14{\pm}8$, $13{\pm}9$ mmHg and mean maximal SBP decreases $20{\pm}11$, $22{\pm}9$ mmHg following the IV injection of 3, $5{\mu}g$ isoproterenol, respectively. The incidence of hypotension was similar in both groups. Isoproterenol 3 and $5{\mu}g$ produced 75%, 100% sensitivity in the HR criteria ($\geq$ 20 bpm increase) and 60%, 70% sensitivity in the SBP criteria ($\geq$ 15 mmHg), respectively. Conclusions: These results indicate that based on the HR response, the epidural test dose containing $5{\mu}g$ isoproterenol to simulate an intravascular administration is a more reliable marker than $3{\mu}g$ isoproterenol in adult healthy patients during enflurane anesthesia.

• 대한방사선방어학회:학술대회논문집
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• 2011.11a
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• pp.212-213
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• 2011

The biological effects of low dose ionizing radiation (LDIR) remain insufficiently understood. We examined for the scientific evidence to show the biological effects of LDIR using radiation-sensitive immune cells. We found that Ikaros protein was responsed to low dose-dependent effects of gamma radiation in IM-9 B lymphocytes. Ikaros encodes zinc finger transcription factors that is important regulators of a hematopoietic stem cells (HSCs) progression to the B lymphoid lineage development, differentiation and proliferation. In this study, we observed that cell proliferation was enhanced from 10% to 20% by LDIR (0.05 Gy) in IM-9 B lymphocytes. The Ikaros protein was phosphorylated in its serine/threonine (S/T) region and decreased its DNA binding activity in the cells exposed to LDIR. We found that Ikaros phosphorylation was up-regulated by CK2/AKT pathway and the residues of ser-304 and ser-306 in Ikaros was phosphorylated by LDIR. We also observed that Ikaros protein was localized from the nucleus to the cytoplasm after LDIR and bound with Autotaxin (ENPP2, ATX) protein, stimulating proliferation, migration and survival of immune cells. In addition, we found that the lysoPLD activity of ATX was dependent on Ikaros-ATX binding activity. These results indicate that the Ikaros is an important regulator of immune activation. Therefore, we suggest that low dose ionizing radiation can be considered as a beneficial effects, stimulating the activation of immune cells.

• Natural Product Sciences
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• v.5 no.1
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• pp.25-32
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• 1999

The pharmacological actions of ambrein were investigated alone or in combination as a pretreatment with agonists (adrenaline, noradrenaline, acetylcholine, histamine, nicotine), antagonists (atropine, atenolol) and calcium channel blocker (verapamil) in vivo in anaesthetized SWR rats using blood pressure, heart rate and myocardial contractility as parameters. Ambrein in the dose range of 50-200 mg/kg to the normotensive anaesthetized rats demonstrated negative chronotropic effect and increased the myocardial contractility significantly. At the mid dose (100 mg/kg) this increase in contractile force was 36% and 44% above the normal at 30 min and 60 min intervals post-treatment, respectively. Both of the lower and high doses (50 mg/kg and 200 mg/kg) had similar effects. Furthermore, this contractile response was dose related. Also, this compound produced a considerable increase in myocardial contractility when used as a pretreatment with some agonists and antagonists. The results on blood pressure did not show a considerable change when ambrein was used alone. However, ambrein pretreatment at the dose of 100 mg/kg did not block the effects of adrenaline, noradrenaline, isoprenaline and acetylcholine on heart rate and blood pressure. On the other hand, this pretreatment attenuated the sympathoadrenal effects of nicotine significantly. Chronotropic and blood pressure changes produced by histamine were also inhibited by ambrein pretreatment. This pretreatment significantly reversed the effects of atenolol but failed to demonstrate any change in the negative chronotropic, inotropic and hypotensive responses induced by verapamil. It is concluded that ambrein induced nonselective dose dependent antagonism of the effects of some agonists and antagonists require contribution of some neuromediators. However, the positive isotropic effects of ambrein possibly involve the enhancement of slow Ca channels and/or activation of ${\beta}-adrenergic$ receptors in the heart. At this moment it is difficult to explain the exact mode of action of ambrein and the studies dealing with Ca channel blocker and adrenergic blocker followed by ambrein may help to define the factors which contribute to its positive inotropic effects.

• Radiation Oncology Journal
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• v.37 no.3
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• pp.185-192
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• 2019

Purpose: The effectiveness of thoracic radiation therapy (TRT) in extensive-stage small cell lung cancer (ES-SCLC) patients is increasingly reported, but there is no definite consensus on its application. The aim of this study was to identify factors associated with better outcomes of TRT among patients with ES-SCLC, focusing on whether a higher TRT dose could improve treatment outcome. Materials and Methods: The medical records of 85 patients with ES-SCLC who received TRT between January 2008 and June 2017 were retrospectively reviewed. Eligibility criteria were a biological effective dose with α/β = 10 (BED) higher than 30 Gy₁₀ and completion of planned radiotherapy. Results: During a median follow-up of 5.3 months, 68 patients (80.0%) experienced disease progression. In univariate analysis, a BED >50 Gy₁₀ was a significant prognostic factor for overall survival (OS; 40.8% vs. 12.5%, p = 0.006), progression-free survival (PFS; 15.9% vs. 9.6%, p = 0.004), and intrathoracic PFS (IT-PFS; 39.3% vs. 20.5%, p = 0.004) at 1 year. In multivariate analysis, a BED >50 Gy₁₀ remained a significant prognostic factor for OS (hazard ratio [HR] = 0.502; 95% confidence interval [CI], 0.287-0.876; p = 0.015), PFS (HR = 0.453; 95% CI, 0.265-0.773; p = 0.004), and IT-PFS (HR = 0.331; 95% CI, 0.171-0.641; p = 0.001). Response to the last chemotherapy was also associated with better OS in both univariate and multivariate analysis. Conclusion: A TRT dose of BED >50 Gy₁₀ may be beneficial for patients with ES-SCLC. Further studies are needed to select patients who will most benefit from high-dose TRT.

• Journal of Pharmacopuncture
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• v.23 no.1
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• pp.18-24
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• 2020

Objectives: Pain is considered as a cause of sickness and the most prevalent symptom which makes people visit a physician. Nowadays, combination therapy is becoming useful to relieve chronic and postsurgical pain. The aim of this study was to study the promethazine (as an antihistamine) interactions with antinociceptive effect of diclofenac (as a non-steroidal anti-inflammatory drugs). Methods: In initial part of the study, we investigate the analgesic effect of diclofenac. Using writhing test, we demonstrate that diclofenac significantly reduces writhe response induced by acetic acid in a dose-dependent manner. In this study, we evaluate the combination effect of promethazine on diclofenac analgesic effect. Results: We observed that diclofenac inhibited pain in the dose dependent manner which means that by increasing dose of diclofenac a significant decrease in pain was observed. This experimental setup allowed calculation of the dose that caused 50% antinociception (ED50) for diclofenac. The ED50 for diclofenac in this study was determined to be 9.1 mg/kg according our previous study. Additionally, promethazine was showed a dose-dependent inhibition of writhes. The combination of different doses of promethazine (2, 4, 6 mg / kg) with diclofenac ED50 (9.1 mg / kg) was injected to mice. Promethazine 4 and 6 mg / kg in combination with diclofenac had significantly led to increase analgesic effect of diclofenac. Conclusion: In conclusion, these results add important information to the existing knowledge on combination of diclofenac and antihistamine in pain therapies to be used in clinical practice and maybe helpful in designing the future guidelines.

• YAKHAK HOEJI
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• v.40 no.3
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• pp.326-334
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• 1996

Effects of methanol extract of Astragali Radix (AR) on the immune responses were studied using ICR mice. Mice were divided into 4 groups (10mice/group), and methanol extracts of AR at doses of 0.05, 0.25 and 1.25g/kg were orally administered to ICR mice once a day for 2 weeks. Mice were immunized and challenged with sheep red blood cells (SRBC). The results of this study were summarized as follows; (1) Methanol extract of AR at 0.05, 0.25 and 1.25g/kg didn't affect the weight ratios of thymus to body, as compared with those in controls, but significantly increased spleen weight ratio. (2)Methanol extract of AR at 0.05 and 0.25g/kg significantly increased hemagglutination titer and splenic plaque forming cells corresponding to humoral immunity, as compared with those in controls, but their enhancements were somewhat lowered at a high dose (1.25g/kg). (3) Methanol extract of AR at 0.05 and 0.25g/kg siginificantly increased delayed-type hypersensitivity reaction resulted from cell-mediated immunity, as compared with those in controls, but not so significant increases were observed at a high dose (1.25g/kg). (4) Methanol extract of AR at 0.05 and 0.25g/kg significantly increased phagocytic activity and the number of circulating leukocyte compared with those in controls, but their enhancements were lowered at a high dose (1.25g/kg). These results suggest that methanol extract of Astragali Radix increased humoral and cell-mediated immune responses, phagocytic activity and the number of circulating leukocyte, dependent upon dose, but inhibited their enhancement effects were decreased at a high dose (1.25g/kg).

• Nuclear Engineering and Technology
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• v.53 no.6
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• pp.1991-1999
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• 2021

The response changes of the specific growth rate of Lemna minor duckweed was modeled using the logarithms of frond numbers on tritium activity concentration and gamma radiation dose from cobalt 60. The concept of average specific growth rate depends on the general exponential growth pattern, where toxicity is estimated based on the effect on the growth rate. One of the main questions of the effect of the radiation dose on duckweed is how to correlate the effect of beta radiation with the effect of any other radiation for modeling radiation on Lemna minor. Experimental data were extrapolated by utilizing the OECD guidelines. A linear relationship of absorbed dose and activity concentration was obtained for the average dependency growth rate of Lemna minor as D = (0.1257)·A^0.585. The dose rate of gamma irradiation from ⁶⁰Co increases with tritium activity dependence, on the specific growth rate of the Lemna minor duckweed. An increase in the tritium activity causes a decrease in the specific growth rate of the Lemna minor duckweed. It indicates that as the quantity of the beta radiation dose increase in Lemna minor duckweed, a higher quantity of gamma radiation will be required to cause the same effect in the specific growth rate of Lemna minor duckweed. The relation between the inhibition of the Lemna minor seedling growth and gamma and beta radiation dosage agrees roughly with that between the decrease of survival rate or fertility and dosage.