• Journal of Yeungnam Medical Science
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• v.5 no.1
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• pp.147-151
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• 1988

Esophageal cancers are highly malignant neoplasms. Prognosis of esophageal cancer treated by external irradiation alone is rather poor because of local recurrence and distant metastasis. Recently intracavitary irradiation has been used as a boost therapy after external irradation to optain better local control. One case of esophageal cancer has been treated by high dose rate remote-controlled afterloading unit as boost therapy after external irradiation. The result was excellent in short term follow up esophagogram but esophageal bleeding and esophagotracheal fistula were noted in further follow up examination after inappropriate posttreatment management including insufficient chemotherapy due to poor general condition. We reviewed possible causes of esophageal bleeding and esophagotracheal fistula after external irradiation and high dose rate ICR.

• Radiation Oncology Journal
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• v.14 no.1
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• pp.41-52
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• 1996

Purpose : This paper reports a dosimetric study of 88 patients treated with a combination of external radiotherapy and high dose rate ICR for FIGO stage IIB carcinoma of the cervix. The purpose is to investigate the correlation between the radiation doses to the rectum, external radiation dose to the whole pelvis, ICR reference volume, TDF BED and the incidence of late rectal complications, retrospectively. Materials and Methods : From November 1989 through December 1992, 88 patients with stage IIB cervical carcinoma received radical radiotherapy at Department of Radiation Oncology in Yonsei University Hospital. Radiotherapy consisted of 44-54 Gy(median 49 Gy) external beam irradiation plus high dose rate intracavitary brachytherapy with 5 Gy per fraction twice a week to a total dose of 30 Gy on point A. The maximum dose to the rectum by contrast(r, R) and reference rectal dose by ICRU 38(dr, DR) were calculated. The ICR reference volume was calculated by Gamma Dot 3.11 HDR planning system, retrospectively The time-dose factor(TDF) and the biologically effective dose (BED) were calculated. Results : Twenty seven($30.7\%$) of the 88 patients developed late rectal complications:12 patients($13.6\%$) for grade 1, 12 patients($13.6\%$) for grade 2 and 3 patients($3.4\%$) for grade 3. We found a significant correlation between the external whole pelvis irradiation dose and grade 2, 3 rectal complication. The mean dose to the whole pelvis for the group of patients with grade 2, 3 complication was Higher, $4093.3\pm453.1$ cGy, than that for the patients without complication, $3873.8\pm415.6$ (0.05$7163.0\pm838.5$ cGy, than that for the Patients without rectal complication, $0772.7\pm884.0$ (p<0.05). There was no correlation of the rate of grade 2, 3 rectal complication with the iCR rectal doses(r, dr), ICR reference volume, TDF and BED. Conclusion : This investigation has revealed a significant correlation between the dose calculated at the rectal dose by ICRU 38(DR) or the most anterior rectal dose by contrast(R) dose to the whole pelvis and the incidence of grade 2, 3 late rectal complications in patients with stage IIB cervical cancer undergoing external beam radiotherapy and HOR ICR. Thus these rectal reference points doses and whole pelvis dose appear to be useful Prognostic indicators of late rectal complication in high dose rate ICR treatment in cervical carcinoma.

• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.3
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• pp.48-55
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• 2009

Purpose: As Korean nuclear law doesn't have any clear guideline about the dose and the external dose rate(uSv/h) requiring hospitalization in radioactive iodine treated patients, the patients are discharged when they meet the guideline of IAEA Basic Safety Standards(BSS). We measured external dose rate(${\mu}Sv/h$) of inpatient underwent 3700MBq (100 mCi) $^{131}I$ radioiodine treatment and considering external dose rate(${\mu}Sv/h$), residual activity(mCi) and excretion rate(%) we found the time for RA to be lowered from 3700MBq (100 mCi) to 1110 MBq (30 mCi) to give reference to set a guideline for discharge. Materials and Methods: Forty-two patients underwent thyroidectomy and scheduled for radioiodine treatment, who received 3700MBq (100 mCi) of $^{131}I$ orally and had no renal disease were examined. After 1, 2, 4, 8, and 20, 24, 40 hours iodine uptake and before/after the urination, the external dose rate(${\mu}Sv/h$) measured using FH40G-L(Thermo Fisher Scientific Inc., MA) at a distance and a height of 1 m for 20 sec on the average. Results and Conclusions: At 20 hours, the external dose rate was decreased to $49{\pm}13\;{\mu}Sv$/h, namely, 78% of administrated radioactivity was excreted and 814 MBq (30 mCi) was residual, and it met the accepted limit for discharge of (IAEA, BSS) under 1110 MBq (30 mCi) (1 m at 66 uSv/h).

• The Korean Journal of Nuclear Medicine Technology
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• v.20 no.1
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• pp.28-31
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• 2016

Purpose $^{223}Ra-Dichloride$ is used for the medicine of castration-resistant prostate cancer (CRPC) and which emits ${\alpha}-ray$ of 28 Mev that is used for therapy. However $^{223}Ra-Dichloride$ emits ${\beta}-ray$ of 3.6% and ${\gamma}-ray$ of 1.1%(80,156,270 keV) aside from ${\alpha}-ray$ in decay. Therefore we would like to evaluate external radiation expose dose rate of ${\gamma}-ray$ of $^{223}Ra-Dichloride$. Materials and Methods We calculated external radiation expose dose rate using ${\gamma}-constant$ of $^{223}Ra-Dichloride$, $^{99m}Tc$ based on Health physics(2012). $^{223}Ra-Dichloride$ of 3.5 MBq and $^{99m}Tc-MDP$ of 740 MBq were applied. external radiation expose dose rate 15 times from 1m by survey meter. Results ${\gamma}-contant$ of $^{223}Ra$, $^{99m}Tc-MDP$ from 1m distance based on Health physics(2012) is 0.0469, 0.0215. calculated value of external radiation expose dose rate was $16{\mu}Sy$, $34{\mu}Sy$ which activity is $^{223}Ra-Dichloride$ of 3.5 MBq and $^{99m}Tc-MDP$ of 740 MBq from 1 m and measured mean value of 1 m was $0.7{\mu}Sy/h$, $18{\mu}Sy/h$. Conclusion ${\gamma}-constant$ of $^{223}Ra$ is higher than $^{99m}Tc$ based on Health physics(2012). however calculated maximum external radiation expose dose rate of $^{223}Ra-Dichloride$ is lower than $^{99m}Tc$ due to actually used quantity of activity of $^{223}Ra-Dichloride$ is small. measured value of $^{223}Ra-Dichloride$ is also lower than $^{99m}Tc-MDP$. Therefore external radiation expose dose rate of ${\gamma}-ray$ of $^{223}Ra-Dichloride$ is very low.

• Journal of Radiation Protection and Research
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• v.45 no.2
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• pp.53-68
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• 2020

Background: International organizations such as the World Health Organization (WHO) and the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) reported public exposure doses due to radionuclides released in the Fukushima nuclear accident a few years after the event. However, the reported doses were generally overestimated due to conservative assumptions such as a longer stay in deliberate areas designated for evacuation than the actual stay. After these reports had been published, more realistic dose values were reported by Japanese scientists. Materials and Methods: The present paper reviews those reports, including the most recently published articles; and summarizes estimated effective doses (external and internal) and issues related to their estimation. Results and Discussion: External dose estimation can be categorized as taking two approaches-estimation from ambient dose rate and peoples' behavior patterns-and measurements using personal dosimeters. The former approach was useful for estimating external doses in an early stage after the accident. The first 4-month doses were less than 2 mSv for most (94%) study subjects. Later on, individual doses came to be monitored by personal dosimeter measurements. On the basis of these measurements, the estimated median annual external dose was reported to be < 1 mSv in 2011 for 22 municipalities of Fukushima Prefecture. Internal dose estimation also can be categorized as taking two approaches: estimation from whole-body counting and estimation from monitoring of environmental samples such as radioactivity concentrations in food and drinking water. According to results by the former approach, committed effective dose due to ¹³⁴Cs and ¹³⁷Cs could be less than 0.1 mSv for most residents including those from evacuated areas. Conclusion: Realistic doses estimated by Japanese scientists indicated that the doses reported by WHO and UNSCEAR were generally overestimated. Average values for the first-year effective doses for residents in two affected areas (Namie Town and Iitate Village) were not likely to reach 10 mSv, the lower end of the doses estimated by WHO.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.2
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• pp.167-175
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• 2019

Objectives: The purpose of this study was to evaluate airborne radon and thoron levels and estimate the effective doses of workers who made household goods and mattresses using monazite. Methods: Airborne radon and thoron concentrations were measured using continuous monitors (Rad7, Durridge Company Inc., USA). Radon and thoron concentrations in the air were converted to radon doses using the dose conversion factor recommended by the Nuclear Safety and Security Commission in Korea. External exposure to gamma rays was measured at the chest height of a worker from the source using real-time radiation instruments, a survey meter (RadiagemTM 2000, Canberra Industries, Inc., USA), and an ion chamber (OD-01 Hx, STEP Co., Germany). Results: When using monazite, the average concentration range of radon was $13.1-97.8Bq/m^3$ and thoron was $210.1-841.4Bq/m^3$. When monazite was not used, the average concentration range of radon was $2.6-10.8Bq/m^3$ and the maximum was $1.7-66.2Bq/m^3$. Since monazite has a higher content of thorium than uranium, the effects of thoron should be considered. The effective doses of radon and thoron as calculated by the dose conversion factor based on ICRP 115 were 0.26 mSv/yr and 0.76 mSv/yr, respectively, at their maximum values. The external radiation dose rate was $6.7{\mu}Sv/hr$ at chest height and the effective dose was 4.3 mSv/yr at the maximum. Conclusions: Regardless of the use of monazite, the total annual effective doses due to internal and external exposure were 0.03-4.42 mSv/yr. Exposures to levels higher than this value are indicated if dose conversion factors based on the recently published ICRP 137 are applied.

• Nuclear Engineering and Technology
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• v.53 no.1
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• pp.273-281
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• 2021

The radiological safety of the spent resin treatment facility with a¹⁴C treatment capacity of 1 ton/day was evaluated in terms of the external and internal exposure of worker according to operation scenario. In terms of external dose, the annual dose for close work for 1 h/day at a distance of more than 1 m (19.8 mSv) satisfied the annual dose limit. For 8 h of close work per day, the annual dose exceeded the dose limit. For remote work of 2000 h/year, the annual dose was 14.4 mSv. Lead shielding was considered to reduce exposure dose, and the highest annual dose during close work for 1 h/day corresponded to 6.75 mSv. For close work of 2000 h/year and lead thickness exceeding 1.5 cm, the highest value of annual dose was derived as 13.2 mSv. In terms of internal exposure, the initial year dose was estimated to be 1.14E+03 mSv when conservatively 100% of the nuclides were assumed to leak. The allowable outflow rate was derived as 7.77E-02% and 2.00E-01% for the average limit of 20 mSv and the maximum limit of 50 mSv, respectively, where the annual replacement of the worker was required for 50 mSv.

• Journal of Radiation Protection and Research
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• v.37 no.2
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• pp.103-107
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• 2012

This paper analyzes changes in the external radiation dose rate of PET-CT test patients as a part of providing basic materials for reduction of radiation exposure to PET-CT test patients. In theory the measurement of external radiation dose rate of PET-CT test patients shows that the further the distance from the patient injected with radioactive pharmaceutical and a longer time elapsement from the injection leads to a smaller amount of radiation. Particularly, the amount of radiation marked the highest in the chest was at 4.17 minutes immediately after the intravenous injection and in the head after 77.47 minutes after urination in advance to the PET-CT test. As in the generalized information, it is desired to keep distance between the patient and caretakers or professionals to reduce the amount of radiation exposure from PET-CT test patients and to resume contact the patient after the time when the radiation has reduced. If contact is unavoidable, it is desired to keep at least 200cm from the patient. In addition, the amount of radiation reached the highest in the chest at first and then in the head from 77 minutes after injection. Accordingly, it would be helpful in achieving the optimization if contact is made based on the patient's physical characteristics. This study is significant as it measures changes in radiation the dose rate by; distance from the PET-CT test patient, time elapsed, and specific parts of body. Further studies based on the findings in this paper are required to analyze changes in radiation dose rate in accordance with individual characteristics unique to PET-CT patients and to utilize the results to reduce the amount of radiation patient, caretakers and professions are exposed.

• Journal of Radiation Protection and Research
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• v.48 no.2
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• pp.59-67
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• 2023

Background: This study aims to reevaluate natural radiation exposure, following up on our previous study conducted in 2019, and to assess the associated risk of lung cancer to the public residing in the gold mining areas of Betare-Oya, east Cameroon, and its vicinity. Materials and Methods: Gamma-ray spectra collected using a 7.62 cm×7.62 cm in NaI(Tl) scintillation spectrometer during a car-borne survey, in situ measurements and laboratory measurements performed in previous studies were used to determine the outdoor absorbed dose rate in air to evaluate the annual external dose inhaled by the public. For determining internal exposure, radon gas concentrations were measured and used to estimate the inhalation dose while considering the inhalation of radon and its decay products. Results and Discussion: The mean value of the laboratory-measured outdoor gamma dose rate was 47 nGy/hr, which agrees with our previous results (44 nGy/hr) recorded through direct measurements (in situ and car-borne survey). The resulting annual external dose (0.29±0.09 mSv/yr) obtained is similar to that of the previous study (0.33±0.03 mSv/yr). The total inhalation dose resulting from radon isotopes and their decay products ranged between 1.96 and 9.63 mSv/yr with an arithmetic mean of 3.95±1.65 mSv/yr. The resulting excess lung cancer risk was estimated; it ranged from 62 to 216 excess deaths per million persons per year (MPY), 81 to 243 excess deaths per MPY, or 135 excess deaths per MPY, based on whether risk factors reported by the U.S. Environmental Protection Agency, United Nations Scientific Committee on the effects of Atomic Radiation, or International Commission on Radiological Protection were used, respectively. These values are more than double the world average values reported by the same agencies. Conclusion: There is an elevated level of risk of lung cancer from indoor radon in locations close to the Betare-Oya gold mining region in east Cameroon. Therefore, educating the public on the harmful effects of radon exposure and considering some remedial actions for protection against radon and its progenies is necessary.

• Journal of Radiation Protection and Research
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• v.47 no.1
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• pp.30-38
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• 2022

Background: Residential areas have some factors on the external exposure of residents, who usually spend a long time in these areas. Although various survey has been carried out by the government or the research institutions after the Fukushima Daiichi Nuclear Power Plant accident, the mechanism of radiocesium inventory in the terrestrial zone has not been cleared. To better evaluate the radiation environment, this study investigated the temporal changes in air dose rate and ¹³⁷Cs inventories (Bq/m²) in residential areas and agricultural fields. Materials and Methods: Air dose rate and ¹³⁷Cs inventories were investigated in residential areas located in an evacuation zone at 5-8 km from the Fukushima Daiichi Nuclear Power Plant. From December 2014 to September 2018, the air dose rate distribution was investigated through a walking survey (backpack survey), which was conducted by operators carrying a γ-ray detector on their backs. Additionally, from December 2014 to January 2021, the ¹³⁷Cs inventories on paved and permeable grounds were also measured using a portable γ-ray detector. Results and Discussion: In the areas where decontamination was not performed, the air dose rate decreased faster in residential areas than in agricultural fields. Moreover, the ¹³⁷Cs inventory on paved surfaces decreased with time owing to the horizontal wash-off, while the ¹³⁷Cs inventory on permeable surfaces decreased dramatically owing to the decontamination activities. Conclusion: These findings suggest that the horizontal wash-off of ¹³⁷Cs on paved surfaces facilitated the air dose rate decrease in residential areas to a greater extent compared with agricultural fields, in which the air dose rate decreased because of the vertical migration of ¹³⁷Cs. Results of this study can explain the faster environmental restoration in a residential environment reported by previous studies.