• Nuclear Engineering and Technology
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• 제54권7호
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• pp.2586-2591
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• 2022

In the present work, we have irradiated the DI-BSCCO superconducting tapes with the 100 keV deuterium ions to investigate the effect of ion irradiation on their critical current (Ic). The damage simulations are carried out using the binary collision approximation method to get the spatial distribution and depth profile of the damage events in the high temperature superconducting (HTS) tape. The point defects are formed near the surface of the HTS tape. These point defects change the vortex profile in the superconducting tape. Due to the long-range interaction of vortices with each other, the Ic of the tape degrades at the 77 K and self magnetic field. The radiation dose of 2.90 MGy degrades the 44% critical current of the tape. The results of the displacement per atom (dpa) and dose deposited by the deuterium ions are used to fit an empirical relation for predicting the degradation of the Ic of the tape. We include the dpa, dose and columnar defect terms produced by the incident particles in the empirical relation. The fitted empirical relation predicts that light ion irradiation degrades the Ic in the DI-BSCCO tape at the self field. This empirical relation can also be used in neutron irradiation to predict the lifetime of the DI-BSCCO tape. The change in the Ic of the DI-BSCCO tape due to deuterium irradiation is compared with the other second-generation HTS tape irradiated with energetic radiation.

• The Korean Journal of Pain
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• 제35권3호
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• pp.311-318
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• 2022

Background: Ketamine is widely used in infants and young children for procedural sedation and anesthesia. The aim of this study was to evaluate the efficacy and safety of low dose oral ketamine to control pain and distress in children during intravenous (IV) cannulation. Methods: This is a prospective, randomized, double-blind study, including children aged between 3 and 6 years requiring a non-emergent IV-line placement. Children were randomly assigned to two groups, treated either with oral ketamine or a placebo. All patients were monitored for vital signs. Pain was assessed using the Children's Hospital of Eastern Ontario Pain Scale (CHEOPS) and Wong-Baker Faces Pain Rating Scale (WBFS) scales and sedation using a 5-point sedation score. The facility of IV-line placement was measured by a 3-point scale. Adverse effects were recorded after 1 and 24 hours. Results: A total of 79 and 81 children were entered in the ketamine and placebo groups, respectively. The heart and respiratory rates increased significantly in the placebo group. The median CHEOPS 4 (95% confidence interval [CI]: 3, 4, P < 0.001) and WBFS 6 (95% CI: 4, 6, P < 0.001) scores decreased statistically in the ketamine group. IV-line placement was 50% easier in the ketamine group (95% CI: 37%, 63%, P < 0.001). No serious adverse effects were observed in all cases. Conclusions: Low dose oral ketamine effectively decreased the pain and distress during IV cannulation in children without any significant adverse reactions.

• Radiation Oncology Journal
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• 제23권4호
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• pp.223-229
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• 2005

Purpose: In this work we designed and made MPBP(Multi Purpose Brachytherapy Phantom). The MPBP enables one to reproduce the same patient set-up in MPBP as the treatment of the patient and we tried to get an exact analysis of rectal doses in the phantom without need of in-vivo dosimetry. Materials and Methods: Dose measurements were tried at a point of rectum 1, the reference point of rectum, with a diode detector for 4 patients treated with tandem and ovoid for a brachytherapy of a cervix cancer. Total 20 times of rectal dose measurements were made with 5 times a patient. The set-up variation of the diode detector was analyzed. The same patient set-ups were reproduced in self-made MPBP and then rectal doses were measured with TLD. Results: The measurement results of the diode detector showed that the set-up variation of the diode detector was the maximum $11.25{\pm}0.95mm$ in the y-direction for Patient 1 and the maximum $9.90{\pm}4.50mm,\;20.85{\pm}4.50mm,\;and\;19.15{\pm}3.33mm$ in the z-direction for Patient 2, 3, and 4, respectively. Un analyzing the degree of variation in 3 directions the more variation was showed in the z-direction than x- and y-direction except Patient 1. The results of TLD measurements in MPBP showed the relative maximum error of 8.6% and 7.7% at a point of rectum 1 for Patient 1 and 4, respectively and 1.7% and 1.2% for Patient 2 and 3, respectively. The doses measured at R1 and R2 were higher than those calculated except R point of Patient 2. this can be thought to related to the algorithm of dose calculation, whcih corrects for air and water but is guessed not to consider the correction for the scattered rays, but by considering the self-error (${\pm}5%$) TLD has the relative error of values measured and calculated was analyzed to be in a good agreement within 15%. Conclusion: The reproducibility of dose measurements under the same condition as the treatment could be achieved owing to the self-made MPMP and the dose at the point of interest could be analyzed accurately. If a treatment is peformed after achieving dose optimization using the data obtained in the phantom, dose will be able to be minimized to important organs.

• The Journal of Korean Society for Radiation Therapy
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• 제30권1_2호
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• pp.49-63
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• 2018

Purpose : The purpose of this study is investigating the changes of treatment plan and comparing skin dose with or without the skin flash. To investigate optimal applications of the skin flash, the changes of skin dose of each plans by various thicknesses of skin flash were measured and analyzed also. Methods and Material : Anthropomorphic phantom was scanned by CT for this study. The 2 fields hybrid IMRT and the 6 fields static IMRT were generated from the Eclipse (ver. 13.7.16, Varian, USA) RTP system. Additional plans were generated from each IMRT plans by changing skin flash thickness to 0.5 cm, 1.0 cm, 1.5 cm, 2.0 cm and 2.5 cm. MU and maximum doses were measured also. The treatment equipment was 6MV of VitalBeam (Varian Medical System, USA). Measuring device was a metal oxide semiconductor field-effect transistor(MOSFET). Measuring points of skin doses are upper (1), middle (2) and lower (3) positions from center of the left breast of the phantom. Other points of skin doses, artificially moved to medial and lateral sides by 0.5 cm, were also measured. Results : The reference value of 2F-hIMRT was 206.7 cGy at 1, 186.7 cGy at 2, and 222 cGy at 3, and reference values of 6F-sIMRT were measured at 192 cGy at 1, 213 cGy at 2, and 215 cGy at 3. In comparison with these reference values, the first measurement point in 2F-hIMRT was 261.3 cGy with a skin flash 2.0 cm and 2.5 cm, and the highest dose difference was 26.1 %diff. and 5.6 %diff, respectively. The third measurement point was 245.3 cGy and 10.5 %diff at the skin flash 2.5 cm. In the 6F-sIMRT, the highest dose difference was observed at 216.3 cGy and 12.7 %diff. when applying the skin flash 2.0 cm for the first measurement point and the dose difference was the largest at the application point of 2.0 cm, not the skin flash 2.5 cm for each measurement point. In cases of medial 0.5 cm shift points of 2F-hIMRT and 6F-sIMRT without skin flash, the measured value was -75.2 %diff. and -70.1 %diff. at 2F, At -14.8, -12.5, and -21.0 %diff. at the 1st, 2nd and 3rd measurement points, respectively. Generally, both treatment plans showed an increase in total MU, maximum dose and %diff as skin flash thickness increased, except for some results. The difference of skin dose using 0.5 cm thickness of skin flash was lowest lesser than 20 % in every conditions. Conclusion : Minimizing the thickness of skin flash by 0.5 cm is considered most ideal because it makes it possible to keep down MUs and lowering maximum doses. In addition, It was found that MUs, maximum doses and differences of skin doses did not increase infinitely as skin flash thickness increase by. If the error margin caused by PTV or other factors is lesser than 1.0 cm, It is considered that there will be many advantages in with the skin flash technique comparing without it.

• The Journal of Korean Medicine
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• 제15권2호
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• pp.241-252
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• 1994

It is known that the pattern of combustion temperature can be classified into preheating, heating. retaining and cooling periods. In this experiment. the authors have studied the heating mechanism by the density of moxa material during the heating and retaining periods. The starting point. the point at which it begins to reach the maximum gradient temperature. the ending point of the heating period. and the ending point of the retaining period were measured in order to get effective stmulation by repetition of moxa-combustion. For the experiment. samples of 300mg. 400mg, and 500mg of moxa material were molded into conical molds with each 10mm in diameter and height resulting in the volume of $0.26cm^3$. The following results were obtained: The $300mg/0.26cm^3$ denstiy sample reached al1 points tested faster than the samples of $400mg/0.26cm^3$ and $500mg/0.26cm^3$ It dose not reveal any statistical differences between $400mg/0.26cm^3$ and $500mg/0.26cm^3$ in the ending point. the point at which it begins to reach the maximum gradient temperature of the heating period or the ending point of the reataining period The only difference shown was in the starting point of the heating period. According to the above results. it is concluded that the lower density moxa material reached each point of the the respective period faster than the high density moxa material.

• Radiation Oncology Journal
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• 제23권3호
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• pp.143-156
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• 2005

Background: The best dose-fractionation regimen of the definitive radiotherapy for cervix cancer remains to be clearly determined. It seems to be partially attributed to the complexity of the affecting factors and the lack of detailed information on external and intra-cavitary fractionation. To find optimal practice guidelines, our experiences of the combination of external beam radiotherapy (EBRT) and high-dose-rate intracavitary brachytherapy (HDR-ICBT) were reviewed with detailed information of the various treatment parameters obtained from a large cohort of women treated homogeneously at a single institute. Materials and Methods: The subjects were 743 cervical cancer patients (Stage IB 198, IIA 77, IIB 364, IIIA 7, IIIB 89 and IVA 8) treated by radiotherapy alone, between 1990 and 1996. A total external beam radiotherapy (EBRT) dose of $23.4\~59.4$ Gy (Median 45.0) was delivered to the whole pelvis. High-dose-rate intracavitary brachytherapy (HDR-IBT) was also peformed using various fractionation schemes. A Midline block (MLB) was initiated after the delivery of $14.4\~43.2$ Gy (Median 36.0) of EBRT in 495 patients, while In the other 248 patients EBRT could not be used due to slow tumor regression or the huge initial bulk of tumor. The point A, actual bladder & rectal doses were individually assessed in all patients. The biologically effective dose (BED) to the tumor ($\alpha/\beta$=10) and late-responding tissues ($\alpha/\beta$=3) for both EBRT and HDR-ICBT were calculated. The total BED values to point A, the actual bladder and rectal reference points were the summation of the EBRT and HDR-ICBT. In addition to all the details on dose-fractionation, the other factors (i.e. the overall treatment time, physicians preference) that can affect the schedule of the definitive radiotherapy were also thoroughly analyzed. The association between MD-BED $Gy_3$ and the risk of complication was assessed using serial multiple logistic regression models. The associations between R-BED $Gy_3$ and rectal complications and between V-BED $Gy_3$ and bladder complications were assessed using multiple logistic regression models after adjustment for age, stage, tumor size and treatment duration. Serial Coxs proportional hazard regression models were used to estimate the relative risks of recurrence due to MD-BED $Gy_{10}$, and the treatment duration. Results: The overall complication rate for RTOG Grades $1\~4$ toxicities was $33.1\%$. The 5-year actuarial pelvic control rate for ail 743 patients was $83\%$. The midline cumulative BED dose, which is the sum of external midline BED and HDR-ICBT point A BED, ranged from 62.0 to 121.9 $Gy_{10}$ (median 93.0) for tumors and from 93.6 to 187.3 $Gy_3$ (median 137.6) for late responding tissues. The median cumulative values of actual rectal (R-BED $Gy_3$) and bladder Point BED (V-BED $Gy_3$) were 118.7 $Gy_3$ (range $48.8\~265.2$) and 126.1 $Gy_3$ (range: $54.9\~267.5$), respectively. MD-BED $Gy_3$ showed a good correlation with rectal (p=0.003), but not with bladder complications (p=0.095). R-BED $Gy_3$ had a very strong association (p=<0.0001), and was more predictive of rectal complications than A-BED $Gy_3$. B-BED $Gy_3$ also showed significance in the prediction of bladder complications in a trend test (p=0.0298). No statistically significant dose-response relationship for pelvic control was observed. The Sandwich and Continuous techniques, which differ according to when the ICR was inserted during the EBRT and due to the physicians preference, showed no differences in the local control and complication rates; there were also no differences in the 3 vs. 5 Gy fraction size of HDR-ICBT. Conclusion: The main reasons optimal dose-fractionation guidelines are not easily established is due to the absence of a dose-response relationship for tumor control as a result of the high-dose gradient of HDR-ICBT, individual differences In tumor responses to radiation therapy and the complexity of affecting factors. Therefore, in our opinion, there is a necessity for individualized tailored therapy, along with general guidelines, in the definitive radiation treatment for cervix cancer. This study also demonstrated the strong predictive value of actual rectal and bladder reference dosing therefore, vaginal gauze packing might be very Important. To maintain the BED dose to less than the threshold resulting in complication, early midline shielding, the HDR-ICBT total dose and fractional dose reduction should be considered.

• Radiation Oncology Journal
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• 제7권1호
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• pp.81-83
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• 1989

This study, involving thirty-two patients with carcinoma of uterine cervix treated by high dose rate intracavitary irradiation using a remotely controlled afterloading system, compares the doss at point A and 8 with the Curie-minutes prescription. A linear least-square regression analysis was used to compare the two sets of date. Correlation coefficients between doses at points A and B and the Ci-min prescription are 0.92 (p<0.001) and 0.90 (p<0.001), respectively, and linear relationship is observed between these two system. The limitation and significance of the comparison of the two approaches to intracavitary dosimetry is discussed.

• Radiation Oncology Journal
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• 제26권1호
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• pp.24-34
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• 2008

Purpose: To assess the efficacy of the use of accelerated hyperfractionated radiotherapy(AHRT) for locally advanced uterine cervix cancers. Materials and Methods: Between May 2000 and September 2002, 179 patients were identified with FIGO stage IIB, IIIB, and IVA cancers. Of the 179 patients, 45 patients were treated with AHRT(AHRT group) and 134 patients were treated with conventional radiotherapy(CRT group), respectively. Patients undergoing the AHRT regimen received a dose of 30 Gy in 20 fractions(1.5 $Gy{\times}2$ fractions/day) to the whole pelvis. Subsequently, with a midline block, we administered a parametrial boost with a dose of 20 Gy using 2 Gy fractions. Patients also received two courses of low-dose-rate brachytherapy, up to a total dose of 85{\sim}90 Gy to point A. In the CRT group of patients, the total dose to point A was $85{\sim}90$ Gy. The overall treatment duration was a median of 37 and 66 days for patients that received AHRT and CRT, respectively. Statistical analysis was calculated by use of the Kaplan-Meier method, the log-rank test, and Chi-squared test. Results: For patients that received cisplatin-based concurrent chemotherapy and radiotherapy, the local control rate at 5 years was 100% and 79.2% for the AHRT and CRT group of patients, respectively(p=0.028). The 5-year survival rate for patients with a stage IIB bulky tumor was 82.6% and 62.1% for the AHRT group and CRT group, respectively(p=0.040). There was no statistically significant difference for severe late toxicity between the two groups(p=0.561). Conclusion: In this study, we observed that treatment with AHRT with concurrent chemotherapy allows a significant advantage of local control and survival for locally advanced uterine cervix cancers.

• The Korean Journal of Pain
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• 제12권2호
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• pp.263-267
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• 1999

We have observed retroperitoneal hematoma after trigger point injections of quadratus lumborum in a patient with chronic low back pain. Severe flank pain and dyspnea was observed three hours after injection of local anesthetic and steroid to the trigger point of quadratus lumborum muscle. There was fuge hematoma in abdominal CT image around the right kidney, which displaced and compressed the kidney anteriorly. Following infusion of contrast media, extravasation through renal vein and IVC was notified. Patient had a past history of having been treated with platelet aggregation inhibitor and lower dose aspirin treatment after cerebral ischemia for a year, but coagulative function was within normal range. Patient was admitted 12 days for bed rest, pain control and transfusion. We need to take greater care with a frequent aspiration and exact direction of needle, during trigger point injection of quadratus lumborum, particu right side, to avoid vascular injury.

• The Korean Journal of Pain
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• 제12권1호
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• pp.75-80
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• 1999

Background: Despite tension type headache is popular, the exact mechanism and method of treatment are not certain yet. So, we supposed the basic mechanism of tension type headache is myogenic, and did Tienchu acupoint block, occipital nerve block, and trigger point injection in tension type headache patients. Methods: Fifty-seven tension type headache patients were treated with local anesthetics and small dose of steroid. The intensity of pain and effect of every treatment was evaluated as Verbal Rating Score (VRS; 0~10) before and after every treatment. Evaluation of treatment was based on the time of treatment (1,2 times, 3 times, 4,5 times). Goal of treatment was VRS reaching below two point and it was considered as treated state. Results: Symptom improvement rates of each treatment were 90% (1, 2 times), 91% (3 times), 70% (4, 5 times) respectively. VRS reduction more than 50% rates were 60%, 64%, 60% respectively. Treated state (VRS<2) rates were 33%, 27%, 30% respectively. Conclusion: Tienchu acupoint block, occipital nerve block, trigger point injection were sorts of most effective and simply applicable modalities of treatment in tension type headache.