• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.2
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• pp.77-82
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• 2010

Purpose: As PET/CT come into wide use, it caused increasing of expose in clinical use. Therefore, Korea Food and Drug Administration issued Patient DRL (Diagnostic Reference Level) in CT scan. In this study, to build the basis of patient dose reduction, we analyzed effective dose in transmission scan with CT scan. Materials and Methods: From February, 2010 to March 180 patients (age: $55{\pm}16$, weight: $61.0{\pm}10.4$ kg) who examined $^{18}F$-FDG PET/CT in Asan Medical Center. Biograph Truepoint 40 (SIEMENS, GERMANY), Biograph Sensation 16 (SIEMENS, GERMANY) and Discovery STe8 (GE healthcare, USA) were used in this study. Per each male and female average of 30 patients doses were analyzed by one. Automatic exposure control system for controlling the dose can affect the largest by a patient's body weight less than 50 kg, 50-60 kg less, 60 kg more than the average of the three groups were divided doses. We compared that measured value of CT-expo v1.7 and ImPACT v1.0. The relationship between body weight and the effective dose were analyzed. Results: When using CT-Expo V1.7, effective dose with BIO40, BIO16 and DSTe8 respectably were $6.46{\pm}1.18$ mSv, $9.36{\pm}1.96 $mSv and $9.36{\pm}1.96$ mSv for 30 male patients respectably $6.29{\pm}0.97$ mSv, $10.02{\pm}2.42$ mSv and $9.05{\pm}2.27$ mSv for 30 female patients respectably. When using ImPACT v1.0, effective dose with BIO40, BIO16 and DSTe8 respectably were $6.54{\pm}1.21$ mSv, $8.36{\pm}1.69$ mSv and $9.74{\pm}2.55$Sv for 30 male patients respectably $5.87{\pm}1.09$ mSv, $8.43{\pm}1.89$ mSv and $9.19{\pm}2.29$ mSv for female patients respectably. When divided three groups which were under 50 kg, 50~60 kg and over 60 kg respectably were 6.27 mSv, 7.67 mSv and 9.33 mSv respectably using CT-Expo V1.7, 5.62 mSv, 7.22 mSv and 8.91 mSv respectably using ImPACT v1.0. Weight and the effective dose coefficient analysis showed a very strong positive correlation(r=743, r=0.693). Conclusion: Using such a dose evaluation programs, easier to predict and evaluate the effective dose possible without performing phantom study and such dose evaluation programs could be used to collect basic data for CT dose management.

• The Journal of Korean Society for Radiation Therapy
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• v.24 no.2
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• pp.95-106
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• 2012

Purpose: The objective of this study was to investigate the usefulness of an IMRT treatment plan according to whether there was a shell-type pseudo target during radiation therapy for patients in Stage III or IV of non-small cell lung cancer (NSCLC). Materials and Methods: After setting an IMRT (Intensity-Modulated Radiation Therapy, IMRT) plan for when there was a shell-type pseudo target (SPT) and when there was none (WSPT) with 22 patients in Stage III or IV of NSCLC, the investigator analyzed dose-volume histograms (DVHs) and made assessment with dosimetric comparisons such as homogeneity index (HI) inside the tumor target, conformity index (CI) of the tumor target, spinal cord maximum dose, Esophagus $V_{50%}$, mean lung dose (MLD), and $V_{40%}$, $V_{30%}$, $V_{20%}$, $V_{10%}$, $V_{5%}$. Results: The mean CI of WSPT and SPT was $1.22{\pm}0.04$ and $1.16{\pm}0.032$ ($.000^*$), respectively, and the mean HI of WSPT and SPT was $1.06{\pm}0.015$ and $1.07{\pm}0.014$ ($.000^*$), respectively. In SPT, the mean of each CI difference decreased by $-5.16{\pm}2.54%$, while HI increased by average $0.81{\pm}0.47%$. Esophagus $V_{50%}$ recorded $14.54{\pm}12.01%$ (WSPT) and $12.14{\pm}11.09%$ ($.000^*$, SPT) with the mean of SPT differences dropping by $-26.37{\pm}25.05%$. Mean spinal cord maximum dose was $3,898.44{\pm}1,075.0$ cGy (WSPT) and $3,810.8{\pm}1,134.9$ cGy ($.004^*$, SPT) with SPT dropping by average $-3.36{\pm}5.81%$. As for lung $V_{X%}$, the mean of $V_{5%}$ and $V_{10%}$ differences was $-1.62{\pm}2.29%$ ($.006^*$) and $-1.98{\pm}5.02%$ ($.005^*$), respectively with SPT making a decrease. The mean of V20%, V30%, and V40% differences was $-3.51{\pm}3.07%$ ($.000^*$), $-4.84{\pm}6.01%$ ($.000^*$), and $-6.16{\pm}8.46%$ ($.001^*$), respectively, with SPT making a decrease with statistical significance. In MLD assessment, SPT also dropped by average $-2.83{\pm}2.41%$ ($.000^*$). Those results show that SPT allows for mean 169 cGy (Max: 547 cGy, Min: 6.4 cGy) prescription dose. Conclusion: An IMRT treatment plan with SPT during radiation therapy for patients in Stage III or IV of NSCLC will help to reduce the risk of lung toxicity and radiation-induced pneumonia by cutting down radiation doses entering the normal lung, reduce the local control failure rate during radiation therapy due to increasing prescription doses to a certain degree, and increase treatment effects.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.4
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• pp.79-85
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• 2023

A novel low-temperature co-fired ceramic (LTCC) dielectric, composed of (1-4x)Bi_1.5Zn_1.0Nb_1.5O₇-3xBi₂Zn_2/3Nb_4/3O₇-2xLiZnNbO₄ (x=0.03-0.21), was synthesized through reactive liquid phase sintering of Bi_1.5Zn_1.0Nb_1.5O₇-xLi₂CO₃ ceramic at temperatures ranging from 850℃ to 920℃ for 4 hours. During sintering, Li₂CO₃ reacted with Bi_1.5Zn_1.0Nb_1.5O₇, resulting in the formation of Bi₂Zn_2/3Nb_4/3O₇, and LiZnNbO₄. The resulting sintered body exhibited a relative sintering density exceeding 96% of the theoretical density. By altering the initial Li₂CO₃ content (x) and consequently modulating the volume fraction of Bi_1.5Zn_1.0Nb_1.5O₇, Bi₂Zn_2/3Nb_4/3O₇, and LiZnNbO₄ in the final sintered body, a sample with high dielectric constant (ε_r), low dielectric loss (tan δ), and the temperature coefficient of dielectric constant (TCε) characterized by NP0 specification (TCε ≤ ±30 ppm/℃) was achieved. As the Li₂CO₃ content increased from x=0.03 mol to x=0.15 mol, the volume fraction of Bi₂Zn_2/3Nb_4/3O₇ and LiZnNbO₄ in the composite increased, while the volume fraction of Bi_1.5Zn_1.0Nb_1.5O₇ decreased. Consequently, the dielectric constant (εr) of the composite materials varied from 148.38 to 126.99, the dielectric loss (tan δ) shifted from 5.29×10^-4 to 3.31×10^-4, and the temperature coefficient of dielectric constant (TCε) transitioned from -340.35 ppm/℃ to 299.67 ppm/℃. A dielectric exhibiting NP0 characteristics was achieved at x=0.09 for Li₂CO₃, with a dielectric constant (ε_r) of 143.06, a dielectric loss (tan δ) value of 4.31×10^-4, and a temperature coefficient of dielectric constant (TCε) value of -9.98 ppm/℃. Chemical compatibility experiment with Ag electrode revealed that the developed composite material exhibited no reactivity with the Ag electrode during the co-firing process.