• Journal of the Korean Physical Society
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• v.73 no.10
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• pp.1571-1576
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• 2018

We developed and evaluated an algorithm to calculate the target radiation dose in cancer patients by measuring the transmitted dose during 3D conformal radiation treatment (3D-CRT) treatment. The patient target doses were calculated from the transit dose, which was measured using a glass dosimeter positioned 150 cm from the source. The accuracy of the transit dose algorithm was evaluated using a solid water phantom for five patient treatment plans. We performed transit dose-based patient dose verification during the actual treatment of 34 patients who underwent 3D-CRT. These included 17 patients with breast cancer, 11 with pelvic cancer, and 6 with other cancers. In the solid water phantom study, the difference between the transit dosimetry algorithm with the treatment planning system (TPS) and the measurement was $-0.10{\pm}1.93%$. In the clinical study, this difference was $0.94{\pm}4.13%$ for the patients with 17 breast cancers, $-0.11{\pm}3.50%$ for the eight with rectal cancer, $0.51{\pm}5.10%$ for the four with bone cancer, and $0.91{\pm}3.69%$ for the other five. These results suggest that transit-dosimetry-based in-room patient dose verification is a useful application for 3D-CRT. We expect that this technique will be widely applicable for patient safety in the treatment room through improvements in the transit dosimetry algorithm for complicated treatment techniques (including intensity modulated radiation therapy (IMRT) or volumetric modulated arc therapy (VMAT).

• Radiation Oncology Journal
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• v.36 no.1
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• pp.63-70
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• 2018

Purpose: The objective of this study was to compare dosimetric characteristics of three-dimensional conformal radiotherapy (3D-CRT) and two types of intensity-modulated radiotherapy (IMRT) which are step-and-shoot intensity modulated radiotherapy (s-IMRT) and modulated arc therapy (mARC) for thoracic esophageal cancer and analyze whether IMRT could reduce organ-at-risk (OAR) dose. Materials and Methods: We performed 3D-CRT, s-IMRT, and mARC planning for ten patients with thoracic esophageal cancer. The dose-volume histogram for each plan was extracted and the mean dose and clinically significant parameters were analyzed. Results: Analysis of target coverage showed that the conformity index (CI) and conformation number (CN) in mARC were superior to the other two plans (CI, p = 0.050; CN, p = 0.042). For the comparison of OAR, lung V5 was lowest in s-IMRT, followed by 3D-CRT, and mARC (p = 0.033). s-IMRT and mARC had lower values than 3D-CRT for heart $V_{30}$ (p = 0.039), $V_{40}$ (p = 0.040), and $V_{50}$ (p = 0.032). Conclusion: Effective conservation of the lung and heart in thoracic esophageal cancer could be expected when using s-IMRT. The mARC was lower in lung $V_{10}$, $V_{20}$, and $V_{30}$ than in 3D-CRT, but could not be proven superior in lung $V_5$. In conclusion, low-dose exposure to the lung and heart were expected to be lower in s-IMRT, reducing complications such as radiation pneumonitis or heart-related toxicities.

• The Journal of the Korea Contents Association
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• v.15 no.6
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• pp.297-302
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• 2015

High-energy medical linear accelerator on the dose to the thyroid cancer during radiotherapy were evaluated using optical stimulation luminescence dosimeters(OSLD) using. Scattered's influence in the case of 3D-CRT 25.4 mSv, 28.8 mSv, 31.3 mSv, 26.5 mSv, 27.4 mSv 5 times with an average 27.9 mSv, in the IMRT 46.8 mSv, 43.2 mSv, 42.3 mSv, 41.5 mSv, 44.1 mSv to five times the average of 43.6 was the result of mSv. In the case of light neutron dosimetry results 3D-CRT 3 mSv, 3 mSv, 3.4 mSv, 3.5 mSv, 3.1 mSv to five times the average 3.2 mSv, in the IMRT 5.1 mSv, 4.8 mSv, 4.2 mSv, 4.8 mSv, 4.9 mSv, to five times the average of 4.7 was the result of mSv. Both parties and the light scattered neutrons were significantly appreciated compared to IMRT 3D-CRT. Treatment of cancer using radiation workers, as in this study, and that a significant amount of scattered rays in the adjacent normal tissues during radiation therapy using energy assessment to influence by fully aware of this information is necessary for the exposure reduction efforts the feed.

• Journal of radiological science and technology
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• v.36 no.3
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• pp.237-244
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• 2013

The purpose of this study is to compare method in the treatment of breast cancer using dose index. And, it is to find the optimized treatment technique to the patient. The phantom filled with tissue-equivalent material were used simulation and treatment as techniques of 3D-CRT, IMRT, VMAT was planned using Eclipse v10. By using HI(homogeneity index), CI(Conformity index), OED(Organ equivalent dose), EAR(Excess Absolute Risk), were assessed for each treatment plans. HI and CI of 3D-CRT, IMRT, VMAT were calculated 16.89, 11.21, 9.55 and 0.59, 0.61, 0.83. The organ average doses of Lt lung, Rt lung, liver, heart, esophagus, cord, Lt breast, trachea and stomach were 0.01 ~ 2.02 Gy, 0.36 ~ 5.01 Gy, 0.25 ~ 2.49 Gy, 0.14 ~ 6.92 Gy, 0.03 ~ 2.02 Gy, 0.01 ~ 1.06 Gy, 0.25 ~ 6.08 Gy, 0.08 ~ 0.59 Gy, 0.01 ~ 1.34 Gy, respectively. The OED, EAR of the IMRT and VMAT show higher than 3D-CRT. As the result of this study, we could confirm being higher dose index(HI, CI) in IMRT and VMAT than 3D-CRT, but doses of around normal organs was higher IMRT, VMAT than 3D-CRT.

• Journal of the Korean Society of Radiology
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• v.17 no.3
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• pp.473-479
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• 2023

In this study, the dose of photoneutrons generated during radiotherapy of prostate cancer using high energy was measured using a photo-stimulated luminescence dosimeter. In addition, this study was intended to study the probability of side effects occurring in the abdomen. A medical linear accelerator capable of generating 15 MV energy, True Beam STx (Varian Medical Systems, USA) and a radiation treatment planning system (Eclipse, Varian Medical Systems, USA) were used. A human body phantom was installed on the couch of the linear accelerator, and an Albedo Neutron Optical Stimulation Luminescence Neutron Detector (Landauer Inc., IL, USA) was used to measure the photoneutron dose. The photoneutron dose value in the abdomen of VMAT and 3C-CRT was 52.8 mSv, more than twice as high as VMAT compared to 3D-CRT. During radiotherapy of prostate cancer, the probability of causing side effects in the abdomen due to light neutron dose was calculated to be 3.2 per 1,000 for VMAT and 1.4 for 3D-CRT. By studying the abdomen, which has a major side effect that can occur during radiotherapy of prostate cancer, it is expected that it will be used as a meaningful study to study the quality of life and stochastic effect of prostate cancer patients

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.395-398
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• 2002

The spherical aberration and optical integer (f) of the electron gun's main lens in color CRT is obtained, using electron beam trajectory. A spherical aberration is obtained from the relation between the object plane and the image of a beam trajectory. To analyze beam profile, 3rd and 1st order coefficient were obtained and used. It is shown that, in practice, they are applied to electron gun design.

• Journal of the Korean Society of Radiology
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• v.16 no.7
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• pp.857-862
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• 2022

The purpose of this study was to evaluate a three-dimensional conformal radiotherapy (3D-CRT) treatment plan with regard to head tilting in whole-brain radiotherapy (WBRT) using TomoDirect (TD) mode in Tomotherapy. WBRT 3D-CRT by TD was compared for a total of five head tilt angles (-20°, -10°, 0°. +10° and +20°). The dose homogeneity index (HI) and prescription dose index (CI) were calculated to confirm the target coverage. The maximum and average doses for critical organs such as the lens, eyeball and parotid glands were calculated for different angles of head tilting. The HI and CI were closet to the result value of 1 at the head tilted angle +10° and +20°. At a head tilted angle of +10°, the dose to the lens and eyeballs decreased by about 74% and about 30%, when compared with the reference angle (0°), respectively. The results of this study suggest that a head angle of +10 with chin-up would save adequate target coverage and reduce exposure dose to the lens.

• Radiation Oncology Journal
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• v.37 no.4
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• pp.279-285
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• 2019

Purpose: This study was conducted to compare the outcome of three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) for the postoperative treatment of biliary tract cancer. Materials and Methods: From February 2008 to June 2016, 57 patients of biliary tract cancer treated with curative surgery followed by postoperative 3D-CRT (n = 27) or IMRT (n = 30) were retrospectively enrolled. Results: Median follow-up time was 23.6 months (range, 5.2 to 97.6 months) for all patients and 38.4 months (range, 27.0 to 89.2 months) for survivors. Two-year recurrence-free survival is higher in IMRT arm than 3D-CRT arm with a marginal significance (25.9% vs. 47.4%; p = 0.088). Locoregional recurrence-free survival (64.3% vs. 81.7%; p = 0.122) and distant metastasis-free survival (40.3% vs. 55.8%; p = 0.234) at two years did not show any statistical difference between two radiation modalities. In the multivariate analysis, extrahepatic cholangiocarcinoma, poorly-differentiated histologic grade, and higher stage were significant poor prognostic factors for survival. Severe treatment-related toxicity was not significantly different between two arms. Conclusions: IMRT showed comparable results with 3D-CRT in terms of recurrence, and survival, and radiotherapy toxicity for the postoperative treatment of biliary tract cancer.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.47.2-47.2
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• 2017

We present the results of astrometric observations using water masers around a semi-regular variable star R Crt. The observations were carried out for two years with the Korean VLBI Network (KVN). The absolute positions of the water masers from R Crt are successfully obtained at 10 epochs in total. By tracking the positions of the water maser emission, we directly measured the annual parallax and distance of R Crt. The measured distance to R Crt enables us to estimate the actual 3D velocity of water masers around R Crt. Our research suggests the possibility of performing astrometric studies with the KVN. As a next step, we are going to enhance the astrometric accuracy by observing SiO masers.

• The Journal of Korean Society for Radiation Therapy
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• v.28 no.2
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• pp.171-178
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• 2016

Purpose : In order to minimize the dose of femoral head as an appropriate treatment plan for rectal cancer radiation therapy, we compare and evaluate the usefulness of 3-field 3D conformal radiation therapy(below 3fCRT), which is a universal treatment method, and 5-field 3D conformal radiation therapy(below 5fCRT), and Volumetric Modulated Arc Therapy (VMAT). Materials and Methods : The 10 cases of rectal cancer that treated with 21EX were enrolled. Those cases were planned by Eclipse(Ver. 10.0.42, Varian, USA), PRO3(Progressive Resolution Optimizer 10.0.28) and AAA(Anisotropic Analytic Algorithm Ver. 10.0.28). 3fCRT and 5fCRT plan has $0^{\circ}$, $270^{\circ}$, $90^{\circ}$ and $0^{\circ}$, $95^{\circ}$, $45^{\circ}$, $315^{\circ}$, $265^{\circ}$ gantry angle, respectively. VMAT plan parameters consisted of 15MV coplanar $360^{\circ}$ 1 arac. Treatment prescription was employed delivering 54Gy to recum in 30 fractions. To minimize the dose difference that shows up randomly on optimizing, VMAT plans were optimized and calculated twice, and normalized to the target V100%=95%. The indexes of evaluation are D of Both femoral head and aceta fossa, total MU, H.I.(Homogeneity index) and C.I.(Conformity index) of the PTV. All VMAT plans were verified by gamma test with portal dosimetry using EPID. Results : D of Rt. femoral head was 53.08 Gy, 50.27 Gy, and 30.92 Gy, respectively, in the order of 3fCRT, 5fCRT, and VMAT treatment plan. Likewise, Lt. Femoral head showed average 53.68 Gy, 51.01 Gy and 29.23 Gy in the same order. D of Rt. aceta fossa was 54.86 Gy, 52.40 Gy, 30.37 Gy, respectively, in the order of 3fCRT, 5fCRT, and VMAT treatment plan. Likewise, Lt. Femoral head showed average 53.68 Gy, 51.01 Gy and 29.23 Gy in the same order. The maximum dose of both femoral head and aceta fossa was higher in the order of 3fCRT, 5fCRT, and VMAT treatment plan. C.I. showed the lowest VMAT treatment plan with an average of 1.64, 1.48, and 0.99 in the order of 3fCRT, 5fCRT, and VMAT treatment plan. There was no significant difference on H.I. of the PTV among three plans. Total MU showed that the VMAT treatment plan used 124.4MU and 299MU more than the 3fCRT and 5fCRT treatment plan, respectively. IMRT verification gamma test results for the VMAT plan passed over 90.0% at 2mm/2%. Conclusion : In rectal cancer treatment, the VMAT plan was shown to be advantageous in most of the evaluation indexes compared to the 3D plan, and the dose of the femoral head was greatly reduced. However, because of practical limitations there may be a case where it is difficult to select a VMAT treatment plan. 5fCRT has the advantage of reducing the dose of the femoral head as compared to the existing 3fCRT, without regard to additional problems. Therefore, not only would it extend survival time but the quality of life in general, if hospitals improved radiation therapy efficiency by selecting the treatment plan in accordance with the hospital's situation.