• Radiation Oncology Journal
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• 제31권4호
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• pp.252-259
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• 2013

Purpose: To report the results of dosimetric comparison between intensity-modulated radiotherapy (IMRT) using Tomotherapy and four-box field conformal radiotherapy (CRT) for pelvic irradiation of locally advanced rectal cancer. Materials and Methods: Twelve patients with locally advanced rectal cancer who received a short course preoperative chemoradiotherapy (25 Gy in 5 fractions) on the pelvis using Tomotherapy, between July 2010 and December 2010, were selected. Using their simulation computed tomography scans, Tomotherapy and four-box field CRT plans with the same dose schedule were evaluated, and dosimetric parameters of the two plans were compared. For the comparison of target coverage, we analyzed the mean dose, $V_{nGy}$, $D_{min}$, $D_{max}$, radical dose homogeneity index (rDHI), and radiation conformity index (RCI). For the comparison of organs at risk (OAR), we analyzed the mean dose. Results: Tomotherapy showed a significantly higher mean target dose than four-box field CRT (p = 0.001). But, $V_{26.25Gy}$ and $V_{27.5Gy}$ were not significantly different between the two modalities. Tomotherapy showed higher $D_{max}$ and lower $D_{min}$. The Tomotherapy plan had a lower rDHI than four-box field CRT (p = 0.000). Tomotherapy showed better RCI than four-box field CRT (p = 0.007). For OAR, the mean irradiated dose was significantly lower in Tomotherapy than four-box field CRT. Conclusion: In locally advanced rectal cancer, Tomotherapy delivers a higher conformal radiation dose to the target and reduces the irradiated dose to OAR than four-box field CRT.

• 한국방사선학회논문지
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• 제14권5호
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• pp.613-618
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• 2020

간동맥화학색전술 중 사용되고 있는 Fast Low Dose C-arm CT의 평균선량을 DSA의 평균선량과 비교해 보고, 전체 누적선량에서 검사기법별 평균선량 분석을 통해 피폭선량을 분석해 보았다. 본원에서 환자 50명을 임의로 선정하여 Fast Low Dose C-arm CT와 DSA의 DAP 및 Air Kerma를 조사하여 비교하였으며, 4가지 검사기법(DSA, Fast Low Dose C-arm CT, Roadmap, Fluoroscopy)의 누적선량(DAP, Air Kerma)이 차지하는 비율을 분석하였다. 통계적인 비교 분석을 위해 통계프로그램 SPSS 20.0을 이용하여 대응표본 T검정, ANOVA 검증(post hoc test : Tukey)하였다. Fast Low Dose C-arm CT가 DSA에 비해 평균선량(DAP, Air Kerma)이 통계적으로 유의하게 낮았다.(p<.001) 간동맥화학색전술에서 항암제 주입 전후로 Fast Low Dose C-arm CT를 적극 활용하여 DSA의 검사 횟수를 줄인다면 환자의 의료방사선 피폭을 감소시킬 수 있다.

• 대한방사선기술학회지:방사선기술과학
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• 제42권6호
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• pp.483-489
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• 2019

This paper obtained and compared these dose values by setting and comparing the X-ray imaging conditions (tube voltage 60 kVp, 70 kVp, 80 kVp, tube current 10 mAs, 16 mAs and X-ray field size are 10 × 10 cm, 15 × 15 cm). Each dose value was measure 10 times and represented as an average value. The purpose of this experiment is to serve as a reference for the X-ray exposure of diagnostic areas according to the type of dosimeter and to help with another dose measurement. The results of the experiment showed very little difference between the glass dosimeter(GD) and semiconductor dosimeter values due to changes in tube voltage of 60, 70, 80 kVp, regardless of field sized, but for dose area product(DAP), the difference in dose value was significant according to field size.

• 방사선산업학회지
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• 제12권4호
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• pp.297-302
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• 2018

The wedge filter has two movements, fixed and dynamic. In this study, the depth dose distribution was analyzed to determine the stability of the dose distribution and dose volume histograms obtained by evaluating the usability of the critical normal tissue dose around the tumor dose. The depth dose was analyzed from the dose distribution from a Linac (6 MV and 10 MV irradiation field of energy $20{\times}20cm^2$, wedge filter with a SSD of 100 cm and $15^{\circ}$, $30^{\circ}$, $45^{\circ}$ Y1-in (Left -7 cm), Y2-out(Right +7 cm). To analyze the fluctuations of the depth dose, a fixed wedge and dynamic wedge toe portion was examined according to the energy and angle because the size of the fluctuations was included in the error bound and did not show significant differences. The neck, breast, and pelvic dosimetry in tumor tissue are measured more commonly with a dynamic wedge than a fixed wedge presumably due to the error range. On the other hand, dosimetry of the surrounding normal tissue is more common using a fixed wedge than with a dynamic wedge.

• 대한방사선기술학회지:방사선기술과학
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• 제44권3호
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• pp.189-194
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• 2021

This study was conducted to reduce the exposure dose to the breast and adjacent organs as the number of Mammography increased. Therefore, it has been designed a shield in lead, bismuth + tungsten, and bismuth that does not require to be equipped by the patient, in which each type of shield was compared and analyzed of radiation exposure dose to breast, thyroid, and eye. Using a mammography machine, optically stimulated luminescent dosimeter(OSLD) was inserted to bilateral breast, thyroid, and eye of a dosimetry phantom to measure dose radiated onto the phantom. Shielding device was made in different thickness of 2mm, 3mm, and 5mm and dose evaluation was performed by measuring the dose while using lead, bismuth, and bismuth + tungsten prosthesis. When each shields combined with shielding device, were compared of dose, all showed similar does reduction in the dose to breast, thyroid, and eye in both cranialcaudal and mediolateraloblique view. Based on the current study, bismuth and bismuth + tungsten can replace conventional lead shield and it is anticipated to safely and conveniently reduce radiation exposure to breast, thyroid, and eye with the shield that does not require to be equipped.

• Nuclear Engineering and Technology
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• 제54권10호
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• pp.3816-3823
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• 2022

This work analyzed the dosimetric difference between the intensity modulated radiotherapy (IMRT), partial/single/double-arc volumetric modulated arc therapy (PA/SA/DA-VMAT) techniques in treatment planning for treating more than one target of lung cancer at different isocenters. IMRT and VMAT plans at different isocenters were created systematically using a Harold heterogeneous lung phantom. The conformity index (CI), homogeneity index (HI), gradient index (GI), dose-volume histogram and mean and maximum dose of the PTV were calculated and analyzed. Furthermore, the dose-volume histogram and mean and maximum doses of the OARs such as right lung, contralateral lung and non GTV were determined from the plans. The IMRT plans showed the superior target dose coverage, higher mean and maximum values than other VMAT techniques. PA-VMAT technique shows more lung sparing and DA-VMAT increases the V_5/10/20 values of contralateral lung than other VMAT and IMRT techniques. The IMRT technique achieves highly conformal dose distribution to the target than other VMAT techniques. Comparing to the IMRT plans, the higher V_5/10/20 and mean lung dose were observed in the contralateral lung in the DA-VMAT.

• 대한디지털의료영상학회논문지
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• 제11권2호
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• pp.101-107
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• 2009

With the recent development of diagnosis using radiation and increasing demand of the medical treatment, we need to minimize radiation exposure dose. So, This is the method which reduce patient dose by measuring surface dose of radiographic change factor and by comparing theoretical and actual dose, when we take an X-ray which is generally used. By changing the factor of kV, mAs, FSD, whose range is 60 to 120 kV, 20 to 100 mAs, 80 to 180 cm, we compared theoretical surface dose with actual surface dose calculated by the simple calculation program, Bit system, and NDD-M method As a result, when kV and mAs were higher, theoretical surface dose and actual surface dose were more increased. but the higher FSD was, the more decreased surface dose was. According to this, the error were measured about 0.1 to 0.2 mGy in low dose part and about 0.7 to 1.5 mGy in high dose part. Therefore, this shows that theoretical surface dose calculation method is more correct in low dose part than in high dose part. In conclusion, we will have to make constant efforts which can reduce patient and radiographer's exposure dose, studying methods which can predict patient's radiation exposure dose more exactly.

• 대한방사선기술학회지:방사선기술과학
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• 제38권4호
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• pp.347-353
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• 2015

디지털 흉부단층합성법 검사에서 부가필터 사용에 따른 환자의 선량과 화질의 특성을 비교해보고자 하였다. 부가필터의 종류는 구리, 알루미늄, 니켈을 사용하였으며, 이 때 각 각의 부가필터에 따른 유효선량, 면적선량을 측정해 보았고, 화질의 물리적 평가방법으로 signal to noise ratio (SNR)과 contrast to noise ratio (CNR)을, 시각적 평가방법으로 contrast detail (CD) phantom을 이용한 CD 곡선을 비교하였다. 그 결과 부가필터별 조사선량이 비슷한 두께는 0.3 mmCu, 3 mmAl, 0.3 mmNi 였으며 부가필터를 사용하지 않았을 때 보다 조사선량 값이 평균 33.1% 감소하였다. 각 필터 별 dose area product (DAP) 선량값을 측정한 결과 Ni를 사용하였을 때 선량이 72.9% 감소하여 가장 낮았으며, 필터별 DAP 값은 통계적으로 유의한 차이를 보였다(p<0.01). 유효선량은 Ni를 사용하였을 때 가장 낮은 선량 값을 보였고, 필터를 사용하지 않았을 때 0.102 mSv에 비해 48.0% 감소하였다. CD phantom에 의한 시각적 화질평가에서는 각 필터별로 비슷한 양상을 나타냈으며, 3가지 부가필터를 사용 하였을 때 S NR과 CNR은 평균 19.07, 1 8.17% 감소함을 보였다. 결론적으로 디지털 흉부 단층합성법 검사에서 부가필터로 Ni을 사용할 경우 유효선량 및 DAP 선량 감소, 화질에서 가장 적절함을 알 수 있었다.

• Radiation Oncology Journal
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• 제36권1호
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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.

• 환경생물
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• 제21권4호
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• pp.384-391
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• 2003

The induction of chromosome aberrations in Hordeum vulgare germs after irradiation is studied for the dose range of 10 to 1,000 mGy. The relationship between the frequency of aberrant cells and the absorbed dose is shown to be non -linear and has a dose-independent plateau within the range of 56-467 mGy where the level of cytogenetic damage is statistically significantly distinguished from the spontaneous level. The comparison of the goodness of the experimental data fitting with mathematical models of different complexities, using the most common quantitative criteria, demonstrates the benefit of the piecewise linear model over the linear and polynomial ones in approximating the cytogenetical disturbance frequency. The results of our study support the conclusion about indirect mechanism of chromosome aberrations induced by low doses or dose rates mutagenesis.