• Journal of radiological science and technology
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• v.38 no.3
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• pp.229-235
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• 2015

Mammoplasty is currently increasing not only for cosmetic surgery, but as well as for the recovery after breast cancer surgery. The prostheses inserted into the breasts of women who have undergone mammoplasty, hide the breast substances and it is becoming increasingly difficult to diagnose breast disease, and fear is growing by the concern of the prostheses bursting by the strap. So we want to develop a strap applicable to women with prostheses inserted, to determine the usefulness, and we also want to compare the utility by comparing the total area of the Inner and Outer parts of the breast and Posterior Nipple Line (PNL), after obtaining video by applying the existing strap and the developed strap to phantom of the prostheses inserted patient shape. When the pressure by the developed pressure, the total area increased by 10.09% from CC view to $9,813.797mm^2$, 3.88% from CC-ID view to $7,621.531mm^2$, PNL increased by 3.41% from CC view to $90.916mm^2$, 1.64% from CC-ID view to$75.357mm^2$. And the breast tissue of the thorax side increased 3.53% from CC view to $177.725mm^2$, and 6.57% from CC-ID view to $152.510mm^2$, and we could verify that the prostheses were completely eliminated in the CC-ID images of developed strap, compared with the existing strap.

• Journal of radiological science and technology
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• v.38 no.3
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• pp.221-228
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• 2015

Purpose: In digital mammography QC program was used for the purpose of reducing low-dose and high-definition images of the radiation dose. Materials and Methods: In digital mammography using a QC phantom according to the average glandular dose in the exposure method MLO view $0^{\circ}C$, $30^{\circ}C$, $45^{\circ}C$, $50^{\circ}C$, $55^{\circ}C$, $70^{\circ}C$, was measured at $90^{\circ}C$ intervals, an image with Hologic QC program to the SNR and CNR was measured to evaluate. Results: The average dose in the MLO view was wired to $90^{\circ}C$ when the maximum was 1.75 mGy, it decreased approximately 6% was measured at $45^{\circ}C$ 1.65 mGy. In addition, 1.67 mGy, manual record, there were an average wired in accordance with the exposure dose and the dose of 1.52 mGy difference in the way auto filter. Image quality evaluation at every angular section SNR 50 ~ 52, shows a slight difference in CNR 11 ~ 12, it was included in the manufacturer's recommended value. Conclusion: The dose was lowest in MLO view $45^{\circ}C$, the difference between SNR and CNR were insignificant. The method of exposure will need a way to reduce the exposure of the patient's body or unnecessary patient by placing a difference in settings in which the characteristics.

• Journal of the Korea Convergence Society
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• v.7 no.1
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• pp.89-95
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• 2016

The purpose of this experiment intend to evaluate the quality of the image based on the orbit and basal ganglia with high radiosensitivity for the noise, SNR and dose using the five kinds patient fixing pad in brain phantom MDCT(BrillianceTM CT 64 slice, PHILIPS, Netherward). The noise had a higher values in AP than those of others, but the SNR was lower in AP than those of others. The SNR was higher in UP than those of RP, PP, SP and AP. The UP, RP and PP were no statistically significant(p>0.05), whereas it was significant difference between UP, RP, PP and SP, AP(p<0.05). This is causes of the noise difference is generated due to the differences in the radiation absorption dose in accordance with each the component of the absorbed dose level of the detector according to the reference line and each of SOML when the radiation exposured. The CTDIvol(mGy) and DLP of orbit and basal ganglia were 56.95, 911.50, respectively. There is no difference between both mean dose. In conclusion, it is possible to distinguish among a kind of 5 patient fixing pad by using brain phantom MDCT. Overall, patient fixing pad of UP, RP and PP based on a brain phantom MDCT can provide useful information.

• Investigative Magnetic Resonance Imaging
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• v.13 no.2
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• pp.117-126
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• 2009

Purpose : A numerical method of designing a multiple quantum filter (MQF) is presented for the optimum detection of myo-inositol (mI), an important brain metabolite, by using in vivo proton nuclear magnetic resonance spectroscopy ($^1$-HMRS). Materials and Methods : Starting from the characterization of the metabolite, the filter design includes the optimization of the sequence parameters such as the two echo times (TEs), the mixing time (TM), and the flip angle and offset frequency of the 3rd $90^{\circ}$ pulse which converts multiple quantum coherences (MQCs) back into single quantum coherences (SQCs). The optimized filter was then tested both in phantom and in human brains. Results : The results demonstrate that the proposed MQF can improve the signal-to-background ratio of the target metabolite by a factor of more than three by effectively suppressing the signal from the background metabolites. Conclusion : By incorporating a numerical method into the design of MQFs in $^1$-HMRS the spectral integrity of a target metabolite, in particular, with a complicated spin system can be substantially enhanced.

• Journal of Biomedical Engineering Research
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• v.24 no.2
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• pp.77-82
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• 2003

Virtual colonoscopy is a non-invasive computerized procedure to detect polyps by examining the colon from a CT data set. To fly through the inside of colons. the extraction of a suitable flight-path is necessary to Provide the viewpoint and view direction of a virtual camera. However. manual path extraction by Picking Points is a very time-consuming and difficult task due 1,c, the long and complex shape of colon. Also, existing automatic methods are computationally complex. and tend to generate an improper and/or discontinuous path for complicated regions. In this paper, we propose a fast flight-path generation algorithm using the distance and order maps. The order map Provides all Possible directions of a path. The distance map assigns the Euclidean distance value from each inside voxel to the nearest background voxel. By jointly using these two maps. we can obtain a proper centerline regardless of thickness and curvature of an object. Also, we Propose a simple smoothing technique that guarantees not to collide with the surface of an object. The phantom and real colon data are used for experiments. Experimental results show that for a set of human colon data, the proposed algorithm can provide a smoothened and connected flight-path within a minute on an 800MHz PC. And it is proved that the obtained flight-Path provides successive volume-rendered images satisfactory for virtual navigation.

• Progress in Medical Physics
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• v.11 no.2
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• pp.117-122
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• 2000

The IP(imaging plate) has been widely used to measure the two-dimensional distribution of incident radiation since it has a high sensitivity, reusability, a wide dynamic range, a high position resolution. Particularly, the easiness of acquiring digitized image using IP poses a strong merit because recent trend of data handling prefers image digitization. In order to test its usefulness in photon beam dosimetry, we measured the off-axis ratio(OAR) on portal planes and percent depth dose(PDD) within a phantom using IP, and compared the results with the data based on EGS4 Monte Carlo particle transport code, ion-chambers, conventional films. For the measurement, we used 6 MV X-rays, various field sizes. As a result, IP showed significant deviation from ion-chamber measurement: a significant overresponse, 100% greater than that of ion-chamber measurement at deep part of the phantom. Filtration of low-energy scattered photons at deep part of the phantom using 0.5 mm thick lead sheets did improve the result, only to the unacceptable extent. However, portal dose measurement showed possibilities of If as a dosimeter by showing errors less than 5%, as compared with film measurement.

• Progress in Medical Physics
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• v.1 no.1
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• pp.31-42
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• 1990

The finding of long lived free radicals produced by ionizing radiation in organic crystals and the quantification of this effect by electron spin resonance(ESR) spactroscopy has proven excellent dosimetric applicability. The tissue equivalent alanine dosimeter also appear appropriate for radiation therapy level dosimetry. The dose measurement was performed in a Rando phantom using high energy photons as produced by high energy medical linear accelerator and cobalt-60 teletherapy unit. The absorbed dose range of the ESR/alanine dosimetry system could be extended down to 0.1 Gy. The response of the alanine dosimeters was determined for photons at different therapeutic dose levels from less than 0.1 Gy to 100 Gy and the depth dose measurements were carried out for photon energies of 1.25MeV, 6 and 10 MV with alanine dosimeters in Rando phantom. Comparisons between ESR/alanine in a Rando phantom and ion chamber in a water phantom were made performing depth dose measurements to examine the agreement of both methods under field conditions.

• Progress in Medical Physics
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• v.11 no.2
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• pp.91-99
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• 2000

This is a preliminary study for developing the method of the dose reconstruction in the patients, irradiated by mega-voltage photon beams from the linear accelerator, using the transit dose distributions. In this study we present the method of three-dimensional dose reconstruction and evaluate the method by computer simulation. To acquire the dose distributions in the patients (or phantoms) we first calculate the differences between the doses at the arbitrary points in the patients and the doses at the corresponding points where the transit doses are measured. Then, we can get the dose in the patients from the measured transit dose and the calculated value of the difference. The dose differences are calculated by applying the inverse square law and using the linear attenuation coefficient. The scatter to primary dose ratios, which are calculated by the Monte Carlo program using the CT data of the patient (or phantoms), are also used in the calculations. For the evaluation of this method we used various kinds of homogeneous and inhomogeneous phantoms and calculated the transit dose distributions with the Monte Carlo program. From the distributions we reconstructed the dose distributions in the phantom. We used mono-energy Photon beam of 1.5MeV and Monte Carlo program EGS4. The comparison between the dose distributions reconstructed using the method and the distributions calculated by the Monte Carlo program was done. They agreed within errors of -4%∼+2%. This method can be used to predict the dose distributions in the patient

• Journal of the Korean Society of Radiology
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• v.12 no.5
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• pp.549-555
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• 2018

The medical imaging technique images the contrast formed based on the difference in absorption coefficient of X-rays which changes according to the composition and thickness of the object. At this time, not only primary rays entering the image detector but also scattered rays greatly affect the image quality. Therefore, in this paper, Forward scattering rate and Scattered to primary ratio analysis were performed through Monte Carlo simulation in order to consider influence of scattered ray generated according to object thickness and radiation exposure area change on image quality. In the study, the Forward scattering rate corresponding to the thickness of the object was analyzed at a maximum of 15.3%p and the Scattered to primary ratio was analyzed at 2.00 to 4.54, but it was analyzed as maintaining a constant value for radiation exposure area change. Based on these results, the thickness of the object should be considered as a factor influencing the quality of the image, but radiation exposure area verified that it is a factor that does not affect the image quality. We believe that the results of this research can be utilized as basic information of scattered radiation to improve image quality.

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.2
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• pp.57-61
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• 2014

Purpose Iodine (I-131) is one of the most widely used radioactive isotopes for therapeutic in the field of nuclear medicine. Therapeutic I-131 capsule is made out of lead to shield high energy radiation. Accurate dosimetry is necessarily required to perform safe and effective work for relative workers. The Monte Carlo method is known as a method to predict the absorbed dose distribution most accurately in radiation therapy and many researchers constantly attempt to apply this method to the dose calculation of radiotherapy recently. This paper aims to calculate distance dependent and activity dependent therapeutic I-131 capsule using GEANT4. Materials and Methods Therapeutic capsules was implemented on the basis of the design drawings. The simulated dose was determined by generating of gamma rays of energy to more than 364 keV. The simulated dose from the capsule at the distance of 10 cm and 100 cm was measured and calculated in the model of water phantom. The simulated dose were separately calculated for each position of each detector. Results According to the domestic regulation on radiation safety, the dose at 10 cm and 100 cm away from the surface of therapeutic I-131 capsule should not exceed 2.0 mSv/h and 0.02 mSv/h, respectively. The simulated doses turned out to be less than the limit, satisfying the domestic regulation. Conclusion These simulation results may serve as useful data in the prediction of hands dose absorbed by I-131 capsule handling. GEANT4 is considered that it will be effectively used in order to check the radiation dose.