• Journal of Radiation Protection and Research
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• v.25 no.1
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• pp.3-9
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• 2000

The Korea Atomic Energy Research Institute acquired the Lawrence Livermore National Laboratory phantom for calibration of germanium detectors used for in vivo measurement of radionuclides deposited in human lungs. The manufacturer inscribed concentric circles as a phoswich detector positioning guides on the phantom's torso plate and its overlay plates, and provided the effective thickness of the chest wall for each plate measured at locations over the circles. However, since the germanium detectors are of different sizes, the areas considered for phoswich detectors were no. longer applicable for the locations of the germanium detectors on the phantom. Therefore, we re-evaluated the effective thickness of the phantom to determine if the manufacturer' s data are valid for germanium detectors in use for in vivo lung counting or if new values must be implemented. Differences no more than 3% in effective thickness were found between the germanium detector regions to be used at the Korea Atomic Energy Research Institute and the phoswich detector regions prescribed by the manufacturer.

• Journal of the Korean Society of Radiology
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• v.9 no.7
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• pp.467-471
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• 2015

This study's purpose is improve image quality to keep accurate tube angle in order to recognize distortion degree conditions by patient's position or tube angle and to provide exact clinical informations when taking chest AP projection for patient which have L-tube in stomach. The experimental equipment was ELMO-T6S by SHIMADZU corporation, then we put L-tube which attached 1 mm gap scales ruler on chest phantom surface. The experiment set by 90 kVp, 4 mAs, 120 cm distance. Each phantom position which changed supine, 30degree, 45degree, 60degree on the table exposured direct, ${\pm}5degree$, ${\pm}10degree$, ${\pm}15degree$ to head and feet directions. As a result, L-tube tip's position was changed by patient's position and tube angle. When patient's position is supine, tip's position change was lower than 30degree, 45degree, 60degree. We have to adjust patient's position or tube angle in order to occur image distortion by fault tube angle when confirming correct position L-tube tip through chest x-ray. Also, Radiological technologist try to make accurate evaluation index for satisfied L-tube insertion.

• Korean Journal of Digital Imaging in Medicine
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• v.13 no.4
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• pp.165-169
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• 2011

The purpose of this study is to compare the measurement result of radiation dose by using standard thoracic phantom and ionization chamber to advice proposal in the shooting condition of chest PA projection at hospitals recently. And to understand the change between radiation dose and resolution in different conditions. The period this study was from August 2010 to September 2010 and the subjects of the study was 3 general hospitals, 4 personal hospitals and 1 laboratory at the college. Finally we study with 6 DR, 1 CR, and 4 F/S equipments. Most hospitals met advice proposal, but some of the hospitals exceed advice dose from the result of our study. We can lower radiation dose about 25% when kVp is lowered about 20% in DR equipment. And we can lower radiation dose about 50% when mAs is lowered about 35%. The image quality was similar to the original in the study. Most hospitals which exceed advice dose were personal hospitals. The reason why it happened is that radiation dose for chest PA projection at personal hospitals is higher than general hospitals and the personal hospitals' equipments are older than general hospitals' equipments. We guess that patients' radiation dose of chest PA projection can be lowered from the result.

• Journal of the Korean Society of Radiology
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• v.17 no.5
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• pp.725-733
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• 2023

The purpose of this study is to evaluate the effectiveness of virtual grid software (VGS). The purpose of this study is to evaluate the changes in energy and object thickness by dividing the use of VGS into two cases (Without-VGS) without using a movable grid. We attempted to determine the effectiveness of VGS by acquiring images using a chest phantom and a thigh phantom and analyzing SNR and CNR. In the chest phantom and femoral phantom, the tube flow was fixed at 2.5 mAs, and the tube voltage was changed by 10 kVp from 60 to 100 kVp to measure SNR and CNR, and SNR was about 1.09 to 8.86% higher in the chest phantom than in Without-VGS, and CNR was 4.18 to 14.56% higher in the VGS than in Without-VGS. And in the femoral phantom, SNR was about 9.78 to 18.05% higher in VGS than in Without-VGS, and CNR was 21.07 to 44.44% higher in VGS than in Without-VGS. The tube voltage was fixed at 70 kVp in the chest phantom and the femoral phantom, and the amount of tube current was changed at 2.5 to 16 mAs, respectively, and after X-ray irradiation, SNR and CNR were measured in the chest phantom, which was about 1.49 to 11.11% higher in VGS than in Without-VGS, and CNR was 4.76 to 13.40% higher in VGS than in Without-VGS. And in the femoral phantom, SNR was about 2.22 to 17.38% higher in VGS than in Without-VGS, and CNR was 13.85 to 40.46% higher in VGS than in Without-VGS. Therefore, if an inspection is required with a mobile X-ray imaging device, it is believed that good image quality can be obtained by using VGS in an environment where it is difficult to use a mobile grid, and it is believed that the use of mobile X-ray devices can be increased.

• Journal of the Korean Society of Radiology
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• v.9 no.7
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• pp.473-478
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• 2015

Abdominal obesity is one of the most influential index to predict of insulin resistance syndrome/metabolic syndrome in social demographic characteristics. It is matter of fact that radiation dose are increasing with development of medical treatment and device. In this study, we estimated distortion between reference image and entrance surface dose when take a chest radiography forward chest phantom assumed abdominal obesity. When angle of chest phantom incline $5^{\circ}$ forward, thoracic transverse and longitudinal diameter increase 1.22% and 0.44% each. Also cardiac transverse diameter increase 1.01% and cardio-throracic ratio (CTR) decrease 0.27% in the same situation of incline to $5^{\circ}$ forward. Thoracic transverse diameter shows the largest increase, and CTR was decreased. But entrance surface dose to phantom increase significantly 6.12% when angle of chest phantom incline $5^{\circ}$ forward. In conclusion, we have to pay attention to accurate positioning, to prevent a distortion of image through incline, and make patients not to expose to additional radiation.

• Journal of the Korean Society of Radiology
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• v.12 no.1
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• pp.23-30
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• 2018

To evaluate the effect of patient size on effective dose and image quality for Digital Chest Tomosynthesis(DTS) using additional 0.3 mm copper filtration. Eighty artificial nodules were placed in the thorax phantom("Lungman," Kyoto Kagaku, Japan), and Digital Chest Tomosynthesis(DTS) images of the phantom were acquired both with and without added 0.3 mm Cu filtration. To simulate patients of three sizes: small, average size and oversize, one or two 20-mm-thick layer of PMMA(polymethyl methacrylatek) blocks were placed on the phantom. The Effective dose was calculated using Monte Carlo simulations. Two evaluations of image quality methods have been employed. Three readers counted the number of nodules detected in the lung, and the measured contrast-to-noise ratios(CNRs) were used. Data were analyzed statistically. The ED reduced $26{\mu}Sv$ in a phantom, $33{\mu}Sv$ in one 20-mm-thick layer of PMMA block placed on the phantom, and $48{\mu}Sv$ in two 20-mm-thick layer of PMMA blocks placed on the phantom. The Effective dose(ED) differences between DTS with and without filtration were significant(p<0.05). In particular, when we used two 20-mm-thick layer of PMMA blocks placed on the phantom, the ED was significantly reduced by 36% compared with those without additional filtration. Nodule detection sensitivities were not different between with and without added filtration. Differences of CNRs were statistically insignificant(p>0.05). Use of additional filtration allows a considerable dose reduction during Digital Chest Tomosynthesis(DTS) without loss of image quality. In particular, additional filtration showed outstanding result for effective dose reduction on two 20-mm-thick layer of PMMA blocks placed on the phantom. It applies to overweight patients.

• Radiation Oncology Journal
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• v.1 no.1
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• pp.41-45
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• 1983

To obtain 7 MeV electron beam which is suitable for treatment of the chest wall after radical of modified radical mastectomy, the authors reduced the energy of electron beam by means by Lucite plate inserted in the beam. To determine the proper thickness of the Lucite plate necessary to reduce the energy of 9 MeV electron beam to 6 MeV, dosimetry was made by using a parallel plate ionization chamber in polystyrene phantom. Separation between two adjacent fields, 7 MeV for chest wall and 12 MeV for internal mammary region, was studied by means of film dosimetry in both polytyrene phantom and Humanoid phantom. The results were as follows. 1. The average energy of 9 MeV electron beam transmitted through the Lucite plate was reduced. Reduction was proportional to the thickness of the Lucite plate in the rate of 1.7 MeV/cm. 2. The proper thickness of the Lucite plate necessary to obtain 6 MeV electron beam from 9 MeV was 1.2 cm. 3. 7 MeV electron beam, 80% dose at 2cm depth, is adequate for treatment of the chest wall. 4. Proper separation between two adjacent electron fields, 7 MeV and 12 MeV, was 5mm on both flat surface and sloping surface to produce uniform dose distribution.

• Journal of radiological science and technology
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• v.40 no.4
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• pp.567-573
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• 2017

The purpose of this study was to evaluate whether or not there was artifact when the upper limb could not be lifted to the top of the head during multi-detector computed tomography(MDCT) scans of the chest and abdomen. Contrast radiography of the human and chest phantom was performed with 128channal MDCT. Under the same conditions(120 kVp, 110 mAs, standard algorithm)both hands lifted up and put down each time in the human experiment. In the chest phantom experiment, the radiography was carried out when the upper limb phantom was adjusted at a certain distance(0, 3, 7 cm) from the chest phantom. Subsequently, the values of Noise, CT number, SNR, and CNR were measured in the field of concern. The noise value of fat, rib, and muscle increased when the arm was lifted in humans(0.79, 47.8, 27%). Furthermore, when the upper limb was lowered, the noise value of muscle and lung increased in the phantom(31.2, 9.4%). In addition, the noise value of the muscles and lung decreased by 5, 25.12% and 5.6, 15.35% as the upper limb moved about 0,3,7cm away from the chest. When the chest and abdominal radiography were performed, in the case of the presence of other parts outside the inspection area, the probability of artifact was minimal while the distance was more than 3cm away from the upper limb to the chest and abdomen.

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.1
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• pp.10-18
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• 2014

Purpose: Among different PET/CT devices which are composed of same PET model but different CT models, SUV, usually used for quantitative evaluation, was measured to assess the accuracy of follow up scans in different PET/CT and confirm that interequipment compatibility is useful in arranging the PET/CT exam appointment. Materials and Methods: Using ACR PET Phantom, PET NEMA IEC Body Phantom, SNM Chest Phantom and Ge-68 cylinder Phantom, $SUV_{mean}$ and $SUV_{max}$ was measured by 3 different models of PET/CT (Discovery 690, Discovery 690Elite and Discovery 710, GE) made in same company. ANOVA was used to evaluate the significant difference in the result. Results: In the result, the average of $SUV_{max}$ was D690 (25 mm-1.82, 16 mm-1.75, 12 mm-1.73, 8 mm-1.44), D690E (25 mm-1.76, 16 mm-1.92, 12 mm-1.78, 8 mm-1.55) and D710 (25 mm-1.84, 16 mm-1.89, 12 mm-1.77, 8 mm-1.61) in ACR Phantom, D690 (25 mm-2.26, 16 mm-2.25, 12 mm-1.92, 8 mm-1.85), D690E (25 mm-2.45, 16 mm-2.25, 12 mm-2.05 8 mm-1.91) and D710(25 mm-2.49, 16 mm-2.20, 1 2mm-2.30, 8 mm-2.05) in PET NEMA IEC Body Phantom, D690-1.04, D690E-1.10 and D710-1.09 in SNM Chest Phantom and D690-0.81, D690E-0.81, D710-0.84 in Ge-68 cylinder Phantom. The differences between average SUV of 4 phantoms were $SUV_{mean}$-1.87%, $SUV_{max}$-2.15%. And also as a result of ANOVA analysis, there was no significant difference statistically. Conclusion: If different models of PET/CT have same specification of PET system, there was no significant difference in $SUV_{mean}$ and $SUV_{max}$ even though they have different CT system. And also differences of $SUV_{mean}$ and $SUV_{max}$ in phantom images were under 5% which many manufacturers recommend. Therefore, follow up scan will be possible using different PET/CT if it has same specification of PET system with the previous PET/CT. This information will enable the accurate comparative analysis when conducting follow up scans and be helpful to schedule PET/CT exam more effectively.

• Progress in Medical Physics
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• v.20 no.4
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• pp.199-207
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• 2009

It is important to initialize Image Plate (IP) completely for removing residual latent image by sodium lamp for reliability and repeatability of computed radiography (CR) system. The purpose of this study was to evaluate latent images of computed radiography (CR) images respect to delay time after erasure of foregone latent image and its effect, and erasure level. Erasure thoroughness for CR acceptance test from American Association of Physicist in Medicine (AAPM) Report 93 (2006) was also evaluated. Measurements were made on a CR (Agfa CR 25; Agfa, BELGIUM) system. Chest postero-anterior (PA), Hand PA, L-spine lateral radiographs were chosen for evaluation. Chest phantom (3D-torso; CIRS, USA) was used for Chest PA and L-spine lateral radiography. For Hand PA radiography, projections was done without phantom. Except Hand PA radiographs, noise was increased with delay time, and ghost image was appeared on overexposed area. Effect of delay after erasure on latent image was not seen on naked eye, but standard deviation (SD) of pixel value on overexposed area was relatively higher than that of other areas. On Hand PA and Chest PA radiographs, noise were not occurred by adjustment of erasure level. On L-spine lateral images at lower erasure level than standard level, noise including ghost image were occurred because of high tube current. Erasure thoroughness of CR system in our department was to be proved by these evaluation. The results of this study could be used as a baseline for IP initialization and reliability of CR images.