• The Journal of Korean Society for Radiation Therapy
• /
• v.15 no.1
• /
• pp.19-27
• /
• 2003

I. Purpose In special cases of Total Body Irradiation(TBI), Half Body Irradiation(HBI), Non-Hodgkin's lymphoma, E-Wing's sarcoma, lymphosarcoma and neuroblastoma a large field can be used clinically. The dose distribution of a large field can use the measurement result which gets from dose distribution of a small field (standard SSD 100cm, size of field under $40{\times}40cm2$) in the substitution which always measures in practice and it will be able to calibrate. With only the method of simple calculation, it is difficult to know the dose and its uniformity of actual body region by various factor of scatter radiation. II. Method & Materials In this study, using Multidata Water Phantom from standard SSD 100cm according to the size change of field, it measures the basic parameter (PDD,TMR,Output,Sc,Sp) From SSD 180cm (phantom is to the bottom vertically) according to increasing of a field, it measures a basic parameter. From SSD 350cm (phantom is to the surface of a wall, using small water phantom. which includes mylar capable of horizontal beam's measurement) it measured with the same method and compared with each other. III. Results & Conclusion In comparison with the standard dose data, parameter which measures between SSD 180cm and 350cm, it turned out there was little difference. The error range is not up to extent of the experimental error. In order to get the accurate data, it dose measures from anthropomorphous phantom or for this objective the dose measurement which is the possibility of getting the absolute value which uses the unlimited phantom that is devised especially is demanded. Additionally, it needs to consider ionization chamber use of small volume and stem effect of cable by a large field.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.12 no.3
• /
• pp.171-175
• /
• 2008

Purpose: There have been something difficulties in locating focuses and quantitative analysis in case of pediatric patients because of the relatively small body compared to adults. This author of this study, therefore, evaluated the usefulness of DFOV (Display Field Of View) according to its changes in PET/CT image reconstruction by means of the phantom experiment and pediatric patients examination. Materials & Methods: 0.023 MBq/cc of $^{18}F$-FDG was put into the uniform NU2-94 phantom, and then emission scan was acquired for 10 minutes. For reconstruction, DFOV values were changed to 50, 45, 40, 35, 30, and 25 cm respectively. As for patient images, 20 patients who were diagnosed as the one or suspicion of the children tumor are targeted from Oct 2007 to Jan 2008. For image reconstruction, 50 cm was the basis of DFOV, and the value was adjusted to DFOV 45 cm to 25 cm respectively. In the phantom and the reconstruction image of pediatric patients, the changes in pixel size and $SUV_{max}$ according to DFOV changes were analyzed. Results: As DFOV decreased to 50, 45, 40, 35, 30, and 25 cm by means of the phantom, the pixel size was changed to 3.906, 3.515, 3.125, 2.734, 2.343, and 1.953 mm respectively. Besides, as a result of reconstruction DFOV in images of pediatric patients to 50, to 25 cm, the different values of $SUV_{max}$ are shown as 3.3, 7.3, 12, 14, 18% and 2.6, 4.3, 5.0, 7.0, 10.0% on respectively when 50 cm was the standard. Conclusion: In $SUV_{max}$ using the phantom, as DFOV decreased every 5 cm, the mean value gradually increased. With 50 cm as the standard, the increase rates were 3.7, 6.5, 11.2, 19.5, and 32.1% respectively. As for pediatric patients image too, as DFOV decreased, the rates increased as in the phantom experiment. In image reconstruction, since DFOV decrease regardless of matrix size change reduced the pixel size, the image quality can be improved. This would be more useful than reconstruction and enlarge images of pediatric patients in the same way of examining adults. However, when the value of 35 cm DFOV was applied, this may result in truncated artifact, and thus the application should be properly controlled. Change of DFOV may produce better image for pediatric patients, but changes of SUV values according to DFOV change should be considered in reading.

• Journal of the Korean Society of Radiology
• /
• v.12 no.6
• /
• pp.737-743
• /
• 2018

Patient exposure dose exposure test, which is one of the items of accuracy control of Computed Tomography, conducts measurements every year based on the installation and operation of special medical equipment under Article 38 of the Medical Law, And keep records. The CT-Dose phantom used for dosimetry can accurately measure doses, but has the disadvantage of high price. Therefore, through this research, the existing CT - Dose phantom was similarly manufactured with a 3D printer and compared with the existing phantom to examine the usefulness. In order to produce the same phantom as the conventional CT-Dose phantom, a 3D printer of the FFF method is used by using a PLA filament, and in order to calculate the CTDIw value, Ion chambers were inserted into the central part and the central part, and measurements were made ten times each. Measurement results The CT-Dose phantom was measured at $30.44{\pm}0.31mGy$ in the periphery, $29.55{\pm}0.34mGy$ CTDIw value was measured at $30.14{\pm}0.30mGy$ in the center, and the phantom fabricated using the 3D printer was measured at the periphery $30.59{\pm}0.18mGy$, the central part was $29.01{\pm}0.04mGy$, and the CTDIw value was measured at $30.06{\pm}0.13mGy$. Analysis using the Mann - Whiteney U-test of the SPSS statistical program showed that there was a statistically significant difference in the result values in the central part, but statistically significant differences were observed between the peripheral part and CTDIw results I did not show. In conclusion, even in the CT-Dose phantom made with a 3D printer, we showed dose measurement performance like existing CT-Dose phantom and confirmed the possibility of low-cost phantom production using 3D printer through this research did it.

• Journal of the Korean Society of Radiology
• /
• v.13 no.4
• /
• pp.565-572
• /
• 2019

In this study, shielding analysis of material and thickness of 3D printer filaments was performed for the manufacture of custom shielding by radiation workers during outdoor radiographic test. The shielding was attached to the ICRU Slab Phantom after selecting the voxel source $^{192}Ir$ and $^{75}Se$ through simulation using MCNPX, and the distance between the source and the slab Phantom was set at 100 cm. The 12 shielding materials were divided into 5 mm units up to 200 mm from the absence of shielding materials to evaluate the energy absorbed per unit mass of each shielding material. The results showed that the shielding effect was high in the order of ABS + Tungsten, ABS + Bismuth, PLA + Copper, PLA + Iron from all sources of radiographic test. However, compared to lead, the shielding effect was somewhat lower. Based on this study in the future, further study of the atomic number and the high density filament material is necessary.

• Journal of the Microelectronics and Packaging Society
• /
• v.23 no.1
• /
• pp.29-34
• /
• 2016

In this study, development of multichannel filter module and characteristic evaluation for bio imaging were studied. The filter module was fabricated in order to realize near infrared fluorescence imaging of 700 nm and 800 nm wavelength ranges, and contrast imaging analysis for characteristic evaluation of the filter module was studied through signal to back ground ratio (SBR), controlled by parameters such as magnification, exposure, gain. Furthermore, phantoms, which are biomimetic tissue with equal optical properties of kidney and liver, were fabricated to study characteristics of both filter module depending on thickness and exposure amount of light source for bio imaging analysis. The fabricated filter module has more than 4 of SBR difference despite changes of magnification, exposure, gain, and in the case of the kidney phantom and the liver phantom, contrast imaging of more than 4 of SBR was confirmed on 50 mA, 60 mA exposure amount of light source respectively.

• Progress in Medical Physics
• /
• v.15 no.2
• /
• pp.63-69
• /
• 2004

HDR brachytherapy administers a large dose of radiation in a short time compare with LDR, and its optimization for treatment is related to several complex factors, such as physical, radiation and optimization algorithms, so there is a need for these to be verified for accurate dose delivery. In our approach, a previous study concerning the phantom for dose verification has been modified, and a new pelvic phantom fabricated for the purpose of localization, including a structure enabling the use of a CT or MRI system. In addition, a comparison study was performed to verify an orthogonal method that is commonly used for brachytherapy localization by comparing target coordinates from a CT system. Since the developed phantom was designed to simulate the clinical setups of cervix cancer, it included an air-filled bladder and a rectum structure shaped sphere and cylinder An N-shaped localizer was used to obtain precision coordinates from both CT and films. Moreover, the IDL 5.5 software program for Windows was used to perform coordinates analysis based on an orthogonal algorithm. The film results showed differences within 1.0 mm of the selected target points compare with the CT coordinates. For these results, a Plato planning system (Nucletron, Netherlands) could be independently verified using this phantom and software. Furthermore, the new phantom and software will be efficient and powerful qualify assurance (QA) tools in the field of brachytherapy QA.

• Progress in Medical Physics
• /
• v.17 no.4
• /
• pp.187-191
• /
• 2006

The purpose of this study was to measure the dose distribution from the moving phantom for the respiratory motion. The phantom for TLD measurement was designed and built for this study based on the multiple plates for placing TLD and film. The TLDs may be inserted at 3 mm intervals in each TLD plate. For the measurements, TLD plate was inserted into the phantom at 1.5 cm ($d_{max}$) depth, and phantom was allowed to move in SI directions in the range of 1 to 2 cm with 0.5 cm interval for 6 MV X-ray beams. Penumbra and FWHM were measured at both moving state and compared stationary. It was found that penumbra increased 0.71 cm at stationary and 2.10 cm at moving state in 2 cm movement, and that FWHM are 7.52 cm for stationary state and 7.02 cm for moving state (2 cm movement). In this study, film was used to compared with TLD results of measurements and simitar results were observed. Therefore, it is expected that TLD moving phantom may be useful for the treatment of tumors that move due to the respiratory motion.

• Journal of the Korean Society of Radiology
• /
• v.11 no.3
• /
• pp.109-115
• /
• 2017

The purpose of this study was to evaluate the clinical efficacy of 128 MDCT (multi-detector computed tomography) for reducing the CareDose 4D dose and comparing the image quality with the fixed tube current technique. For this purpose, we conducted the phantom and clinical studies to evaluate the exposure dose and image of the subject before and after applying the CareDose 4D system in abdominal examination using 128 MDCT. In the phantom study, ROI (Region of interest) was located at the center, 3, 6, 9, 12 o'clock, into two groups: group A without CareDose 4D and Group B applied were measured. In the clinical study, ROI was located at the liver 8 segments, divided into two groups too. The measured items were CT number, noise, and dose length product (DLP) dose. The result of CTDIvol (CT Dose Index volume) measurements in phantom and clinical studies were lower than those before CareDose 4D application, and dose and effective dose were also measured lower (p<.05). There was no difference in CT number before and after application (p>.05). In conclusion, using CareDose 4D, we can obtain optimal image information without deteriorating image quality while reducing patient dose.

• Journal of Digital Convergence
• /
• v.12 no.10
• /
• pp.345-351
• /
• 2014

The purpose of this study is to offer more accurate information in whole spine examination of 3 spot DR through the comparative study about image distortion as making the flat phantom and measuring horizontal, vertical ratio and cobb angle of the virtual. We produced $H(40cm){\times}V(116cm){\times}D(2.3cm)$ flat acrylic phantom with lattice type of lead plate. We took projection respectively 3 times, total 9 times in each equipments using manufactured phantom as changing OFD to 6, 12, 18 cm. We measured a horizontal and vertical length of lead lattice and calculated the ratio. As appointing arbitrary points in the phantom and we measured cobb angle. The results of horizontal, vertical ratio measured CR type 0.98~1.01, scan DR type 0.96~0.97 and 3 spot DR 0.99~1.01. Cobb angle measured $52.5{\sim}53.3^{\circ}$, $52.1{\sim}54.3^{\circ}$ and $52.8{\sim}53.2^{\circ}$. Finally we can say that 3 spot DR method is an accurate method without any distortion in whole spine radiography.

• Journal of the Korean Society of Radiology
• /
• v.13 no.3
• /
• pp.473-479
• /
• 2019

PET-CT improves performance and reduces the time by combining PET and CT of spatial resolution, and uses CT scan for attenuation correction. This study analyzed PET image evaluation. The condition of the tube voltage and current of CT will be changed using. Uniformity phantom and resolution phantom were injected with 37 MBq $^{18}F$ (fluorine ; 511 keV, half life - 109.7 min), respectively. PET-CT (Biograph, siemens, US) was used to perform emission scan (30 min) and penetration scan. And then the collected image data were reconstructed in OSEM-3D. The same ROI was set on the image data with a analyzer (Vinci 2.54, Germany) and profile was used to analyze and compare spatial resolution and image quality through FWHM and SI. Analyzing profile with pre-defined ROI in each phantom, PET image was not influenced by the change of tube voltage or exposure dose. However, CT image was influenced by tube voltage, but not by exposure dose. When tube voltage was fixed and exposure dose changed, exposure dose changed too, increasing dose value. When exposure dose was fixed at 150 mA and tube voltage was varied, the result was 10.56, 24.6 and 35.61 mGy in each variables (in resolution phantom). In this study, attenuation image showed no significant difference when exposure dose was changed. However, when exposure dose increased, the amount of dose that patient absorbed increased too, which indicates that CT exposure dose should be decreased to minimum to lower the exposure dose that patient absorbs. Therefore future study needs to discuss the conditions that could minimize exposure dose that gets absorbed by patient during PET-CT scan.