• The Journal of Korean Society for Radiation Therapy
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• v.34
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• pp.73-82
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• 2022

Purpose: The purpose of this study is to evaluate the effectiveness of reducing the absorbed dose to the ovaries and the quality of the CBCT image when using the Halcyon^TM Fast kV CBCT of cervical cancer patients of child-bearing age who performed ovarian transposition Materials and Methods : Contouring of the cervix and ovaries required for measurement was performed on the computed tomography images of the human phantom (Alderson Rando Phantom, USA), and three Optically Stimulated Luminescence Dosimeter(OSLD) were attached to the selected organ cross-section, respectively. In order to measure the absorbed dose to the cervix and ovaries in the Truebeam^TM pelvis mode (Hereinafter referred to as TP), The Halcyon^TM Pelvis mode (Hereinafter referred to as HP) and The Halcyon^TM Pelvis Fast mode (Hereinafter referred to as HPF), An image was taken with a scan range of 17.5 cm and also taken an image that reduced the Scan range to 12.5cm. A total of 10 cumulative doses were summed, It was replaced with a value of 23 Fx, the number of cervical cancer treatments, and compared In additon, uniformity, low contrast visibility, spatial resolution, and geometric distortion were compared and analyzed using Catphan 504 phantom to compare CBCT image quality between equipment. Each factor was repeatedly measured three times, and the average value was obtained by analysing with the Doselab (Mobius Medical Systems, LP. Versions: 6.8) program. Results: As a result of measuring absorbed dose by CBCT with OSLD, TP and HP did not obtain significant results under the same conditions. The mode showing the greatest reduction value was HPF versus TP. In HPF, the absorbed dose was reduced by 39.8% in the cervix and 19.8% in the ovary compared to the TP in the scan range of 17.5 cm. the scan range was reduced to 12.5 cm, absorbed dose was reduced by 34.2% in the cervix and 50.5% in the ovary. In addition, result of evaluating the quality of the image used in the above experiment, it complied with the equipment manufacturer's standards with Geometric Distortion within 1mm (SBRT standard), Uniformity HU, LCV within 2.0%, Spatial Resolution more than 3 lp/mm. Conclusion: According to the results of this experiment, Halcyon^TM can select more various conditions than Truebeam^TM in treatment of fertility woman who have undergone ovarian Transposition , because it is important to reduce the radiation dose by CBCT during radiation therapy. So finally we recommend Halcyon^TM Fast kV CBCT which maintains image quality even at low mAs. However, it is consider that the additional exposure to low doses can be reduced by controlling the imaging range for patients who have undergone ovarian transposition in other treatment machines.

• Journal of the Korean Society of Radiology
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• v.15 no.7
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• pp.1065-1072
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• 2021

In Computed Tomography, abdominal examination showed the highest proportion of use, and effort of reducing the radiation dose is required. Recently introduced Iterative Reconstruction(IR) is repetitive reconstruction technique of Computed Tomography. SIEMENS' IR, ADMIRE and GE's IR, ASIR-V, were used in this examination. Noise, % Contrast, and High contrast resolution were measured by using ACR phantom for image quality evaluation. In addition, CTDI_vol and DLP displayed in the CT device were used for dose evaluation. When FBP and IR were compared, stage 2 to stage 5 of ADMIRE and 10, 30, 50, 70, and 90% of ASIR-V were applied, noise could be reduced from a minimum of 0.46 to a maximum of 2.38 in ADMIRE compared to FBP, and noise from a minimum of 0.51 to a maximum of 2.5 in ASIR-V compared to FBP. Also, % Contrast and High contrast resolution of FBP and IR were no statistical difference. When IR was used for abdominal CT examination, the radiation dose of ADMIRE is reduced by 25.39% compared to the radiation dose of FBP. Also, the radiation dose of ASIR-V is reduced by 16.61% compared to the radiation dose of FBP. In conclusion, it is believed that if IR is applied during abdominal CT examination, the radiation dose can be reduced without deteriorating the image quality.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.1
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• pp.46-53
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• 2010

Purpose: The static image of nuclear medicine study should be acquired without a motion, however, it is difficult to acquire static image without movement for the serious patients, advanced aged patients. These movements cause decreases in reliability for quantitative and qualitative analysis, therefore re-examination was inevitable in the some cases. Consequently, in order to improve the problem of motion artifacts, the authors substituted the dynamic acquisition technique for the static acquisition, using motion correction. Materials and Methods: A capillary tube and IEC body phantom were used. First, the static image was acquired for 60 seconds while the dynamic images were acquired with a protocol, 2 sec/frame${\times}$30 frames, under the same parameter and the frames were summed up into one image afterwards. Also, minimal motion and excessive motion were applied during the another dynamic acquisition and the coordinate correction was applied towards X and Y axis on the frames where the motion artifact occurred. But the severe blurred images were deleted. Finally, the resolution and counts were compared between the static image and the summed dynamic images which before and after applying motion correction, and the signal of frequency was analysed after frequency spatial domain was transformed into 2D FFT. Supplementary examination, the blind test was performed by the nuclear medicine department staff. Results: First, the resolution in the static image and summed dynamic image without motion were 8.32 mm, 8.37 mm on X-axis and 8.30 mm, 8.42 mm on Y-axis, respectively. The counts were 484 kcounts, 485 kcounts each, so there was nearly no difference. Secondly, the resolution in the image with minimal motion applying motion correction was 8.66 mm on X-axis, 8.85 mm on Y-axis and had 469 kcounts while the image without motion correction was 21.81 mm, 24.02 mm and 469 kcounts in order. So, this shows the image with minimal motion applying motion correction has similar resolution with the static image. Lastly, the resolution in the images with excessive motion applying motion correction were 9.09 mm on X-axis, 8.83 mm on Y-axis and had 469 kcounts while the image without motion correction was 47.35 mm, 40.46 mm and 255 kcounts in order. Although there was difference in counts because of deletion of blurred frames, we could get similar resolution. And when the image was transformed into frequency, the high frequency was decreased by the movement. However, the frequency was improved again after motion correction. In the blind test, there was no difference between the image applying motion correction and the static image without motion. Conclusion: There was no significant difference between the static image and the summed dynamic image. This technique can be applied to patients who may have difficulty remaining still during the imaging process, so that the quality of image can be improved as well as the reliance for analysis of quantity. Moreover, the re-examination rate will be considerably decreased. However, there is a limit of motion correction, more time will be required to successfully image the patients applying motion correction. Also, the decrease of total counts due to deletion of the severe blurred images should be calculated and the proper number of frames should be acquired.

• Korean Journal of Digital Imaging in Medicine
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• v.12 no.2
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• pp.133-138
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• 2010

The purpose of this study was to survey and test quality control of mammography system. The conclusion of this study is as follows ; First, The rate of pass for phantom image test shows that Film-Screen mammography system(F/S) and computed mammography system(CR) is 80%, Indirect digital mammography system(DR) is 100%. Second, The test of exposure dose shows that F/S is 921 mR. CR is 1,140 mR, DR is 474 mR. The grade of this testament is CR > F/S > DR. Third, The test of average glandular dose shows that F/S is 1,336 mGy, CR is 1,635 mGy, DR is 1,26 mGy. The grade of this testament is CR > F/S > DR. Fourth, The testament of resolution shows as follows F/S is 11~13 Lp/mm, CR is 4~5 Lp/mm, and DR is 5~7 Lp/mm(F/S > DR > CR) Fifth, The survey of projection, cassette, development and reading shows that user are indifference.

• 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 radiological science and technology
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• v.31 no.4
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• pp.389-399
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• 2008

Corrections of attenuation, scatter and resolution are important in order to improve the accuracy of single photon emission computed tomography (SPECT) image reconstruction. Especially, the heart movement by respiration and beating cause the errors in the corrections. Myocardial phantom is used to verify the correction methods, but there are many different parts in the current phantoms in actual human body. Therefore the results using a phantom are often considered apart from the clinical data. We developed a new phantom that implements the human body structure around the thorax more faithfully. The new phantom has the small mediastinum which can simulate the structure in which the lung adjoins anterior, lateral and apex of myocardium. The container was made of acrylic and water-equivalent material was used for mediastinum. In addition, solidified polyurethane foam in epoxy resin was used for lung. Five different sizes of myocardium were developed for the quantitative gated SPECT (QGS). The septa of all different cardiac phantoms were designed so that they can be located at the same position. The proposed phantom was attached with liver and gallbladder, the adjustment was respectively possible for the height of them. The volumes of five cardiac ventricles were 150.0, 137.3, 83.1, 42.7 and 38.6ml respectively. The SPECT were performed for the new phantom, and the differences between the images were examined after the correction methods were applied. The three-dimensional tomography of myocardium was well reconstructed, and the subjective evaluations were done to show the difference among the various corrections. We developed the new cardiac and torso phantom, and the difference of various corrections was shown on SPECT images and QGS results.

• Korean Journal of Digital Imaging in Medicine
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• v.14 no.1
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• pp.37-42
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• 2012

Pediatric head and neck phantom, using the rate by focusing distance and grid images, Image J using the Quality Assessment and Dose Area Product compared. X-ray laboratory equipment due to the Philips Digital DIAGNOST a 110 cm FFD set and using ACE Non-grid, focusing distance 110 cm (12 : 1), 140 cm (12 : 1), 180 cm (8 : 1) Focused grid, Acryl Phantom (Fluke Model 76-2 Series Phantom) 15.24 cm, by resolution chart image acquisition, image evaluation program (Image J Ver. 1.4.3.67, USA) imaging experiments were analyzed using. Dose Area Product in the Non Grid 0.028 $mGy{\cdot}cm^2$, focusing distance 110 cm (12 : 1), the 0.129 $mGy{\cdot}cm^2$, 140 cm (12 : 1), the 0.135 $mGy{\cdot}cm^2$, 180 cm (8 : 1) was measured with a 0.110 $mGy{\cdot}cm^2$ Non Grid, focusing distance 110 cm (12 : 1), 140 cm (12 : 1), 180 cm (8 : 1) Image obtained when grid using the image J program focusing distance 110 cm with grid based on the measured SNR and PSNR Non Grid if the SNR the 17.307 dB, PSNR of the 20.002 dB, if the SNR 28.755 dB, PSNR was measured by the 31.451 dB. Image J image analysis through the streets, rather than focusing on grid by the rate that could see an increase in dose. Select the grid by a small dose rate reduction is possible.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.506-508
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• 2002

As an advancement of medical imaging modalities and analyzing software with multi-function, active researches to acquire high contrast and high resolution image being done. In recently, development of medical imaging modalities like as Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) is aiming to display anatomical structure more accuracy and faster. Thus, one of the important areas in CT today is the use of CT scanner for the quantitative evaluation of 3-D reconstruction images from 2-D tomographic images. In CT system, the effective slice thickness and the quality of 3-D reconstructed image will be influenced by imaging acquisition parameters (e.g. pitch and scan mode). In diagnosis and surgical planning, the accurate distance measurements of 3-D anatomical structures play an important role and the accuracy of distance measurements will depend on the acquisition parameters such as slice thickness, pitch, and scan mode. The skull phantom was scanned with SDCT for various acquisition parameters and acquisition slice thicknesses were 3 and 5 mm, and reconstruction intervals were 1, 2, and 3 mm to each pitch. 3-D visualizations and distance measurements were performed with PC based 3-D rendering and analyzing software. Results showed that the image quality and the measurement accuracy of 3-D SDCT images are independent to the reconstruction intervals and pitches.

• Journal of Biomedical Engineering Research
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• v.24 no.4
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• pp.339-346
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• 2003

MRI provides anatomical structure information with superb spatial resolution that can be utilized in clinical surgeries. Advanced image processing techniques in conjunction with the MRI-guided surgery is expected to be of great importance in brain surgeries in the near future. In this paper, we introduce an image-guided surgery technique using the stereo matching method. To perform image-guided biopsy operations, we made MRI markers, camera markers and a detection probe marker. To evaluate the accuracy of the image-guided system. we made a silicone phantom. Using the phantom and markers, we have performed MRI-guided experiments with a 1.5 Tesla MRI system. It has been verified from phantom experiments that our system has a positioning error less than 1.5%. Compared with other image guided surgery system, our system shows better positioning accuracy.

• Journal of radiological science and technology
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• v.37 no.4
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• pp.295-305
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• 2014

This study is to provide accurate information as medical imaging equipment to check for the presence of body disease US equipment. We investigated the status of medical US equipment performance in Daegu and criteria US phantom (ATS-539) for US equipment performance measurements. The results in this study, 1. US phantom measurement results: The test passed rate were 88.6% and the failed rate were 11.4%. 2. The difference between the group of mean and the pass/failed groups were statistically significant. Focal zone and 4 mm functional resolution in the two items that are not present the passing standard. 3. The difference was statistically significant number of years and used equipment and pass the failed equipment (4.13 vs 7.25 years). We investigated the performance status of US equipment used in the clinical area in Daegu. The basis for the two items are not present this proposed passing standard. Equipment performance was associated with the number of years of using US equipment. It is necessary to maintain the best performance of the equipment phantom measurements for performance testing of US equipment.