• Journal of the Korean Society of Radiology
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• v.17 no.3
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• pp.473-479
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• 2023

In this study, the dose of photoneutrons generated during radiotherapy of prostate cancer using high energy was measured using a photo-stimulated luminescence dosimeter. In addition, this study was intended to study the probability of side effects occurring in the abdomen. A medical linear accelerator capable of generating 15 MV energy, True Beam STx (Varian Medical Systems, USA) and a radiation treatment planning system (Eclipse, Varian Medical Systems, USA) were used. A human body phantom was installed on the couch of the linear accelerator, and an Albedo Neutron Optical Stimulation Luminescence Neutron Detector (Landauer Inc., IL, USA) was used to measure the photoneutron dose. The photoneutron dose value in the abdomen of VMAT and 3C-CRT was 52.8 mSv, more than twice as high as VMAT compared to 3D-CRT. During radiotherapy of prostate cancer, the probability of causing side effects in the abdomen due to light neutron dose was calculated to be 3.2 per 1,000 for VMAT and 1.4 for 3D-CRT. By studying the abdomen, which has a major side effect that can occur during radiotherapy of prostate cancer, it is expected that it will be used as a meaningful study to study the quality of life and stochastic effect of prostate cancer patients

• Journal of the Korean Society of Radiology
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• v.17 no.5
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• pp.685-691
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• 2023

This study aims to raise awareness of the exposure index according to the Sub-ROI in clinical use by studying the effect of Sub-ROI's change on exposure index and dose during Chest PA examination. In this study, to examine the changes in EI and ESD according to the Sub-ROI setting, the irradiation conditions were set to 120 kVp, 200 mA, 2 mAs, and the SID was fixed to 180cm. Five types of Sub-ROI were used. The average value of EI according to the Sub-ROI's change was 135.58 ± 0.89 in AEC, 100.80 ± 0.80 in VR, 143.43 ± 0.76 in HR, 103.22 ± 0.68 in LS, and 102.79 ± 0.84 in SS. The mean value of ESD was 30.28±0.50 µGy in AEC, 30.16 ± 0.44 µGy in VR, 30.30 ± 0.46 µGy in HR, 30.23 ± 0.46 µGy in LS, and 30.28 ± 0.51 µGy in SS. As a result of this study, based on the AEC mode recommended by the manufacturer, the VR (25.7%), LS (23.9%), and SS (24.2%) modes decreased, and the HR mode increased by 5.7%. However, ESD was not affected by the Sub-ROI's change. Therefore, Sub-ROI may change EI during the Chest PA examination, it is considered that Sub-ROI should be used appropriately when setting protocols in clinical use.

• Journal of the Korean Society of Radiology
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• v.17 no.5
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• pp.693-699
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• 2023

Ultrasound is widely used in the medical field for non-destructive and non-invasive disease diagnosis. In order to improve the disease diagnosis accuracy of diagnostic medical images, improving spatial resolution is a very important factor. In this study, we aim to model the super resolution convolutional neural network (SRCNN) algorithm in ultrasound images and analyze its applicability in the medical diagnostic field. The study was conducted as an experimental study using Field II simulation and open source clinical liver hemangioma ultrasound imaging. The proposed SRCNN algorithm was modeled so that end-to-end learning can be applied from low resolution (LR) to high resolution. As a result of the simulation, we confirmed that the full width at half maximum in the phantom image using a Field II program was improved by 41.01% compared to LR when SRCNN was used. In addition, the peak to signal to noise ratio (PSNR) and structural similarity index (SSIM) evaluation results showed that SRCNN had the excellent value in both simulated and real liver hemangioma ultrasound images. In conclusion, the applicability of SRCNN to ultrasound images has been proven, and we expected that proposed algorithm can be used in various diagnostic medical fields.

• Journal of the Korean Society of Radiology
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• v.17 no.6
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• pp.865-872
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• 2023

The purpose of this study was to analyze fabrics suitable for use as examination gowns to determine whether examination gowns affect imaging during anterior to posterior chest examinations(Chest AP) on a digital X-ray system. Examination gowns in use at five medical centers in Seoul were collected and included modal, tencel, cotton, and rayon fabrics. The selection of fabrics was based on studies that reported fabrics with good tactile, absorbent, stretchable, and wrinkle resistance. Phantoms of five hospital gowns and four fabrics, arranged in overlapping layers from one to eight, were created and examined on a digital X-ray system in both Chest AP examination. The images examined were subjected to a first-step profile analysis, a second-step signal intensity averaging analysis, and a third-step microscopic analysis. The results showed that all nine materials had an increasing impact on the image as the number of layers of fabric increased, with the modal fabric having the least impact on the image in the first, second, and third analyses. In conclusion, as the resolution of digital x-ray systems increases, the impact of examination clothing on the image will increase, and research to find suitable materials for examination clothing will continue to be necessary.

• Journal of the Korean Society of Radiology
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• v.17 no.7
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• pp.1115-1122
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• 2023

This study aimed to present reasonable reception bandwidth application standards for the purpose of suppressing metal objects during MRI examinations. For this purpose, T2 contrast images were acquired using high-speed spin echo technology on a phantom made of screws for spinal surgery, and metal objects were detected. In addition, images were obtained by increasing the reception bandwidth from 100 Hz/PX to 800 Hz/PX by 100 Hz/PX. The metal artifacts were determined as the sum of the areas of the signal attenuation area and the signal accumulation area. In addition, Pearson correlation analysis was performed to analyze the pattern of metal artifacts according to imaging variables. As a result, the signal accumulation area did not change significantly as the reception bandwidth increased (p>0.05), but the signal loss area and the area of metal artifacts decreased as the reception bandwidth increased (p<0.05). Interestingly, the area of metal objects decreased to a maximum in the section where the reception bandwidth was increased from 100 Hz/PX to 200 Hz/PX, consistent with the section where the echo spacing was reduced to a maximum due to the increase in reception bandwidth. In addition, the correlation analysis results also showed that the eco spacing was more related to the signal attenuation area and the area of metal objects than to the reception bandwidth. Therefore, if the reception bandwidth is increased for the purpose of reducing metal objects, it is reasonable to set it based on a value that minimizes the echo spacing in consideration of image quality factors.

• Journal of the Korean Society of Radiology
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• v.17 no.7
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• pp.1123-1131
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• 2023

This study aimed to present a method to effectively suppress metal artifacts caused by spinal fusion surgery during spinal MRI study. For this purpose, a phantom made of spinal surgery screws was created to reproduce the metal artifact. Then, images were acquired with 1.5T and 3.0T MRI to evaluate changes in metal artifacts according to magnetic field strength. In addition, metal artifacts were evaluated by increasing the receive bandwidth to 200, 400 and 800 Hz/PX. As a result, metal artifacts occurring in images obtained from the 1.5T MRI decreased by approximately 52.2% compared to images obtained from the 3.0T MRI, showing a significant difference (p<0.05). In particular, the signal loss and signal pile up areas were reduced by approximately 52.81% and 42.71%, respectively, showing a significant effect in suppressing metal artifacts. On the other hand, when images were acquired while increasing the receive bandwidth from 200 to 800 Hz/PX, there was no significant effect, with a decrease of up to 8.93% for the 1.5T MRI and up to 10.98% for the 3.0T MRI (p>0.05). As a result of this study, increasing the receive bandwidth reduced signal loss and reduced some metal artifacts, but did not have a significant effect because it did not suppress signal pile up. However, when the magnetic field strength was reduced from 3.0T to 1.5T, signal loss and signal pile up were greatly reduced, effectively improving the metal artifact. Therefore, in order to suppress metal artifacts caused by spinal fusion surgery, study using a low magnetic field MRI can be said to be the most effective method.

• Journal of the Korean Society of Radiology
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• v.17 no.5
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• pp.751-759
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• 2023

Breast ultrasonography is difficult to image in fatty breasts and to find micro-calcification, but the discovery of micro-calcification is very important for breast cancer screening. Among the color Doppler artifact of ultrasound, twinkle artifact mainly occur on strong reflectors such as stones or calcification in images, and evaluation methods using them are clinically being used. In this study, we are conducting experiments on the color Doppler settings of ultrasound equipment, such as repetition frequency, ensemble, persist, wall filtering, smoothing, linear density, and dissociation value, by producing a breast simulation phantom using the largest amount of calcium phosphate among breast implants. The purpose of this study was to improve the contrast of twinkle artifact in breast ultrasound examinations and to maximize their use in clinical practice. As a result, the pulse repetition frequency occurred in the range of 3.6 kHz to 7.2 kHz, and did not occur above 10.5 kHz. For ensembles, twinkle artifact occurred in all sizes of calcification under low conditions, and in threshold settings, the twinkle artifact increased slightly only under 80 to 100 conditions, and did not occur in 1 mm size calcification. Persist, wall filter, smoothing, and line density settings did not have much meaning in the setting variable because conditions did not increase by condition, and pulse repetition frequency, ensemble, and thresholds had the greatest impact on the twinkling artifact image. This study is expected to help examiners select optimal conditions to effectively increase twinkle artifact by adjusting color Doppler settings.

• The Korean Journal of Nuclear Medicine Technology
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• v.28 no.1
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• pp.71-79
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• 2024

Purpose: This study aims to identify SUV, SNR, spatial resolution, and axial uniformity under the same reconstruction conditions and to find out the differences between equipment models. Materials and Methods: The equipment was GE's Discovery 600, 710, IQ, MI(GE Healthcare, USA), and the Phantom used ACR(American College of Radiology) Flangeless Esser Phantom and PET/SPECT Performance Phantom. The PET/SPECT Performance Phantom injected 18F-FDG at a concentration of 3.8 kBq/mL, and the ACR Flangeless Esser Phantom made the conditions for Hot Spot and Background activity for 4 : 1. Image evaluation was compared and evaluated for SUV, SNR, spatial resolution, and axial uniformity with the same reconstruction that added SharpIR of VPHD. Results: The SUV_max showed a difference up to 4.6% with an average of 2.71, 2.35, 1.89, and 1.43 from Hot Spot 1 to 4, and the SUV_mean showed a difference up to 4.7% with 2.06, 1.75, 1.49, and 1.27. There was a difference up to 5% between equipment, and there was no significant difference between both SUV_max and SUV_mean. SNR showed a difference up to 0.04 with an average of 0.37, 0.26, 0.18, and 0.11. FWHM showed a difference up to 0.27. Lastly, COV of axial uniformity was up to 0.018. Conclusion: SUV showed differences within 5% between equipment and showed no significant difference. This is considered to be used as basic data that can be used for the development and replacement of equipment because it has the advantage of being able to observe with a large number of equipment.

• Journal of the Korean Society of Radiology
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• v.18 no.1
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• pp.27-36
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• 2024

In this study, When acquisition thyroid scintigraphy images, a parallel hole collimator was applied, and the difference from the pinhole collimator was quantitatively analyzed under each image acquisition condition. Visual size, resolution, sensitivity, signal to noise ratio (SNR), and contrast to noise ratio (CNR) were evaluated using thyroid phantom and point source. When comparing visual size, it was confirmed that an image similar to the size of the pinhole collimator could be obtained only when a magnification ratio of about 2.00 to 2.09 times when applying a parallel hole collimator. There was no tendency in FWHM(mm) measurement using a point source, and sensitivity was high in the parallel hole collimator. SNR and CNR were high when using a low magnification ratio, matrix size of 128×128, and a parallel hole collimator. In images of similar size to the naked eye, when the matrix size was the same, both SNR and CNR were high in the pinhole collimator. Therefore, when performing a thyroid scintigraphy test, if appropriate conditions are set according to the situation of each hospital and a parallel hole collimator is applied, it can be a good option in terms of equipment utilization and work efficiency.

• The Journal of Korean Society for Radiation Therapy
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• v.35
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• pp.33-39
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• 2023

Purpose: The purpose of this study is to find out the dose variation according to thickness of the air gap between the patient's body surface and immobilization device in the treatment plan. Materials and Methods : Four conditions were created by adjusting the air gap thickness using 5 mm bolus, ranging from 0 mm to 3 mm bolus. Immobilization was placed on top in each case. And computed tomography was used to acquire images. The treatment plan that 430 cGy (Relative Biological Effectiveness,RBE) is irradiated 6 times and the dose of 2580 cGy (RBE) is delivered to 95% of Clinical Target Volume (CTV). The dose on CTV was evaluated by Full Width Half Maximum (FWHM) of the lateral dose profile and skin dose was evaluated by Dose Volume Histogram (DVH). Result: Results showed that the FWHM values of the lateral dose profile of CTV were 4.89, 4.86, 5.10, and 5.10 cm. The differences in average values at the on the four conditions were 3.25±1.7 cGy (RBE) among D_95% and 1193.5±10.2 cGy (RBE) among D_95% respectively. The average skin volume at 1% of the prescription dose was 83.22±4.8%, with no significant differences in both CTV and skin. Conclusion: When creating a solid-type immobilization device for carbon particle therapy, a slight air gap is recommended to ensure that it does not extend beyond the dose application range of the CTV.