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$Inter fractional ent…$

Inter fractional entrance dose monitoring as quality assuran…

Introduction: This study describes a simple method of inter‑fractional photon beam monitoring to measure the entrance dose of radiation treatment using Gafchromic EBT3 film.

Materials and Methods: The film was placed at the center of a 1‑cm thick phantom shaped like a block tray and fixed on the accessory tray of the gantry. The entrance dose was measured following the placement of the film in the accessory tray. The dose distribution calculated with the treatment planning system was compared with the dose distribution on the irradiated EBT3 films. The effectiveness of this methodology, as determined by gamma passing rates, was evaluated for the 22 fields of eight three‑dimensional conformal radiotherapy (3D‑CRT) plans and the 41 fields of nine intensity‑modulated radiotherapy (RT) plans. The plans for three‑dimensional conformal RT included treatments of the rectum, liver, breast, and head and neck, whereas the plans for intensity‑modulated RT included treatments of the liver, brain, and lung.

Results: The gamma passing rates for 3D‑CRT ranged from 96.4% to 99.5%, with the mean gamma passing rate for 22 fields being 98.0%. The gamma passing rate for intensity‑modulated RT ranged from 96.1% to 98.9%, with the mean gamma passing rate for 41 fields being 97.7%. All gamma indices were over the 95% tolerance level.

Conclusions: The methodology described in this study, based on Gafchromic EBT3 film, can be utilized for inter‑fractional entrance dose monitoring as quality assurance during RT. Clinical application of this method to patients can verify the accuracy of beam delivery in the treatment room.

Sun Young Moon

Department of Bio‑convergence Engineering, Korea University, Seoul

Proton Therapy Center, National Cancer Center, Goyang, Korea

Yunhui Jo, Jaehyeon Seo, Myonggeun Yoon

Department of Bio‑convergence Engineering, Korea University, Seoul

Dongho Shin,

Proton Therapy Center, National Cancer Center, Goyang, Korea

Journal of Cancer Research and Therapeutics - Volume 18 - Issue 4 - July-September 2022: 1152-1158

Tumor treating fields (TTF) treatment enhances radiation-ind…

Purpose:Tumor treating fields (TTF) therapy is a noninvasive method that uses alternating electric fields to treat various types of cancer. This study demonstrates the combined effect of TTF and radiotherapy (RT) in vitro on pancreatic cancer, which is known to be difficult to treat.

Materials and methods: In CFPAC-I and HPAF-II pancreatic cancer cell lines, the combined in vitro effect of TTF and RT was evaluated by measuring cell counts, markers of apoptosis, and clonogenic cell survival. The synergy effects were verified using the Valeriote and Carpentier equations.

Results: TTF and RT inhibited cancer cell growth more effectively than did mono therapy with TTF or RT. The combined treatment also enhanced apoptosis more than mono therapy, as shown by as says for cleaved poly (ADP-ribose) polymerase (PARP) and annexin V. In addition, on the survival curve, this treatment method has been shown to work synergistically.

Conclusion:These results suggest that combined treatment with TTF and RT may be a good alter-native treatment for patients with pancreatic cancer

Yunhui Jo

Department of Bio-convergence Engineering, Korea University, Seoul, Korea

Geon Oh, Yongha Gi, Heehun Sung, Myonggeun Yoon

Department of Bio-medical Engineering, Korea University,Seoul, Korea

Eun Bin Joo, Suk Lee

Department of Radiation Oncology, College of Medicine, Korea University, Seoul, Korea

INTERNATIONAL JOURNAL OF RADIATION BIOLOGY2020, VOL. 96, NO. 12, 1528–1533

Utility of fast non-local means (FNLM) filter for detection …

Purpose: This study was aimed to evaluate the utility based on imaging quality of the fast non-local means (FNLM) filter in diagnosing lung nodules in pediatric chest computed tomography (CT).

Methods: We retrospectively reviewed the chest CT reconstructed with both filtered back projection (FBP) and iterative reconstruction (IR) in pediatric patients with metastatic lung nodules. After applying FNLM filter with six h values (0.0001, 0.001, 0.01, 0.1, 1, and 10) to the FBP images, eight sets of images including FBP, IR, and FNLM were analyzed. The image quality of the lung nodules was evaluated objectively for coefficient of variation (COV), contrast to noise ratio (CNR), and point spread function (PSF), and subjectively for noise, sharpness, artifacts, and diagnostic acceptability.

Results: The COV was lowest in IR images and decreased according to increasing h values and highest with FBP images (P < 0.001). The CNR was highest with IR images, increased according to increasing h values and lowest with FBP images (P < 0.001). The PSF was lower only in FNLM filter with h value of 0.0001 or 0.001 than in IR images (P < 0.001). In subjective analysis, only images of FNLM filter with h value of 0.0001 or 0.001 rarely showed unacceptable quality and had comparable results with IR images. There were less artifacts in FNLM images with h value of 0.0001 compared with IR images (p < 0.001).

Conclusion: FNLM filter with h values of 0.0001 allows comparable image quality with less artifacts compared

Jina Shim, Myonggeun Yoon*

Department of Bio-Convergence Engineering, Korea University, Seoul, Republic of Korea

Department of Diagnostic Radiology, Severance Hospital, Seoul, Republic of Korea

Mi-Jung Lee*

Department of Radiology and Research Institute of Radiological Science, Severance Children’s Hospital, Yonsei University, College of Medicine, Seoul, Republic of Korea

Youngjin Lee

Department of Radiological Science, Gachon University, Incheon, Republic of Korea

Physica Medica 81 (2021) 52-89

A new real-time personal dosimeter with position monitoring …

Personal dosimeters are used to measure the amount of radiation exposure in individual radiation workers. We aimed to replace existing personal dosimeters and evaluate a real-time scintillator-based dosimeter by monitoring its radiation dose and checking the location exposed to radiation in the workspace. The developed dosimeter measured the radiation dose based on a scintillating fiber (SF) bundle, and comprised a silicon photomultiplier (SiPM), ultra-wide-band (UWB)-based location detecting system, and Bluetooth system. The SF bundle was exposed to radiation-emitted light, and the photons were amplified and converted to electrical signals through the SiPM. These signals were transferred to the user through the Bluetooth system and monitored. To evaluate the feasibility of this mechanism as a dosimeter, we performed characteristic tests, such as dose linearity, dependence on dose rate, energy, exposed angle, and location coordinate mapping. Also, the dose distribution formed in circles around the iso-center was measured to confirm the feasibility of monitoring the exposure dose and location and to enable the radiation worker to move freely in a workspace. We confirmed dose linearity, independence from energy and angle, and accuracy of location monitoring in our device. The user’s locations were measured with a difference of − 6 cm and − 4.8 cm on the x- and the y-axes, respectively. The measured doses on our developed dosimeter were 62.7, 32.3, 21.0, and 15.4 mSv at distances of 50, 100, 150, and 200 cm from the iso-center. In other words, all measured doses at several points showed an error within 5% as compared to doses provided by the conventional pocket dosimeter. These results show that the developed SF-based dosimeter is advantageous in monitoring the exposure dose and location in real time, and has significant potential as a new personal dosimeter for radiation workers.

Sun Young Moon, Myonggeun Yoon

Department of Bio-Convergence Engineering, Korea University, Seoul, South Korea

Sun-Young Kim, Dongho Shin

Proton Therapy Center, National Cancer Center, Goyang, South Korea

J. Korean Phys. Soc. 78, 1133–1140 (2021).

Clinical application of a gantry-attachable plastic scintill…

Purpose: The entrance beam fluence of therapeutic proton scanning beams can be monitored using a gantry-attachable plastic scintillating plate (GAPSP). This study evaluated the clinical application of the GAPSP using amethod that measures intensity modulated proton therapy (IMPT) beams for patient treatment.

Methods: IMPT beams for the treatment of nine patients, at sites that included the spine, head and neck, pelvis, and lung, were measured using the GAPSP, composed of an EJ-212 plastic scintillator and a CMOS camera. All energy layers distinguished by the GAPSP were accumulated to determine the dose distribution of the treatment field. The evaluated fields were compared with reference dose maps verified by quality assurance.

Results: Comparison of dose distributions of evaluation treatment fields with reference dose distributions showed that the 3%/1 mm average gamma passing rate was 96.4%, independent of the treatment site, energy range and field size. When dose distributions were evaluated using the same criteria for each energy layer, the average gamma passing rate was 91.7%.

Conclusions: The GAPSP is a suitable, low-cost method for monitoring pencil beam scanning proton therapy, especially for non-spot scanning or additional collimation. The GAPSP can also estimate the treatment beam by the energy layer, a feature not common to other proton dosimetry tool.

Seonghoon Jeong

Proton Therapy Center, National Cancer Center, Goyang, Republic of Korea

Myonggeun Yoon⁎ , Jaehyeon Seo

Department of Bio-Convergence Engineering, Korea University, Seoul, Republic of Korea

Kwangzoo Chung,⁎ , Sung Hwan Ahn , Boram Lee,

Department of Radiation Oncology, Samsung Medical Center, Seoul, Republic of Korea

Physica Medica 77(2020)181-186

Sensitivity of radio-photoluminescence glass dosimeters to a…

Background

This study investigated the effect of accumulated doses on radio-photoluminescence glass dosimeters (RPLGDs) from measurements involving mega-voltage photons.

Methods

Forty-five commercially available RPLGDs were irradiated to estimate their dose responses. Photon beams of 6, 10, and 15 MV were irradiated onto the RPLGDs inside a phantom, which were divided into five groups with different doses and energies. Groups 1 and 2 were irradiated at 1, 5, 10, 50, and 100 Gy in a sequential manner; Group 3 was irradiated 10 times with a dose of 10 Gy; and Groups 4 and 5 followed the same method as that of Group 3, but with doses of 50 Gy and 100 Gy, respectively. Each device was subjected to a measurement reading procedure each time irradiation.

Results

For the annealed Group 1, RPLGD exhibited a linearity response with variance within 5%. For the non-annealed Group 2, readings demonstrated hyperlinearity at 6 MV and 10 MV, and linearity at 15 MV. Following the 100 Gy irradiation, the readings for Group 2 were 118.7 ± 1.9%, 112.2 ± 2.7%, and 101.5 ± 2.3% at 6, 10, and 15 MV, respectively. For Groups 3, 4, and 5, the responsiveness of the RPLGDs gradually decreased as the number of repeated irradiations increased. The percentage readings for the 10th beam irradiation with respect to the readings for the primary beam irradiation were 84.6 ± 1.9%, 87.5 ± 2.4%, and 93.0 ± 3.0% at 6 MV, 10 MV, and 15 MV, respectively.

Conclusions

The non-annealed RPLGD response to dose was hyperlinear for the 6 MV and 10 MV photon beams but not for the 15 MV photon beam. Additionally, the annealed RPLGD exhibited a fading phenomenon when the measurement was repeated several times and demonstrated a relatively large fading effect at low energies than at high energies.

Dong Wook Kim, Han-Back Shin, Min-Joo Kim, Yu-Yun Noh, Hojae Kim, Min Cheol Han, Jihun Kim, Su Chul Han, Kyung Hwan Chang, Hojin Kim, Kwangwoo Park, Jinsung Kim

Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, Korea

Jiwon Sung, Jaeman Son

Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea

Myonggeun Yoon

Department of Bio-Convergence Engineering, Korea University, Seoul, Korea

Dongho Shin

Proton Therapy Center, National Cancer Center, Goyang, Korea

PLOS ONE | https://doi.org/10.1371/journal.pone.0234829 December 3, 2020

Feasibility Study of Beam Angle Optimization for Proton Trea…

This study describes a method that uses a genetic algorithm to select optimal beam angles in proton therapy and evaluates the effectiveness of the proposed algorithm in actual patients. In the use of the genetic algorithm to select the optimal angle, a gene represents the angle of each field and a chromosome represents the combination of beam angles. The fitness of the genetic algorithm, which represents the suitability of the chromosome to the solution, was quantified by using the dose distribution. The weighting factors of the organs used for fitness were obtained from clinical data through logistic regression, reflecting the dose characteristics of actual patients. Genetic operations, such as selection, crossover, mutation, and replacement, were used to modify the population and were repeated until an evaluation based on fitness reached the termination criterion. The proposed genetic algorithm was tested by assessing its ability to select optimal beam angles in three patients with liver cancer. The optimal results for fitness, planning target volume (PTV), normal liver, and skin in the population were compared with the clinical treatment plans, a process that took an average of 36.8 minutes. The dose-volume histograms (DVHs) and the fitness of the genetic algorithm plans did not differ significantly from the actual treatment plans. These findings indicate that the proposed genetic algorithm can automatically generate proton treatment plans with the same quality as actual clinical treatment plans.

Jaehyeon Seo, Yunhui Jo, Sunyoung Moon and Myonggeun Yoon∗

Department of Bio-convergence Engineering, Korea University, Seoul 02841, Korea

Sung Hwan Ahn, Boram Lee and Kwangzoo Chung†

Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea

Seonghoon Jeong

Department of Proton Therapy Center, National Cancer Center, Goyang 10408, Korea

Journal of the Korean Physical Society, Vol. 77, No. 4, August 2020, pp. 312∼316

Thymidine decreases the DNA damage and apoptosis caused by t…

Background

Tumor-treating fields (TTFields) is an emerging non-invasive cancer-treatment modality using alternating electric fields with low intensities and an intermediate range of frequency. TTFields affects an extensive range of charged and polarizable cellular factors known to be involved in cell division. However, it causes side-effects, such as DNA damage and apoptosis, in healthy cells.

Objective

To investigate whether thymidine can have an effect on the DNA damage and apoptosis, we arrested the cell cycle of human glioblastoma cells (U373) at G1/S phase by using thymidine and then exposed these cells to TTFields.

Methods

Cancer cell lines and normal cell (HaCaT) were arrested by thymidine double block method. Cells were seeded into the gap of between the insulated wires. The exposed in alternative electric fields at 120 kHz, 1.2 V/cm. They were counted the cell numbers and analyzed for cancer malignant such as colony formation, Annexin V/PI staining, γH2AX and RT-PCR.

Results

The colony-forming ability and DNA damage of the control cells without thymidine treatment were significantly decreased, and the expression levels of BRCA1, PCNA, CDC25C, and MAD2 were distinctly increased. Interestingly, however, cells treated with thymidine did not change the colony formation, apoptosis, DNA damage, or gene expression pattern.

Conclusions

These results demonstrated that thymidine can inhibit the TTFields-caused DNA damage and apoptosis, suggesting that combining TTFields and conventional treatments, such as chemotherapy, may enhance prognosis and decrease side effects compared with those of TTFields or conventional treatments alone.

Hyesun Jeong, Sunghoi Hong

School of Biosystems and Biomedical Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea

Hyesun Jeong, Sunghoi Hong

Department of Public Health Science, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea

Yunhui Jo, Myonggeun Yoon

Department of Bio- Convergence Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea

Genes Genom 43, 995–1001 (2021)

Evaluating direct and indirect effects of low-energy electro…

Monte Carlo simulations can classify DNA damage into different types and predict the amount of energy deposited. Geant4-DNA was used to predict simple and complex DNA damage induced by irradiation of low-energy electrons at 0.1–50 keV. The number of molecules generated at different energy levels of radiation was analyzed after observing the gradual changes in the level of water radiolysis. ADNA model was used to categorize direct damage according to the location of strand breaks at the atomic level. The parameters of energy threshold (minimum amount of energy needed to break DNA strands) and 10 base pairs (maximum distance that separates two strand breaks) were set. All instances of water radiolysis including the main OH radical occurred most frequently at 1 keV followed by at 1.5 and 0.5 keV. Direct strand breaks most commonly occurred at 0.5 keV followed by at 0.3 keV. Finally, most of strand breaks occurred more frequently at 0.5 keV than at 0.3 keV. The computational measure-ment results for indirect and direct effects of irradiation depend on the type of simulation code and the DNA model used. Values used in Geant4 (physics list, chemical interaction time and energy threshold)may also influence the results.

Eunae Choi and Myong Geun Yoon

Department of Bio Convergence Engineering, Korea University, Seongbuk-gu, Republic of Korea

Kwon Su Chon

Catholic University of Daegu, Gyeongsan, Republic of Korea

RADIATION EFFECTS & DEFECTS IN SOLIDS2020, VOL. 175, NOS. 11–12, 1042–1051

Biophysical Model Including a Potentially Lethal Damage Repa…

The amount of potentially lethal damage repair (PLDR) is a significant factor in the process of modeling the survival curves of cells irradiated with fractionated carbon beams. Because the amount of PLDR generally depends on the features of the cells and the linear energy transfer (LET), the amount of PLDR of cells irradiated with fractionated carbon beams shows distinct differences from that of cells irradiated with X-rays. This study considered a new parameter dependent on the correlation between the PLDR trait (T) of the cells over a time interval (Δ) at the fractionated carbon beam irradiation. The survival curves of the cells irradiated with fractionated carbon beams n times were predicted using the ζ and the Ψ values from the delay assay. This study aims to overcome the barriers of traditional methods by developing a new survival curve model with new parameters based on an analysis of the PLDR traits of cells over time interval in fractionated carbon beam irradiation and to suggest a model that produces results significantly closer to the experimental data.

Eunae Choi and Myonggeun Yoon∗

Department of Bio-convergence Engineering, Korea University, Seoul 02841, Korea

Masao Suzuki and Naruhiro Matsufuji

National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan

Wonguyn Jung

Korea Institute of Radiological and Medical Science, Seoul 01812, Korea

Journal of the Korean Physical Society, Vol. 77, No. 2, July 2020, pp. 161∼167

Development of a Daily-Treatment Beam-Monitoring System Base…

This study describes the development of a simple method to assess inter-fractional deviations of delivered proton beams in treatment rooms. To monitor the treatment beam, we measured the field-by-field beam fluences by attaching the EBT3 film to the snout, followed by a simple constancy check based on comparisons between the reference beam fluences (acquired during the pre-treatment quality assurance process) and the test beam fluences (acquired during treatment). The feasibility of the proposed treatment beam-monitoring system was confirmed by evaluating 12 treatment fields for each of six patients (brain, liver, prostate, lung, cranial and spinal area, and head and neck). The constancy of the treatment beams was verified by using a gamma index analysis to compare three measurements per field with the reference beam fluence. On the basis of the 3%/3 mm criterion, the average gamma-index passing rates for all measurements were over 99.6%. These results suggest that the constancy of fractional proton beams delivered to patients in treatment rooms can be verified with EBT3 film-based proton-beam monitoring system that can be easily attached to the treatment nozzle and is cost effective.

Seonghoon Jeong

Proton Therapy Center, National Cancer Center, Goyang Korea

Myonggeun Yoon∗

Department of Bio-convergence Engineering, Korea University, Seoul, Korea

Kwangzoo Chung†

Department of Radiation Oncology, Samsung Medical Center, School of Medicine, Sungkyunkwan University, Seoul, Korea

Journal of the Korean Physical Society, Vol. 76, No. 8, April 2020, pp. 769∼773

Synergistic effect of TTF and 5-FU combination treatment on…

The present study investigated the therapeutic potential of combining tumor-treating fields (TTF), a novel cancer treatment modality that employs low-intensity, alternating electric fields, with 5-fluorouracil (5-FU), a standard chemotherapy drug used for treating pancreatic cancer. The HPAF-II and Mia-Paca II pancreatic cancer cell lines were treated with TTF, 5-FU, or their combination. Combination treatment produced a significantly greater inhibitory effect on cancer cell proliferation than each single modality. Furthermore, combination therapy induced a substantially higher rate of pancreatic cancer cell apoptosis and exhibited a synergistic effect in clonogenic assays. Additionally, combination treatment showed a greater inhibition of cancer cell migration and invasion than either TTF or 5-FU alone. In conclusion, these findings suggest that the synergistic properties of TTF and 5-FU result in greater therapeutic efficacy against pancreatic cancer cells than either modality alone and may improve survival rates in patients with pancreatic cancer.

Yunhui Jo

Institute of Global Health Technology (IGHT), Korea University, Seoul 02841, Republic of Korea

Eunjun Lee, Geon Oh, Yongha Gi, Myonggeun Yoon

Department of Bio-Medical Engineering, Korea University, Seoul 02841, Republic of Korea

Myonggeun Yoon

FieldCure Ltd., Seoul 02852, Republic of Korea

Study of multistep Dense U-Net-based automatic segmentation …

Background: Despite extensive efforts to obtain accurate segmentation of magnetic resonance imaging (MRI) scans of a head, it remains challenging primarily due to variations in intensity distribution, which depend on the equipment and parameters used. Purpose: The goal of this study is to evaluate the effectiveness of an automatic segmentation method for head MRI scans using a multistep Dense U-Net (MDU-Net) architecture.

Methods: The MDU-Net-based method comprises two steps. The first step is to segment the scalp, skull, and whole brain from head MRI scans using a convolutional neural network (CNN). In the first step, a hybrid network is used to combine 2.5D Dense U-Net and 3D Dense U-Net structure. This hybrid network acquires logits in three orthogonal planes (axial, coronal, and sagittal) using 2.5D Dense U-Nets and fuses them by averaging. The resultant fused probability map with head MRI scans then serves as the input to a 3D Dense U-Net. In this process, different ratios of active contour loss and focal loss are applied. The second step is to segment the cerebrospinal fluid (CSF), white matter, and gray matter from extracted brain MRI scans using CNNs. In the second step, the histogram of the extracted brain MRI scans is standardized and then a 2.5D Dense U-Net is used to further segment the brain’s specific tissues using the focal loss. A dataset of 100 head MRI scans from an OASIS-3 dataset was used for training, internal validation, and testing, with ratios of 80%, 10%, and 10%, respectively. Using the proposed approach, we segmented the head MRI scans into five areas (scalp, skull, CSF, white matter, and gray matter) and evaluated the segmentation results using the Dice similarity coefficient (DSC) score, Hausdorff distance (HD), and the average symmetric surface distance (ASSD) as evaluation metrics.We compared these results with those obtained using the Res-U-Net, Dense U-Net, U-Net++, Swin-Unet, and H-Dense U-Net models.

Results: The MDU-Net model showed DSC values of 0.933, 0.830, 0.833, 0.953, and 0.917 in the scalp, skull, CSF, white matter, and gray matter, respectively. The corresponding HD values were 2.37, 2.89, 2.13, 1.52, and 1.53 mm, respectively.The ASSD values were 0.50, 1.63, 1.28, 0.26, and 0.27 mm, respectively. Comparing these results with other models revealed that the MDU-Net model demonstrated the best performance in terms of the DSC values for the scalp, CSF, white matter, and gray matter. When compared with the H-Dense UNet model,which showed the highest performance among the other models,the MDU-Net model showed substantial improvements in the HD view, particularly in the gray matter region, with a difference of approximately 9%. In addition, in terms of the ASSD, the MDU-Net model outperformed the H-Dense U-Net model, showing an approximately 7% improvements in the white matter and approximately 9% improvements in the gray matter.

Conclusion: Compared with existing models in terms of DSC, HD, and ASSD, the proposed MDU-Net model demonstrated the best performance on average and showed its potential to enhance the accuracy of automatic segmentation for head MRI scans.

Yongha Gi, Geon Oh, Hyeongjin Lim, Yousun Ko, Jinyoung Hong, Eunjun Lee, Sangmin Park, Taemin Kwak, Sangcheol Kim, Myonggeun Yoon*

Department of Bio-medical Engineering, Korea University, Seoul, Republic of Korea

Yunhui Jo

Institute of Global Health Technology (IGHT), Korea University, Seoul, Republic of Korea

Sangmin Park, Taemin Kwak, Sangcheol Kim, Myonggeun Yoon*

Field Cure Ltd., Seoul, Republic of Korea

Comparison of filtered back projection with fast non-local m…

This study aimed to quantitatively analyze the effciency of the fast non-local means (FNLM) filter in increasing the nodule detection sensitivity in pediatric chest computed tomography (CT) using 3D-printed lung nodules. For that purpose, we compared filtered back projection (FBP) with FNLM filter with iterative reconstruction (IR) method. The performance of the proposed FNLM filter was compared through various quantitative evaluations by modeling the previously used noise reduction methods. When the FNLM filter was applied to the acquired FBP reconstruction method-based CT image, the coeffcient of variation and contrast-to-noise ratio values in the lung nodule region showed similar values to those of the IR method. In addition, it was demonstrated that the point spread function value that can evaluate sharpness can be improved by using the FNLM filter. In conclusion, the results of this study are expected to maximize the image quality and reduce the dose by fusing the CT image reconstructed by the FBP method and the FNLM filter with excellent characteristics.

Jina Shim

Department of Diagnostic Radiology, Severance Hospital, 50-1, Yonsei-ro, Seodaemun-gu, Seoul, Republic of Korea

Myonggeun Yoon*

Department of Bioengineering, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul, Republic of Korea

Youngjin Lee*

Department of Radiological Science, Gachon University, 191, Hambakmoe-ro, Yeonsu-gu, Incheon, Republic of Korea

Application of Fast Non-Local Denoising Approach in Digital …

Introduction: Chest X-ray imaging has become the most commonly used, as it is the primary method for lung cancer screening during medical check-ups. The radiation dose should be minimized to ensure that the patients are not overexposed to radiation. However, radiation dose reduction results in increased noise in the chest X-ray image. Thus, the purpose of this study was to evaluate the utility of fast non-local means (FNLM) filters to reduce radiation dose while maintaining sufficient image quality.

Material and Methods: This study evaluates three filters (median, Wiener, and total variation) and a newly proposed filter (fast non-local means (FNLM)), which reduce image noise. A realistic anthropomorphic phantom is used to compare images acquired depending on positions such as anterior-posterior, lateral, and posterior-anterior, using a self-produced 3D printed lung nodule phantom. To evaluate image quality, we used the normalized noise power spectrum (NNPS), contrast to noise ratio (CNR), and coefficient of variation (COV) evaluation parameters.

Results: The NNPS and COV were lowest and the CNR was highest with FNLM images. FNLM filter outperforms other compared filters in terms of noise reduction.

Conclusion: Therefore, the use of an FNLM filter is recommended, because it reduces the radiation dose to a patient and thus minimizes the risk of cancer, while maintaining diagnostic quality.

Jina Shim

Department of Diagnostic Radiology, Severance Hospital, Seoul, Republic of Korea

Myonggeun Yoon

Department of Bio-Convergence Engineering, Korea University, Seoul, Republic of Korea

Youngjin Lee

Department of Radiological Science, Gachon University, 191, Hambakmoero, Yeonsu-gu, Incheon, Republic of Korea

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