Publications by authors named "Kyu H Choi"

Purpose: This study aimed to provide quantitative information for implementing Lattice radiotherapy (LRT) using a medical linear accelerator equipped with the Millennium 120 multi-leaf collimator (MLC). The research systematically evaluated the impact of varying vertex diameters and separations on dose distribution, peak-to-valley dose ratio (PVDR), and normal tissue dose.

Methods: A cylindrical Virtual Water™ phantom was used to create LRT treatments using the Eclipse version 16.

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Purpose: Despite the decades of using radiation therapy (RT) for Graves' ophthalmopathy, the effects and optimal timing remain unclear. We retrospectively analyzed to evaluate the overall efficacy and response, predictive factors, and the effective timing of RT by assessing steroid requirement after RT in patients without prior surgery.

Methods And Materials: Between 2008 and 2022, we analyzed 74 patients with Graves' ophthalmopathy who received RT to both orbits.

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Surface-bound molecular motors can drive the collective motion of cytoskeletal filaments in the form of nematic bands and polar flocks in reconstituted gliding assays. Although these "swarming transitions" are an emergent property of active filament collisions, they can be controlled and guided by tuning the surface chemistry or topography of the substrate. To date, the impact of surface topography on collective motion in active nematics is only partially understood, with most experimental studies focusing on the escape of a single filament from etched channels.

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Objective: Among cervical adenocarcinomas, well-differentiated gastric adenocarcinoma of the uterine cervix (WD-GAS), previously termed adenoma malignum (minimal deviation adenocarcinoma) is not well understood. Because of its rarity and difficulty in diagnosis, there is no standard care for WD-GAS. Thus, we conducted the first multicenter retrospective study on WD-GAS to clarify prognostic factors for long-term survival and recurrence.

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Purpose: The purpose of the study was to develop a predictive model for vertebral compression fracture (VCF) prior to spinal stereotactic body radiation therapy (SBRT) using radiomics features extracted from pre-treatment planning CT images.

Methods: A retrospective analysis was conducted on 85 patients (114 spinal lesions) who underwent spinal SBRT. Radiomics features were extracted from pre-treatment planning CT images and used to develop a predictive model using a classification algorithm selected from nine different machine learning algorithms.

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Understanding pairwise interactions between colloidal particles out of equilibrium has a profound impact on dynamical processes such as colloidal self assembly. However, traditional colloidal interactions are effectively quasi-static on colloidal timescales and cannot be modulated out of equilibrium. A mechanism to dynamically tune the interactions during colloidal contacts can provide new avenues for self assembly and material design.

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Colloids often behave in a manner similar to their counterparts in molecular space and are used as model systems to understand molecular behavior. Here, we study like-charged colloidal attractions between a permanent dipole on an interfacial particle and its induced dipole on a water-immersed particle caused by diffuse layer polarization. We find that the scaling behavior of the measured dipole-induced dipole (D‒I) interaction via optical laser tweezers is in good agreement with that predicted from the molecular Debye interaction.

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This study investigates the effects of interparticle interactions and wettability on the particle attachment efficacy to the oil‒water interface. Three types of PS particles with different surface functional groups were examined at varying salt concentrations and the number of particles injected into the interface. Based on the microfluidic method and the surface coverage measurement, we found that the two contributing factors significantly influenced particle attachment efficiency to the interface, while the wettability factor has a major contribution.

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Purpose: Quality assessment of breast cancer treatment in South Korea showed the upward standardization of the grade since 2013, but treatment disparities still have existed. This study analyzed the five year trend between 2013 and 2017 in the assessment of breast cancer treatment practice using the Korean health insurance data.

Materials And Methods: All the medical records including surgery, chemotherapy, and radiotherapy for 7,354 patients a year on average were evaluated.

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Interactions among colloidal particles govern the hierarchical microstructure and its physical properties. Here, optical laser tweezers and Monte Carlo simulations are used to evaluate the effects of azimuthal rotation of Janus particles at the oil-water interface on interparticle interactions. We find that the capillary-induced attractive force between two Janus particles at the interface can be relaxed by azimuthal rotation around the critical separation region, at which the capillary force is ∼0.

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Introduction: This study was conducted to investigate changes and new trends over the past 6 years by analyzing the current status of precocious puberty (PP) treatment and treatment costs in Korea between 2016 and 2021.

Materials And Methods: Annual and monthly number of patients diagnosed with PP from 2016 to 2021 were reviewed using the data from Healthcare Bigdata Hub. Annual medical insurance expenses for the treatment of PP were also reviewed.

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Objectives: The pathologic nodal stage of human papillomavirus (HPV)-related oropharyngeal cancer (OPC) patients is classified according to the number of lymph nodes (LNs), as revised in 2018. Previous studies showed that the LN ratio (LNR) could be also a significant prognostic factor in head and neck cancer, but there are few studies on the LNR in HPV-related [HPV(+)] OPC. The aim of the present study was to analyze the predictive value of the LNR for survival and recurrence in HPV(+) OPC patients.

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Background: Paroxysmal sympathetic hyperactivity (PSH) is characterized by exacerbated sympathetic discharge following severe brain injury. Here, we reports a patient diagnosed with PSH after ICH concurrent with hypothalamic injury, as demonstrated by diffusion tensor imaging (DTI).

Methods: A 27-year-old man patient was diagnosed with spontaneous intraventricular hemorrhage and intracerebral hemorrhage in both frontal lobes.

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Background: Atrial fibrillation (AF) has been a leading cause of cerebral infarction, but the association with motor outcome after cerebral infarction remains unreported. In this study, we attempted to identify whether AF affects motor outcomes after cerebral infarction.

Methods: Seventy-six patients with a first-incidence cerebral infarction and who completed 6 months of rehabilitation were recruited to this retrospective study.

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Background: The impact of left ventricular diastolic dysfunction (LVDD) on cardiovascular (CV) outcomes in patients with pre-dialysis chronic kidney disease (CKD) has been rarely unveiled. We here investigated the association of LVDD with CV outcomes and all-cause mortality in patients with pre-dialysis CKD.

Methods: A total of 2,135 patients with pre-dialysis CKD from the Korean Cohort Study for Outcomes in Patients With Chronic Kidney Disease (KNOW-CKD) cohort were dichotomized by the absence or presence of LVDD, which was defined as the ratio of the early transmitral blood flow velocity to early diastolic velocity of the mitral annulus (/') > 14.

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Background: Although it is well known that low bone mineral density (BMD) is associated with an increased risk of cardiovascular disease (CVD) and mortality in the general population, the prognostic role of bone mineral density (BMD) has not been established in the chronic kidney disease (CKD) population. Therefore we aimed to evaluate the association between BMD and the risk of CVD and cardiovascular mortality in patients with predialysis CKD.

Methods: This prospective cohort study was conducted with 1957 patients with predialysis CKD Stages 1-5.

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Circulating osteoprotegerin (OPG) is a biomarker for cardiovascular complications that are closely related to chronic kidney disease (CKD). To investigate the association between circulating OPG level with long-term visit-to-visit blood pressure variability (BPV) in patients with pre-dialysis CKD, a total of 1855 subjects with CKD from stage 1 to pre-dialysis stage 5 from a prospective cohort were analyzed. Long-term visit-to-visit BPV was determined by average real variability (ARV), standard deviation (SD), and coefficient of variation (CoV) of systolic and diastolic blood pressure (SBP and DBP).

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Background: Osteoprotegerin is an important regulator of bone metabolism and vascular calcification. The association between serum osteoprotegerin level and chronic kidney disease (CKD) progression has not been elucidated. We investigated the prognostic value of serum osteoprotegerin levels in nondialysis CKD patients.

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Cardiovascular disease is a major complication of chronic kidney disease. The coronary artery calcium (CAC) score is a surrogate marker for the risk of coronary artery disease. The purpose of this study is to predict outcomes for non-dialysis chronic kidney disease patients under the age of 60 with high CAC scores using machine learning techniques.

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Purpose: Positron-emission tomography (PET)-CT has recently been used for diagnostic imaging and radiotherapy for myeloid sarcoma, but there is little research on predicting the response of radiotherapy. The aim of this study was to analyze the association between PET-CT variables and the response to radiotherapy in patients with myeloid sarcoma.

Materials And Methods: This study was conducted in myeloid sarcoma patients who received radiotherapy and PET-CT before and after radiotherapy.

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To investigate the association of body weight variability (BWV) with adverse cardiovascular (CV) outcomes in patient with pre-dialysis chronic kidney disease (CKD), a total of 1867 participants with pre-dialysis CKD from Korean Cohort Study for Outcomes in Patients With Chronic Kidney Disease (KNOW-CKD) were analyzed. BWV was defined as the average absolute difference between successive values. The primary outcome was a composite of non-fatal CV events and all-cause mortality.

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Article Synopsis
  • A study assessed the impact of adding vaginal brachytherapy (VB) to pelvic external radiotherapy (ERT) on local recurrence and survival in cervical cancer patients with close or positive vaginal margins after surgery.
  • The research included 60 patients treated from 1997 to 2018, finding that those who received ERT + VB had a significantly better 5-year local control (100%) and pelvic control (95.8%) compared to those who received ERT alone (81.3% and 76.8%, respectively).
  • Despite the improved local and pelvic control, there was no significant difference in overall survival or recurrence-free survival between the two treatment groups, and adding VB did not lead to increased late toxicity.
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Article Synopsis
  • - This study examines current practices in radiation therapy for HPV-related oropharyngeal cancer, focusing on the radiation dose and treatment area prescribed by oncologists in Korea.
  • - A survey of 42 radiation oncologists revealed a mix of treatment approaches, with most prescribing doses over 60 Gy, but some opting for lower doses, particularly in postoperative settings.
  • - Findings indicate that while about 20% of oncologists are implementing dose de-escalation, a significant majority are not, highlighting a need for consensus guidelines following ongoing research.
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Background And Aims: Decreased kidney function is an important risk factor for cardiovascular disease (CVD). However, assessing risk of CVD may be difficult when there is a gap between creatinine- and cystatin C-based estimated glomerular filtration rate (eGFR). We studied the association of the difference in eGFRs with major adverse cardiovascular events (MACE) in patients with chronic kidney disease (CKD).

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Background: Although uric acid (UA) is regarded as a risk factor for cardiovascular disease, whether UA is an independent risk factor contributing to coronary artery calcification in chronic kidney disease (CKD) is not well known. We evaluated whether UA level is associated with coronary artery calcium (CAC) score in a predialysis CKD cohort.

Methods: A total of 1,350 subjects who underwent coronary computed tomography as part of the KoreaN Cohort Study for Outcome in Patients With Chronic Kidney Disease were analysed.

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