Solution-Driven Imprinting Lithography of Sol-Gel ZnO Thin Films for Liquid Crystal Display.

We present a simple and economically convenient method to fabricate nanopatterned ZnO films by imprinting lithography and use them for the layer alignment of liquid crystal (LC) displays. First, a one-dimensional nanopattern was obtained by laser interference lithography on a silicon wafer, and the silicon mold replica was transferred onto a flexible polydimethylsiloxane (PDMS) sheet for conformal patterning. The so-obtained PDMS mold was then applied on a ZnO film spin-coated on a glass substrate. During the imprinting process, the temperature was controlled from 100 to 250 °C to observe the transferring morphologies of the ZnO film; the nanopattern was successfully transferred at annealing temperatures of 200 and 250 °C because the ZnO film at the sol state filled the cavities of the PDMS nanopattern and solidified, forming a negative replica of the nanopattern. The direction of the nanopatterned ZnO film served as a guide for aligning the LC molecules on the LC surface at the centimeter scale and, due to their elastic characteristics and group behavior, propagating their directional states in the LC bulk. The resulting LC cell exhibited an enhanced electro-optical performance and high thermal endurance above 180 °C. The geometry of the alignment layer increased the electric field on the ZnO film and showed reduced threshold voltage. In addition, since flexible devices are generally based on polyimide, which imidized at around 200 °C, the relatively low annealing temperatures of our fabricated nanopatterned ZnO film allow it to be mounted on such devices without any deterioration of the underlying thermoplastic substrate. Therefore, nanopatterned ZnO has a considerable potential for advanced LC displays.

Formation of Wrinkle Structures on Styrene-b-isoprene-b-styrene Films Using One-Step Ion-Beam Irradiation.

We investigated the wrinkle formation on ion-beam (IB)-irradiated substrates coated with the thermoplastic elastomer styrene-b-isoprene-b-styrene (SIS) and demonstrate a relation of the wrinkle structure and the newly formed top layer induced by IB. IB irradiation led to polymer cross-linking on the surface, thereby forming a new skin layer, a finding which was supported by an X-ray photoelectron spectroscopy analysis, Young moduli calculated using force-distance curves, and time-of-flight secondary ion mass spectrometry depth profiling. The wrinkle wavelength increased according to the irradiation time, which indicates that the latter mainly increased the thickness of the cross-linking layer. The increase in the wrinkle wavelength varied from 420 to 670 nm by changing the IB irradiation time. In this paper, we present not only the expectation of wrinkle fabrication using our method but also the possibility of choosing diverse materials such as the thermoplastic elastomer SIS for fabrication of wrinkle structures.

One-dimensional surface wrinkling for twisted nematic liquid crystal display based on ultraviolet nanoimprint lithography.

Surface wrinkling method is used to fabricate a 1-dimensional nanostructure. The structure is transferred to an ultraviolet cured polymer which is used as an alignment layer. The anisotropic geometry serves as a guide for aligning liquid crystal molecules uniformly without defects. The TN-LC cell showed a successful LC switching, with a response time of 20.5 ms, and a threshold voltage of 2.00 V. It also exhibited high thermal stability above 180°C. The proposed UV-cured polymers with 1-D nano wrinkle geometry can be a candidate for alternative alignment techniques, for advanced liquid crystal devices with high thermal budgets.

Physicochemical Modification Effect on Homogeneously Aligned Liquid Crystals Based on the Nickel Oxide Thin Film.

We demonstrated homogeneous liquid crystal (LC) alignment on Nickel Oxide (NiO) films subjected to ion beam (IB) irradiation. Uniform LC alignment was achieved at high IB intensity values of 1200 and 1800 eV. To determine the mechanism of LC alignment following IB irradiation, physicochemical analysis was performed using atomic force microscopy and X-ray photoelectron spectroscopy. IB irradiation with high intensity increases uniformity of the surface, and IB irradiation induces the formation of oxygen vacancies and increases the NiO (Ni2+) phase components. Hence, both of the smooth surface and the strong van der Waals interactions between the NiO film and the LC molecules provides the LC molecules with a stable anchor on the surface, leading to uniform LC alignment on NiO films after IB irradiation. IB-irradiated NiO exhibited a high transparency of 85% in the visible light range as compared with the 83% average transmittance of conventional polyimide, which makes the IB-irradiated NiO alignment layer attractive in display devices.

Formyl Peptide Receptor 2 Is Involved in Cardiac Repair After Myocardial Infarction Through Mobilization of Circulating Angiogenic Cells.

Increasing evidence suggests that circulating angiogenic cells (CACs) promote repair of ischemic tissues. Activation of formyl peptide receptor 2 (Fpr2) has been reported to stimulate repair of ischemic heart. This study was conducted to investigate the role of Fpr2 on CAC mobilization and cardiac protection in myocardial infarction (MI). WKYMVm, a strong agonist for Fpr2, was administered in a murine model of acute MI, and mobilization of CACs including endothelial progenitor cells (CD34+ Flk1+ or Sca1+ Flk1+ cells) in peripheral blood was monitored. CAC mobilization by daily injection of WKYMVm for the first 4 days after MI was as efficient as granulocyte colony-stimulating factor and provided myocardial protection from apoptosis with increased vascular density and preservation of cardiac function. Transplantation of bone marrow (BM) from green fluorescent protein mice showed that BM-derived cells homed to ischemic heart after WKYMVm treatment and contributed to tissue protection. Transplantation of BM from Fpr2 knockout mice showed that Fpr2 in BM cells is critical in mediation of WKYMVm-stimulated myocardial protection and neovascularization after MI. These results suggest that activation of Fpr2 in BM after WKYMVm treatment provides cardiac protection through mobilization of CACs after MI, which may lead to the development of a new clinical protocol for treating patients with ischemic heart conditions. Stem Cells 2017;35:654-665.

Tailoring the Orientation and Periodicity of Wrinkles Using Ion-Beam Bombardment.

The present study demonstrates that surface reformation in polydimethylsiloxane can be controlled using ion-beam (IB) irradiation. This can be done by simply varying the IB incidence angle and requires no change in the energy source. By controlling the incidence angle of IB irradiation, we were able to continuously control the pattern of the wrinkle structure, that is, a randomly formed pattern or an anisotropic one. Moreover, the directional characteristics of the wrinkle pattern control the alignment of liquid crystal molecules. This control is a function of the incidence angle of the IB. These simple methods can provide considerable flexibility in the fabrication of wrinkle structures.

Homogeneous liquid crystal alignment characteristics on solution-derived HfYGaO films treated with IB irradiation.

Solution-derived HfYGaO films have been treated by ion beam (IB) irradiation and used as liquid crystal (LC) alignment layers. Solution processing was adopted due to its simplicity, high throughput, and facile composition modification. Homogeneous and uniform LC alignment was achieved on the IB-irradiated HfYGaO films, and when these films were adopted in twisted nematic (TN) cells, electro-optical performance comparable to that of TN cells with conventional polyimide layers was achieved, with almost no capacitance-voltage hysteresis. Moreover, LC cells based on IB-irradiated HfYGaO films had a high thermal budget. The proposed IB-irradiated solution-derived HfYGaO films have considerable potential for use in advanced LC applications.

Comparison of non-vitamin K antagonist oral anticoagulants and warfarin on clinical outcomes in atrial fibrillation patients with renal dysfunction.

AIMS: We aimed to compare the efficacy and safety between non-vitamin K antagonist oral anticoagulants (NOACs) and warfarin in atrial fibrillation (AF) patients according to renal dysfunction. METHODS AND RESULTS: We analysed 1319 patients who had been taken oral anticoagulants. They were classified into patients taking NOACs (n = 326) and warfarin (n = 993). Renal dysfunction was defined as the estimated glomerular filtration rate <60 mL/min by using the Chronic Kidney Disease Epidemiology Collaboration equation. The composite clinical outcomes were defined as the composite of death, hospitalization, and new-onset strokes. Safety outcomes were composed of major and minor bleeding. Subgroup analyses for clinical and safety outcomes were performed according to renal dysfunction during median 596 (506-612) follow-up days. The prevalence of renal dysfunction was similar between the two groups. The incidences of death, hospitalization, and strokes were not different between the two groups. However, the incidences of major bleeding was significantly higher in patients taking warfarin. In the subgroup analysis with renal dysfunction, the use of NOACs significantly improved the composite clinical outcomes (adjusted hazard ratio, HR, 0.30, 95% confidence interval, CI, 0.11-0.77, interaction P = 0.018) and major bleeding (adjusted HR 0.18, 95% CI 0.07-0.45, interaction P = 0.199) even after the covariate adjustment. However, in patients without renal dysfunction, there were no differences in the incidences of the composite clinical outcomes between the two groups. CONCLUSIONS: The benefit of NOACs was more prominent in AF patients with renal dysfunction than without renal dysfunction. These results suggest that NOACs as the first choice oral anticoagulant in AF patients with renal dysfunction.

Red cell distribution width as a novel predictor for clinical outcomes in patients with paroxysmal atrial fibrillation.

AIMS: Elevated red cell distribution width (RDW) has been known to be associated with adverse long-term outcomes in patients with cardiovascular diseases. We aimed to evaluate relationship between RDW values and clinical outcomes in patients with paroxysmal atrial fibrillation (AF). METHODS AND RESULTS: We analysed 567 patients who were newly diagnosed as paroxysmal AF. Clinical outcomes were analysed after median 4.8 (3.4-6.9) years follow-up. The composite clinical outcomes were defined as the composite of death, hospitalization due to heart failure, and new-onset stroke. Bleeding events were composed of major and minor bleeding. The relationship of RDW with clinical outcomes was assessed using continuous or categorical variables as quartiles: <12.8, 12.8-13.2, 13.3-13.8, and ≥13.9%. Patients with the highest RDW quartile were the oldest and had more frequent history of heart failure. CHA2DS2-VASc score was increased along with increasing RDW quartiles (1.75 ± 1.48 vs. 1.77 ± 1.63 vs. 1.87 ± 1.61 vs. 2.33 ± 1.65, P = 0.008). Incidence of new-onset stroke (log-rank P = 0.032), the composite clinical outcomes (log-rank P = 0.014), and bleeding events (log-rank P = 0.001) were increased as increasing RDW quartiles. Multivariate analysis identified that RDW was a significant predictor for new-onset stroke [adjusted hazard ratio (HR) 1.32, 95% confidence interval (CI) 1.06-1.65, P = 0.015], the composite clinical outcomes (adjusted HR 1.21, 95% CI 1.03-1.41, P = 0.017), and bleeding events (adjusted HR 1.36, 95% CI 1.13-1.64, P = 0.001). CONCLUSIONS: RDW can be a new, useful, novel predictor of clinical and safety outcomes in patients with paroxysmal AF.

Nickel Oxide Nanoparticles Doped Liquid Crystal System for Superior Electro-Optical Properties.

We examined the properties of nematic liquid crystal (N-LC) systems with dispersed nickel oxide nanoparticles (NPs). Uniform LC alignments with regular pretilt angles were achieved on rubbed polymer surface regardless of NiO nanoparticles concentration. We confirmed the electro-optical characteristics of twisted nematic (TN) cells containing NiO nanoparticles on rubbed polymer surface, which exhibited lower threshold voltages and faster response times with less capacitance hysteresis than pure LC cells. It is clear that the response time of TN cells on rubbed polymer surfaces decreases with increasing the NiO nanoparticles concentration. These results demonstrate the relationship between NP doping concentration and trapping of impurity ions, and were confirmed by a software simulation of electric flux and field density. NiO nanoparticles in the LC cells focused the electric field flux and strengthened the electric field. Further, NiO nanoparticles in LC medium trapped charged ionic impurities and suppressed the screen effect, leading to a stronger electric field and the van der Waals interactions between LC molecules and the alignment layers.

Cardioprotective effect of fimasartan, a new angiotensin receptor blocker, in a porcine model of acute myocardial infarction.

Cardioprotective effect of fimasartan, a new angiotensin receptor blocker (ARB), was evaluated in a porcine model of acute myocardial infarction (MI). Fifty swine were randomized to group 1 (sham, n=10), group 2 (no angiotensin-converting enzyme inhibitor [ACEI] or ARB, n=10), group 3 (perindopril 2 mg daily, n=10), group 4 (valsartan 40 mg daily, n=10), or group 5 (fimasartan 30 mg daily, n=10). Acute MI was induced by occlusion of the left anterior descending artery for 50 min. Echocardiography, single photon emission computed tomography (SPECT), and F-18 fluorodeoxyglucose cardiac positron emission tomography (PET) were performed at baseline, 1 week, and 4 weeks. Iodine-123 meta-iodobenzylguanidine (MIBG) scan was done at 6 weeks for visualization of cardiac sympathetic activity. Left ventricular function and volumes at 4 weeks were similar between the 5 groups. No difference was observed in groups 2 to 5 in SPECT perfusion defect, matched and mismatched segments between SPECT and PET at 1 week and 4 weeks. MIBG scan showed similar uptake between the 5 groups. Pathologic analysis showed similar infarct size in groups 2 to 5. Infarct size reduction was not observed with use of fimasartan as well as other ACEI and ARB in a porcine model of acute MI.

Protective role of 5-azacytidine on myocardial infarction is associated with modulation of macrophage phenotype and inhibition of fibrosis.

We examined whether a shift in macrophage phenotype could be therapeutic for myocardial infarction (MI). The mouse macrophage cell line RAW264.7 was stimulated with peptidoglycan (PGN), with or without 5-azacytidine (5AZ) treatment. MI was induced by ligation of the left anterior descending coronary artery in rats, and the rats were divided into two groups; a saline-injection group and a 5AZ-injection group (2.5 mg/kg/day, intraperitoneal injection). LV function was evaluated and immunohistochemical analyses were performed 2 weeks after MI. Cardiac fibrosis was induced by angiotensin II (AngII) infusion with or without 5AZ (5 mg/kg/day) in mice. Nitric oxide was produced by PGN, which was reduced by 77.87% after 5AZ treatment. Both induction of inducible nitric oxide synthase (iNOS) and iNOS promoter activity by PGN were inhibited by 5AZ. Ejection fraction (59.00 ± 8.03% versus 42.52 ± 2.58%), contractility (LV dP/dt-max, 8299.76 ± 411.56 mmHg versus 6610.36 ± 282.37 mmHg) and relaxation indices (LV dP/dt-min, -4661.37 ± 210.73 mmHg versus -4219.50 ± 162.98 mmHg) were improved after 5AZ administration. Cardiac fibrosis in the MI+5AZ was 8.14 ± 1.00%, compared with 14.93 ± 2.98% in the MI group (P < 0.05). Arginase-1(+)CD68(+) macrophages with anti-inflammatory phenotype were predominant in the infarct border zone of the MI+5AZ group, in comparison with the MI group. AngII-induced cardiac fibrosis was also attenuated after 5AZ administration. In cardiac fibroblasts, pro-fibrotic mediators and cell proliferation were increased by AngII, and these increases were attenuated after 5AZ treatment. 5AZ exerts its cardiac protective role through modulation of macrophages and cardiac fibroblasts.

Polarized UV cured reactive mesogens for fast switching and low voltage driving liquid crystal device.

Uniaxial alignment of liquid crystals (LCs) is prerequisite for a vast number of LC applications. To accomplish stable and uniform LC orientation, an alignment process to orient the LCs is required. Herein, we demonstrate a simple strategy for fabricating novel LC alignment layers that ensures well aligned LC, superior switching without any capacitance hysteresis, low transmittance loss, and high thermal stability with sufficient anchoring action. Thin films of reactive mesogens (RMs) were transferred onto conventional homeotropic polyimides from a UV-cured RM stamp via contact printing. LC displays using defect free RM/PI polymeric stacks exhibited superior electro-optic (EO) properties to those containing rubbed PI layers. This approach allows for the fabrication of various-mode LC displays such as twisted nematic (TN), in-plane switching (IPS), and optically compensated bend (OCB) mode LCDs by changing the combinations of RMs, base PIs and LCs.

High performance twisted nematic liquid crystal display with solution-derived YZO surface modification via ion-beam irradiation.

Solution-derived YZO films were investigated as liquid crystal (LC) alignment layers modified by ion beam (IB) irradiation. Solution processing was adopted in place of the sputtering method for the deposition of YZO films as LC alignment layers. Uniform and homogeneous LC alignment was achieved to produce a high performance LC system. X-ray photoelectron spectroscopy analysis showed that surface reformation of YZO films by annealing and IB irradiation affects the uniformity of the LC alignment. Superior electro-optical characteristics of twisted nematic LC cells constructed from IB-irradiated YZO films were observed, which indicates that the proposed solution-derived YZO films have strong potential for use in the production of advanced LC displays.

New strategy for detection of subclinical coronary atherosclerosis in asymptomatic patients with type 2 diabetes based on cardiac multi-detector computed tomography and treadmill test.

BACKGROUND: The current screening strategy for subclinical coronary atherosclerosis in asymptomatic diabetic patients is not sufficient in real clinical practice. A new strategy was investigated that uses cardiac multi-detector computed tomography (MDCT) and a treadmill test (TMT). METHODS AND RESULTS: A total of 445 self-referred asymptomatic diabetic patients underwent cardiac MDCT. The treatment plan was determined according to the new strategy that uses MDCT and TMT. All patients underwent clinical follow-up and cardiac events were investigated. The incidence of subclinical atherosclerosis was 49.4%. The group without plaque underwent clinical follow-up without treatment and did not experience any cardiac events in 675.1 person-years of follow-up. Among patients with subclinical atherosclerosis without significant stenosis (n=136) who received medical treatment only, 11 patients experienced cardiac events over 326.4 person-years. The patients with significant stenosis (n=84) underwent TMT. Patients with positive TMT (n=14) underwent coronary angiograms and revascularization therapy was performed in all of them over 39.2 person-years. Patients with negative TMT (n=70) underwent medical treatment, and 27 of them experienced cardiac events. The incidence of cardiac death was 0% during 3 years of follow-up. CONCLUSIONS: The new strategy for detecting subclinical atherosclerosis on MDCT combined with TMT may be a useful method for minimizing the mortality rate from cardiovascular disease in asymptomatic diabetic patients.

Characteristics, in-hospital and long-term clinical outcomes of nonagenarian compared with octogenarian acute myocardial infarction patients.

We compared clinical characteristics, management, and clinical outcomes of nonagenarian acute myocardial infarction (AMI) patients (n=270, 92.3 ± 2.3 yr old) with octogenarian AMI patients (n=2,145, 83.5 ± 2.7 yr old) enrolled in Korean AMI Registry (KAMIR). Nonagenarians were less likely to have hypertension, diabetes and less likely to be prescribed with beta-blockers, statins, and glycoprotein IIb/IIIa inhibitors compared with octogenarians. Although percutaneous coronary intervention (PCI) was preferred in octogenarians than nonagenarians, the success rate of PCI between the two groups was comparable. In-hospital mortality, the composite of in-hospital adverse outcomes and one year mortality were higher in nonagenarians than in octogenarians. However, the composite of the one year major adverse cardiac events (MACEs) was comparable between the two groups without differences in MI or re-PCI rate. PCI improved 1-yr mortality (adjusted hazard ratio [HR], 0.50; 95% confidence interval [CI], 0.36-0.69, P<0.001) and MACEs (adjusted HR, 0.47; 95% CI, 0.37-0.61, P<0.001) without significant complications both in nonagenarians and octogenarians. In conclusion, nonagenarians had similar 1-yr MACEs rates despite of higher in-hospital and 1-yr mortality compared with octogenarian AMI patients. PCI in nonagenarian AMI patients was associated to better 1-yr clinical outcomes.

The association of socioeconomic status with three-year clinical outcomes in patients with acute myocardial infarction who underwent percutaneous coronary intervention.

The aim of this study was to evaluate whether the clinical outcomes were associated with socioeconomic status (SES) in patients with acute myocardial infarction (AMI) who underwent percutaneous coronary intervention (PCI). The author analyzed 2,358 patients (64.9 ± 12.3 yr old, 71.5% male) hospitalized with AMI between November 2005 and June 2010. SES was measured by the self-reported education (years of schooling), the residential address (social deprivation index), and the national health insurance status (medical aid beneficiaries). Sequential multivariable modeling assessed the relationship of SES factors with 3-yr major adverse cardiovascular events (MACEs) and mortality after the adjustment for demographic and clinical factors. During the 3-yr follow-up, 630 (26.7%) MACEs and 322 (13.7%) all-cause deaths occurred in 2,358 patients. In multivariate Cox proportional hazards regression modeling, the only lower education of SES variables was associated with MACEs (hazard ratio [HR], 1.41; 95% confidence interval [CI], 1.04-1.91) and mortality (HR, 1.93; 95% CI, 1.16-3.20) in the patients with AMI who underwent PCI. The study results indicate that the lower education is a significant associated factor to increased poor clinical outcomes in patients with AMI who underwent PCI.

Effect of statin treatment in patients with acute myocardial infarction and left ventricular systolic dysfunction according to the level of high-sensitivity C-reactive protein.

The effects of statins on the prognosis of patients with left ventricular (LV) systolic dysfunction remain controversial. The aim of this study was to assess the effect of statin treatment on clinical outcomes in acute myocardial infarction (AMI) patients with LV systolic dysfunction. A total of 5,119 AMI patients with LV ejection fraction less than 50% on the initial echocardiogram were analyzed in the Korean Acute Myocardial Infarction Registry. The study population was divided into 4 groups according to the level of high sensitivity C-reactive protein (hs-CRP) and statin treatment: low hs-CRP (hs-CRP ≤ 2.0 mg/L) and high hs-CRP (hs-CRP > 2 mg/L) with or without statin therapy. We evaluated the incidence of major adverse cardiac events (MACEs) including cardiac death, reinfarction, target lesion revascularization, and coronary artery bypass grafting during a 12-month period in each group. Statin therapy did not significantly prevent the MACEs in the low hs-CRP groups (with statin: 10.1% versus without statin: 12.0%, P = 0.249). In the high hs-CRP groups, however, the incidence of MACEs was significantly decreased with statin treatment (with statin: 11.3%, without statin: 20.8%, P < 0.001). These findings were consistently observed in all subgroups of the high-hs CRP group, including the subgroup with an LV ejection fraction less than 40%. In a multivariable logistic regression analysis of the high hs-CRP group, lack of statin therapy was a significant predictor of MACE incidence (odds ratio: 1.573, 95% confidence interval: 1.079-2.293, P = 0.018). The statin treatment was associated with better outcome in AMI and LV dysfunction patients with hs-CRP ≥ 2 mg/dL.

Comparison of triple anti-platelet therapy and dual anti-platelet therapy in patients with acute myocardial infarction who had no-reflow phenomenon during percutaneous coronary intervention.

BACKGROUND: No-reflow phenomenon is a serious complication of percutaneous coronary intervention (PCI) and associated with poor prognosis. The aim of this study was to determine whether triple anti-platelet therapy could improve clinical outcome in patients with acute myocardial infarction (AMI) who had no-reflow phenomenon during PCI compared with dual anti-platelet therapy. METHODS AND RESULTS: A total of 727 eligible patients received either dual anti-platelet therapy (aspirin and clopidogrel; dual group, n=532) or triple anti-platelet therapy (aspirin, clopidogrel, and cilostazol; triple group, n=195). The triple group received additional cilostazol for at least 1 month. One-year major adverse cardiac events (MACE) including death, myocardial infarction (MI), target vessel revascularization (TVR) and coronary artery bypass graft (CABG) were evaluated. The triple group had a similar incidence of major bleeding and in-hospital mortality compared with the dual group. At 1 year, the triple group had significantly lower cardiac mortality (17.7% vs. 11.8%, log-rank P=0.039), lower all-cause mortality (19.0% vs. 12.3%, log-rank P=0.035), and lower incidence of composite MACE (25.9% vs. 16.9%, adjusted hazard ratio, 0.50; 95% confidence interval: 0.31-0.80, P=0.004) compared with the dual group with no differences in MI and TVR. CONCLUSIONS: Triple anti-platelet therapy seems to be superior to dual anti-platelet therapy in patients with AMI who had no-reflow phenomenon during PCI.

Radiation shielding effects of lead equivalent thickness of a radiation protective apron and distance during C-arm fluoroscopy-guided pain interventions: A randomized trial.

BACKGROUND: The present study aimed to evaluate the degree of radiation shielding effects according to lead equivalent thickness and distance during C-arm fluoroscopy-guided lumbar interventions. METHODS: The exposure time and air kerma were recorded using a fluoroscope. The effective dose (ED) was measured with and without the shielding material of the lead apron using 2 dosimeters at 2 positions. According to the lead equivalent thickness of the shielding material and distance from the side of the table, the groups were divided into 4 groups: group 1 (lead equivalent thickness 0.6 mm, distance 0 cm), group 2 (lead equivalent thickness 0.6 mm, distance 5 cm), group 3 (lead equivalent thickness 0.3 mm, distance 0 cm), and group 4 (lead equivalent thickness 0.3 mm, distance 5 cm). Mean differences such as air kerma, exposure time, ED, and ratio of EDs (ED with protector/ED without protector) were analyzed. RESULTS: A total of 400 cases (100 cases in each group) were collected. The ratio of ED was significantly lower in groups 1 and 2 (9.18 ±â€…2.78% and 9.56 ±â€…3.29%, respectively) when compared to that of groups 3 and 4 (21.93 ±â€…4.19% and 21.53 ±â€…4.30%, respectively). The reductive effect of a 5-cm distance was 33.3% to 36.1% when comparing the ED between groups 1 and 2 and groups 3 and 4. CONCLUSIONS: The 0.3- and 0.6-mm lead equivalent thickness protectors have a radiation attenuation effect of 78.1% to 78.5% and 90.4% to 90.8%, respectively. The 5-cm distance from the side of the table reduces radiation exposure by 33.3% to 36.1%.