• Asian Pacific Journal of Cancer Prevention
• /
• 제16권14호
• /
• pp.6159-6162
• /
• 2015

Purpose: To evaluate efficacy of transarterial chemoembolization (TACE) combined with radiofrequency ablation (RFA) in treatment of patients with hepatocellular carcinoma. Materials and Methods: During January 2009 to March 2012, 80 patients with hepatocellular carcinoma underwent TACE, with or without RFA. Alfafetoprotein (AFP) was checked before and after procedure. CT scans were obtained one month after TACE or RFA for all patients to evaluate tumor changes. Complete response+partial response+stable disease (CR+PR+SD)/n were used to assess the disease control rate (DCR). Survival at 3, 6 and 12 months was compared in both groups. Results: AFP levels in TACE + RFA group dropped rapidly, becoming obviously lower than that of the TACE group. In the TACE + RFA group DCR was 93.8%, while only 76.8% in the TACE group. The treatment effect between the two groups was statistically significant (P<0.05) by Ridit analysis. 1 year survival rate in the TACE + RFA group was 92.5%, significantly higher than that of the TACE group at 77.5% (P<0.05). Conclusions: TACE and RFA as combined therapy method for patients with middle and terminal stage HCC gives full play to synergy between the two and improves the therapeutic effect.

• Journal of Chest Surgery
• /
• 제56권2호
• /
• pp.90-98
• /
• 2023

Background: Atrial fibrillation (AF) is the most common type of cardiac arrhythmia. Totally thoracoscopic ablation (TTA) is a surgical treatment showing a high success rate as a hybrid procedure with radiofrequency catheter ablation to control AF. This study compared the early complications of warfarin and non-vitamin K antagonist oral anticoagulants (NOACs) in patients who underwent TTA. Methods: This single-center retrospective cohort study enrolled patients who underwent planned TTA for AF from February 2012 to October 2020. All patients received postoperative anticoagulation, either with warfarin or a NOAC (apixaban, rivaroxaban, dabigatran, or edoxaban). Propensity score matching was performed for both groups. Early complications were assessed at 12 weeks after TTA and were divided into efficacy and safety outcomes. Both efficacy and safety outcomes were compared in the propensity score-matched groups. Results: Early complications involving efficacy outcomes, such as stroke and transient ischemic attack, were seen in 5 patients in the warfarin group and none in the NOAC group. Although the 2 groups differed in the incidence of efficacy outcomes, it was not statistically significant. In safety outcomes, 11 patients in the warfarin group and 24 patients in the NOAC group had complications, but likewise, the between-group difference was not statistically significant. Conclusion: Among patients who underwent TTA, those who received NOACs had a lower incidence of thromboembolic complications than those who received warfarin; however, both groups showed a similar bleeding complication rate. Using a NOAC after TTA does not reduce efficacy and safety when compared to warfarin.

• 한국정밀공학회지
• /
• 제26권3호
• /
• pp.25-31
• /
• 2009

Femto-second laser ablation with the various feed velocities of the Invar alloy and the micro surface milling for the processing condition were studied. We used a regenerative amplified Ti:sapphire laser with a 1kHz repetition rate, 184fs pulse duration time and 785nm wavelength. Femto-second laser pulse was irradiated on the Invar alloy with the air blowing at the condition of various laser peak powers and feed velocities. An ablation characteristic according to feed velocity of the Invar alloy was appeared as the non-linear type at different zone of energy fluence. The micro surface milling of the Invar alloy using a mapping method was investigated. The optimal condition of micro surface milling was laser peak power of 22.8mW, feed velocity of 1 mm/s, beam gap of $1{\mu}m$. With the optimal processing condition, the fine rectangular shape without burr and thermal damage was achieved. Using the femto-second laser system, it demonstrates excellent tool for micro surface milling of the Invar alloy without heat effects and poor edge.

• 한국정밀공학회지
• /
• 제17권8호
• /
• pp.134-139
• /
• 2000

In order to understand the removal mechanism and seek the optimal conditions. KrF excimer laser ablation of Cr films on glass substrates is investigated. The surface morphology of the laser-irradiated spot is examined by SEM. The measured single-shot ablation rate is found to be about two times the result of numerical analysis based on a surface vaporization model and heat conduction theory. Surface morphology examination indicates that the Cr film is removed by the sequence of melting-surface vaporization-,melt expulsion by plasma recoil and that the outmost ripple of the diffraction pattern gives a strong effect on the morphology of molten Cr during the melting and vaporization processes. To seek the optimal process parameters for micro patterning morphological investigation is carried out experimentally on samples having different chromium film thicknesses. Optimal processing conditions are determined to enhance the accuracy and quality of thin film removal for micro patterning.

• Nuclear Engineering and Technology
• /
• 제49권3호
• /
• pp.645-650
• /
• 2017

This technical note demonstrates the feasibility of using laser ablation inductively coupled plasma mass spectrometry for the characterization of U-7Mo/Ale5Si dispersion fuel. Our measurements show 5.0% Relative Standard Deviation (RSD) for the reproducibility of measured $^{98}Mo/^{238}U$ ratios in fuel particles from spot analysis, and 3.4% RSD for $^{98}Mo/^{238}U$ ratios in a NIST-SRM 612 glass standard. Line scanning allows for the distinction of U-7Mo fuel particles from the Al-5Si matrix. Each mass spectrum peak indicates the presence of U-7Mo fuel particles, and the time width of each peak corresponds to the size of that fuel particle. The size of the fuel particles is estimated from the time width of the mass spectrum peak for $^{98}Mo$ by considering the scan rate used during the line scan. This preliminary application clearly demonstrates that laser ablation inductively coupled plasma mass spectrometry can directly identify isotope ratios and sizes of the fuel particles in U-Mo/Al dispersion fuel. Once optimized further, this instrument will be a powerful tool for investigating irradiated dispersion fuels in terms of fission product distributions in fuel matrices, and the changes in fuel particle size or shape after irradiation.

• 한국레이저가공학회지
• /
• 제9권3호
• /
• pp.15-21
• /
• 2006

A Polypropylene (PP) film was ablated using a femtosecond laser with a center wavelength of 785 nm, a pulse width of 184 fs and a repetition rate of 1 kHz. Increments of both pulse energy and the shot number of pulses lead to co-occurrence of photochemical and thermal effect, demonstrated by the spatial expansion of rim on the surface of PP. The shapes of the laser-ablated PP films were imaged by a scanning electron microscope (SEM) and measured a 3D optical measurement system (NanoFocus). And, the oxygen transmission rate (ORT) of periodically laser-ablated PP film were characterized by oxygen permeability tester for modified atmosphere packaging (MAP) of fresh fruit and vegetable. Our results demonstrate that femtosecond pulsed laser is efficient tools for breathable packaging films in modifying the flow of air and gas into and out of a fresh produce container, where the micropatterns are specifically tailored in size, location and number which are easily controlled by laser pulse energy and pulse patterning system.

• 대한영상의학회지
• /
• 제85권3호
• /
• pp.618-630
• /
• 2024

목적 본 연구는 낭성 및 고형성 혼합 갑상선 결절 치료에서 고주파 절제술 단독요법과 에탄올 절제 후 고주파 절제술 요법의 유효성 및 안전성을 비교하고자 하였다. 대상과 방법 본 연구는 초음파 유도 하 조직검사에서 양성으로 확인된 243개의 낭성 및 고형성 혼합 갑상선 결절을 대상으로 진행됐으며, 243개의 결절은 243명의 환자로부터 진단되었다. 연구 대상이 된 결절들은 고주파 절제술 단독요법과 에탄올 절제 후 고주파 절제술 요법을 받은 군의 두 군으로 나누어 분류됐다. 본 연구는 각 군에서의 시술 후 부피 감소율, 치료 성공률, 증상 및 미용 문제의 개선 정도를 평가하였다. 또한 시술 후 연관된 합병증이나 부작용이 발생하였는지 확인하였다. 결과 고주파 절제술 단독 요법 군에는 204명의 환자가 포함되었고, 에탄올 절제 후 고주파 절제술 요법 군에는 39명의 환자가 포함되었다. 단독요법군과 혼합요법 군에서 최종 추적 검사 시 평균 부피 감소율은 각각 81.6%와 87.2%였다. 두 군에서의 장기적 치료 성공률은 각각 90.2%와 97.4%였다. 치료 결과는 마지막 추적 관찰 시기에서 두 군에서 유사하게 나타났다. 대부분 낭성 결절에 국한된 추가 분석에서도 두 군 간에 치료 효과에 있어 유의미한 차이가 없었다. 증상 및 미용적 문제는 두 군에서 모두 현저하게 개선되었다. 시술 후 연관된 큰 합병증은 두 군 모두에서 발생하지 않았다. 결론 에탄올 절제 후 고주파 절제술 혼합 요법이 고주파 절제술 단독요법에 비해 약간 더 나은 치료 방법이지만, 두 치료 요법 모두 낭성 및 고형성 혼합 결절의 치료에 안전하고 효과적인 방법이다.

• Korean Journal of Radiology
• /
• 제21권6호
• /
• pp.764-772
• /
• 2020

Objective: Laser ablation is a therapeutic modality used to reduce the volume of large benign thyroid nodules. Unsatisfactory reduction and regrowth are observed in some treated nodules. The aim of the study was to evaluate the long-term outcomes of laser treatment for solid nodules during a 5-year follow-up period, the regrowth rate, and the predictive risk factors of nodule regrowth. Materials and Methods: We retrospectively evaluated patients with benign, solid, cold thyroid nodules who underwent laser ablation and were followed-up for 5 years. According to the selection criteria, 104 patients were included (median baseline nodule volume, 12.5 mL [25.0-75.0%, 8-18 mL]; median energy delivered, 481.5 J/mL [25.0-75.0%, 370-620 J/mL]). Nodule volume, thyroid function test results, and ultrasound were evaluated at baseline and then annually after the procedure. Results: Of 104 patients, 31 patients (29.8%) had a 12-month volume reduction ratio (VRR) < 50.0% and 39 (37.5%) experienced nodule regrowth. Of these 39 patients, 17 (43.6%) underwent surgery and 14 (35.9%) underwent a second laser treatment. The rate of nodule regrowth was inversely related to the 12-month VRR, i.e., the lower the 12-month VRR, the higher the risk of regrowth (p < 0.001). The mean time for nodule regrowth was 33.5 ± 16.6 months. The 12-month VRR was directly related to time to regrowth, i.e., the lower the 12-month VRR, the shorter the time to regrowth (p < 0.001; R² = 0.3516). Non-spongiform composition increased the risk of regrowth with an odds ratio of 4.3 (95% confidence interval [CI] 1.8-10.2; p < 0.001); 12-month VRR < 50.0% increased the risk of regrowth with an odds ratio of 11.7 (95% CI 4.2-32.2; p < 0.001). Conclusion: The VRR of thyroid nodules subjected to similar amounts of laser energy varies widely and depends on the nodule composition; non-spongiform nodules are reduced to a lesser extent and regrow more frequently than spongiform nodules. A 12-month VRR < 50.0% is a predictive risk factor for regrowth and correlates with the time to regrowth.

• 대한영상의학회지
• /
• 제81권3호
• /
• pp.620-631
• /
• 2020

목적 5 cm 이하 크기의 간암을 가진 92명의 환자군에서 식염수 주입방식 전극을 이용한 고주파 소작술의 국소 재발률과 예후인자를 평가하였다. 대상과 방법 2009년부터 2015년까지 간암으로 식염수 주입전극 고주파 소작술을 받은 92명 환자(148개 간암)를 대상으로 하였다. 후향적으로 기술적인 성공과 효능, 국소 재발률을 분석하였다. 국소 재발의 가능한 예후인자로써 혈관주위종양, 횡경막하종양, 인공복수 유무, 2 cm이상 크기, 이전 간동맥색전술 치료 여부를 평가하였다. 결과는 각각의 병변 별로 분석하였다. 결과 1~97.4개월의 추적관찰 기간 동안 누적 국소 재발률은 1년, 3년, 5년에서 각각 7.9%, 11.4%, 14.6%였다. 5년 누적 국소 재발률은 혈관주위간암과(35.1%; p = 0.009) 횡경막하간 암에서(38.9%; p = 0.002) 각각 비교군에 비해 유의미하게 높았다. 다른 예후인자들에서 국소 재발률의 유의미한 차이는 없었다(p > 0.05). 결론 식염수 주입전극을 이용한 고주파 소작술은 5 cm 이하 크기의 간암을 국소 재발률 증가없이 안전하고 효과적으로 치료할 수 있다. 그렇지만 식염수 주입전극으로도 혈관 주위와 횡경막하 위치의 간암은 다른 부위에 비해 국소 재발률이 높으므로, 혈관주위간암과 횡경막하간암은 식염수 주입전극을 이용한 고주파 소작술에서도 국소 재발의 위험성이 크다는 것을 유념하여야 한다.

• Korean Journal of Radiology
• /
• 제24권8호
• /
• pp.761-771
• /
• 2023

Objective: To investigate the association among the electrode placement method, electrode type, and local tumor progression (LTP) following percutaneous radiofrequency ablation (RFA) for small hepatocellular carcinomas (HCCs) and to assess the risk factors for LTP. Materials and Methods: In this retrospective study, we enrolled 211 patients, including 150 males and 61 females, who had undergone ultrasound-guided RFA for a single HCC < 3 cm. Patients were divided into four combination groups of the electrode type and placement method: 1) tumor-puncturing with an internally cooled tip (ICT), 2) tumor-puncturing with an internally cooled wet tip (ICWT), 3) no-touch with ICT, and 4) no-touch with ICWT. Univariable and multivariable Cox proportional-hazards regression analyses were performed to evaluate the risk factors for LTP. The major RFA-related complications were assessed. Results: Overall, 83, 34, 80, and 14 patients were included in the ICT, ICWT, no-touch with ICT, and no-touch with ICWT groups, respectively. The cumulative LTP rates differed significantly among the four groups. Compared to tumor puncturing with ICT, tumor puncturing with ICWT was associated with a lower LTP risk (adjusted hazard ratio [aHR] = 0.11, 95% confidence interval [CI] = 0-0.88, P = 0.034). However, the cumulative LTP rate did not differ significantly between tumor-puncturing with ICT and no-touch RFA with ICT (aHR = 0.34, 95% CI = 0.03-1.62, P = 0.188) or ICWT (aHR = 0.28, 95% CI = 0-2.28, P = 0.294). An insufficient ablative margin was a risk factor for LTP (aHR = 6.13, 95% CI = 1.41-22.49, P = 0.019). The major complication rates were 1.2%, 0%, 2.5%, and 21.4% in the ICT, ICWT, no-touch with ICT, and no-touch with ICWT groups, respectively. Conclusion: ICWT was associated with a lower LTP rate compared to ICT when performing tumor-puncturing RFA. An insufficient ablation margin was a risk factor for LTP.