Comparison between high-frequency irreversible electroporation and irreversible electroporation ablation of small swine liver: follow-up of DCE-MRI and pathological observations / 中华医学杂志(英文版)

BACKGROUND@#High-frequency irreversible electroporation (H-FIRE) is a novel, next-generation nanoknife technology with the advantage of relieving irreversible electroporation (IRE)-induced muscle contractions. However, the difference between IRE and H-FIRE with distinct ablation parameters was not clearly defined. This study aimed to compare the efficacy of the two treatments in vivo.@*METHODS@#Ten Bama miniature swine were divided into two group: five in the 1-day group and five in the 7-day group. The efficacy of IRE and H-FIRE ablation was compared by volume transfer constant (Krans), rate constant (Kep) and extravascular extracellular volume fraction (Ve) value of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), size of the ablation zone, and histologic analysis. Each animal underwent the IRE and H-FIRE. Temperatures of the electrodes were measured during ablation. DCE-MRI images were obtained 1, 4, and 7 days after ablation in the 7-day group. All animals in the two groups were euthanized 1 day or 7 days after ablation, and subsequently, IRE and H-FIRE treated liver tissues were collected for histological examination. Student's t test or Mann-Whitney U test was applied for comparing any two groups. One-way analysis of variance (ANOVA) test and Welch's ANOVA test followed by Holm-Sidak's multiple comparisons test, one-way ANOVA with repeated measures followed by Bonferroni test, or Kruskal-Wallis H test followed by Dunn's multiple comparison test was used for multiple group comparisons and post hoc analyses. Pearson correlation coefficient test was conducted to analyze the relationship between two variables.@*RESULTS@#Higher Ve was seen in IRE zone than in H-FIRE zone (0.14 ± 0.02 vs. 0.08 ± 0.05, t = 2.408, P = 0.043) on day 4, but no significant difference was seen in Ktrans or Kep between IRE and H-FIRE zones at all time points (all P > 0.05). For IRE zone, the greatest Ktrans was seen on day 7, which was significantly higher than that on day 1 (P = 0.033). The ablation zone size of H-FIRE was significantly larger than IRE 1 day (4.74 ± 0.88 cm2vs. 3.20 ± 0.77 cm2, t = 3.241, P = 0.009) and 4 days (2.22 ± 0.83 cm2vs. 1.30 ± 0.50 cm2, t = 2.343, P = 0.041) after treatment. Apoptotic index (0.05 ± 0.02 vs. 0.73 ± 0.06 vs. 0.68 ± 0.07, F = 241.300, P  0.05). Electrode temperature variations were not significantly different between the two zones (18.00 ± 3.77°C vs. 16.20 ± 7.45°C, t = 0.682, P = 0.504). The Ktrans value (r = 0.940, P = 0.017) and the Kep value (r = 0.895, P = 0.040) of the H-FIRE zone were positively correlated with the number of hepatocytes in the ablation zone.@*CONCLUSIONS@#H-FIRE showed a comparable ablation effect to IRE. DCE-MRI has the potential to monitor the changes of H-FIRE ablation zone.

Comparative analysis on morning and evening absolute dose output stability of medical linear accelerator / 医学研究生学报

Objective The ionization chamber of ELEKTA medical linear accelerator monitoring is open to environmental factors such as temperature, air pressure, and humidity that may affect the stability of absolute dose output .The article aimed to ana-lyze the morning and evening absolute dose output stability at different energies of ELEKTA SYNERGY medical linear accelerator . Methods The absolute doses at different energies of medical linear accelerators were calibrated according to the IAEA TRS -277 re-port, and WI3 type solid water was used to perform repeated measurements in the morning and in the evening for 52 consecutive days under the same measurement conditions , during which a water tank measurement was conducted at random intervals per week to verify the accuracy of WI3 solid water measurements. Results The maximum deviation of WI3 solids water and tank measurement at all en -ergies was 0.5％ and the maximum deviations of daily energy stability at different energies were : -2.0％ (6MV), 1.9％ (15MV), 1.8％ (6MeV), -2.4％ (8MeV), -2.3％ (10MeV), -2.0％ (12MeV), 2.1％ (15MeV).The differences of 6MV, 15MV, 8MeV, and 10MeV energies in morning and evening paired t tests were statistically significant (P<0.05) without clinical significance, while no statistic significance was found in the differences of 6MeV, 12MeV, and 15MeV energies ( P >0.05). Conclusion Elekta Synergy medical linear accelerator shows excellent stability in absolute dose output.