%0 Journal Article
%T ¡®Relationship between thermal dose and cell death for ¡°rapid¡± ablative and ¡°slow¡± hyperthermic heating¡¯
%A Gail ter Haar
%A Ian Rivens
%A John Civale
%A Petros X. E. Mouratidis
%A Richard Symonds-Tayler
%J International Journal of Hyperthermia
%D 2019
%R https://doi.org/10.1080/02656736.2018.1558289
%X Abstract Aim: Thermal isoeffective dose (TID) has not been convincingly validated for application to predict biological effects from rapid thermal ablation (e.g., using >55£¿¡ãC). This study compares the classical method of quantifying TID (derived from hyperthermia data) with a temperature-adjusted method based on the Arrhenius model for predicting cell survival in vitro, after either ¡®rapid¡¯ ablative or ¡®slow¡¯ hyperthermic exposures. Methods: MTT assay viability data was obtained from two human colon cancer cell lines, (HCT116, HT29), subjected to a range of TIDs (120¨C720 CEM43) using a thermal cycler for hyperthermic (>2£¿minutes, <50£¿¡ãC) treatments, or a novel pre-heated water bath based technique for ablative exposures (<10£¿seconds, >55£¿¡ãC). TID was initially estimated using a constant RCEM>43¡ãC=0.5, and subsequently using RCEM(T), derived from temperature dependent cell survival (injury rate) Arrhenius analysis. Results: ¡®Slow¡¯ and ¡®rapid¡¯ exposures resulted in cell survival and significant regrowth (both cell lines) 10£¿days post-treatment for 240 CEM43 (RCEM>43¡ãC=0.5), while 340-550 CEM43 (RCEM>43¡ãC =0.5) delivered using ¡®rapid¡¯ exposures showed 12£¿¡À£¿6% viability and ¡®slow¡¯ exposures resulted in undetectable viability. Arrhenius analysis of experimental data (activation energy ¦¤E£¿=£¿5.78£¿¡À£¿0.04£¿¡Á£¿105 J mole£¿1, frequency factor A£¿=£¿3.27£¿¡À£¿11£¿¡Á£¿1091£¿sec£¿1) yielded RCEM=0.42£¿*£¿e0.0041*T which better-predicted cell survival than using R CEM> 43¡ãC=0.5. Conclusions: TID calculated using an RCEM(T) informed by Arrhenius kinetic parameters provided a more consistent, heating strategy independent, predictor of cell viability, improving dosimetry of ablative thermal exposures. Cell viability was only undetectable above 305£¿¡À£¿10 CEM43 using this revised measure
%U https://www.tandfonline.com/doi/full/10.1080/02656736.2018.1558289