Using units of CEM 43°C T₉₀, local hyperthermia thermal dose can be delivered as prescribed

Abstract

A randomized study was designed in dogs with spontaneous soft tissue sarcomas to gain information about the relationship between hyperthermia dose and outcome. The study compared two levels of thermal dose applied to dogs with heatable tumours, so it was necessary to deliver either a low (2-5 CEM 43 degrees C T90) or high (20-50 CEM 43 degrees C T90) thermal dose as precisely as possible. It was also desirable to have similar numbers of hyperthermia treatments in each thermal dose group. Identification of heatable tumours and randomization to high or low heat dose group was done during the first hyperthermia treatment. This was readily accomplished using mapping of temperatures in thermometry catheters, manual recording of thermal data, and visual inspection of raw thermal data with subsequent adjustment of the duration of the hyperthermia treatment. An analysis of precision of thermal dose delivery was conducted after approximately 50% of projected accrual had been met in a randomized phase III assessment of thermal dose effect. Fifty-four dogs were eligible for randomization; in 48 dogs the tumour was deemed heatable according to predetermined temperature criteria applied during the first heat treatment. Twenty-four dogs were randomized to the high heat dose group, and 24 to the low heat dose group. Median (range) total thermal dose for dogs in the high dose group was 43.5 CEM 43 degrees C T90 (16.4-66.6) compared to 3.2 CEM 43 degrees C T90 (2.1-4.6) for dogs in the low dose group. There was no overlap of thermal doses between groups. Thus, thermal dose could be delivered accurately, being within the predetermined range in 47 of the 48 dogs. Thermal dose quantified as CEM 43 degrees C T50, however, did overlap between groups and the clinical significance of this finding will not be known until outcome data are analysed. Most dogs in both groups received five hyperthermia treatments. Median (range) treatment duration for dogs in the high dose group was 300 min (147-692) compared to III min (51-381) for dogs in the low dose group. Relatively simple but accurate methods of delivering prescribed thermal dose as described herein will aid the translation of clinical hyperthermia from the research setting into more general practice once the characteristics of the relationship between hyperthermia dose and outcome are understood.

Thermal Dose Is Related to Duration of Local Control in Canine Sarcomas Treated with Thermoradiotherapy

“…Note that there were eight dogs (four in each thermal dose group) that did not finish all planned hyperthermia treatments due to various reasons. The median (interquartile range) number of temperature points was 21 (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27). There was excellent temperature discrimination between thermal dose groups (Fig.…”

“…In prior work, we determined that a prescribed thermal dose could be delivered accurately (25). This was accomplished by visual inspection of measured temperatures, estimation of the 10th percentile temperature (T90), and adjustment of power and/or treatment time until the prescribed CEM43jCT90 dose was delivered.…”

Electrokinetics of Temperature for Development and Treatment of Effusions

“…The dosing problem is one of the main barriers to the wide clinical acceptance of hyperthermia in oncology [63]. The present dosing in hyperthermia is explained by the following principles: 1) Isothermal heating of the target trying to distribute the temperature as homogeneously as possible [64];…”

Nanoheating without Artificial Nanoparticles Part II. Experimental Support of the Nanoheating Concept of the Modulated Electro-Hyperthermia Method, Using U937 Cell Suspension Model

“…The thermal processes in hyperthermia are generally described by Arrhenius plots [54]. The proposed reference temperature in the hyperthermia dose is 43°C [55], which is also determined by the Arrhenius thermal actions [2], and the dose function for clinical use is also based on this thermal effect [56].…”