Thermometry considerations in localized hyperthermia

Abstract

The introduction of local hyperthermia as a method of cancer therapy implies the necessity of quantitative measurements of the thermal dose. Our intention is to describe the nature of the problem, both physically and physiologically, with illustrations drawn from thermographic measurements in phantoms and in animals. The characteristics of a thermometry calibration facility are described. Some measurement problems associated with conventional thermometer probes are mentioned and several new thermometers which were developed for use in the electromagnetic fields are reviewed. We present some of the concepts that will guide the development of noninvasive thermometry. Systemic hyperthermia is not considered. We recommend that other reviews specifically directed toward localized hyperthermia be prepared on the methods of heating and on thermal physiological problems.

MRI thermometry in phantoms by use of the proton resonance frequency shift method: application to interstitial laser thermotherapy

“…Non-invasive temperature monitoring is important for the development of hyperthermia and thermotherapy (Cetas andConnor 1978, Bolomey andHawley 1990), and magnetic resonance imaging (MRI) seems to be a promising method. Three main parameters, the spin-lattice relaxation time (T 1 ), the molecular diffusion coefficient and the proton resonance frequency, have been examined with respect to their temperature dependence (LeBihan 1995, Jolesz andZientara 1995).…”

Response of two mouse tumours to hyperthermia with CCNU or melphalan

“…In this study we have used probes with a diameter of 02 mm, which is very small compared to the diameter of the heated limbs (9.5-11.5 mm). Cetas & Connor (1978) have also reported that the use of temperature sensors mounted in hypodermic needles can lead to measurement errors due to thermal conduction along the metal sheath, and tnese errors can be important when using such probes for measurements in tissues at depths < 3 mm. We have therefore used only unsheathed thermocouple probes for the temperature measurements reported here.…”

Speed of Sound

“…Difficulties also arise due to the substantial variation of the sound speed at a given temperature from tissue to tissue and from specimen to specimen. There was a suggestion that dc=dT is sufficiently better behaved as to be useful Cetas & Connor 1978;Nasoni et al 1979), particularly if one has prior knowledge of regional distributions of particular tissue types and if the differential speed information is combined with differential attenuation data (Haney & O'Brien 1982). If all that is required is an image to show the position of a localised alteration of temperature with time, then such images can be made using echo strain estimation methods to measure the spatial distribution of echo stretching or contraction due to localised heating or cooling (Seip et al 1996;Bamber et al 1997;Miller et al 2002Miller et al , 2003.…”