TY - JOUR
T1 - Temperature and SAR measurements in deep-body hyperthermia with thermocouple thermometry
AU - de Leeuw, A. A.
AU - Crezee, J.
AU - Lagendijk, J. J.
PY - 1993
Y1 - 1993
N2 - Multisensor (7-14) thermocouple thermometry is used at our department for temperature measurement with our 'Coaxial TEM' regional hyperthermia system. A special design of the thermometry system with high resolution (0.005 degrees C) and fast data-acquisition (all channels within 320 ms) together with a pulsed power technique allows assessment of specific absorption rate (SAR) information in patients along catheter tracks. A disadvantage of thermocouple thermometry, EM interference, is almost entirely eliminated by application of absorbing ferrite beads around the probe leads. We investigated the effect of remaining disturbance on the temperature decay after power-off, both experimentally in phantoms and in the clinic, and with numerical simulations. Probe and tissue characteristics influence the response time tau dist of the decay of the disturbance. In our clinical practice a normal pulse sequence is 50 s power-on, 10 s power-off: a response time longer than the power-off time results in a deflection of the temperature course at the start. Based on analysis of temperature decays correction of temperature is possible. A double-pulse technique is introduced to provide an initial correction of temperature, and fast information about accuracy. Sometimes disturbance with a relatively long response time occurs, probably due to a bad contact between probe, catheter and/or tissue. Thermocouple thermometry proved to be suitable to measure the SAR along a catheter track. This is used to optimize the SAR distribution by patient positioning before treatment. A clinical example illustrates this
AB - Multisensor (7-14) thermocouple thermometry is used at our department for temperature measurement with our 'Coaxial TEM' regional hyperthermia system. A special design of the thermometry system with high resolution (0.005 degrees C) and fast data-acquisition (all channels within 320 ms) together with a pulsed power technique allows assessment of specific absorption rate (SAR) information in patients along catheter tracks. A disadvantage of thermocouple thermometry, EM interference, is almost entirely eliminated by application of absorbing ferrite beads around the probe leads. We investigated the effect of remaining disturbance on the temperature decay after power-off, both experimentally in phantoms and in the clinic, and with numerical simulations. Probe and tissue characteristics influence the response time tau dist of the decay of the disturbance. In our clinical practice a normal pulse sequence is 50 s power-on, 10 s power-off: a response time longer than the power-off time results in a deflection of the temperature course at the start. Based on analysis of temperature decays correction of temperature is possible. A double-pulse technique is introduced to provide an initial correction of temperature, and fast information about accuracy. Sometimes disturbance with a relatively long response time occurs, probably due to a bad contact between probe, catheter and/or tissue. Thermocouple thermometry proved to be suitable to measure the SAR along a catheter track. This is used to optimize the SAR distribution by patient positioning before treatment. A clinical example illustrates this
U2 - https://doi.org/10.3109/02656739309032056
DO - https://doi.org/10.3109/02656739309032056
M3 - Article
C2 - 8245580
SN - 0265-6736
VL - 9
SP - 685
EP - 697
JO - International journal of hyperthermia
JF - International journal of hyperthermia
IS - 5
ER -