Noninvasive thermometry with a clinical x-ray CT scanner

Area of Science:

• Medical Imaging
• Biophysics
• Thermometry

Background:

• CT scanners measure CT numbers proportional to electron density.
• Temperature variations cause density changes, leading to CT number shifts.
• Noninvasive thermometry is crucial for monitoring cancer hyperthermia treatments.

Purpose of the Study:

• To investigate the potential of CT number shifts for noninvasive thermometry.
• To evaluate CT thermometry in vitro for cancer hyperthermia applications.

Main Methods:

• In vitro study using water and muscle tissue samples.
• Utilized an EMI-7070 CT scanner to measure CT numbers.
• Analyzed the relationship between CT numbers, density, and temperature.

Main Results:

• A linear relationship exists between CT number and water density (10-55°C).
• Linear CT number-temperature relationship observed in the hyperthermia range (36-50°C).
• CT number thermal shifts of ~0.4 HU/°C (water) and ~0.45 HU/°C (muscle) were recorded.

Conclusions:

• Thermally generated CT number shifts show promise for noninvasive thermometry.
• Feasible temperature discrimination of a fraction of a degree Celsius is achievable.
• CT thermometry can be applied to monitor temperature during cancer hyperthermia.