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Simulation of Radiation Dose Response in Phantom for CT

H. Chen-Mayer1 R.E. Tosh1
1National Institute of Standards and Technology, Gaithersburg, MD, USA

Output of temperature waveform.

The radiation dose produced by an x-ray CT scanner to the patient is conventionally referenced to measurements performed by an ionization chamber in a phantom. On a fundamental level, the radiation absorbed dose, J/kg, can be determined directly by the temperature rise in the absorbing material. We model the temperature response in a high density polyethylene (HDPE) phantom.

Use of COMSOL Multiphysics: A PE cylinder with 2D axial symmetry is heated by a planar source with a 2.8 s on/off cycle. The simulation performed with a pure PE phantom gives a much lower contrast for the beam on/off transitions. Adding glass and wire materials prduced better matching with the experimental data, but still needs adjestment of the beam power.

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