Corrections
Currently, the most sophisticated algorithms are mod-
el-based - some examples: pencil beam, convolution/superposition, and semi-
Monte Carlo techniques).
Dose reduction can occur at air cavity surfaces and - lung due to a partial loss of
electronic equilibrium. The effect is more pronounced for small fields (<6 × 6 cm2)
and high-energy beams (>6 MV).
Dose to soft tissue within bone is two to five times higher in the - orthovoltage
and superficial range of beam energies. It is about 3% to 10% higher in the
megavoltage range used clinically
Dose within bone depends on - beam energy.
Fusion techniques are used to combine their images with - the corresponding CT
images to provide geometric accuracy of external contour and internal anatomy.
How are the signal values for an ultrasound, MRI, and PET corrected? - with
electron density.
Imaging modalities such as ultrasound, MRI, and PET are useful in - mapping out
structural and/or functional anatomy,