Background Image
Table of Contents Table of Contents
Previous Page  223 / 1311 Next Page
Information
Show Menu
Previous Page 223 / 1311 Next Page
Page Background

Keeping things in perspective

• GTV

PTV margin

– All cells in the GTV are considered to be tumor

– P

underdosage

= P

geometrical miss

– Use margin prescription

• CTV

PTV margin

– In the CTV there is a probability of tumor cells

– P

underdosage

= P

geometrical miss

x P

presence of tumor cells

– Margin can probably be smaller

• Caveat: Tumor cell probability is needed