|
Accurate corrections for tissue inhomogeneities are a critical part of isodose treatment planning. Although most computerized treatment planning systems currently use CT image data, these systems frequently use empirical formulae in computing correction factors for tissue inhomogeneities. The Electron Density CT Phantom can be used to establish the relationship between the electron density of various tissues and their corresponding CT number (in Hounsfield Units, HU). This data can then be transferred to the computerized treatment planning system for more accurate corrections for tissue inhomogeneities. Scanning this phantom on a periodic basis provides data useful for the Quality Assurance Program of both the CT scanner and the treatment planning system.
The Electron Density CT Phantom consists of a Solid Water® disk approximating the size of an average pelvis. A matrix of sixteen holes in the disk hold interchangeable rods made of various tissue and water simulating materials. The physical density (g/cm3) and electron density relative to water of the rod materials are profiled on a specification sheet that is provided with each phantom. The phantom also has a pattern of small air holes with known spacings for checking the CT scanner’s distance measurement accuracy. A carrying case is included.
Specifications
Disk Material: Solid Water
Diameter: 12.9”
Height: 2”
Weight with Disk and Rods: 10.7 lbs.
Weight with Case: 24 lbs.
|
