Tissue Characterization CT Phantom

©JRT Associates 2008

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 Tissue Characterization Phantom can be used to calibrate the CT unit by establishing 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.

The Tissue Characterization Phantom consists of a Solid Water disc approximating the size of an average pelvis. A matrix of sixteen holes in the disc hold interchangeable plugs made of various tissue and water-simulating materials. The physical density (g/cm³) and electron density relative to water of the plug materials are listed in the user’s manual. 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.

Scanning this phantom on a period basis provides data useful for the Quality Assurance Program of both the CT scanner and the treatment planning system.

467 Electron Density CT Phantom

467-019 Titanium Rod Insert

467-TOMO Tomotherapy TE Plugs, Set