Computerized tomographic scanner with shaped radiation filter.

摘要

The invention comprises a shaped filter (D) and a filter correction circuitry (G) for computerized tomographic scanners. The shaped filter (D) is a generally U-shaped block (200) of filter material which is adapted to be mounted between the source (B) of radiation and the scan circle (10). The U-shaped block (200) has a parabolic recess (204). The filter material may be berryllium, aluminum, sulphur, calcium, titanium, erbium, copper, and compounds including oxides and alloys thereof. The filter correction circuit (G) comprises a first filter correction profile adding circuit (50) for adding a first scaler valve to each intensity valve in a data line. The data tine is operated on by a beam hardness correction polynominal. After the beam hardness polynomial correction operation (F), a second filter correction circuit (80) adds a second filter correction profile consisting of a table of scalor values, one corresponding to each intensity reading in the data line.