Treatment planning in Cobalt-60 radiotherapy using computerized tomography techniques

Cobalt-60 transmission measurements were made through an Alderson phantom utilizing a transverse axial tomographic device and a NaI (Tl) detector. Measurements were made on different sections of the phantom for as many as 162 angles and 120 linear increments. The attenuation coefficients were reconstructed using both convolution and algebraic reconstruction techniques. Three-dimensional isodose distributions were obtained using the reconstructed attenuation coefficients. Comparison with standard treatment plans and measured isodose distribution using TLD techniques suggest that a more accurate isodose distribution may be obtained using the reconstructed attenuation coefficients, particularly in regions involving tissue heterogeneities.