DOSIMETER GEL AND MR-IMAGING FOR VERIFICATION OF CALCULATED DOSE DISTRIBUTIONS IN CLINICAL RADIATION-THERAPY

A dosimeter gel, based on an agarose gel infused with a ferrous sulpha te solution and evaluated in a magnetic resonance scanner, was used fo r complete Verification of calculated dose distributions. Two standard treatment procedures, treatment of cancer in the urinary bladder and treatment of breast cancer after modified radical mastectomy, were exa mined using pixel-by-pixel and dose volume histogram comparison. The d ose distributions calculated with the dose planning system was in very good agreement with the measured ones. However, in the case of the mo re complicated breast cancer treatment, some discrepancies were found, mainly at the beam abutment region. This may be explained by held dis placements errors and by a small limitation of the dose planning utili sing small electron beams in this region. The dosimeter gel system hav e proven to be a useful tool for dosimetry in clinical radiation thera py applications.