Tangential breast irradiation: a multi-centric intercomparison of dose using a mailed phantom and thermoluminescent dosimetry.

Purpose: To measure the accuracy of radiation therapy of the breast planned with 2D and 3D algorithms.
Materials and Methods: The accuracy of radiation therapy of the breast with 2D and 3D algorithms was investigated as a national intercomparison using a semi-anatomical breast phantom. The dose was measured with thermoluminescent (TL) dosemeters.
Results: The mean deviation of measured to planned dose at isocentre was -2.7%. The influence of some planning and irradiation factors is evaluated.
Conclusion: The study demonstrates that beam energy and the use of CT have no marked influence on the accuracy of dose calculations, care has to be exercised when wedges are used and even with sophisticated 3D algorithms there is a systematic error in the dose received by the patient.