Dosimetric end-to-end tests in a national audit of 3D conformal radiotherapy

•End-to-end radiotherapy audits have been performed on 94 occasions in Australia.•Conformal fields were assessed on an anthropomorphic thorax phantom.•Dose after lung measured low for analytical anisotropic algorithm (AAA) calculations.•AAA also overestimated dose in tangential fields as used in breast cancer treatments.•AAA underestimated dose to points inside lung inhomogeneities.•Superposition and convolution algorithms had problems with large angle wedges.