Fig. 1.

A is the pelvic configuration of the CIRS phantom, B the lung configuration and C the head and neck configuration. D-F are the corresponding axial slices containing the density inserts. The CT Number Linearity inserts are located in the red layer shown in A and C. For the lung configuration, the inner sections of the phantom (062MA-01, 062MQA-50) were removed while for the H&N configuration the outer parts (062MA-02, 062MA-36) were removed. The phantom includes eight or 16 tissue equivalent inserts with known physical density. The parts on the left side in A and B are put aside for visualization purposes and are put back in place for image acquisition. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)