Quality assurance, Safety, Audit and standards, CT, Computer applications, Radioprotection / Radiation dose, Radiotherapy techniques
I. Williams1, J. Lye1, A. Alves1, M. Shaw1, J. Supple1, F. Gibbons2, S. Keehan1; 1VIC/AU, 2QLD/AU
Both Level II and III audits include measurements in a defined low dose region in the centre of a wrap-around C-shape (LII case 14 and LIII case 6 – no lung; LII case 15 and LIII case 7 – with lung).
The Level III audit also includes a “complex case” with two adjacent target structures and a fully encapsulated low dose region (case 8).
Figures 3 and 4 show the mean local dose difference in the exclusion volume as a function of mean measured dose in the exclusion volume for LII cases 14 and 15 respectively.
Figures 5 – 7 are the equivalent plots for LIII cases 6 – 8 respectively.
Level III cases have a single measurement point within the exclusion volume.
These figures illustrate a relationship between lower dose in the tissue sparing region and increased discrepancy between the planned and measured dose.
Figures 8 and 9 show the local dose variations for the exclusion volumes in LII and LIII audits (all cases) respectively.
Significant differences between algorithms was observed and the general trends between them were quite similar for both LII and LIII audit data.
The exception is the Xio Superposition algorithm for which the ACDS has only one audit at each level.
the data to-date cannot be used to draw inference.