New conformity indices based on the calculation of distances between the target volume and the volume of reference isodose

作者：Park J M; Park S Y; Ye S J; Kim J H; Carlson J; Wu H G^*

来源：British Journal of Radiology, 2014, 87(1043): 20140342.

DOI：10.1259/bjr.20140342

Objective: To present conformity indices (CIs) based on the distance differences between the target volume (TV) and the volume of reference isodose (V-RI).
Methods: The points on the three-dimensional surfaces of the TV and the V-RI were generated. Then, the averaged distances between the points on the TV and the V-RI were calculated (CIdistance). The performance of the presented CIs were evaluated by analysing six situations, which were a perfect match, an expansion and a reduction of the distance from the centroid to the V-RI compared with the distance from the centroid to the TV by 10%, a lateral shift of the V-RI by 3 cm, a rotation of the V-RI by 45 degrees and a spherical-shaped V-RI having the same volume as the TV. The presented CIs were applied to the clinical prostate and head and neck (H&N) plans.
Results: For the perfect match, CIdistance was 0 with 0 as the standard deviation (SD). When expanding and reducing, CIdistance was 10 and -10 with SDs <1.3, respectively. With shifting and rotating of the V-RI, the CIdistance was almost 0 with SDs >11. The average value of the CIdistance in the prostate and H&N plans was 0.13 +/- 7.44 and 6.04 +/- 23.27, respectively.
Conclusion: The performance of the CIdistance was equal or better than those of the conventional CIs.
Advances in knowledge: The evaluation of target conformity by the distances between the surface of the TV and the V-RI could be more accurate than evaluation with volume information.

• 出版日期2014-11