ESTRO 2024 - Abstract Book

S4760

Physics - Quality assurance and auditing

ESTRO 2024

The accuracy in volume and position of the two end-results, GTVacc_Ar and GTVacc_Ve, was compared with GTVacc_GT for all patients by calculating the Dice Coefficients (DC), denoted as DC_Ar and DC_Ve, respectively.

The DC is calculated as twice the overlap between two volumes divided by the sum of the two volumes:

DC = 2*( A ∩ B )/( A + B ),

where A and B represent two volumes. DC ranges from 0 (no overlap) to 1 (perfect overlap and equal volume sizes).

Results:

The results from the volume, motion, and DC measurements for all GTVs are shown in Table 1 . The average volume of the GTVs was 3.6cc, and the volume ratio due to tumor motion (GTVacc_GT / GTV) was 2.3. The range of volume ratios was 1.6-2.8 for all patients, except for one, which was 5.5 (Pt. 3) , indicating a larger tumor motion for this patient (see Figure 1 ).

GTVacc_Ar - GTVacc_GT (cc)

GTVacc_Ve - GTVacc_GT (cc)

Pt. No

GTV (cc)

GTVacc_GT (cc)

GTVacc_GT / GTV

DC_Ar

DC_Ve