ESTRO 2024 - Abstract Book

S2984

Interdiscplinary - Other

ESTRO 2024

specific quality assurance (PSQA) measurements following our clinical protocol for each delivered DAPT fraction. The time taken for each step of the DAPT workflow for each fraction was recorded.

Results:

The DAPT treatments were delivered on average in 17.5 minutes [range: 15-21], with only 6.20 minutes [range:4:47-6:47] required between acquisition of the daily CT and start of treatment. Clinical evaluation showed that the daily optimized plans were either comparable or better than the template plan. Indeed an improvement in daily target coverage (increase in the minimum dose delivered to the CTV of up to 2.7% (cf Dmin picture below) and a reduction in dose to normal tissue was calculated for each daily fraction, thus indicating that a DAPT workflow utilizing full re-optimization could maintain or improve the template dose distribution. Comparison of dose reconstruction from log files and daily plans showed high accuracy, with 100% of voxels agreeing at the 3%/3mm level. In addition, post-treatment PSQA confirmed the accuracy of the delivered dose, with all measurements passing our clinical tolerances for measurement-based PSQA. Finally, CTDI measurements were performed to assess imaging dose. For all daily (low dose) CTs, the estimated CTDI dose was lower than that from weekly control CT’s acquired using a standard protocol (17.15mGy (5*3.43 mGy) for daily CT’s compared to 20.95mGy for the weekly).

Average duration [range] (min)

Set-up and CT acquisition

3:12 [2:15-4:00]

Online adaptive steps

Registration

2:00 [1:33-3:00]

Initial integrity checks

1:05 [0:55-1:26]

Daily structure approval

1:14 [0:52-2:00]

Daily Plan clinical evaluation & approval

1:12 [0:37-2:00]

Plan QA (incl. check of secondary dose)

0:49 [0:44-1:00}

Delivery

7:00 [6:00-8:00]

Table: DAPT treatment time

Figure 1 illustrates the developed @DAPT software supporting the ultra-fast adaptation workflow. In the upper section, it presents the dose distribution of the template plan optimized using the pre-treatment CT on the left