ESTRO 2024 - Abstract Book

S5515

RTT - Patient care, preparation, immobilisation and IGRT verification protocols

ESTRO 2024

Offline support consisted of a quality assurance (QA) program regarding target delineation monitoring by RO and dosimetric evaluation by MPE. RO evaluated target coverage offline in week 1 and an expert RTT in week 2-4. To gain insight into the performance of the delegated tasks by the RTT, the RO retrospectively assessed the GTV delineation of fraction 1,3,5,10,15 and 20 of the first 14 bladder cancer patients treated in the RTT-only workflow. GTV delineation was scored in four categories: no edits required, clinical acceptable, major adjustments required and inacceptable. MPE evaluated dosimetry in between two consecutive fractions.

The OIS was used for multidisciplinary communication about offline QA.

Casus discussions were held to share knowledge gained from QA in a multidisciplinary manner.

Results:

Online support

The traffic light protocol has been developed during the first stage. If necessary, in response to feedback from RO, MPE and RTT, periodic adjustments followed in the second stage (Figure 1). Possible trends were monitored, e.g. deviations from GTV and OAR delineation, hot- and coldspots and MU. In the first stage a small dedicated team of RO and MPE were available for online support live or on-call with videoconferencing. It was challenging to keep the availability schedule up to date. After the first stage the entire team of RO and MPE were trained and online support in the event of a “red” traffic light was provided by all RO and MPE. A small team of MPE extensively checked dosimetry, e.g. hot- and coldspots and MU, of all fractions retrospectively during the first stage of the first oART target area. MPE checked a random fraction of each subsequent oART target area. RO retrospectively checked fractions of bladder cancer patients treated in the RTT-only workflow (Figure 2). In 14% of the fractions major adjustments were required. In 61% of the fractions the adjustments were clinically acceptable and in 25% no edits were required. In none of the fractions inacceptable edits were assessed in the GTV delineation. Offline support

Results were shared with RTT through case discussions, e.g. acceptability of GTV adjustments.

Conclusion:

A support system in an RTT-only oART workflow in terms of target and OAR delineation, target and OAR coverage and dosimetry was set up in the first stage with a dedicated team. In the second stage support became “business as usual” carried out by the entire team.