ESTRO 2024 - Abstract Book

S5496

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

ESTRO 2024

largest random error was 2.4mm (AP), 1.7mm (LR) and 1.9mm (SI). Interventional marker matching was required for 35% (7/20), 40% (8/20) and 25% (5/20) of the overall treatment sessions for patients 1, 2 and 3 respectively.

Figure 1: Figure A, B and C show the marker positional errors in the SI, AP and LR directions respectively. The different colour curves represent the different patients, and the solid and dotted lines show the calculated systematic and random component of the particular fraction. The square markers show the fraction where interventional marker match was carried out to re-align the marker to planned position due to intra-fractional motion exceeding the tolerance.

Conclusion:

We have reported the results of the first three prostate cancer patients who had undergone RGPT in NCCS. Large intra-fraction motions in excess of 2 mm were observed and intervention was required in 25-40% of the treatment sessions. This supports the clinical use of RGPT in tracking tumour motion to ensure precise dose delivery to the tumour which is especially important when we transit to hypo-fractionated treatment regimen.

Keywords: 4D treatment, fiducial marker, motion management

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