Evolution of the gross tumour volume extent during radiotherapy for glioblastomas

Background and purpose Tumour growth during radiotherapy may lead to geographical misses of the target volume. This study investigates evolution tumour extent evaluates need for plan adaptation ensure dose coverage in glioblastoma patients. Materials methods The prospective included 29 patients referred 59.4 Gy 33 fractions. Magnetic resonance imaging (MRI) was performed at time treatment planning, fraction 10, 20, 30, three weeks after end radiotherapy. gross volume (GTV) defined as T1w contrast-enhanced region plus surgical cavity on each MRI set. relative GTV maximum distance (Dmax) actual outside original were measured. Based location planned dose, a clinical decision made whether adapt treatment. Results Dose not compromised, none plans adapted. median Dmax (range) 5.7 (2.0–18.9) mm, 8.0 (2.0–27.4) (1.9–27.3) 8.9 (1.9–34.4) mm follow-up. observed 10 correlated with values follow-up (R = 0.74, p < 0.001 R 0.79, 0.001, respectively). Conclusion Large variations observed, changes often occurred early Plan our cohort due sufficient CTV margins.