What references do you use for multi-parametric MRI delineation of the GTV in prostate cancer for prostate nodule?

In FLAME, the boost volume was the GTV on mpMRI as judged by the treating physician without any formal contouring guidelines (Kerkmeijer et al., PMID 33471548). There were differences in MRI protocols and physician judgement resulting in significant differences in tumor volumes between centers (van Schie et al., PMID 29731160), speaking to the heterogeneity in contouring strategies on this study. In practice, differences in contoured volumes may not produce significant differences in plans, especially when the boost dose prescription is sufficiently high and OAR constraints are prioritized over boost volume coverage. Although the initiation of FLAME predated the PIRADS system, using the PIRADS v2.1 criteria (Turkbey et al., PMID 30898406) [...

This is an important question because FLAME did something quite remarkable in oncology: demonstrate a DFS benefit *without* increasing toxicity. We would, of course, want all eligible patients to benefit from this result and approach. But even radiologists need a lot of training to accurately identify prostate tumors.

The uncertainties and trade-offs are laid out well by @Dr. First Last.

I use an advanced diffusion MRI technique we have developed at UC San Diego to highlight the tumor (called RSI). We are studying whether this technique makes it easier for radiation oncologists to identify tumors and whether it improves their accuracy. @Dr. First Last will be presenting the results as a poster at ASTRO and an oral presentation at RSNA. Stay t...