From detecting tumour DNA in our bloodstreams to making cancer cells stand out in an MRI scan, this week, coinciding with the NCRI Cancer Conference, we explore how best ways to detect cancer and monitor tumours during treatment. Plus, in the news, what a dog's wagging tail can tell you about its mood, the chemistry behind fireworks, how wind farms could be made up to 30% more efficient just by moving the turbines around, and the electronic blood that could help to shrink supercomputers...