The reason to avoid such foods and the exercise is that the scan involved a radioactive glucose injection and cancer cells soak up glucose, so they glow in the scan, but exercise and caffeine, by raising the heartrate and excess glucose in the system affect this process as that the ability to show up the cancer cells from others is impaired. He wasn’t allowed breakfast this morning, so hungry and warmly dressed (the scanner likes to be cool) he trundled slowly to the infirmary, freewheeling as much as possible. He found it an interesting experience, technologically, but after, though he was allowed to eat again, he is radioactive. There was a glow about him, when he returned, but it was just the cycling jacket. So while we have been guzzling down bread and pasta, we have done so from opposite ends of the table and sat as far from each other as possible all afternoon. This is easier in our flat than in Bartimaeus which is only 6 foot wide.