Kathryn Oatey is the first NHS patient in Britain to be scanned with a new machine that gives doctors the best picture they have ever had of a breast cancer.
She has come to the Royal Free Hospital in London after receiving chemotherapy for a breast cancer detected by a conventional X-ray last summer. The new machine - called a PET scanner - will tell doctors whether it is working.
Her breast hangs free and a ring of detectors moves up and down to scan for the cancer. About an hour ago she had an injection of a special mildly radioactive sugar. Cancer cells devour the sugar more than others and so show up in the scan.
The PET scanner can spot cancers only two millimetres across. It can spot the first signs of it spreading. It can tell the difference between benign and malignant tumours. It can spot cancers in breasts that contain dense tissue - difficult to do with X-rays. And it can spot cancers close to the chest wall - again, hard to see on an X-ray scan.
Kathryn has to lie still for 20 minutes while the image builds up. The whole process takes a few hours, so this £800,000 machine is not going to replace X-rays for mass screening.
But it will enable doctors to make some tough calls with much better information than they had in the past: Is treatment working? Is the cancer spreading? Is it benign?
For Kathryn, the answer is that her treatment is working. She will still need surgery to remove what is left of the cancer, but she won't need a mastectomy - just a lumpectomy which is much more limited surgery.
And for many other patients, the PET scanner can give equally important answers.