[1e-9]

There currently is no good candidate for a imaging modality that can be used for a general screening program to find the top 15 to 20 cancers and I am unaware of anything on the near horizon. Such a scan would have to examine the neck thru the groin area to cover even just 10 out of the top 15 or so cancer types. Since screening involves patients with no symptoms, most patients won't actually have any disease and thus the imaging must be inexpensive, must have high sensitivity, must have a reasonable false positive rate, must involve little to no radiation, and must not require injection of contrast agents or radioactive tracers. That eliminates all of the imaging modalities I can think of that can examine large areas of the body for cancer. The best we have today are compromises on these criteria for patients that are at relatively high risk, such as a smoker or a cancer survivor, or for highly focused screening programs such as what we have for breast cancer.