My story concerns an inter-dimensional consciousness that lures children into itself by manifesting as magical wonderlands with wacky characters (think a creepy Sesame Street or Lazy Town).
The real story starts with an adult survivor returning to one of these environments (kind of like It).
They learn that the consciousness gives off ionizing radiation to whoever is inside it.
They do this to young children so that when they're 8 they have developed leukemia and are full of immature white blood cells, which the consciousness feeds on. Basically it takes 8 years to 'prep' its victims or 'fatten them up' for consuming.
My question is, during that 8-year-period, how much ionizing radiation would the child need to take in to develop to that condition?