A hospital uses a computer model to compare two arrangements for aiming high-energy gamma radiation at a tumour. Both arrangements deliver the required dose to the tumour.
The model estimates the effects on healthy cells in the path of the radiation.
| Treatment plan | Healthy cells in the path of the radiation | Healthy cells killed | Surviving healthy cells with altered DNA |
|---|---|---|---|
| P | 2500 | 500 | 80 |
| Q | 1800 | 300 | 45 |
Calculate the percentage of surviving healthy cells with altered DNA for each treatment plan.
Explain why the data support choosing treatment plan Q, but cannot be used to predict how many healthy cells will become cancerous.