物理 幅射

我相信你指的是[電離輻射]若吸收過多為何會對身體做成損害。

電離輻射對生物細胞的傷害最主要是其電離性質，把細胞內的分子電離，從而改變細胞的結構和特性。

以下一段，是取材自香港天文台的網頁，可作參考:

[在輻射的作用下，人體內的生物大分子，如核酸、蛋白質等會被電離或激發。這些生物大分子的性質會因此而改變，細胞的功能及代謝亦遭到破壞。實驗證明輻射可令DNA斷裂或阻礙分子複製。此外，人體內的生物大分子存在於大量水分子中，當輻射作用於水分子時，水分子亦會被電離或激發，產生有害的自由基(如 OH-1、 H+ 自由基等)，繼而使在水分子環境中的生物大分子受到損傷。]

更詳盡的資料可參閱香港天文台網頁:

http://www.weather.gov.hk/education/dbcp/rad_health/chi/r1.htm?menu=rad_health

As the radiation is a kind of energy, as cells absorb this energy can lead to varies kind of change in cells, as your mention in Mrs. Curie, due to the long time exposion to radiaoactive substance, her cells become cancer cell. Normal cells will terminate them after certain of time after its DNA was damaged. But cancer cells do not, as the DNA was damage, it won't kill itself but continue to grow and become functionless, and do damage to other cells, as it will take up nutritions and "swallow" other cell.

On the other case, a large dose of exposion radiation and lead to death, human body absorb too much radiation and many cells' DNA was damaged. From the normal procedure this cells will terminate them in a short period of time, but as you can imaginate, many cells kill themself in a short time will lead to disable of functions of the organ(s) from this cells, as organs are not functioning, it will make other organs got damage, finally as so many cells are dead, it will lead to death.

You can search on web of dose, it is a unit to measure exposion to radiation.