Like I said, they won't send them ill equipped, good doctors are a must.
It might be, but still, it's only gamma radiation (most of it at least). Not that harmful. Scientists in the early 1900 who studied the newly discovered radiation carried and worked with all types of radiation, including alpha, all day long (without knowing the effects of it), yet most did not die under the age of 60. Of course, it's dangerous and not healthy but it won't be an instant kill, let alone the gamma rays on Mars. You don't have to worry about that that much.