How concrete walls protect hospital personnels from unnecessary exposure to x-rays?

my friend had been working in a hospital for 15 years. his office is located just behind the wall of the x ray room. he is still healthy.
Explain how concrete walls protect hospital personnels from unnecessary exposure to x-rays.

The dedicated x-ray rooms within a hospital or imaging facility are always shielded with lead in the walls. X-ray machines, which use low doses of radiation, such as a mammographic or DEXA machine, can be used in rooms which are not lead shielded. This is due to the low penetrating quality of the x-ray beam. There are federal laws in place which dictate the safety parameters a x-ray department or facility must use.

The following is from a website which has questions answered by qualified medical personel who are experts in radiation and it's effects. Here is what I found:

"QUESTION: I would like to know what kind of materials should be used in an x-ray room, for example, doors, etc., in order to protect all the people working outside.

ANSWER: X-ray rooms are shielded as necessary to make sure that radiation doses to persons outside the room do not exceed state limits for radiation workers or members of the public, based on who has access to the areas next to the x-ray room. Typically, the rooms are shielded with sheets of lead. When lead is used, it usually is glued on the backside of the sheets of drywall that make the room walls (the lead sheets overlap to prevent gaps in the shielding). For doors, the lead is usually "sandwiched" on both sides by wood. In addition, small pieces of lead are placed behind outlet boxes and over screws that hold the drywall up. It is usually difficult to tell if a room is shielded just by looking at it. The best place to see it is along the door edges if the door contains a sheet of lead.

Lead is not the only choice for x-ray room shielding, but it is the most commonly used due to cost and minimal thickness to achieve the amount of shielding desired. Some facilities use concrete or cinder block. Mammography facilities usually only require two sheets of drywall, for example, not lead, due to the low penetration ability of the x rays.

Ken "Duke" Lovins, CHP"

http://hps.org/publicinformation/ate/q35...

thats a thick, question what with 15 years experience! omg

Right, I have learnt this in science. X-rays are penetrating but it can not go through concrete walls because the vibrations are not big enough to go through a concrete wall. So that is why your friend is not unhealthy.

it depends how thick the walls are, a 1 foot concrete wall would not actually stop the xrays from going through because the x-ray electro-magnetic wave length of the rays is so small that they can pentrate and go through most materials, one exception is lead which blocks the rays because it is so dense