The following exposures of bone marrow to radiation during typical x-ray examinations are listed below in millirems, a measurement of radiation.

The maximum on the job yearly exposure for Canadian and U.S. radiation workers has been set at 5,000 millirems. Low doses spread out over a period of time are not as harmful as larges doses at once because the body has time to recover.

HIGH DOSE GROUP                                                                                         

Barium enema: lower GI series

875

Pelvimetry: examination to evaluate the proportions of the birth canal

595

Barium meal: upper GI series

535

Mammography: breast examination

1000

Lumbosacral spine (lower spine)

450

Small bowel series

422

IV pyelogram

420

Lumbar spine

347

Thoracic spine

247

MEDIUM DOSE GROUP

Gallbladder

168

Abdomen

147

Ribs

143

Pelvis

133

Skull

78

Hip

72

LOW DOSE GROUP

Cervical spine (neck)

52

Femur (upper leg)

21

Dental (full mouth series)

9

Dental (panorex)

1

Dental (bitewing)

0.5

To put things in perspective, each time you fly from coast to coast you receive 4 millirems of background radiation, or the equivalent of four panoramic radiographs.

As well, there is background radiation from concrete buildings, roads and even the sun! Just standing around you receive more than 3 bitewing x-rays worth of radiation every day

We would have to take almost 10,000 dental x-rays to reach your maximum safe yearly dose!

When you weigh this against all the serious conditions such as decay, periodontal disease, abscesses and cancer that can go undetected without x-rays, it seems like a pretty fair tradeoff.