Washington ( CNN ) -- Radiation from airport body scanners penetrates organs beneath the skin but at low doses that meet national standards , according to a study by Marquette University 's Department of Biomedical Engineering . But the study 's author , professor Taly Gilat-Schmidt , said the research does not answer the biggest question on travelers ' minds : Are scanners safe ? She said more independent research is needed . The Marquette study subjected government and vendor data to sophisticated computer modeling to estimate the radiation doses travelers receive when they are scanned by backscatter machines , one of two types of imagers used to detect weapons at security checkpoints . The Transportation Security Administration has maintained that the machines are safe , exposing travelers to about the same radiation they receive by flying about two minutes at cruising altitude . A passenger would have to receive more than 17,000 screenings in a year -- about 47 screenings a day , 365 days a year -- to exceed government standards , the TSA says . The Marquette study says that the backscatter dose is `` comparable '' to one minute of exposure to cosmic radiation and considerably lower than radiation levels of other X-ray procedures , such as a mammogram . But it balks at calling the exposures safe , saying cosmic and backscatter radiation are different and that both the risks and benefits of backscatter need to be quantified . Experts : Body scanning 'woefully inadequate ' abroad . John Sedat , a University of California , San Francisco , professor of biochemistry and biophysics , is against the TSA 's use of backscatter technology . He criticized the Marquette report , saying it was based on TSA data instead of independent testing of machines . `` It 's a valid criticism , '' responded Gilat-Schmidt . `` I think that 's valid , and we put that criticism ( in the paper ) . But that 's how research is . It 's not the whole enchilada . It 's one step ; not the whole step . '' `` I think it 's very important to have independent studies , '' she said . Gilat-Schmidt said that she goes through backscatter X-ray machines , but `` I do n't feel comfortable putting my kids through them . '' `` That 's because in the medical imaging community , it 's always stressed that the ( radiation ) dosage should be as low as possible . And in this case , the lowest possible is not going through them . There 's an alternative technology out there , '' she said . Two options are millimeter wave machines , which use radio waves , and physical pat-downs . The Marquette paper will be published in the June issue of Medical Physics , an international journal of medical physics research and practice , produced by the American Association of Physicists in Medicine . The research was conducted by Marquette student Michael Hoppe with Gilat-Schmidt 's assistance . A TSA spokesman said the agency was aware of the Marquette study but had not yet done a thorough analysis of it .
The Transportation Security Administration maintains the machines are safe . The backscatter dose is `` comparable '' to one minute of exposure to cosmic radiation . A critic complains the study was based on TSA data instead of independent testing .