As you may or not know, ultrasound units can be purchased by anyone in the public regardless of education or certification. The American Institute of Ultrasound in Medicine (AIUM) requires calibration for membership, but being a member is not required to practice sonography. This would be all fine and dandy except that some untrained people open up mom-and-pop ultrasound shops at the mall.
This is concerning because people without technical backgrounds may not know the importance of maintaining their equipment with routine calibration and maintenance. Over time electronics becomes damaged and defective, lowering image quality and other such things.
As of today, even equipment maintained by hospitals are not calibrated frequently. Lacking calibration will lead to lowered image quality, which may then lead to more ultrasound being used to compensate. Further, uncalibrated machines may misrepresent relative risks.
Please sign the petition at http://www.change.org/petitions/health-risks-of-prenatal-ultrasound-the-urgent-need-for-more-research-and-regulation to call attention to this problem. Units for Ob-Gyn use should be held to the same safety standards as X-Ray and other radiology equipment.