• Decrease font size
  • Return font size to normal
  • Increase font size
U.S. Department of Health and Human Services

About FDA

  • Print
  • Share
  • E-mail

FY 2000 X-Ray Instrument Calibration, Field Support, And Laboratory Accreditation

OST laboratories provide traceability to the national standards for all x-ray measurements related to enforcing FDA regulations, including those promulgated under the Mammography Quality Standards Act (MQSA) and the Radiation Control for Health and Safety Act (RCHSA). This program supplies the following: calibrated x-ray instruments for the routine compliance programs and all related field supplies; support for special measurements needed by field personnel such as measuring CT beam profiles; measuring radiation from contaminated medical products, etc.; and technical experts for developing standards for radiation safety for non-medical uses of radiation. The laboratory is presently accredited for calibrating three classes of x-ray instruments in radiation fields typical of general radiography, mammography, and electronic product radiation.

X-ray Calibration Laboratory
Key words: calibration, x-ray measurement, laboratory accreditation.

OST is responsible for the traceability to National Standards of ionizing radiation measurements made by FDA or used in FDA compliance programs. This mission is fulfilled by operating a secondary standard laboratory accredited by the National Voluntary Laboratory Accreditation Program (NVLAP). In FY 2000, a total of 1,750 accredited calibrations of radiation measuring instruments were performed by irradiation in known x-ray fields. Additionally, 704 electrical pre-calibrations of instruments and 149 calibrations of noninvasive kVp meters were performed. Since many state agencies perform FDA inspections and sometimes use their own equipment, states rely heavily on this CDRH calibration service. In FY 2000, 65% of the calibrations were for instruments owned by FDA, 30% for instruments owned by state agencies, and 5% for instruments owned by other federal agencies. A significant 72% of the instruments calibrated were designated for testing compliance with the RCHSA of 1968. Another 21 % were designated for testing compliance with the Mammography Quality Standards Reauthorization Act of 1998. The remaining 7 % of the instrument calibrations were in support of the Nationwide Evaluation of X-ray Trends (NEXT). OST keeps track of approximately 2800 pieces of equipment, including information on instrument usage and calibration data. The instruments are located at over 500 inspector stations throughout the country and U.S. territories.


In May 2000, following a site inspection by NVLAP, the laboratory received accreditation for 13 mammography calibration beams. These x-ray beams were added to the general diagnostic beams already in the Scope of Accreditation. As required by NVLAP, the laboratory this year has participated in a Proficiency Test administered by the National Institute of Standards and Technology (NIST) and has undergone an internal audit of operating procedures and of the Quality System.

Radiation Safety Standard for Personnel Security Screening Systems
Key words: security screening, x-ray.

A current issue of concern to FDA is the use of ionizing radiation for security screening. Several installations of x-ray security scanners are presently in operation in this country. FDA has regulatory jurisdiction over these devices. OST has led the effort to develop an ANSI Health Physics Society consensus standard to address the radiation safety issues of this practice. The group convened in November 1999 and, after one year, is close to completing a first draft of the standard. It is anticipated that the new standard will be an important influence on the way these products are regulated. OST staff have given presentations to the TEPRSSC (Technical Electronic Product Radiation Safety Standards Committee) on this effort.

Dosimetry Evaluations In Premarket Submissions
Key words: dosimetry, PTCA, restenosis, brachytherapy

Every year more than 500,000 patients are treated with percutaneous transluminal coronary angioplasty (PTCA) for heart-related problems. Of these, over 300,000 will have a stent implanted, and 30 to 40% of them will need to be treated for restenosis. Ionizing radiation has shown some promise in reducing the number of in-stent restenoses. OST has performed the dosimetry evaluation for IDE and PMA submissions using intravascular brachytherapy sources to inhibit restenosis. The dosimetry for intravascular brachytherapy differs significantly from conventional low-energy interstitial brachytherapy in that the dose at millimeter distances from the sources is critical. In addition, there are numerous source designs, various source isotopes, and different dose rates versus distance from source distributions. These variations add more complications to evaluating the dosimetry associated with these sources in determining the safety and efficacy of the device. Similarly, OST scientists have taken an active role in standardizing the dosimetry for palladium and iodine brachytherapy seeds used in the treatment of prostate cancer. The Office has provided the FDA liaison to the American Association of Physicists in Medicine (AAPM) and to the Council of Ionizing Radiation Measurements and Standards (CIRMS) to ensure that FDA's concerns related to measuring radiation from medical equipment and brachytherapy sources are addressed. OST staff has also served on an ad hoc committee and worked with the Nuclear Regulatory Commission and ORA on calibration and production issues. A series of six lectures entitled, "Ionizing Radiation Primer" were provided to the ODE reviewers responsible for intravascular brachytherapy devices.

Technical Standards Development 
Keywords: NCCLS, ANSI, standards, automation

OST serves as the government representative on the NCCLS Area Committee on Laboratory Automation. FDA comments were incorporated into the five standards developed by this committee. FDA comments noted that the elements of the standard only represent a portion of a complete life-cycle development process, and a note alerting users to that fact is included in each of the standards. FDA also provided other comments identifying the need to develop standard conformance processes for these and subsequent standards. The standards were completed within the ambitious time frame established at the beginning of the committee’s deliberations.

OST represents CDRH at the quarterly meetings of the ANSI Healthcare Informatics Standards Board (HISB). HISB acts to coordinate standards development for a computerized patient record and has solicited comment from CDRH on any regulatory impact such standards might have on FDA regulatory activities. OST has arranged for HISB to hear information on the status of recognized standards, NDC code regulation, and FDA’s electronic signature regulations. Scientists also provided reports on regulatory guidance on computer product regulations as well as FDA’s initiatives for electronic data transmission and encryption. Based on information from OST staff, HISB was provided a high-level overview of a "requirements" document that HISB might use in developing its web site. This document emphasized the requirements for meeting the needs of a very diverse user population like that connecting to FDA’s web site.

Re-Engineering FDA’s Regulated Product Information System
Key words: re-engineering, prototype

OST participated in a workgroup investigating problems the Center encounters when obtaining data from its existing data systems. OST prepared a list of over 200 "needs," based on a sample user population in the Center, ORA, CDER, and CBER. This report served as the basis of a presentation to senior staff on issues that should be addressed by developing an information system more suited to the changes in technology and information needs of an "electronic business" scenario that exists today. OST is providing technical advice on a prototype requirements document for senior staff to review as they consider the feasibility of developing an information system that can better serve the needs of staff in order to provide timely and appropriate regulatory response to public health issues.