[Code of Federal Regulations] [Title 21, Volume 8] [Revised as of April 1, 2008] From the U.S. Government Printing Office via GPO Access [CITE: 21CFR1000.50] [Page 592-593] TITLE 21--FOOD AND DRUGS CHAPTER I--FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) PART 1000_GENERAL--Table of Contents Subpart C_Radiation Protection Recommendations Sec. 1000.50 Recommendation for the use of specific area gonad shielding on patients during medical diagnostic x-ray procedures. Specific area gonad shielding covers an area slightly larger than the region of the gonads. It may therefore be used without interfering with the objectives of the examination to protect the germinal tissue of patients from radiation exposure that may cause genetic mutations during many medical x-ray procedures in which the gonads lie within or are in close proximity to the x-ray field. Such shielding should be provided when the following conditions exist: (a) The gonads will lie within the primary x-ray field, or within close proximity (about 5 centimeters), despite proper beam limitation. Except as provided in paragraph (b) or (c) of this section: (1) Specific area testicular shielding should always be used during those examinations in which the testes usually are in the primary x-ray field, such as examinations of the pelvis, hip, and upper femur; (2) Specific area testicular shielding may also be warranted during other examinations of the abdominal region in which the testes may lie within or in close proximity to the primary x-ray field, depending upon the size of the patient and the examination techniques and equipment employed. Some examples of these are: Abdominal, lumbar spine and lumbosacral spine examinations, intravenous pyelograms, and abdominal scout film for barium enemas and upper GI series. Each x-ray facility should evaluate its procedures, techniques, and equipment and compile a list of such examinations for which specific area testicular shielding should be routinely considered for use. As a basis for judgment, specific area testicular shielding should be considered for all examinations of male patients in which the pubic symphysis will be visualized on the film; (3) Specific area gonad shielding should never be used as a substitute for careful patient positioning, the use of correct technique factors and film processing, or proper beam limitation (confinement of the x-ray field to the area of diagnostic interest), because this could result in unnecessary doses to other sensitive tissues and could adversely affect the quality of the radiograph; and (4) Specific area gonad shielding should provide attenuation of x- rays at least equivalent to that afforded by 0.25 millimeter of lead. (b) The clinical objectives of the examination will not be compromised. (1) Specific area testicular shielding usually does not obscure needed information except in a few cases such as oblique views of the hip, retrograde urethrograms and voiding cystourethrograms, visualization of the rectum and, occasionally, the pubic symphysis. Consequently, specific area testicular shielding should be considered for use in the majority of x-ray examinations of male patients in which the testes will lie within the primary beam or within 5 centimeters of its edge. It is not always possible to position shields on male patients so that no bone is obscured. Therefore, if all bone structure of the pelvic area must be visualized for a particular patient, the use of shielding should be carefully evaluated. The decision concerning the applicability of shielding for an individual patient is dependent upon consideration of the patient's unique anthropometric characteristics and the diagnostic information needs of the examination. (2) The use of specific area ovarian shielding is frequently impractical at present because the exact location of the ovaries is difficult to estimate, and the shield may obscure visualization of portions of adjacent structures such as the spine, ureters, and small and large bowels. However, it may be possible for [[Page 593]] practitioners to use specific area ovarian shielding during selected views in some examinations. (c) The patient has a reasonable reproductive potential. (1) Specific area shielding need not be used on patients who cannot or are not likely to have children in the future. (2) The following table of statistical data regarding the average number of children expected by potential parents in various age categories during their remaining lifetimes is provided for x-ray facilities that wish to use it as a basis for judging reproductive potential: Expected Number of Future Children Versus Age of Potential Parent \1\ ------------------------------------------------------------------------ Male Female Age parent parent ------------------------------------------------------------------------ Fetus............................................... 2.6 2.6 0 to 4.............................................. 2.6 2.5 5 to 9.............................................. 2.7 2.5 10 to 14............................................ 2.7 2.6 15 to 19............................................ 2.7 2.6 20 to 24............................................ 2.6 2.2 25 to 29............................................ 2.0 1.4 30 to 34............................................ 1.1 .6 35 to 39............................................ .5 .2 40 to 44............................................ .2 .04 45 to 49............................................ .07 0 50 to 54............................................ .03 0 55 to 64............................................ .01 0 Over 65............................................. 0 0 ------------------------------------------------------------------------ \1\ Derived from data published by the National Center for Health Statistics, ``Final Natality Statistics 1970,'' HRA 74-1120, vol. 22, No. 12, Mar. 20, 1974. [41 FR 30328, July 23, 1976; 41 FR 31812, July 30, 1976]