The goal of all medical imaging that uses ionizing radiation, including radiography, is to manage the radiation dose (exposure) to the patient to be commensurate with the medical purpose. Radiography is the most commonly performed imaging procedure in children [1, 2] (Figure 1) and the use of gonadal shielding during these procedures should be re-evaluated.
Usage of gonadal shielding: Past and Present
In the U.S., gonadal shielding recommendations, which date back to 1950s [3-7], were based on what was understood at that time about potential heritable genetic effects from exposure to ovaries and testes.
- FEDERAL REGISTER 1976  from which state regulations have been largely based: “Gonad shielding of not less than 0.25 or 0.5 millimeter lead equivalent material shall be used for patients who have not passed the reproductive age during radiographic procedures in which the gonads are in the useful beam, except for cases in which this would interfere with the diagnostic procedure.” and “Gonad shielding is desirable because studies indicate that exposure to ionizing radiation causes mutations in germinal tissue, which may adversely affect future generations.” (Page 30327)
- Subsequent modifications to the intent of the original recommendations include:
- Recent (April 1, 2019) U.S. Food and Drug Administration (FDA) proposed amendment to its regulations to repeal the existing recommendations (21 CFR 1000.50) on gonadal shielding in their entirety (84 FR 12147).
- The Conference on Radiation Control Program Directors (CRCPD), which provides Suggested State Regulations for Control of Radiation (SSRCR) to promote and foster uniformity of radiation control laws and regulations, recommended the following guidance: “shielding shall be used during radiographic procedures in which the gonads are in the useful beam, except for cases in which this would interfere with the diagnostic procedure” A 2015 revision of this SSRCR removed the above requirement. Nevertheless, derivations are still commonly found in state regulations.
- However, the current practice does not consistently reflect these modifications.
- A recent commentary by Marsh  noted that from a survey of a group of radiologic technologists, 86% of respondents would continue to shield patients even if the practice instituted a policy to not provide routine shielding .
- Routine gonadal shielding is an expectation of patients, caregivers and the public and of technologists/radiographers. In some practices, failure to perform gonadal shielding can result in severe disciplinary action against technologists.
In summary, the practice of routine use of gonadal shields for children during abdominal and pelvic radiography, as well as procedures of more remote regions largely continues.
Why should this change?
Evidence supporting a reduction in the use of gonadal shielding:
1. ICRP 103 reduced the gonadal weighting factor (for estimation of effective dose) from 0.20 to 0.08 (Figure 2)
a. Hereditary effects of gonads from ionizing radiation exposure in humans at diagnostic levels of exposures were considered a much greater concern previously, but evidence since the 1950’s no longer supports this.
b. Statistically significant positive genetic effects in humans have not been demonstrated
c. Other unshielded organs such as the colon, stomach, liver, and bone marrow have higher assigned radiosensitivities (0.12) and are not shielded
2. Current radiographic examinations have substantially lower doses than procedures in the 1950s
Radiation doses from diagnostic x-ray examinations are ~ 20 - 25 times less radiation today: 1951 vs 2019 [6, 7]
Adult KUB (entrance air kerma):
1951 ~ 11 – 12 mGy
2019 ~ 0.5 mGy
Newborn KUB (entrance air kerma):
1951 ~ 1.4 mGy
2019 0.07 mGy
3. Most radiation is due to internal scatter:
a. Internal scatter cannot be prevented by shielding, although it can be reduced with collimation
b. Shielding may provide <10% attenuation to ovaries when in field of exposure; scattered x-rays outnumber primary x-rays during abdominal imaging. There is no reduction in internal scatter when gonads are outside of the primary exposure field
4. Shielding may increase overall exposure when using automatic exposure control (AEC)  (Figure 3):
a. AEC is intended to provide consistent image quality across various patient sizes
i. to appropriately adjust exposure, AEC sensors must not be covered by shielding materials
ii. if covered, AEC may increase exposure time with greater exposure to all other organs (some with higher sensitivities/weighting factors) surrounding the gonads)
5. Child movement:
a. Young children may move following placement of shields prior to the exposure resulting in
i. change in the anticipated area to be shielded
ii. change from region expected to be obscured by the shield
6. Diagnostic impact:
a. Radioprotective shields in the field of exposure will obscure underlying anatomy 
i. Lee et al : up to 43% of pediatric pelvic radiographs.
ii. May necessitate retakes
b. The impact of this diminished anatomic information depends on the nature of the clinical question (Figure 4).
7. Placements of the shields may not result in complete gonadal coverage (Figures 5, 6):
a. Even when shields are placed based on recommendations such as using external landmarks 
i. Especially of the ovaries in girls
ii. Fawcett et al : 306 female patients: “In children under the age of 7 years, more than half (19/37) had at least one ovary outside the true pelvis.” “Given the high risk of obscuring critical landmarks, coupled with the new evidence that even accurate placement will not necessarily protect the ovaries, the use of pelvic shields in girls should be reconsidered.”
iii. Meta analysis of 243 publications : 34% of radiographs had correct shielding placement
b. May be incorrectly (i.e., unintended consequences) placed
i. Frantzen et al : in 91% of pelvic radiographic examinations of girls and 66% of boys
ii. Lee et al : in up to 63% of radiographs of the pelvis
iii. significantly higher in females (85%) than males (52%) 
a. Reuse of shields not properly cared for between multiple patients could poses a hygiene risk
1. Many years of legacy practice of gonadal shielding. Technologists/radiographers will be confronted with this change in practice
2. Incomplete penetration or understanding of changes to legacy recommendations for routine use of shielding
3. Technologist/radiographer education and certification that may not be based on current evidence for shielding
4. Expectations of parents/caregivers (psychological detriment of not shielding)
5. Potential disharmony with shielding in other practice, such as pediatric dentistry
6. Length of time to have current evidence incorporated into regulations and guidelines by relevant authorities