Location of the ovaries in children and efficacy of gonadal shielding in hip and pelvis radiography.

BACKGROUND

Patients with hip disorders undergo multiple radiographic examinations, so gonadal radiation risk should be minimized. Inaccurate shield placement, including obscuring landmarks, has been widely reported, and some studies reported that covering the true pelvis was inappropriate to shield young girls' ovaries. However, no reports on ovaries in Asian patients identified on magnetic resonance imaging exist. We aimed to identify the location of the ovaries in Japanese children and assess the efficacy of gonadal shielding.

METHODS

Female patients aged ≤16 years who underwent magnetic resonance imaging for hip disorders that displayed at least one ovary were included. Sixty ovaries from 31 patients were classified into two age groups: <2 years and >2 years, and the ovaries' position was classified according to the following four zones on the anteroposterior pelvic radiograph: zone 1 (true pelvis) - area surrounded by the line of the anterior superior iliac spines, inner side walls of the ilium, and symphysis pubis; zone 2 - areas lateral to zone 1; zone 3 - sacral area superior to zone 1; and zone 4 - areas lateral to zone 3. The ovaries' position was analyzed according to age group.

RESULTS

Thirty-one ovaries in 16 patients were <2 years, and 29 ovaries in 15 patients were >2 years. Thirteen ovaries in the true pelvis, 18 ovaries in the false pelvis were <2 years, and 27 in the true pelvis and 2 in the false pelvis were in >2 years. In girls aged <2 years, most ovaries in the false pelvis were located in zone 3.

CONCLUSIONS

Girls aged >2 years mostly have their ovaries in the true pelvis, and ovaries in infants tend to be located superior to the true pelvis. Covering the true pelvis is plausible for shielding ovaries. Shields should be placed slightly more cranially than the true pelvis for infants.