Background Idiopathic pediatric artery aneurysm is extremely rare and sometimes behaves like a pelvic neoplasm. As it is associated with a high mortality while ruptured, the accurate diagnosis is indispensable to avoid life-threatening complications. Angiographic imaging is the gold standard for diagnosis and treatment planning of the aneurysm. Due to the considerably higher radiation sensitivity of children, single portal venous-phase scanning of the abdominopelvic computed tomography (CT) is, however, reasonably utilized for the evaluation of a clinically palpable mass; the erroneous diagnosis of such aneurysm can be feasible. Case presentation A giant idiopathic concealed right iliac artery aneurysm in a 47-day-old girl presented with a palpable pelvic mass regardless of unidentifiable predisposing factors. Non-angiographic abdominopelvic CT was reappraised by the radiology consultant according to discordance between the mass characteristics on initial CT report and those on second-look sonography, revealing the concealed aneurysm instead of solid neoplasm as it originated from right internal iliac artery. The patient underwent an emergency laparotomy with successful proximal ligation of right internal iliac artery despite intraoperative aneurysmal rupture. Conclusions Typical CT features for the infantile iliac artery aneurysms may be overlooked, especially if the angiographic phase is omitted; thus, the imaging characteristics of the aneurysms are more difficult to appreciate and can mimic a pelvic neoplasm. Therefore, the identification of the origin of the mass should be more practical to achieve the precise diagnosis.

IntroductionTo estimate occurrence rate of high cumulative radiation exposure from paediatric computed tomography (CT), and to determine influential factors on high-dose inclination.Material and methodsPatients below 18 years old receiving at least 50 mSv of a cumulative dose during a 5-year period in a tertiary care centre were retrospectively enrolled. Individual patient characteristics, diagnoses, frequency of exa­minations, scanner sites, designated scans, and effective doses were recorded. Collective doses were compared among groups of the diagnoses and scanner sites, and regression analyses were applied.ResultsOf 2771 patients, 3.2% received individual cumulative doses between 50 and 303 mSv (median, 74 mSv). Frequency of examinations ranged from 1 to 13 times (median, 4 times) per patient. About 70% of the patients had oncological illness. Radiation was predominantly high in a CT simulator that could contribute the percentage of collective dose to twice that of examinations owing to higher scanning parts and CT dose index. Some scanner sites used higher acquisition phases. Regression analysis showed that the number of scanning parts and phases significantly influenced the cumulative dose inclination (p < 0.05) while frequent examinations did not.ConclusionsThere was a low occurrence of paediatrics with high dose accumulation. Significant factors affecting potentially high exposure were customized CT protocols in the specific scanners.