Learning objectives
During neonatal cardiac CT examination,
the eye lens and gonads are known to be organs at high risk.
Because these organs are located outside the irradiation field,
they cannot be evaluated by the CT dose index (CTDI).
In this study,
the dose measurement was performed using a neonate phantom using small type optically stimulated luminescence dosimeters (OSLD).
Background
For neonatal patients with heart disease,
cardiac X-ray computed tomography (CT) examinations are generally performed as the first choice of radiological examinations. Currently,
cardiac CT examinations are applied in many hospitals because it is possible to perform the procedure in a relatively short time when compared to magnetic resonance imaging examination and nuclear medicine examination. As shown in Fig.
1,
the cardiac CT examination can be performed by rapidly injection of a contrast agent with the adequate imaging timing based on heart rate information from...
Findings and procedure details
For the phantom study,
we used a neonate phantom (Kyoto Kagaku Co.,
Ltd.) and 320-row CT equipment (Aquillion ONE,
Canon Medical System Corporation,
Japan). The irradiation conditions were as follows: 80 kV,
CTDI=10 mGy,
and rotational speed of 0.275 s/rotation. The scanning range was determined so as to the upper range limit is the submandibular,
and the scan length is 16 cm,
from where heart is set at almost center.
The lower range is the upper edge of the iliac crest.
First,
in order to...
Conclusion
In this study,
we focused our attention on exposure dose to the eye lens of a neonate during cardiac CT examination and directly measured exposure dose during examination using a small type OSL dosimeter. We measured the dose contribution for each direction entering the dosimeter and examined appropriate shielding methods for dose reduction by clarifying the mechanism of the eye lens exposure. 70% of scattered X-rays which are exposed to the eye lens were generated from the patient’s body. Additionally,
we found that the dose...
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