Swallowing computed tomography: Dose estimation in a phantom study conducted at various patient reclining angles

Swallowing computed tomography (SCT) is a relatively new technique for the morphological and kinematic analyses of swallowing. However, no optimal scan protocols are available till date. We conducted the present SCT study to estimate the patient dose at various patient reclining positions. A RANDO phantom with a thermoluminescent dosemeter was placed on a hard Table board in a semi-reclining position at the centre and off-centre. According to predetermined scan protocols, irradiation was performed to acquire scanograms at reclining angles of 55^° and 65^°. The effective dose was the lowest at the centre 45^° (3.8 mSv) reclining angle. Comparison between the off-centre (4.6 mSv at 55^°, 6.8 mSv at 65^°) and centre (4.5 mSv, 5.8 mSv) values suggested that the off-centre position is undesirable with regard to the patient dose. Accordingly, we believe that SCT methods must be revised on the basis of these factors.