Image quality and dose assessment of collimator slit width effect in SLOT-SCAN X-ray imaging system

The effect of collimator slit width on patient absorbed dose and image quality is evaluated in the SLOT-SCAN imaging system. For this purpose, GATE Monte-Carlo code was used for simulation. To determine contrast to noise ratio (CNR), copper filters with different thicknesses were used and a 2mm lead filter was applied for the determination of the Modulation Transfer Function (MTF) and Detective Quantum Efficiency (DQE). Spatial resolution was determined by using line-pairs per millimeter test. In addition, the anthropomorphic digital Zubal phantom was used to estimate the patient absorbed dose. As the results showed, the CNR shows 77% reduction by decreasing the collimator slit width from 4 mm to 0.4 mm. Other parameters such as DQE and spatial resolution showed to be constant. Finally, whole-body patient absorbed dose estimation resulted in reduction of 14 times using the 0.4 mm collimator slit. The results showed that decreasing the slit width reduced the patient absorbed dose without any significant change in the image quality.