Dose uniformity analysis among ten 16-slice same-model CT scanners

Area of Science:

• Medical Physics
• Radiological Imaging Technology

Background:

• Multislice computed tomographic (CT) scanners necessitate dose optimization.
• Patient-absorbed radiation dose can vary even between identical CT scanner models.
• Investigating dose output consistency is vital for accurate CT imaging.

Purpose of the Study:

• To analyze the dose output variation of 10 same-model CT scanners.
• To assess dose variations across three standard clinical protocols: adult head, high-resolution chest, and adult abdomen.

Main Methods:

• Utilized 10 GE Lightspeed 16-slice CT scanners.
• Employed PMMA head (16 cm) and body (32 cm) phantoms for dose measurements.
• Calculated volume CT dose index (CTDIvol) using an ion chamber at central and peripheral locations.

Main Results:

• Observed up to 9.4% variation in CTDIvol for the adult head protocol, the highest among tested protocols.
• Measured CTDIvol values were generally lower than system-stored values.
• Dose output variations are influenced by tube aging and intrinsic scanner fluctuations.

Conclusions:

• Significant CTDIvol variation exists even among CT scanners of the same model and protocol.
• This variability can be amplified in scans with higher milliampere-second values and complex multi-phase/multi-location protocols.
• Ensuring consistent CT scanner performance is essential for patient safety and diagnostic accuracy.