Changing radiation dose from diagnostic computed tomography examinations in Saskatchewan

Area of Science:

• Radiology and Imaging
• Medical Physics
• Public Health

Background:

• Computed tomography (CT) is a widely used diagnostic imaging tool.
• Effective radiation dose from CT scans is a critical parameter for patient safety.
• Monitoring radiation doses is essential for quality assurance and dose reduction initiatives.

Purpose of the Study:

• To evaluate changes in provincial mean effective radiation dose for head, chest, and abdomen-pelvis (AP) CT scans since a 2006 survey.
• To assess the impact of updated CT technology and practices on patient radiation exposure.
• To determine if radiation doses remained stable or changed over the study period.

Main Methods:

• Data from 3358 CT examinations across 13 scanners in Saskatchewan were collected in July 2008.
• Projected dose length product (DLP) was compared to 2006 reference data before scanning.
• Projected DLP was converted to effective dose (ED) for head, chest, and AP CTs, considering single-phase and multi-phase scans.

Main Results:

• Mean effective dose (ED) for head CT increased by 19% (3.4 ± 1.6 mSv), while chest CT ED decreased by 31% (9.6 ± 4.8 mSv) and AP CT ED decreased by 17% (16.1 ± 9.9 mSv).
• Single-phase multidetector CT showed dose reductions for chest and AP scans but an increase for head scans.
• Overall per capita radiation dose from CT in Saskatchewan increased by 21% between 2006 and 2008 due to increased utilization and higher head CT doses.

Conclusions:

• Significant reductions in radiation dose and variation were observed for single-phase CT chest and AP examinations.
• CT head dose increased, contributing to a rise in overall per capita radiation exposure from CT.
• Increased CT utilization combined with dose changes necessitates ongoing monitoring and optimization strategies.