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[Low dose helical CT pelvimetry: evaluation of radiation dose and image processing]
S Garnier1, Ph Bertrand, C Chapiron
1Service de radiologie adultes, groupement d'imagerie, CHU Bretonneau, 2 boulevard Tonnellé, 37044 Tours cedex 1.
Journal De Radiologie
|July 10, 2004
Summary
Low-dose helical CT pelvimetry is achievable with radiation doses similar to or lower than conventional CT. Accurate pelvic diameter measurements are possible using specific helical CT settings and reconstruction algorithms.
Area of Science:
- Radiology
- Medical Imaging
- Radiation Dosimetry
Background:
- Conventional CT pelvimetry involves specific imaging protocols.
- Optimizing radiation dose while maintaining diagnostic accuracy is crucial in medical imaging.
Purpose of the Study:
- To assess radiation dose and measurement accuracy of helical CT pelvimetry using phantom studies.
- To compare helical CT pelvimetry with conventional CT pelvimetry.
Main Methods:
- Eight helical CT acquisitions with varying tube current (10-100 mAs) and pitch factors (1.125, 1.375) were performed.
- Radiation dose (CTDIw, DLP) was measured using an ionization chamber in a phantom.
- Pelvic diameter accuracy was evaluated using an ex vivo bony pelvis phantom with 2D MPR, 3D MIP, and 3D SSD reconstructions.
Main Results:
- Helical CT radiation dose decreased linearly with tube current, with doses similar to conventional CT at 25 mAs and reduced at 10 mAs.
- Accurate pelvic diameter measurements were achieved with a pitch of 1.125, 2D MPR for antero-posterior inlet, and 3D MIP for transverse inlet and interspinous distance.
- Tube current variations did not impact the accuracy of pelvic diameter measurements.
Conclusions:
- Low-dose helical CT pelvimetry is feasible using 10-25 mAs and a pitch factor of 1.125.
- Combining helical CT with 2D MPR and 3D MIP reconstructions ensures accurate pelvic diameter measurements.