The patients were scanned at standard-dose CT ( mean -LSB- SD -RSB- volumetric CT dose index , @ -LSB- @ -RSB- mGy ; mean -LSB- SD -RSB- dose-length product , @ @ mGycm ; and mean -LSB- SD -RSB- effective dose , @ -LSB- @ -RSB- mSv ) and at SubmSv dose ( @ -LSB- @ -RSB- mGy , @ -LSB- @ -RSB- mGycm , @ -LSB- @ -RSB- mSv , respectively ) on a Philips @-slice CT scanner with double z-sampling .