Patient dose considerations in computed tomography examinations

Table 1 Selected data from the UK survey on the computed tomography national reference doses

Quantity	CTDIvol (mGy)		DLP (mGy cm)		E (mSv)
Examination/CT scanner type	SSCT	MSCT	SSCT	MSCT	SSCT	MSCT
Routine brain (acute stroke)	60	82.5	760	930	1.7	2.1
Chest (lung cancer: known, suspected or metastasis)	10.5	13.5	430	580	7.3	9.9
Abdomen (liver metastasis)	13	14	460	470	6.9	7.1
Abdomen and pelvis (abscess)	13	14	510	560	8.7	9.5
Chest, abdomen and pelvis (lymphoma staging or follow up)	11	13	760	940	12.9	16

National reference doses (DRL) for computed tomography (CT) on adult patients from the 2003 review of the UK survey. For examinations consisting of two parts (e.g. the routine head CT) the tabulated volume weighted CT dose index (CTDI_vol) value is the average of the respective values of each stage. The DRL values have been derived as rounded third quartiles of the observed distributions using data from a large number of CT facilities in the UK. DLP: Dose length product; E: Effective dose; SSCT: Single slice helical CT; MSCT: Multislice CT.