Table 4.

Comparison of the distributions of CTDI_vol and DLP using reconstruction algorithms

		CTDIvol (mGy)						DLP (mGy cm)
		n	Median	Mean	CV (%)	Reduction Rate (%)	p-value	n	Median	Mean	CV (%)	Reduction Rate (%)	p-value
Adults		Head without contrast agent						Head without contrast agent
	IR	186	63.6	65.0	33.9	17.2	p < 0.05	186	1100.0	1137.7	54.4	3.5	p = 0.45
	FBP	468	71.9	78.5	38.7			472	1105.4	1179.4	59.7
		Head (non-helical) without contrast agent						Head (non-helical) without contrast agent
	IR	77	67.7	69.2	37.7	17.7	p < 0.05	77	1000.0	1009.8	33.6	2.5	p = 0.68
	FBP	237	75.8	84.1	39.0			239	1016.0	1036.0	75.7
		Head (helical) without contrast agent						Head (helical) without contrast agent
	IR	109	61.2	62.0	29.2	14.8	p < 0.05	109	1187.5	1228.0	60.7	7.4	p = 0.22
	FBP	231	70.0	72.8	36.5			233	1292.5	1326.6	43.5
		Head CT angiography with contrast agent						Head CT angiography with contrast agent
	IR	154	45.7	95.3	159.1	−3.0	p = 0.87	156	744.3	967.1	68.1	13.0	p = 0.11
	FBP	138	57.9	92.5	152.3			138	935.0	1111.0	74.9
		Chest without contrast agent						Chest without contrast agent
	IR	241	9.0	10.0	72.0	27.9	p < 0.05	242	352.4	381.6	45.6	22.4	p < 0.05
	FBP	181	12.5	13.8	56.8			182	485.0	491.6	39.8
		Chest with contrast agent (tumour)						Chest with contrast agent (tumour)
	IR	181	10.0	13.1	85.0	23.4	p < 0.05	182	422.5	552.7	69.7	15.5	p < 0.05
	FBP	125	13.9	17.1	99.1			126	559.6	653.8	71.8
		Abdomen and pelvis without contrast agent						Abdomen and pelvis without contrast agent
	IR	232	12.0	13.1	35.7	25.3	p < 0.05	233	608.8	652.9	40.2	18.5	p < 0.05
	FBP	174	15.0	17.6	53.0			175	700.0	801.2	55.8
		Abdomen and pelvis with contrast agent (acute abdomen)						Abdomen and pelvis with contrast agent (acute abdomen)
	IR	196	14.0	21.4	124.9	22.3	p = 0.12	198	798.2	965.9	72.6	15.7	p = 0.06
	FBP	131	16.9	27.5	142.6			132	865.6	1145.9	80.7
		Coronary artery without contrast agent						Coronary artery without contrast agent
	IR	124	6.0	10.2	163.2	4.6	p = 0.83	124	88.7	189.7	171.8	12.3	p = 0.60
	FBP	76	5.0	10.7	138.5			76	83.8	216.4	176.0
		Coronary artery with contrast agent						Coronary artery with contrast agent
	IR	187	50.4	61.9	100.8	33.6	p < 0.05	187	685.0	787.4	69.1	35.7	p < 0.05
	FBP	99	66.6	93.3	101.0			99	1050.0	1224.2	65.7
		Chest and pelvis without contrast agent						Chest and pelvis without contrast agent
	IR	232	11.7	12.8	46.3	24.6	p < 0.05	233	835.5	884.7	37.5	15.9	p < 0.05
	FBP	162	15.0	17.0	45.3			163	985.1	1052.2	37.3
		Liver with non-contrast and contrast agent						Liver with non-contrast and contrast agent
	IR	198	15.6	45.7	203.6	4.1	p = 0.83	200	1057.5	1587.9	297.9	5.3	p = 0.84
	FBP	138	19.9	47.6	144.6			141	974.9	1676.1	185.4
		Whole-body without contrast agent (trauma)						Whole-body without contrast agent (trauma)
	IR	81	12.8	22.2	103.1	24.0	p = 0.15	82	1111.3	1439.7	70.8	27.6	p = 0.40
	FBP	52	17.5	29.2	102.5			52	1275.0	1987.2	228.1
Children (5 years)		Head without contrast agent						Head without contrast agent
	IR	94	33.9	35.2	41.7	20.6	p < 0.05	95	502.5	555.6	43.5	12.1	p < 0.05
	FBP	219	40.6	44.3	59.4			221	599.0	632.0	51.3
		Head (non-helical) without contrast agent						Head (non-helical) without contrast agent
	IR	38	34.1	36.3	51.1	20.4	p < 0.05	39	474.8	486.0	44.2	7.9	p = 0.40
	FBP	109	41.1	45.6	65.8			110	499.3	527.4	53.9
		Head (helical) without contrast agent						Head (helical) without contrast agent
	IR	56	33.1	34.4	33.1	19.9	p < 0.05	56	600.0	604.1	41.2	17.9	p < 0.05
	FBP	110	40.0	42.9	51.4			111	680.0	735.6	44.8
		Head with contrast material (tumour)						Head with contrast material (tumour)
	IR	42	34.5	35.2	44.4	26.2	p < 0.05	42	523.3	636.1	83.0	17.2	p = 0.18
	FBP	55	41.9	47.7	64.1			55	655.8	767.9	55.4
		Chest without contrast agent						Chest without contrast agent
	IR	91	4.5	5.2	64.2	49.9	p < 0.05	92	120.0	148.1	68.5	36.6	p < 0.05
	FBP	48	7.0	10.4	123.5			49	169.0	233.4	105.6
		Chest with contrast agent (tumour)						Chest with contrast agent (tumour)
	IR	68	5.0	5.9	60.9	20.2	p = 0.10	68	144.0	176.3	76.5	1.4	p = 0.92
	FBP	29	5.5	7.5	65.2			29	148.0	178.7	56.9
		Abdomen and pelvis without contrast agent						Abdomen and pelvis without contrast agent
	IR	92	4.9	6.5	69.1	43.1	p < 0.05	95	180.0	240.2	78.0	18.1	p = 0.18
	FBP	48	8.0	11.5	114.5			49	200.0	293.3	82.6
		Abdomen and pelvis with contrast agent (acute abdomen)						Abdomen and pelvis with contrast agent (acute abdomen)
	IR	86	6.0	9.4	122.7	−0.4	p = 0.98	86	230.5	352.7	109.3	−16.1	p = 0.37
	FBP	32	7.6	9.4	62.4			32	280.0	303.9	65.2

CTDI_vol, volume CT dose index; DLP, dose–length product; CV, coefficient of variationIR, iterative reconstruction; FBP, filtered back projection;

n indicates the number of CTDI_vol or DLP values.