Table 1. Measurements of SNR in images acquired with different CTPA protocols and associated radiation dose.

Pitch values/SNR and radiation dose	70 kVp				80 kVp				100 kVp				120 kVp
	0.9	2.2	3.2		0.9	2.2	3.2		0.9	2.2	3.2		0.9	2.2	3.2
Right main pulmonary artery	37.06±5.24	30.69±1.29	27.42±1.81		32.91±0.60	30.53±4.41	24.51±1.63		29.06±1.38	28.01±1.23	30.89±2.90		36.13±0.55	39.15±0.71	42.09±1.19
Left main pulmonary artery	40.22±3.94	29.89±0.30	20.87±2.03		35.27±1.10	28.35±1.30	25.63±0.79		34.38±1.46	31.31±1.23	36.86±2.51		58.83±1.07	47.54±2.32	67.30±3.90
Within right thrombus	4.22±0.13	4.16±0.02	3.28±0.16		4.84±0.30	5.02±0.30	4.92±0.37		6.52±0.27	6.44±0.33	6.37±0.59		10.55±0.71	9.10±0.65	10.07±1.41
Within left thrombus	6.02±0.50	4.99±0.43	4.83±0.49		6.48±0.26	6.49±0.42	4.82±0.42		13.02±0.51	12.36±1.27	10.61±1.04		13.27±1.27	11.73±0.73	10.89±1.09
CTDIvol (mGy)	0.41	0.15	0.12		0.42	0.21	0.21		1.01	0.55	0.55		2.22	1.05	1.05
DLP (mGy/cm)	5.90	2.70	2.20		6.20	4.00	3.60		14.60	10.30	9.50		32.20	19.70	18.10
Effective dose (mSv)	0.08	0.04	0.03		0.09	0.06	0.05		0.20	0.14	0.13		0.45	0.28	0.25

SNR, signal-to-noise ratio; CTPA, computed tomography pulmonary angiography; CTDIvol, volume CT dose index; DLP, dose length product.