Dose Exposure of Patients Undergoing Comprehensive Stroke Imaging by Multidetector-Row CT: Comparison of 320-Detector Row and 64-Detector Row CT Scanners

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Fig 1.
Alderson-Rando phantom. Numbers indicate the sections in which TLDs were placed (Table 1).
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Fig 2.
Scanograms of the 320-detector row CT scanner: A, incremental CCT; B, volume CCT; C, combo protocol; D, neck CT. Scanograms of the 64-detector row CT scanner: E, CTP; F, CTA (head and neck) (incremental CCT is analogous to A).

Table 1:

Doses measured for all protocols on 64-row scanner (Toshiba Aquilion 64)

Organ	W (T)	Noncontrast Head CT		Perfusion		CTA
Organ	W (T)	Dose (mGy)	Weighted Dose (mSv)	Dose (mGy)	Weighted Dose (mSv)	Dose (mGy)	Weighted Dose (mSv)
Hemispheres	0.01	33.31	0.33	66.22	0.66	24.34	0.24
Skin (within scan area)		33.17		75.41		26.27
Skin (total)	0.01	17.43	0.17	37.9	0.38	13.87	0.14
Eye lenses		41.69		6.74		14.86
Pituitary gland		33.7		14.26		20.07
Bone marrow (scan area)		8.4		4.1		22.05
Bone marrow (total)	0.12	4.6	0.56	2.36	0.28	11.88	1.43
Thyroid gland	0.04	1.49	0.06	1.04	0.04	39.17	1.57
Lung	0.12	0.8	0.1	0.48	0.06	2.99	0.36
Esophagus	0.04	0.36	0.01	0.55	0.02	2.78	0.11
Breast	0.12	1.69	0.2	0.39	0.05	1.47	0.18
Liver	0.05	0.37	0.02	0.28	0.01	0.94	0.05
Stomach	0.12	0.53	0.06	0.44	0.05	0.92	0.11
Ovaries	0.08	0.28	0.02	0.33	0.03	0.35	0.03
Lower colon	0.12	0.74	0.09	0.28	0.03	0.24	0.03
Bladder	0.04	0.73	0.03	0.34	0.01	0.57	0.02
Testes	0.08	0.31	0.02	0.27	0.02	0.28	0.02
Effective dose (women)			1.65		1.62		4.27
Effective dose (men)			1.65		1.61		4.26

Table 2:

Doses measured for all protocols on a 320-row scanner (Toshiba Aquilion ONE)

Organ	W (T)	Noncontrast Head CT Volume		Noncontrast Head CT Incremental		CTP + CTA (Intractranial)		CTA (Neck)
Organ	W (T)	Dose (mGy)	Weighted Dose (mSv)	Dose (mGy)	Weighted Dose (mSv)	Dose (mGy)	Weighted Dose (mSv)	Dose (mGy)	Weighted Dose (mSv)
Hemispheres	0.01	31.42	0.31	41.91	0.42	69.91	0.7	3.34	0.03
Skin (scan area)		36.86		42.34		92		3.84
Skin (total)	0.01	19.19	0.19	21.47	0.21	46.49	0.46	3	0.03
Eye lenses		40.23		44.31		44.01		2.39
Pituitary gland		25.24		38.93		52.69		5.3
Bone marrow (scan area)		7.67		12.77		30.17		14.8
Bone marrow (total)	0.12	4.2	0.5	6.97	0.84	15.81	1.9	8.57	1.03
Thyroid gland	0.04	2.54	0.1	3.39	0.14	5.37	0.21	58.6	2.3
Lung	0.12	0.78	0.09	0.4	0.05	0.61	0.07	4.36	0.5
Esophagus	0.04	0.5	0.02	0.63	0.03	0.46	0.02	3.51	0.14
Breast	0.12	1.52	0.18	0.59	0.07	0.98	0.12	2.17	0.26
Liver	0.05	0.77	0.04	0.42	0.02	0.29	0.01	1.16	0.06
Stomach	0.12	0.63	0.08	0.3	0.04	0.29	0.03	1.18	0.14
Ovaries	0.08	0.48	0.04	1.01	0.08	0.42	0.03	0.36	0.03
Lower colon	0.12	0.46	0.06	0.43	0.51	0.23	0.03	0.29	0.03
Bladder	0.04	0.68	0.03	0.59	0.02	0.74	0.03	0.33	0.01
Testes	0.08	0.29	0.02	0.53	0.04	0.43	0.03	0.34	0.03
Effective dose (women)			1.64		2.43		3.61		4.56
Effective dose (men)			1.62		2.39		3.61		4.56

Table 3:

Parameters of the protocols used on the 64-row CT scanner

Parameter	Noncontrast Head CT Scan		CTP	CTA
Parameter	Infratentorial	Supratentorial	CTP	CTA
Lens protection	No		Yes	Yes
Collimation (mm)	2 × 4		4 × 8	0.5 × 64
Table increment (mm)	8 mm	8 mm	None	20.5
Pitch	1		No	0,614
Tube current (mAs_eff)	375	250	50	150
Tube current (mA)	250		50	300
Voltage (kV)	120		120^a	120
Rotation time	1.5 s	1.0 s	1 s	0.5 s
Scan length (mm)	140		32	340.8
Total scan time	24.8 s		45.7 s	23 s
Gantry angulation	Yes		Yes	No

a The Aquilion 64 scanner at the Department of Radiology, Charité Campus Mitte (Berlin, Germany) was one of the first scanners of this type installed. Due to a technical limitation, this Aquilion 64 scanner does not support CTP with 80 kV. Newer versions of the Aquilion 64 scanner allow performing CTP with 80 kV in the same way as the Aquilion ONE does.

Table 4:

Parameters of the protocols used on the 320-row CT scanner

Parameter	Noncontrast Head CT Scan (Volume)	Noncontrast Head CT (Incremental)		Combo (Cerebral CTA + CTP)	Neck CTA
Parameter	Noncontrast Head CT Scan (Volume)	Infratentorial	Supratentorial	Combo (Cerebral CTA + CTP)	Neck CTA
Lens protection	No	No	Yes	Yes
Collimation (mm)	0.5 × 280	2 × 4	2 × 4	0.5 × 320	0.5 × 64
Table increment (mm)	No	8	8	none	20.5
Pitch		1	1	no	0.614
Tube current (mAs_eff)	320	375	250	100	Tube current modulation
Tube current (mA)	320	250		100	Tube current modulation
Voltage (kV)	120	120		80	120
Rotation time	1 s	1.5 s	1 s	1 s	0.5 s
Scan length (mm)	140	140		160	216
Scan time	7.2 s	26.8 s		29.8 s	30.99 s
Gantry angulation	Yes	Yes	Yes	No	No