Siemens SOMATOM Sensation Cardiac Version A60 Operations Instructions download pdf (Page 12)

General

100kV-Protocols

The additional tube voltage 100 kV is now supported.

The system offers a spectrum of 4 kV settings (80 kV,

100 kV, 120 kV and 140 kV) for individual adaptation

of the patient dose in pediatric scans and for optimiza-

tion of the contrast-to-noise ratio in contrast-enhanced

CT angiographic studies.

In contrast enhanced studies, such as CT angiographic

examinations, the contrast-to-noise ratio for fixed

patient dose increases with decreasing tube voltage.

As a consequence, to obtain a given contrast-to-noise

ratio, patient dose can be reduced by choosing lower

kV-settings. This effect is even more pronounced for

smaller patient diameters. It can be demonstrated by

phantom measurements using small tubes filled with

diluted contrast agent embedded in plexiglass phan-

toms with different diameters. The iodine contrast-to-

noise ratio for various kV-settings is depicted in Fig. 1

as a function of the phantom diameter. Compared to

a standard scan with 120 kV, the same contrast-to-

noise ratio in a 32 cm phantom, corresponding to an

average adult, is obtained with 0.49 times the dose

for 80 kV (1.3 times the mAs) and 0.69 times the dose

(1.1 times the mAs) for 100 kV. Ideally, 80 kV should

be used for lowest patient dose. In practice, however,

the use of 80 kV for larger patients is limited by the

available mA-reserves of the X-ray generator.

In these patients, 100 kV is a good compromise and

the preferable choice for CTA examinations. In the

current software version, three protocols applying

100 kV have been introduced: AngioHead100 kV,

Embolism100 kV for pulmonary embolism and

CoronaryCTA100 kV.

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Siemens SOMATOM Sensation Cardiac Version A60 Operations Instructions Page 12