[Dosimetry in conventional and spiral CT in 8 spiral CT scanners of the latest generation].
OBJECTIVE
Measurement of scanner-dependent differences in PCTDI for conventional and spiral CT and evaluation of PCTDI/100 mAs in eight spiral CT scanners of the latest generation.


METHODS
Central PCTDI was evaluated in a PMMA phantom for different scan lengths of conventional and spiral CT in four scanners. Central and peripheral PCTDI/100 mAs, average dose and the quotient between peripheral and central PCTDI/100 mAs were measured with a dedicated 10 cm ionisation chamber positioned within a PMMA phantom using the parameters of a standardised liver protocol and a high-resolution inner ear protocol for eight spiral CT scanners.


RESULTS
Depending on scanner type and scan length PCTDI for the spiral mode is in a range between 11.3% higher and 4.3% lower than that for the conventional mode. PCTDI/100 mAs varies considerably between different CT scanners. For the standardised liver protocol PCTDI/100 mAs varies up to a factor of 2, for the inner ear protocol up to a factor of 4.


CONCLUSIONS
Even in comparable modern CT scanners there are considerable protocol and scanner-dependent differences in PCTDI/100 mAs. The values for his own scanner should be known to each CT user so that he can develop a dose-optimised, patient and problem-orientated examination strategy.
Institut für Radiologische Diagnostik, Klinikum Innenstadt der Ludwig-Maximilians-Universität, München.
R J
RJ
Scheck
E M
EM
Coppenrath
M W
MW
Kellner
K J
KJ
Lehmann
M
M
Mayer
C
C
Rock
J
J
Rieger
L
L
Rothmeier
F
F
Schweden
R
R
Sokiranski
A
A
Bäuml
K
K
Hahn
D007758:Ear, Inner / Q000000981:diagnostic imaging; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging; D008962:Models, Theoretical; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*