Validation of CT doses of SPECT/CT and PET/CT hybrid devices: lessons learned.
The aim of the study was to check the validity of computed tomographic (CT) doses exhibited by SPECT/CT and PET/CT hybrid devices. Dose measurements were taken from four SPECT/CT and four PET/CT cameras commercially available from different manufacturers. A calibrated ionization chamber was placed in whole-body or head phantoms for the acquisition of CT images with clinically used parameters. Computed tomography dose index (CTDIvol) values were calculated according to the IEC 60601-2-44:1999 formula. The measured CTDIvol doses were compared with those preprogrammed by the manufacturer. In the case of the whole-body phantom, the differences between the measured and displayed values varied between -31 and +24% [European document RP162 (2012) sets up the limit for acceptance criterion as ±20%]. The head phantom data showed either an agreement between -10 and +24%, or an underestimation by two-fold. The latter seemed to be because, while preprogramming the doses, the manufacturer had used the whole-body phantom instead of a proper head phantom. The results of the work demonstrate the need for individual dosimetric calibration of every single X-ray tube. Dosimetric checks should be included in the regular quality control programmes of the SPECT/CT and PET/CT devices. Special attention should be paid to head-and-neck and paediatric protocols, in which the use of a head phantom is recommended for dose calibration.
aDepartment of Nuclear Medicine, University of Szeged bEuromedic Diagnostics, Szeged c'Frédéric Joliot-Curie' National Research Institute for Radiobiology and Radiohygiene, Budapest, Hungary.
Terez
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Sera
Tamas
T
Porubszky
Miklos
M
Papos
Richard
R
Elek
Zsuzsanna
Z
Besenyi
Katalin
K
Gion
Andras
A
Bartha
Sandor
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Pellet
Laszlo
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Pavics
D064847:Multimodal Imaging / Q000295:instrumentation*; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000295:instrumentation*; D011829:Radiation Dosage; D015203:Reproducibility of Results; D015899:Tomography, Emission-Computed, Single-Photon / Q000295:instrumentation*; D014057:Tomography, X-Ray Computed / Q000295:instrumentation*