AJR 2004; 183:1172
© American Roentgen Ray Society
Should Low-Kilovoltage Chest CT Protocols Be the Rule for Pediatric Patients?
Jean-François Paul1,
Hicham T. Abada2 and
Anne Sigal-Cinqualbre3
1 Hôpital Marie-Lannelongue Le Plessis-Robinson 92350,
France
2 Hôpital René Dubos Cergy-Pontoise 95303, France
3 Hôpital Marie-Lannelongue Le Plessis-Robinson 92350,
France
We read with great interest the article by Lee at al.
[1] in the March issue of the
American Journal of Roentgenology describing the usefulness of MDCT
in detecting aortic anomalies in children and young adults. To achieve a
low-radiation-dose CT protocol, Lee et al. used 80 kV in pediatric patients
weighing less than 50 kg with concomitant adjustment of the milliampere-second
setting (mAs) based on the weight of the patient. In a recent paper, we showed
that 80 kV was an acceptable setting for chest CT in adults weighing less than
75 kg, without substantial impairment in image quality
[2]. In pediatric patients, we
routinely perform chest CT examinations (> 100 examinations a year) at 80
kV (maximum, 100 mAs), on a Siemens 16-MDCT scanner using submillimetric
collimation. These data indicate that pediatric chest CT could be performed
routinely at low kilovoltage according to the ALARA (as low as reasonably
achievable) principle [3]. At a
constant tube current, decreasing the kilovoltage from 120 to 80 kV results in
a 56% reduction in radiation dose. Additional benefits of 80 kV include higher
vascular contrast and an IV contrast medium reduction up to 50% because of the
higher attenuation of iodine at 80 kV
[2].
However, individual optimization of parameters (kilovoltage and
milliampere-seconds) remains challenging in pediatric patients, and much
remains to be done. In the protocol indicated by Lee et al.
[1], for example, there is a
radiation-dose increase of 225% between a pediatric patient weighing 49 kg (80
kV, 100 mAs) and one weighing 51 kg (120 kV, 100 mAs). Such an increase in the
radiation dose is not justified, in our experience, to keep a constant image
quality. A decrease in tube current is to be considered when increasing the
kilovoltage to avoid a step effect. New intermediate settings (100 kV)
provided recently on new equipment are welcome for the fine adaptation of
individual radiation parameters.
We again thank Lee et al. for the efforts made to reduce radiation dose in
pediatric patients, which represents a challenge in our clinical practice. We
are convinced that 80 kV should become the rule for chest CT in pediatric
patients.
References
- Lee EY, Siegel MJ, Hildebolt CF, Gutierrez FR, Bhalla S, Fallah JH.
MDCT evaluation of thoracic aortic anomalies in pediatric patients and young
adults: comparison of axial, multiplanar, and 3D images.
AJR 2004;182:777
-784[Abstract/Free Full Text]
- Sigal-Cinqualbre AB, Hennequin R, Abada HT, Chen X, Paul JF.
low-kilovoltage multi-detector row chest CT in adults: feasibility and effect
on image quality and iodine dose. Radiology2004; 234: 169-174
(Epub 2004 Feb 27)
- [No authors listed] The ALARA (as low as reasonably achievable)
concept in pediatric CT intelligent dose reduction: multidisciplinary
conference organized by the Society of Pediatric Radiology—August
18–19, 2001. Pediatr Radiol2002; 32:217
-313[Medline]
Reply
Edward Lee and
Marilyn Siegel
Washington University St. Louis, MO 63130
We appreciate the comments of Drs. Paul, Abada, and Sigal-Cinqualbre. We
share concern about the radiation dose from pediatric CT. As Paul et al.
probably recognize, the push to lower radiation dose in pediatric CT has
progressively increased over the past several years and during the time of our
study [1]. We agree that it is
possible to lower radiation dose in pediatric patients and that every effort
should be made to do so without compromising quality.
Paul et al. believe that CT examinations in children should be performed
with 80–100 kV in order to achieve a low radiation dose. In their
experience, the use of a low peak kilovoltage maintains a constant image
quality. However, in a recent article in the AJR by Cody et al.
[2], the authors found
beam-hardening artifact when pediatric CT examinations were performed with 80
kVp and they suggested the use of 100–120 kVp in this population. We
know of no large study that evaluates image quality on CT by varying both peak
kilovoltage and milliampere-second in combination for different sized
pediatric patients. If the authors have assessed image quality by modifying
both peak kilovoltage and milliampere-second in a large population of
pediatric patients, we hope that they will publish their results.
Low-kilovoltage protocols should be routine for children, but it needs to be
shown that image quality is maintained.
References
- Lee EY, Siegel MJ, Hildebolt CF, Gutierrez FR, Bhalla S, Fallah JH.
MDCT evaluation of thoracic aortic anomalies in pediatric patients and young
adults: comparison of axial, multiplanar, and 3D images.
AJR 2004;182:777
-784
- Cody DD, Moxley DM, Krugh KT, O'Daniel JC, Wagner LK, Eftekhari F.
Strategies for formulating appropriate MDCT techniques when imaging the chest,
abdomen, and pelvis in pediatric patients. AJR2004; 182:849
-859[Abstract/Free Full Text]
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