Diagnostic Imaging

        

Head CT

In general, there appears less potential for dose reduction in paediatric head CT than body CT as there is less disparity in paediatric and adult head size than body size. However, there is still some opportunity for dose savings in routine work. We utilize further dose reducing protocols in shunt (hydrocephalus) follow-up examinations, paranasal sinus CT and 3D head examinations used in the investigation of craniosynostosis (fused sutures).

An unenhanced CT is often sufficient to answer management issues in acute situations. Whenever possible, use pre or post-contrast scans, not both. We use contrast CT to evaluate for infection or vascular abnormality. The use of two phase examinations doubles the radiation dose and is useful only in a few clinical indications.
Our current protocols (GE Lightspeed Ultra) are given below, as an example.

Paediatric Neuro Exposure Chart

Axial scans

Age

kVp

Time

mA

mAs

Neonate

100

2 sec

From SB to PF*70PF top of head50

140

100

0-6mos

120

2 sec

From SB to PF*90PF top of head60

180

120

6mos-2yrs

120

2 sec

From SB to PF*100PF top of head70

200

140

3yrs-10yrs

120

2 sec

From SB to PF*100PF top of head80

200

160

Large Teen/ Adult

120

2 sec

From SB to PF*110PF top of head90

220

180

Low Dose Shunt Check

120

2 sec

From SB to PF*70PF top of head50

140

100

Sinuses

120

2 sec

20

40

3D Head

120

1 sec (Helical)

20

20

*PF=POST FOSSASB=SKULL BASE

Other examples of paediatric CT protocols are available from several institutions involving a variety of manufacturers. Please see the list below of references and websites. Further articles which may be helpful to the reader are also suggested.

References

Paediatric CT protocols

Donnelly LF, Frush DP (2003) Pediatric multidetector CT. Radiol Clin North Am 41: 637-655

Frush DP, Soden B, FrushKS, Lowry C (2002) Improved pediatric multidetector CT using a size-based color-coded format. Am J Roentgenol 178: 721-726

Donnelly LF, Emery KH, Brody AS, Laor T, Gylys-Morin VM, Anton CG, Thomas SR, Frush DP (2001) Minimizing radiation dose for pediatric body applications of single-detector helical CT: strategies at a large children’s hospital. American Journal of Radiology 176:303-306

Verdun FR, Lepori D, Monnin P, Valley JF, Schnyder P, Gudinchet F (2004). Management of patient dose and image noise in pediatric CT abdominal examinations. Eur Radiol 14: 835-841

CTisus   Johns Hopkins website giving adult and pediatric CT protocols.

Voch P (2005) CT dose reduction in children. Eur Radiol 15: 2330-2340

Cody DC, Moxley DM, Krugh KT, O’Daniel JC, Wagner LK, Eftekhari F (2004) Strategies for formulating appropriate MDCT techniques when imaging the Chest, Abdomen, and Pelvis in Pediatric Patients. AJR 182:849-859

FDA Public Health Notification(2001): Reducing radiation risk from computed tomography for pediatric and small adult patients

PatersonA, Frush DP, Donnelly LF (2001) Helical CT of the body: are settings adjusted for pediatric patients? American Journal of Radiology 176:297-301

Parameters affecting CT dose

Hamberg LM, Rhea JT, Hunter GJ, Thrall JH (2003) Multidetector Row CT: Radiation Dose characteristics. Radiology 226: 762-772

Lewis M. Radiation Dose issues in multi-slice CT scanning. Available at www.impactscan.org

Malignancy risks associated with ionizing radiation

ICRP Publication no.60. 1990 recommendations of the International Commission on Radiological Protection. Oxford, England: Pergamon, 1991

BEIR VII – Phase 2 (2005) Health risks from exposure to low levels of ionizing radiation. National Academies Press.

Donnelly LF (2002) Lessons from history. Pediatr Radiol 32: 287-292

Risks associated with pediatric CT

Brenner DJ, Elliston CD, Hall EJ, Berdon WE (2001) Estimated risks of radiation-induced fatal cancer from pediatric CT. American Journal of Radiology 176:289-296

Pierce DA, Preston DL (2000) Radiation-related cancer risks at low doses among atomic bomb survivors. Radiation Research 154:178-186

Brenner DJ. Estimating cancer risks from pediatric CT: going from the qualitative to the quantitative. Pediatr Radiol 2002; 32: 228-231.

Conference on the ALARA concept in pediatric intelligent dose reduction (2002) Pediatr Radiol 32 (4): 217-313

Effective doses in CT examinations.

Picano E (2004) Sustainability of medical imaging. BMJ 328: 578-580

FDA website   What are the radiation risks from CT?

Shrimpton PC, Hillier MC, Lewis MA, Dunn M (2005) Doses from Computed Tomography examinations in the UK – 2003 review. NRPB – W67, NRPB Publications.  Huda W. Effective doses to adult and pediatric patients. Pediatr Radiol 2002; 32: 272-279.

Huda W. Effective doses to adult and pediatric patients. Pediatr Radiol 2002; 32: 272-279.

Useful articles for paediatricians

Frush DP, Donnelly LF and RosenNS(2004) Computed tomography and radiation risks: What pediatric health providers should know. Pediatrics 112(4): 951-957

Thomas KE, Parnell-Parmley JE, Haidar S, Moineddin R, Charkot E, BenDavid G and Krajewski C (2006) Assessment of radiation dose awareness among pediatricians. Pediatric Radiology 36: 823-832

American Academy of Pediatrics Grand Rounds8: 41-42 (2002) Think Twice before Ordering that CT.

Radiation Risks and Pediatric Computed Tomography (CT): A guide for health care providers. Published by the National Cancer Institute (2002).