Debra Pennington, MD Director of Imaging Dell Children s Medical Center

Debra Pennington, MD Director of Imaging Dell Children s Medical Center

1 Gray (Gy) is 1 J of radiation energy/ 1 kg matter (physical quantity absorbed dose) Diagnostic imaging doses in mgy (.001 Gy) Sieverts (Sv) are similar but use a weighting factor for radiation type and tissue affected Sv are used in estimates of risk (effective dose) For practical purposes, 1 mgy = 1 msv for a whole body exposure Background exposure is about 3 msv/ year

Ankle 3 views CXR 2 views VCUG Head CT Abdomen CT Bone scan PET

Medical diagnostic doses: weak carcinogen DNA damage Risk to: Individual: cancer Offspring: genetic defects & cancer Gonadal radiation

Extremely small individual lifetime increased cancer mortality: 0.05% - 0.12% for single neonatal head or abdominal CT Benefits nearly always outweigh individual risk This is a public health issue Baseline: 25% of us will develop cancer

OVERALL: 5% per Sievert (Sv), or 1000 msv 1 Sv = radiation sickness ADULT: 1% per Sv CHILD: 15% per Sv CT = was.005 Sv or 5 msv recently With newer IR: 1m Sv or less CXR:.01-.06 msv (.00001-.00006 Sv) 3

As Low As Reasonably Achievable Don t do exams that are not indicated Use imaging without ionizing radiation whenever possible When doing an exam requiring radiation, tailor the exam to the clinical question and size of the child

The mission of the Alliance for Radiation Safety in Pediatric Imaging (the Image Gently Alliance) is, through advocacy, to improve safe and effective imaging care of children worldwide.

Consult with pediatric radiologist or other imaging colleagues Shielding Immobilization Collimation

Scan parameters: Intensity of beam (mas) Speed of patient movement thru beam (pitch) Greater anatomic detail = higher dose CTA neck >>> CT neck

Pitch < 1 Pitch = 1 Pitch > 1

CT dose (Gy) measured with TLD (thermoluminescent dosimeter) placed in phantom CTDIvol & DLP (dose length prod) ARE NOT PATIENT DOSES

Size-specific dose estimate Performed by physicist based on biomorphometry of the child - takes into account corrections based on size of the patient, using conversion factors Use linear measurements from the child, or from the images

Is exam necessary? Adjust scanning parameters for patient size, exam purpose Shielding YES for sensitive organs outside the scan area (lead shields) But NO to bismuth breast shields

Cannot be used with automatic dose modulation Will slightly affect scan quality Dose adjustment, modulation and iterative reconstruction preferred

Use pediatric-specific protocols Use delays sparingly (doubles dose is a second scan) Highest radiation: CTA Shield if possible

One size does not fit all... There's no question: CT helps us save kids' lives. But when we image, radiation matters! Children are more sensitive to radiation. What we do now lasts their lifetimes.

So when we image, let's image gently: More is often not better. When CT is the right thing to do: Child size the kvp and ma. One scan (single phase) is often enough. Scan only the indicated area.

Image Gently and CT safety campaign North American Consensus Guidelines for Pediatric Administered Radiopharmaceutical Activities (updated 2014) Image Gently Back to Basics Digital Radiography Campaign Image Gently Pause and Pulse Fluoroscopy Resources

Open dialogue with your pediatric radiologist Be aware of opportunities to lower radiation dose in children by sending your patients to facilities that have been accredited by the American College of Radiology and other accrediting bodies. Encourage parents to ask questions and then direct them to the Imaging Gently website Direct your imaging colleagues to this website. Make sure they take every effort to decrease administered dose by using the appropriate equipment and post-processing techniques.

1. Pediatr Radiol 2002; 32:221-316 (entire issue) 2. Brenner DJ, Elliston CD, Hall EJ, Berdon WE. Estimated risks of radiation-induced fatal cancer from pediatric CT. Am J Roentgenol 2001; 176:289-296. 3. Hintenlang KM, Williams JL, Hintenlang DE. A survey of radiation dose associated with pediatric plain-film chest X- ray examination. Pediatr Radiol 2002; 32:771-777. 4. Mettler FA, Wiest PW, Locken JA, et al. CT scanning: patterns of use and dose. J Radiol Prot 2000; 20:353-359. 5. Retrieved from http://www.imagegently.org/procedures/digital- Radiography/Educational-Materials.