With respect to cancer risk, children are ten-fold more sensitive to radiation than adults.
One of the first tenets of medical students about patient care is “primum non nocere” (“first, do no harm”). Much has been written about the increased risk of cancer from radiation associated with diagnostic radiology procedures, particularly in children. Concern about this risk has been raised in both the medical literature and in the lay community.
With respect to cancer risk, children are ten-fold more sensitive to radiation than adults. Computerized tomography (CT) is an indispensable diagnostic tool for appropriate indications but it involves relatively significant radiation exposure and is widely believed to be over utilized, especially in children. Alternatives to CT include plain films and ultrasonography, both of which can provide valuable diagnostic information and possibly obviate the need for CT when used appropriately in some clinical situations.
Ultrasonography (US) is particularly suitable as a pediatric imaging modality for several reasons:
- Use of US involves no ionizing radiation, and there are no known harmful effects for patients.
- The quality of US images in most children is excellent due to their relatively small percent body fat, as fat significantly degrades US images.
- Young children are often uncooperative and move during exams, frequently requiring sedation for CT and MRI exams. On the other hand, US exams virtually never require sedation.
- US’s ability to evaluate blood flow to organs and lesions is important in the diagnosis of multiple disorders.
- US is significantly less expensive than CT and MRI, a particularly important consideration in the performance of serial exams or mass screening of patient populations.
Radiologists are frequently asked about indications for and timing of US in certain clinical conditions, which include:
- Hip disorders: US is excellent in the evaluation of the infant hip for developmental dysplasia (DDH). Indications include breech presentation, family history of DDH, asymmetric thigh folds, and hip click or clunk on exam. It is recommended to have US performed in the first two weeks of life if the physical exam is abnormal but to wait until 4-6 weeks of life if there is a risk factor but no abnormality on exam.
- Spine disorders: US can in lieu of spine MRI to screen for tethered cord, filum lipoma, spinal dysraphism, and related disorders in neonates and young infants. After four months of age, there is often significant ossification of the posterior elements of the spine that obscures visualization of the spinal canal. Indications for spine US include deep sacral dimples, anorectal malformations, hairy tufts, and asymmetric natal cleft.
- Neurologic/cranial disorders: Head US is excellent in newborns and infants less than nine months of age to screen for hydrocephalus, intracerebral and intraventricular hemorrhage, and congenital anomalies. The anterior fontanel typically closes between nine and 15 months, after which CT or MRI would be necessary.
- Palpable masses: Palpable masses of the head/neck, abdomen, and extremities at any age can be evaluated by US. In fact, US is the preferred initial examination to determine whether a mass is cystic or solid and vascular or avascular, thus allowing for differentiation of the mass (e.g., likely benign vs. malignant, inflammatory, infectious, etc). Initial evaluation of a mass by US frequently allows a decision to be made about clinical management: 1) following the mass (either clinically and/or by serial US exams; 2) additional radiologic procedures (CT or MRI); or 3) immediate surgery.
In the evaluation of pediatric patients at Northwest Radiology, we make every attempt to minimize the exposure incurred with procedures involving radiation, including CT, plain films and fluoroscopy.
By Kathy S. Clark, MD Northwest Radiology Network Pediatric Radiologist
|
NWR Pediatric Radiologists:
|
|
 |
|
| Kathy Clark, MD | Patricia Ladd, MD |
