Radiation and Computed Tomography in Children… Is there still a cause for ALARAm? Nikhil B. Shah, M.D. Assistant Professor of Pediatrics Division of Pediatric Emergency Medicine Weill Cornell Medical Center Thank you and good morning. I am sure that many of you are aware of the fact that this issue in PEM has received a lot of media attention recently. Its important because everyday we, as clinicians, are expected to make decisions that impact upon the lives of our patients. In making these decisions, it is hoped that we weigh the benefits of the particular test or intervention against any potential risks. So what I’d like to talk to you about today are the radiation risks associated with pediatric CT and how awareness of these risks should impact on our ordering practices.

Disclosure I have no potential, apparent, or real conflict of interest to disclose and DO NOT INTEND to discuss off-label or investigational use of products or services.

Outline Overview Risks of radiation in children Initiatives to reduce radiation exposure in children

Outline Overview Risks of radiation in children Initiatives to reduce radiation exposure in children

Question What is the relative radiation dose of a CT compared to a chest x-ray (CXR)? CT = CXR CT = 1-10 CXR CT = 10-100 CXR CT = 100-250 CXR CT ≥ 500 CXR

Lee et al Radiology April 2004

Question What is the relative radiation dose of a CT compared to a chest x-ray (CXR)? CT = CXR CT = 1-10 CXR CT = 10-100 CXR CT = 100-250 CXR CT ≥ 500 CXR

Why is this issue important? Diagnostic imaging in the pediatric emergency department is increasing Up to 1/3 of studies may not contribute to patient management The primary concern is the radiation risk of unnecessary diagnostic imaging Picano E, BMJ 2004, 328:578-580

Why is this issue important? Unnecessary imaging: Adds to the costs of medical care Puts the child at risk of discovering an “incidentaloma” Subjects the child to unnecessary radiation which increases the lifetime risk for fatal cancers An incidentaloma is an unexpected finding that requires additional evaluation but is eventually found to be irrelevant to the management of the patient. It usually results in further investigations and sometimes other interventions that usually end up demonstrating that the finding is of no clinical significance.

Pierce and Preston, Radiat Res, 2000

Advent of CT 1974 – 1st CT scans performed CT has evolved into an invaluable diagnostic tool 2010 – > 6000 scanners in use CT has revolutionized medicine because it allows doctors to see diseases that, in the past, could often only be found at surgery or at autopsy Currently over 6000 scanners are in use

Impact of CT 700% increase in CT use over past decade CT use continues to increase; growth rate 10% per year Brenner, et al, NEJM 2007

Impact of CT More than 70 million CT scans performed annually in US 11% in children (~10 million) Relatively young technology whose risks are not yet fully quantified That was then, this is now… Parentsand patientsalike have come to expect CT when they come to the ER.

Why the recent upsurge in CT utilization? Increased availability Advances in CT technology (ie, helical CT and MDCT) Faster scanning - sometimes < 1 second Decreased need for sedation

Too good to be true? Despite the many benefits of CT, the radiation exposure associated with this modality has come under increasing scrutiny

Dose Contribution of CT % of Imaging Studies Utilizing Ionizing Radiation % of Total Radiation Dose from Medical Imaging

Comparison of Effective Radiation Doses from X-ray and CT Imaging Study Effective Dose (mSv) Equivalent number of chest x-rays Chest X-ray 0.02 1 Head CT 4 200 Abdominal CT 5 250 Chest CT 3 150 In considering the effective dose of radiation it is helpful to compare the effective dose for different radiologic studies. For example, the radiation from a single abdominal CT is nearly 250 times that of a plain chest radiograph Adapted from Brody, et al, Pediatrics 2007

Societally-Relevant Low Dose Radiation Exposures Source Estimated effective dose (mSv) Natural background radiation 3 mSv/yr Airline passenger (cross country) 0.04 mSv Radiation worker exposure limit 20 mSv/yr Single screening mammogram 3 mSv Radiological bomb (20 block radius) 3-30 mSV Chest X-ray (2 views) 0.1 mSv Head CT 4 mSv Chest CT 3 mSV Abdominal CT 5 mSV

Outline Overview Risks of radiation in children Initiatives to reduce radiation exposure in children

AJR Feb 2001 Much of the recent attention regarding radiation risks from CT in children stemmed from a series of articles published in the American Journal ofRoentgenology in 2001.

One of the sentinel articles on this topic by Brenner, et al sought to assess lifetime cancer mortality risks for different organs attributable to radiation from pediatric CT performed at different ages. They basically multiplied age-dependent lifetime cancer mortality risks (per unit dose) by estimated age-dependent doses produced by various CT examinations. AJR February 2001

Brenner, et al 2001 Most institutions do not adjust dose settings for children Recommended dose reduction in pediatric CT Lifetime cancer mortality risk attributable to CT is considerably higher in children Estimated 1:500 radiation-induced cancer deaths The 1:500 estimate is based on 600K abdominal and head CTs/yr in US on children < 15 years old

Unique Considerations in Children Rapidly dividing cells more sensitive to the effects of radiation 10-fold increase in neoplastic potential compared to equivalent dose in an adult Particularly true for thyroid, breast, and gonadal tissue Longer lifetime during which malignant transformation may occur Rapidly dividing cells are more sensitive to the effects of radiation 10-fold increase in neoplastic potential compared to equivalent dose in an adult Particularly true for thyroid, breast, and gonadal tissue Longer lifetime during which malignant transformation may occur

Hall Pediatric Radiology Apr 2002 pg 226 Most important is age at exposure. Females have greater risk because of breast and thyroid cancer. Hall Pediatric Radiology Apr 2002 pg 226

If we know all this, why is this an issue? CT scans are generally not tailored to the smaller size of children Therefore, children receive a higher radiation dose per unit of tissue compared to an adult for a given study CT

The numbers 1 in 500 to 1:1000 children who have had a CT scan will develop a radiation-induced fatal cancer in their lifetime This correlates to a 0.35% increase over the expected baseline lifetime risk for cancer Does not account for non-fatal cancer

Radiation and Public Health Radiation risk to the individual is small Risk to the population as a whole is considerable given the sheer number of CTs 30% will have more than one scan Dose is cumulative Dose is cumulative - i.e., multiple scans will result in a greater lifetime cancer risk for the individual

A Risk Comparison Activity Risk Driving 7,500 miles 1:1000 (accident risk) Motorcycling for 1,000 miles Abdominal CT scan 1:1000 (risk of radiation-induced cancer) Approx risk in pediatric age group 1:1000 of radiation induced (fatal) cancer at current CT doses. For adults, up to 1:10,000

Radiation and Public Health NCRP reports an increase in effective dose per individual in the US 3.6 mSv in early 1980s to 6.2 mSv in 2006 Indiscriminate use of CT has the potential to become a public health problem NCRP = National Council on Radiation Protection and Measurement

Radiation and Public Health DHHS (2005) -Diagnostic medical radiation added to list of known human carcinogens 2005 BEIR VII report - Diagnostic radiation substantially increases cancer risks Ongoing – Large NCI cohort study evaluating cancer incidence in children who have had CT

Emerging Human Cohorts Chernobyl Airline personnel Nuclear industry workers Radiation therapy patients 2011 Japanese tsunami/earthquake

Outline Overview Risks of radiation in children Initiatives to reduce radiation exposure in children

ALARA ‘As Low As Reasonably Achievable’ Reducing the amount of radiation a child is exposed to while maintaining efficiency and reliability of the diagnostic modality Doses could be reduced by > 30-50% to obtain essentially the same information Various authors have suggested that pediatric CT exposures could be reduced by 30-50% or more relative to adult exposures to obtain essentially the same information.

ALARA ALARA for the radiologist for the clinician

ALARA: for the radiologist Develop weight-based protocols Improve shielding Focused/limited-view studies when feasible Discourage repeat CT studies Consider alternative non-radiation modalities such as MRI or ultrasound Shah & Platt Curr Opin Pediatr 2008

Alternative Imaging Modalities: Ultrasound Advantages No radiation Inexpensive Disadvantages Operator-dependent Impaired diagnostic efficacy in the obese and in retrocecal appendix

Alternative Imaging Modalities: MRI Sparse current literature One report found MRI accurately identified 100% of acute appendicitis in 20 patients MRI may be a valuable imaging technique particularly in children and pregnancy

Alternative Imaging Modalities: MRI Improvement in MRI technology needed Barriers to routine use of MRI in children Cost Availability Need for sedation Improvement in MRI technology needed To enable more rapid sequences Accommodate minor motion artifact To reduce need for sedation Cost, availability, and need for sedation remain current barriers to routine use of MRI in children

Rapid Brain MRI Short shunt/hydrocephalus protocol Useful to look at ventricles, but can also see midline shifts or mass effect Entails sagittal, coronal & axial SSFSE and diffusion weighted sequences Very rapid – approximately 3 minutes SSFSEs (single shot fast spin echo)

AFARA ? for the Clinician AFARA – “As Few As Reasonably Achievable” ? 10-30% of all CT scans may be ‘unnecessary’ Limiting the number of CTs to only those that are clinically indicated Adopting a selective imaging strategy No such thing as AFARA but there should be!

So how do we know which patients to scan? Identify patients at high- or low-risk for a particular outcome of interest using: Clinical decision rules Scoring systems Clinical practice guidelines

What about when the diagnosis is uncertain?

AFARA: for the clinician Role of the pediatric care provider is paramount Responsible for ordering & providing indications and justifications for CT exams Principle source of information about imaging studies, including potential risks

AFARA: for the clinician Educating clinicians about judicious CT use may have the most impact in reducing radiation exposure in children Educating patients about risks, benefits and radiation doses for CT scans

AFARA: for the clinician Explore alternative options and consider true need for a study Role of pediatric radiologist cannot be overemphasized in this decision-making

BUT…. ….aren’t most institutions following these practices already?

A century of progress… 1896 2011

Current Barriers to Selective CT Utilization in the ED Unique demands of ED setting often justify prompt and accurate diagnosis Represents a challenge to all clinicians who care for children Increased potential for litigation May tilt perceived risk-benefit balance towards overuse of CT in children

Alliance for Radiation Safety in Pediatric Imaging in 2007 www.imagegently.org Alliance for Radiation Safety in Pediatric Imaging in 2007 Goal is to raise awareness of the opportunities to lower radiation dose in the imaging of children   Medical education handouts for practitioners and patients.

Summary When medically indicated, the benefits of CT far outweigh the individual risks Recent evidence underscores the importance of judicious utilization of CT Public awareness & education are essential Clinicians and radiologists should present a unified team, who together advocate safe practice in children

Questions?