**9. Patient exposure to radiation**

A point of concern among care providers and parents is the risk of radiation exposure from medical imaging, especially in the pediatric population. Epidemiologic studies have shown that *in utero* exposure to radiation is associated with higher incidence of pediatric cancers, but data related to rates of pediatric and adult cancers are relatively scarce [60]. In recent years, CT scanning has become the favored imaging modality in many clinical scenarios and is likely to see even further increases in use going forward [61–63]. As such, CT utilization in pediatrics has increased markedly over the last 20 years. Over 85 million CT scans are performed annually in the United States, with 5–11% of these performed on children [64]. Before we embark on further discussion, important dose-related information in the context of diagnostic testing is provided in **Table 5**.

solid tumors in children. There is weak evidence regarding the association between radiation exposure and such occurrences (e.g., pediatric astrocytoma and Ewing's sarcoma), but this

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Data regarding the lifetime risk of cancers appear to be more robust. A large retrospective cohort study reviewed >175,000 patients from the NHS registry in England [26]. The authors noted a positive association between dose of radiation from CT imaging and leukemia and brain tumors. They found relative risk of leukemia to be 3.18 in patients who received more than 30 mSv of cumulative radiation. Similarly, they found an increased relative risk of brain cancer to be 2.82 in pediatric patients who received cumulative dosing of 50 mSv or more [26]. The caveat to these data, however, is that these are rare cancers to begin with, thus the absolute relative risk increase is very small. Although the relative risk of brain cancer may nearly triple with significant cumulative radiation exposure, the absolute risk is still exceedingly small. Based on robust statistical models, for every 100,000 skull/brain CT scans in 5-year-old children, eight brain/ central nervous system cancers and four cases of leukemia would result [73]. The same study estimates that 100,000 chest CT scans would lead to an excess of 31 thyroid cancers, 55 breast malignancies, and 1 leukemia case [73]. Consequently, the lifetime risk of cancers, although small, should be discussed with parents of children undergoing CT scanning. Although these studies are largely safe in children, unnecessary exposure to radiation should still be avoided, and diagnostic tests not utilizing ionizing radiation should be used whenever possible. The medical necessity of imaging should be weighed against the relatively small risk of harm when determining the appropriateness of these studies. Again, the greatest risk of cancer appears to exist when children are exposed to cumulative doses of radiation greater than 30–50 mSv.

**10. Pregnancy and reproductive health considerations**

According to the American College of Radiology, no single diagnostic X-ray study or procedure results in radiation exposure sufficient to threaten the well-being of the pregnant patient, the developing embryo, or the fetus [74]. In fact, diagnostic radiation exposures during pregnancy may be safer than the frequent concerns over *in utero* radiation exposure suggest [75]. Moreover, the utilization of diagnostic radiological imaging may entail more benefit than risk in the evaluation of certain maternal injuries or illnesses [76]. As much attention should focus on limiting diagnostic radiation exposure of the gravid woman's breast tissue, to prevent carcinogenesis, as on limiting radiation exposure of the fetus [77, 78]. In the setting of pregnancy, radiation exposure should be limited to 1 mGy during the first trimester, with teratogenicity risk being elevated at 5 mGy [79]. In addition, iodine-containing contrast media may lead to hypothyroidism in the fetus, an additional consideration when performing radiographic studies utilizing contrast material [79]. Counseling of the patient by the referring clinician and by the radiologist is essential in providing informed consent as the benefits and risks of procedures can be opaque and the decision may impart lasting consequences [80]. Impacting 5–7% of all pregnancies, trauma represents an important cause of nonobstetric maternal morbidity and mortality [81]. Consequently, the risk-benefit equation regarding diagnostic imaging in this particular setting is somewhat different, with the mantra that the best way to ensure fetal wellbeing is to aggressively treat the mother [82].

connection is in no way definitive [60].

A typical CT scan of the head of a child carries an average dose of 2–2.5 millisieverts (mSv) of radiation. CT imaging of the chest and abdomen carries doses averaging 3–4 and 5–6 mSv, respectively. The actual dose administered differs from the more nebulous effective dose, as other factors make the amount of radiation exposure more meaningful in children than adults. The effective radiation doses received by children are about 50% higher than those received by adults for similar imaging studies due to smaller body sizes and radiation attenuation [66, 67]. Up to an age of 10, children are approximately three times more sensitive to radiation than adults, which is why longer life expectancy coupled with organ systems that are still developing disproportionately increases the relative burden of pediatric radiation exposure [67–69].

Several studies have attempted to answer questions regarding specific childhood cancer risks associated with radiation exposure. Two studies showed increased incidence of pediatric leukemia in children with medical radiation exposure; however, these studies used retrospective questionnaire data and their result as inconsistent with older data [70, 71]. Certain genetic phenotypes might make some children more sensitive to the effects of radiation and risk of acute lymphocytic leukemia [72]. Very limited data exist on CT-attributable risk of


**Table 5.** Relative radiation level designations along with associated effective adult and pediatric doses, as well as imaging examinations that correspond to said levels [65].

solid tumors in children. There is weak evidence regarding the association between radiation exposure and such occurrences (e.g., pediatric astrocytoma and Ewing's sarcoma), but this connection is in no way definitive [60].

Data regarding the lifetime risk of cancers appear to be more robust. A large retrospective cohort study reviewed >175,000 patients from the NHS registry in England [26]. The authors noted a positive association between dose of radiation from CT imaging and leukemia and brain tumors. They found relative risk of leukemia to be 3.18 in patients who received more than 30 mSv of cumulative radiation. Similarly, they found an increased relative risk of brain cancer to be 2.82 in pediatric patients who received cumulative dosing of 50 mSv or more [26]. The caveat to these data, however, is that these are rare cancers to begin with, thus the absolute relative risk increase is very small. Although the relative risk of brain cancer may nearly triple with significant cumulative radiation exposure, the absolute risk is still exceedingly small. Based on robust statistical models, for every 100,000 skull/brain CT scans in 5-year-old children, eight brain/ central nervous system cancers and four cases of leukemia would result [73]. The same study estimates that 100,000 chest CT scans would lead to an excess of 31 thyroid cancers, 55 breast malignancies, and 1 leukemia case [73]. Consequently, the lifetime risk of cancers, although small, should be discussed with parents of children undergoing CT scanning. Although these studies are largely safe in children, unnecessary exposure to radiation should still be avoided, and diagnostic tests not utilizing ionizing radiation should be used whenever possible. The medical necessity of imaging should be weighed against the relatively small risk of harm when determining the appropriateness of these studies. Again, the greatest risk of cancer appears to exist when children are exposed to cumulative doses of radiation greater than 30–50 mSv.

#### **10. Pregnancy and reproductive health considerations**

**Relative radiation** 

**Adult effective dose estimate range (mSv)**

**9. Patient exposure to radiation**

66 Vignettes in Patient Safety - Volume 4

testing is provided in **Table 5**.

imaging examinations that correspond to said levels [65].

**Pediatric effective dose estimate range** 

A point of concern among care providers and parents is the risk of radiation exposure from medical imaging, especially in the pediatric population. Epidemiologic studies have shown that *in utero* exposure to radiation is associated with higher incidence of pediatric cancers, but data related to rates of pediatric and adult cancers are relatively scarce [60]. In recent years, CT scanning has become the favored imaging modality in many clinical scenarios and is likely to see even further increases in use going forward [61–63]. As such, CT utilization in pediatrics has increased markedly over the last 20 years. Over 85 million CT scans are performed annually in the United States, with 5–11% of these performed on children [64]. Before we embark on further discussion, important dose-related information in the context of diagnostic

A typical CT scan of the head of a child carries an average dose of 2–2.5 millisieverts (mSv) of radiation. CT imaging of the chest and abdomen carries doses averaging 3–4 and 5–6 mSv, respectively. The actual dose administered differs from the more nebulous effective dose, as other factors make the amount of radiation exposure more meaningful in children than adults. The effective radiation doses received by children are about 50% higher than those received by adults for similar imaging studies due to smaller body sizes and radiation attenuation [66, 67]. Up to an age of 10, children are approximately three times more sensitive to radiation than adults, which is why longer life expectancy coupled with organ systems that are still developing disproportionately increases the relative burden of pediatric radiation exposure [67–69]. Several studies have attempted to answer questions regarding specific childhood cancer risks associated with radiation exposure. Two studies showed increased incidence of pediatric leukemia in children with medical radiation exposure; however, these studies used retrospective questionnaire data and their result as inconsistent with older data [70, 71]. Certain genetic phenotypes might make some children more sensitive to the effects of radiation and risk of acute lymphocytic leukemia [72]. Very limited data exist on CT-attributable risk of

☢☢☢ 1–10 0.3–3 Abdomen CT; nuclear medicine bone scan ☢☢☢☢ 10–30 3–10 Abdomen CT with and without contrast; whole

☢☢☢☢☢ 30–100 10–30 CTA chest abdomen pelvis with contrast;

**Table 5.** Relative radiation level designations along with associated effective adult and pediatric doses, as well as

**Example examinations**

transjugular intrahepatic portosystemic shunt

body PET

placement

**(mSv)**

☢ <0.1 <0.03 Chest X-ray; hand X-rays ☢☢ 0.1–1 0.03–0.3 Pelvis X-ray; mammography

O 0 0 Ultrasound; MRI

**level**

According to the American College of Radiology, no single diagnostic X-ray study or procedure results in radiation exposure sufficient to threaten the well-being of the pregnant patient, the developing embryo, or the fetus [74]. In fact, diagnostic radiation exposures during pregnancy may be safer than the frequent concerns over *in utero* radiation exposure suggest [75]. Moreover, the utilization of diagnostic radiological imaging may entail more benefit than risk in the evaluation of certain maternal injuries or illnesses [76]. As much attention should focus on limiting diagnostic radiation exposure of the gravid woman's breast tissue, to prevent carcinogenesis, as on limiting radiation exposure of the fetus [77, 78]. In the setting of pregnancy, radiation exposure should be limited to 1 mGy during the first trimester, with teratogenicity risk being elevated at 5 mGy [79]. In addition, iodine-containing contrast media may lead to hypothyroidism in the fetus, an additional consideration when performing radiographic studies utilizing contrast material [79]. Counseling of the patient by the referring clinician and by the radiologist is essential in providing informed consent as the benefits and risks of procedures can be opaque and the decision may impart lasting consequences [80]. Impacting 5–7% of all pregnancies, trauma represents an important cause of nonobstetric maternal morbidity and mortality [81]. Consequently, the risk-benefit equation regarding diagnostic imaging in this particular setting is somewhat different, with the mantra that the best way to ensure fetal wellbeing is to aggressively treat the mother [82].

#### **11. Radiation exposure as low as reasonably achievable (ALARA)**

registry without impairment of image quality [83]. In another example, appendicitis represents the most common disease process resulting in increased CT scan utilization in children over the last two decades. Clinical practice guidelines advocating for "abdominal sonography first" for the evaluation of appendicitis have demonstrated comparable diagnostic accuracy to CT scan imaging, while reducing CT scan utilization and thus radiation exposure [91]. The Pediatric Emergency Care Applied Research Network collaborative development of a clinical decision guideline for pediatric head trauma is another example of research helping to reduce the medical radiation footprint by reliably identifying patients at low risk for clinically important trau-

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Careful adherence to existing PS protocols, including active surveillance for any signs and/or symptoms of HMRE, is among the most important considerations for facilities/departments providing diagnostic and/or therapeutic radiation services [28]. In addition to direct radiation, the formation of X-ray image is inherently associated with some degree of "scattered radiation" that is the principal source of exposure to the patient and medical staff [28]. This "scatter" increases with both intensity of the X-ray beam and the size of the exposed field [28]. Any hospital employing medical radiation needs to have an infrastructure to support protocols for every step of the way throughout the application of said radiation including patient and healthcare worker safety, proper identification and dosing, and waste management of

The power to harness ionizing radiation for medical uses has a history spanning more than a century. Although its positive impact on the modern-day prowess of the diagnostician is unquestionable, great care must be taken in order to not abuse this technology. Diagnostic imaging with ionizing radiation seems poised to be part of the medical armamentarium for the foreseeable future. Further research is required in all aspects of this field, including more efficient protocols for delivery, custom-tailoring therapy which takes into account the patients' makeup, potential short-term and long-term harmful effects, the prediction and prevention of harm and better safeguards for dosimetry not only for patients but also for healthcare workers. Greater strides must be achieved in the realm of oversight and standardization of practice, as well as a comprehensive, nonpunitive reporting system for adverse events. A multidisciplinary approach from health physicists, radiation safety personnel, and clinicians is paramount for the management of contamination events and for the safe and accurate use of both diagnostic and therapeutic medical radiation. The key for this technology going forward is for education to be widespread among all levels of healthcare, from patients and their families to healthcare providers and policy makers. Research and public health information dissemination will go

hand-in-hand throughout the next century of medical radiation use.

matic brain injuries, for whom CT can routinely be obviated [92].

**12. Safety protocols**

**13. Conclusions**

materials in order to prevent contamination.

Literature suggesting that accrual of cumulative radiation exposures from diagnostic radiological studies, such as CT scans or fluoroscopy, over the course of patients' lifetimes puts them at risk for the potential carcinogenic risks of radiation [83, 84]. One example here comes from the area of endovascular interventional procedures. Since the introduction of endovascular therapy in the late 1980s, there has been incredible growth in this group of procedural modalities. In fact, endovascular procedures have increased approximately 400% over the past decade [85]. The applicability and medical advancements of this form of therapy have revolutionized treatment of our patients. However, there has been an associated cost, including substantial risk of ionizing radiation exposure [86]. Some of the pioneers of endovascular therapy have succumbed to the deleterious consequence of ionizing radiation [87]. Radiation safety practices have made tremendous advances since the discovery of Roentgen's X-rays over 120 years ago. Early practitioners were focused on patient outcomes and providing minimally invasive methods to treat complex disease processes. These sacrifices of early practitioners led to our awareness and knowledge that now allows us to perform truly remarkable treatments to benefit our patients. A number of very practical steps can be taken to reduce radiation exposure to patients, operators, and staff [88, 89]. Awareness itself can be an effective first step in reducing exposure. Once awareness of the problem exists, we can then work to educate and enact training and methodology to achieve maximal safety to our patients and ourselves. However, despite the available data, there remains a significant safety deficit. In 2014, a survey of US vascular surgery trainees found 45% had no formal radiation safety training, 74% were unaware of the radiation safety policy for pregnant females, 48% did not know their radiation safety officer's contact information, and 43% were unaware of the acceptable yearly levels of radiation exposure [90]. However, an important observation was that the trainees who felt their attendings were applying ALARA techniques were much more likely to do so themselves. Therefore, it is incumbent on those of us providing training to the next generation of caregivers to set an example of excellence and expect the same from our trainees. Only by expecting excellence can we hope to achieve superior safety for our patients and ourselves.

Advocates for radiation safety recommend exposing patients, especially children, to as little radiation as possible. This is embodied within the concept of "as low as reasonably achievable" (ALARA) in the context of radiation exposure [84]. As such, ALARA addresses the role for healthcare providers, particularly those caring for children, in reducing exposure to radiation while maintaining the reliability of the diagnostic radiology modality [91]. Multiple methods can be used to achieve ALARA including: adjusting the amount of radiation in the diagnostic study based on patient weight, considering alternative modalities such as sonography or magnetic resonance imaging, enhancing shielding with thyroid or breast shields, focusing on the suspicious area with focused or limited view diagnostic imaging, and discouraging repeat CT scan studies [91]. In one example, although noninvasive multi-slice cardiac-computed tomography angiography (CCTA) can accurately screen for coronary ischemia, its widespread utilization has generated concern because of potential diagnostic radiation exposure. Utilization of a radiation dose reduction program in concert with limiting the image acquisition window for CCTA has demonstrated marked reduction, more than 50%, in estimated radiation doses in a statewide registry without impairment of image quality [83]. In another example, appendicitis represents the most common disease process resulting in increased CT scan utilization in children over the last two decades. Clinical practice guidelines advocating for "abdominal sonography first" for the evaluation of appendicitis have demonstrated comparable diagnostic accuracy to CT scan imaging, while reducing CT scan utilization and thus radiation exposure [91]. The Pediatric Emergency Care Applied Research Network collaborative development of a clinical decision guideline for pediatric head trauma is another example of research helping to reduce the medical radiation footprint by reliably identifying patients at low risk for clinically important traumatic brain injuries, for whom CT can routinely be obviated [92].
