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Background: Current clinical guidelines recommend mammography as the only imaging method for surveillance in asymptomatic survivors of early breast cancer (EBC). However, non-recommended tests are commonly used. We estimated the imaging radiation-induced malignancies (IRIM) risks in survivors of EBC undergoing different imaging surveillance models., Materials and Methods: We built 5 theoretical models of imaging surveillance, from annual mammography only (model 1) to increasingly imaging-intensive approaches, including computed tomography (CT) scan, positron emission tomography-CT, bone scan, and multigated acquisition scan (models 2 through 5). Using the National Cancer Institute's Radiation Risk Assessment Tool, we compared the excess lifetime attributable cancer risk (LAR) for hypothetical survivors of EBC starting surveillance at the ages of 30, 60, or 75 years and ending at 81 years., Results: For all age groups analyzed, there is a statistically significant increase in LAR when comparing model 1 with more intensive models. As an example, in a patient beginning surveillance at the age of 60 years, there is a 28.5-fold increase in the IRIM risk when comparing mammography only versus a schedule with mammography plus CT scan of chest-abdomen and bone scan. We found no differences when comparing models 2 through 5. LAR is higher when surveillance starts at a younger age, although the age effect was only statistically significant in model 1., Conclusion: Non-recommended imaging during EBC surveillance can be associated with a significant increase in LAR. In addition to the lack of survival benefit, additional tests may have significant IRIM risks and should be avoided., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective  To estimate the cumulative radiation exposure and lifetime attributable risk of cancer incidence associated with lung cancer screening using annual low dose computed tomography (CT). Design  Secondary analysis of data from a lung cancer screening trial and risk-benefit analysis. Setting  10 year, non-randomised, single centre, low dose CT, lung cancer screening trial (COSMOS study) which took place in Milan, Italy in 2004-15 (enrolment in 2004-05). Secondary analysis took place in 2015-16. Participants  High risk asymptomatic smokers aged 50 and older, who were current or former smokers (≥20 pack years), and had no history of cancer in the previous five years. Main outcome measures  Cumulative radiation exposure from low dose CT and positron emission tomography (PET) CT scans, calculated by dosimetry software; and lifetime attributable risk of cancer incidence, calculated from the Biological Effects of Ionizing Radiation VII (BEIR VII) report. Results  Over 10 years, 5203 participants (3439 men, 1764 women) underwent 42 228 low dose CT and 635 PET CT scans. The median cumulative effective dose at the 10th year of screening was 9.3 mSv for men and 13.0 mSv for women. According to participants' age and sex, the lifetime attributable risk of lung cancer and major cancers after 10 years of CT screening ranged from 5.5 to 1.4 per 10 000 people screened, and from 8.1 to 2.6 per 10 000 people screened, respectively. In women aged 50-54, the lifetime attributable risk of lung cancer and major cancers was about fourfold and threefold higher than for men aged 65 and older, respectively. The numbers of lung cancer and major cancer cases induced by 10 years of screening in our cohort were 1.5 and 2.4, respectively, which corresponded to an additional risk of induced major cancers of 0.05% (2.4/5203). 259 lung cancers were diagnosed in 10 years of screening; one radiation induced major cancer would be expected for every 108 (259/2.4) lung cancers detected through screening. Conclusion  Radiation exposure and cancer risk from low dose CT screening for lung cancer, even if non-negligible, can be considered acceptable in light of the substantial mortality reduction associated with screening., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.)

Recipients of solid organ transplants (SOT) have extensive diagnostic imaging (DI). The purpose of this study was to quantify this exposure. Children from northern Alberta with SOTs at Stollery Children's Hospital, Edmonton, Alberta January 1, 2006, to July 31, 2012, were included. Effective doses of radiation were estimated using published norms for DI performed post-transplant up to October 16, 2014. The 54 eligible children had 6215 DI studies (5628 plain films, 293 computerized tomography (CT) scans, 149 positron emission topography (PET) -CT scans, 47 nuclear medicine scans and 98 cardiac catheterizations). Children less than 5 years of age underwent more DI studies than did older children (median (IQR) 140 (66-210) vs 49 (19-105), p = 0.010). Children with post-transplant lymphoproliferative disorder (N = 8) had more CT scans (median (IQR) 13 (5.5-36) vs 1 (0-5), p<0.001) and PET-CT scans (median (IQR) 3.5 (1.5-8) vs 0 (0-0), p<0.001) than did other children. The estimated cumulative effective dose attributed to DI studies post-transplant was median (range) 78 (4.1-400) millisievert (mSv), and 19 of 54 children (35%; 95% confidence interval 24-49%) had a dose >100 mSv. In conclusion, a significant proportion of pediatric transplant recipients have sufficient radiation exposure post-transplant for DI to be at potential risk for radiation-induced malignancies., Competing Interests: The authors have declared that no competing interests exist.

Published guidelines for administered activity to pediatric patients undergoing diagnostic nuclear medicine imaging are currently obtained through expert consensus of the minimum values as a function of body weight as required to yield diagnostic quality images. We have previously shown that consideration of body habitus is also important in obtaining diagnostic quality images at the lowest administered activity. The objective of this study was to create a series of computational phantoms that realistically portray the anatomy of the pediatric patient population which can be used to develop and validate techniques to minimize radiation dose while maintaining adequate image quality. To achieve this objective, we have defined an imaging risk index that may be used in future studies to develop pediatric patient dosing guidelines. A population of 48 hybrid phantoms consisting of non-uniform B-spline surfaces and polygon meshes was generated. The representative ages included the newborn, 1 year, 5 year, 10 year and 15 year male and female. For each age, the phantoms were modeled at their 10th, 50th, and 90th height percentile each at a constant 50th weight percentile. To test the impact of kidney size, the newborn phantoms were modeled with the following three kidney volumes: -15%, average, and +15%. To illustrate the impact of different morphologies on dose optimization, we calculated the effective dose for each phantom using weight-based (99m)Tc-DMSA activity administration. For a given patient weight, body habitus had a considerable effect on effective dose. Substantial variations were observed in the risk index between the 10th and 90th percentile height phantoms from the 50th percentile phantoms for a given age, with the greatest difference being 18%. There was a dependence found between kidney size and risk of radiation induced kidney cancer, with the highest risk indices observed in newborns with the smallest kidneys. Overall, the phantoms and techniques in this study can be used to provide data to refine dosing guidelines for pediatric nuclear imaging studies while taking into account the effects on both radiation dose and image quality.

Ionising radiation is increasingly used for the treatment of cancer, being the source of a considerable fraction of the medical irradiation to patients. With the increasing success rate of cancer treatments and longer life expectancy of the treated patients, the issue of secondary cancer incidence is of growing concern, especially for paediatric patients who may live long after the treatment and be more susceptible to carcinogenesis. Also, additional imaging procedures like computed tomography, kilovoltage and megavoltage imaging and positron emission tomography, alone or in conjunction with radiation therapy, may add to the radiation burden associated with the risk of occurrence of secondary cancers. This work has been based on literature studies and is focussed on the assessment of secondary doses to healthy tissues that are delivered by the use of modern radiation therapy and diagnostic imaging modalities in the clinical environment., (© The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Quantifying radiation-induced cancer risks associated with radiological examinations is not easy, which has resulted in much controversy. We can clarify the situation by distinguishing between higher dose examinations, such as CT, positron emission tomography-CT or fluoroscopically guided interventions, and lower dose "conventional" X-ray examinations. For higher dose examinations, the epidemiological data, from atomic bomb survivors exposed to low doses and from direct epidemiological studies of paediatric CT, are reasonably consistent, suggesting that we do have a reasonable quantitative understanding of the individual risks: in summary, very small but unlikely to be zero. For lower dose examinations, we have very little data, and the situation is much less certain, however, the collective dose from these lower dose examinations is comparatively unimportant from a public health perspective.

Purpose: To compare radiation doses and lifetime attributable risks (LARs) of radiation-induced cancer incidence and mortality from breast imaging studies involving the use of ionizing radiation., Materials and Methods: Recent literature on radiation doses from radiologic procedures and organ doses from nuclear medicine procedures, along with Biologic Effects of Ionizing Radiation (BEIR) VII age-dependent risk data, is used to estimate LARs of radiation-induced cancer incidence and mortality from breast imaging studies involving ionizing radiation, including screen-film mammography, digital mammography, digital breast tomosynthesis, dedicated breast computed tomography, breast-specific gamma imaging (BSGI), and positron emission mammography (PEM)., Results: Two-view digital mammography and screen-film mammography involve average mean glandular radiation doses of 3.7 and 4.7 mGy, respectively. According to BEIR VII data, these studies are associated, respectively, with LARs of fatal breast cancer of 1.3 and 1.7 cases per 100,000 women aged 40 years at exposure and less than one case per one million women aged 80 years at exposure. Annual screening digital or screen-film mammography performed in women aged 40-80 years is associated with an LAR of fatal breast cancer of 20-25 cases in 100,000. A single BSGI study involving a label-recommended dose of 740-1100 MBq (20-30 mCi) of technetium 99m-sestamibi is estimated to involve an LAR of fatal cancer that is 20-30 times that of digital mammography in women aged 40 years. A single PEM study involving a labeled dose of 370 MBq (10 mCi) of fluorine 18 fluorodeoxyglucose is estimated to involve an LAR of fatal cancer that is 23 times higher than that of digital mammography in women aged 40 years., Conclusion: A single BSGI or PEM study is associated with a fatal radiation-induced cancer risk higher than or comparable to that of annual screening mammography in women aged 40-80 years.

The use of PET/CT in children has grown substantially in the past few years. There is also an increased interest in keeping the radiation dose to children from CT as low as is clinically practical. This article reviews the physical aspects of both PET and CT separately and how CT is used in the context of PET/CT to provide the practical insight necessary to approach this issue. Understanding radiation dosimetry and its potential for deleterious health effects, having knowledge of the magnitude of the effective dose and the dose to specific organs from PET and CT, and considering the role of CT in the context of PET/CT will allow the reader to reduce the radiation dose to the patient without compromising the quality of the patient's care.

Every year 5 billion diagnostic imaging procedures are performed worldwide, and about 1 out of 2 tests are cardiovascular examinations. According to recent estimates, 30% to 50% of all examinations are partially or totally inappropriate. This represents a potential damage in patients undergoing imaging tests (who take the acute risks of a stress test procedure and/or a contrast study without a commensurable benefit), an exorbitant cost for the society, and an excessive delay in the waiting lists for other patients needing the examination. In case of ionizing radiation, the reduction of useless imaging tests would improve the quality of care also through abatement of the long-term risks related to the dose employed. The radiation dose equivalent of common cardiological imaging examinations corresponds to about 500, 750 and 1000 chest X-rays for stress sestamibi testing, multislice cardiac computed tomography and coronary stenting, respectively. Although direct evaluation of the incidence of cancer in patients submitted to these procedures is not available, according to the latest 2006 Biological Effects of Ionizing Radiation Committee VII the estimated risk of cancer is about 1 in 750 for a computed tomography scan - higher in women (1/500), lower in the elderly (1/1500), and the highest in children (1/100 in female children aged <1 year). Such a risk is probably not acceptable when a diagnostic procedure is inappropriately applied for mass screening (when the risk side of the risk-benefit balance is not considered) or when similar information can be obtained by other means. By contrast, it is fully acceptable in appropriately selected groups as a filter to more invasive, risky and costly procedures.