Estimated risk of radiation-induced cancer from paediatric chest CT: two-year cohort study.

BACKGROUND: The increasing absolute number of paediatric CT scans raises concern about the safety and efficacy and the effects of consecutive diagnostic ionising radiation. OBJECTIVE: To demonstrate a method to evaluate the lifetime attributable risk of cancer incidence/mortality due to a single low-dose helical chest CT in a two-year patient cohort. MATERIALS AND METHODS: A two-year cohort of 522 paediatric helical chest CT scans acquired using a dedicated low-dose protocol were analysed retrospectively. Patient-specific estimations of radiation doses were modelled using three different mathematical phantoms. Per-organ attributable cancer risk was then estimated using epidemiological models. Additional comparison was provided for naturally occurring risks. RESULTS: Total lifetime attributable risk of cancer incidence remains low for all age and sex categories, being highest in female neonates (0.34%). Summation of all cancer sites analysed raised the relative lifetime attributable risk of organ cancer incidence up to 3.6% in female neonates and 2.1% in male neonates. CONCLUSION: Using dedicated scan protocols, total lifetime attributable risk of cancer incidence and mortality for chest CT is estimated low for paediatric chest CT, being highest for female neonates.

Imaging for suspected pulmonary embolism in pregnancy-what about the fetal dose? A comprehensive review of the literature.

OBJECTIVE: To give a comprehensive overview of fetal doses reported in the literature when imaging the pregnant woman with suspected pulmonary embolism (PE). METHODS: A comprehensive literature search in the PubMed, MEDLINE and EMBASE databases yielded a total of 1,687 papers that were included in the analysis and have been analysed with regard to fetal dose in suspected PE radiological imaging strategies. RESULTS: Fetal dose in chest computed tomography (CT) ranges between 0.013 and 0.026 mGy in early and 0.06-0.1 mGy in late pregnancy compared with 99mTc-MAA perfusion scintigraphy with a fetal dose of 0.1-0.6 mGy in early and 0.6-0.8 mGy in late pregnancy. (99m)Tc-aerosol ventilation scintigraphy results in 0.1-0.3 mGy. However, there is concern about female breast irradiation in CT, which is higher than in scintigraphy. CT radiation risks for breast tissue remain unclear. CONCLUSION: Knowledge of dosimetry and radiation risks is crucial in the radiological work-up of suspected PE in pregnancy. It is reasonable to reserve scintigraphy for pregnant patients with normal chest radiography findings and no history of asthma or chronic lung disease. Performing CT applying dose reduction instead of scintigraphy will minimise fetal radiation dose and maximise the diagnostic value.

Long-term outcomes after intracoronary Beta-irradiation for in-stent restenosis in bare-metal stents.

OBJECTIVE: We sought to characterize the long-term outcomes of patients undergoing intracoronary brachytherapy using Beta- irradiation (Beta-BT). BACKGROUND: Beta-BT is effective in reducing angiographic restenosis as well as target vessel revascularization (TVR) in patients with in-stent restenosis (ISR) after bare-metal stenting (BMS). METHODS: 81 consecutive patients undergoing Beta-BT for ISR (irradiated length 32 [32-54] mm) after BMS in native vessels (n = 79) or saphenous vein grafts (n = 2) between 2001 and 2003 were followed. Major cardiac events (MACE), including cardiac death, nonfatal myocardial infarction (MI), and TVR occurring > 1 year or > 1 year were assessed 5.2 (4.4-5.6) years after the index procedure. RESULTS: During the entire follow-up period, the total MACE rate was 49.4%. Within the first year and at > 1 year, MACE rates were 25.9% and 23.5%, cardiac death occurred in 2.4% and 6.2%, and nonfatal MI in 6.2% and 12.3% for annual cardiac death/MI rates of 8.7% at < 1 year and 4.1% thereafter. TVR was required in 19% at < 1 year and in 16% of patients later on. The only independent predictor of MACE occurring < 1 year was an irradiated vessel length > 32 mm (odds ratio [OR] 2.73, 95% confidence interval [CI] 1.10-6.78; p = 0.03). The best, albeit not statistically significant, predictor of MACE occurring at > 1 year was the presence of diabetes mellitus (OR 2.49, 95% CI 0.94-6.57; p = 0.07). CONCLUSIONS: Patients undergoing Beta-BT for ISR after BMS carry a substantial risk of MACE also beyond the first year, with annual cardiac death and nonfatal MI rates of 1.5% and 2.9% up to 5 years postprocedure.