Radiation exposure to the paediatric patient from cardiac catheterization and angiocardiography

Longitudinal Improvements in Radiation Exposure in Cardiac Catheterization for Congenital Heart Disease

Background:

The C3PO-QI (Congenital Cardiac Catheterization Project on Outcomes – Quality Improvement), a multicenter registry launched in 2015, instituted quality improvement (QI) initiatives to reduce patient radiation exposure. Through regular collaboration, this initiative would allow for harmony among active participants, maximizing efforts and efficiency at achieving radiation best practices. This study sought to report these efforts with a detailed methodology for which institutions can target initiatives, reducing radiation exposure, and increasing patient safety.

Methods:

Data were collected prospectively by 8 C3PO-QI institutions between January 1, 2015 and December 31, 2017. Radiation exposure was measured in dose area product per body weight (dose area product/kg; µGy*m 2 /kg) and reported by expected radiation exposure categories (REC) and institution for 40 published unique procedure types. Targeted interventions addressing selected strategic domains for radiation reduction were implemented in the pediatric catheterization labs of the C3PO-QI institutions.

Results:

The study consisted of 15 257 unique cases. Median exposure (dose area product/kg) was decreased by 30% for all procedures. Dose area product/kg was reduced in all 3 REC, with the greatest improvement observed in REC I (REC I, −37%; REC II, −23%; REC III, −27%). Although the baseline radiation exposures and exact percent decrease varied across all C3PO-QI sites, each institution demonstrated improvements in radiation dose over time. These improvements occurred with the implementation of institution-specific QI interventions accelerated by participation in the C3PO-QI multicenter collaborative.

Conclusions:

Substantial radiation dose reductions can be achieved using targeted QI methodology and interventions. Participation in a multicenter QI collaborative may accelerate improvement across all centers due to enhanced engagement and shared learning between sites.

Radiation Risk Categories in Cardiac Catheterization for Congenital Heart Disease: A Tool to Aid in the Evaluation of Radiation Outcomes

To stratify diverse procedure types into categories with similar radiation exposure in cardiac catheterization for congenital heart disease. Radiation exposures for a comprehensive list of specific procedure types and stratification of outcomes based on radiation risk are not currently available. Data between January 2014 and December 2015 were collected on all cases performed at sites participating in C3PO-QI (Congenital Cardiac Catheterization Outcomes Project-Quality Improvement Initiative) and 9 centers were included. Using expert consensus, 40 unique procedure types were defined by diagnostic characteristics or the intervention(s) performed, and dose area product (DAP) per kilogram of body weight (µGy × m²/kg) was summarized. Using empiric and consensus methods, three radiation risk categories were created. A total of 11,735 cases were included for analysis. Thirteen (n = 7918) procedure types with median DAP/kg < 100 were categorized in the low radiation exposure category (median DAP/kg 39). The medium exposure category (n = 1807) consisted of 16 procedure types with median DAP/kg values ranging 100 to < 200 (overall median DAP/kg 131). Finally, the high radiation exposure category (n = 1073) consisted of 11 procedure types with median DAP/kg ≥ 200 (overall median DAP/kg of 231). The radiation exposure risk categories created in this multi-center dataset are a critical step towards the development of a robust risk adjustment methodology for radiation exposure in catheterization for congenital heart disease.

Estimation of Organ and Effective Doses for Neonate and Infant Diagnostic Cardiac Catheterizations

OBJECTIVE

Radiation exposure to neonates and infants during cardiac catheterizations is an important issue. Smaller patient size and higher heart rate in these patients result in a greater need for magnification modes and higher frame rates, all of which contribute to a significant increase in radiation doses. The aims of our study were to evaluate organ and effective doses for neonates and infants during diagnostic cardiac catheterizations on the basis of in-phantom dosimetry and conversion factors from dose-area product (DAP) to the effective dose.

MATERIALS AND METHODS

Organ doses for 0- and 1-year-old children during diagnostic cardiac catheterizations were measured by radiophotoluminescence glass dosimeters implanted in neonate and infant anthropomorphic phantoms. The effective doses were evaluated according to recommendations of the International Commission on Radiologic Protection (ICRP) publication 103.

RESULTS

The mean effective doses evaluated according to ICRP 103 were 7.7 mSv (range, 0.1-18.4 mSv) for a neonate and 7.3 mSv (range, 1.9-18.6 mSv) for an infant. Conversion factors from DAP to the effective dose were 2.2 and 4.0 in posteroanterior and lateral cine angiography, respectively, for a neonate and 1.4 and 2.7 in posteroanterior and lateral cine angiography, respectively, for an infant.

CONCLUSION

The dose data and conversion factors evaluated in this study could be useful for the estimation of radiation exposure in neonates and infants during diagnostic cardiac catheterization.

Patient radiation exposure in a modern, large-volume, pediatric cardiac catheterization laboratory

Radiation exposure from pediatric cardiac catheterization may be substantial, although published estimates vary. We sought to report patient radiation dose across a range of diagnostic and interventional cases in a modern, high-volume pediatric catheterization laboratory. We retrospectively reviewed diagnostic and interventional cases performed in our pediatric catheterization laboratory from 1 April 2009 to 30 September 2011 for which radiation usage data were available as reported by the Artis Zee(®) (Siemens Medical Solutions) system. Electrophysiology cases were excluded. Radiation dose was quantified as air kerma dose (mGy) and dose-area product (DAP; μGy m(2)). The DAP was converted to an effective dose millisievert (mSv) using the Monte Carlo method. Radiation usage data were available from 2,265 diagnostic and interventional cases with an overall median air kerma dose of 135 mGy [interquartile range (IQR) 59-433], median DAP of 760 μGy m(2) (IQR 281-2,810), of which 75 % (IQR 59-90 %) was derived from fluoroscopy, and median effective dose of 6.2 mSv (IQR 2.7-14.1). Air kerma dose from a single camera >2,000 mGy occurred in 1.8 % of cases. Significant differences in all measures of radiation exposure existed based on procedural and interventional types (p = 0.0001), with interventional cases associated with the highest effective dose after adjusting for patient weight category (p < 0.001). Patient weight, age, fluoroscopy time, and proportional use of digital acquisition were independent predictors of exposure (p ≤ 0.001; R (2) = 0.59-0.64). In a modern, large-volume pediatric catheterization laboratory, the median effective dose is 6.2 mSv with a wide range of exposure based on patient- and procedure-specific factors. Radiation monitoring is an important component of a pediatric laboratory and further dose reduction strategies are warranted.

Radiation dose to the brain and subsequent risk of developing brain tumors in pediatric patients undergoing interventional neuroradiology procedures

Radiation dose to the brain and subsequent lifetime risk of diagnosis of radiation-related brain tumors were estimated for pediatric patients undergoing intracranial embolization. Average dose to the whole brain was calculated using dosimetric data from the Radiation Doses in Interventional Radiology Study for 49 pediatric patients who underwent neuroradiological procedures, and lifetime risk of developing radiation-related brain tumors was estimated using published algorithms based on A-bomb survivor data. The distribution of absorbed dose within the brain can vary significantly depending on field size and movement during procedures. Depending on the exposure conditions and age of the patient, organ-averaged brain dose was estimated to vary from 6 to 1600 mGy. The lifetime risk of brain tumor diagnosis was estimated to be increased over the normal background rates (57 cases per 10,000) by 3 to 40% depending on the dose received, age at exposure, and gender. While significant uncertainties are associated with these estimates, we have quantified the range of possible dose and propagated the uncertainty to derive a credible range of estimated lifetime risk for each subject. Collimation and limiting fluoroscopy time and dose rate are the most effective means to minimize dose and risk of future induction of radiation-related tumors.

Patient-Specific Dose and Radiation Risk Estimation in Pediatric Cardiac Catheterization

Background— Because of the higher radiosensitivity of infants and children compared with adults, there is a need to evaluate the doses delivered to pediatric patients who undergo interventional cardiac procedures. However, knowledge of the effective dose in pediatric interventional cardiology is very limited.

Methods and Results— For an accurate risk estimation, a patient-specific Monte Carlo simulation of the effective dose was set up in 60 patients with congenital heart disease who underwent diagnostic (n=28) or therapeutic (n=32) cardiac catheterization procedures. The dose-saving effect of using extra copper filtration in the x-ray beam was also investigated. For diagnostic cardiac catheterizations, a median effective dose of 4.6 mSv was found. Therapeutic procedures resulted in a higher median effective dose of 6.0 mSv because of the prolonged use of fluoroscopy. The overall effect of inserting extra copper filtration into the x-ray beam was a total effective dose reduction of 18% with no detrimental effect on image quality. An excellent correlation between the dose-area product and effective patient dose was found ( r =0.95). Hence, dose-area product is suitable for online estimation of the effective dose with good accuracy. With all procedures included, the resulting median lifetime risk for stochastic effects was 0.08%.

Conclusions— Because of the high radiation exposure, it is important to monitor patient dose by dose-area product instrumentation and to use additional beam filtration to keep the effective dose as low as possible in view of the sensitivity of the pediatric patients.

Effective doses to patients from paediatric cardiac catheterization

The Council Directive of the European Communities 97/43/Euratom requires dose assessment, especially for X-ray examinations of children and if high doses to the patient are involved. Both these aspects apply in cardiac catheterization and angiocardiography of children. Effective doses are a good indicator of radiation risk, particularly for leukaemia. Effective doses have been determined for 2114 infants and children undergoing cardiac catheterization from 1984 to 1996 at the University Hospital in Essen. Conversion factors (effective dose/dose-area product) were calculated based on direct dose-area product measurements for posteroanterior (PA) and lateral (Lat) projections as well as on patient records and examination details. The factors are calculated for eight age groups of children, taking into account the X-ray tube voltage for fluoroscopy and cine-film sequences, with and without zoom mode. Frequency distributions are presented for 2114 patients, for dose-area product, number of angiographic examinations (each combined with one cine-film sequence both PA and Lat) and for calculated effective doses. Highest effective doses are found in newborns (18.0 mSv and 6.5 mSv 90th and 50th percentiles, respectively) compared with adolescents of 15-21 years (8.0 mSv and 3.0 mSv 90th and 50th percentiles, respectively). Effective dose for cardiac catheterization is highest for newborns, in spite of lowest measured dose-area products, because the decreased value of the conversion factors overcompensates for the increase of dose-area product with age. This is especially important because of the higher tumour risk for equal effective dose for young children compared with adults.

Radiation exposure to children during cardiac catheterization

The purpose of this study was to assess the suitability of different radiation dosimetry methods and record radiation exposures during paediatric catheterization. Three methods of dosimetry were employed: thermoluminescent dosimetry (TLD), dose-area product and calculation of entrance surface dose from calibrated exposure factors. Examinations included bi-plane fluoroscopy, and cineangiography for diagnosis and treatment of congenital heart disease. The most suitable method of radiation dosimetry for cardiac catheterization is the use of calculated entrance dose or a dose-area product meter. Children were exposed to high levels of radiation during cardiac catheterization but there was a wide variation in radiation dosage. Careful consideration should be given to the suitability of radiation dosimetry for cardiac catheterization.

Radiation exposure of pediatric patients and physicians during cardiac catheterization and balloon pulmonary valvuloplasty

Thermoluminescent dosimeters were applied to various areas of 61 pediatric patients and physicians to measure radiation doses during routine cardiac catheterization and during 4 cases of balloon pulmonary valvuloplasty. Radiation doses were measured during chest roentgenography, fluoroscopy and cineangiography. Average skin dose to the chest was 121 microGy during chest x-ray, 5,182 microGy during catheterization and 641 mGy during valvuloplasty. For the eyes, thyroid and gonads of the patients, the exposure during routine catheterization was equal to 0.4, 6 and 0.2 chest x-rays, respectively. Radiation dose of the operator was 3 microGy for the eyes and 6 miCroGy in the thyroid. About 56% of the operator's dose could be reduced by thyroid shields, and 80% by lead aprons. The assistant received only 1 microGy outside the thyroid shield. Therefore, we have concluded that the patients' dose during routine catheterization is largely based on our experimental results, but the dose is acceptable based on the risk factor analysis. The skin dose to the right lateral chest of the patient during valvuloplasty is extremely high, perhaps as high as the equivalent of 1,000 chest x-rays. Besides the clinical benefits of valvuloplasty, the long-term radiation-related hazards to the patient should be carefully monitored.

Cytogenetic effects of cardioangiography on blood lymphocytes in children and in vitro effects of contrast medium and low dose radiation

Structural chromosome aberrations were analysed in the peripheral blood lymphocytes of 15 children, aged 1 to 13 years, before, immediately after, 24 hours after and 6 to 8 months after cardioangiographic examination. Statistically significant increases were only demonstrated in the frequency of gaps (p less than 0.05) and, consequently, in the frequency of aberrant cells (p less than 0.05) immediately after cardioangiography. Most of the chromosome damage clearly disappeared within 24 hours. In addition, whole blood cultures were exposed in vitro to low dose radiation, a contrast medium, and radiation together with the contrast medium. No statistically significant differences could be observed in the chromosome aberration frequencies. It was concluded that the modern radiographic procedure, which uses very low radiation doses and less contrast medium, does not cause a consistent, permanent increase of chromosomal damage in the lymphocytes of children. However, the situation may be different if the child undergoes many radiographic examinations or the radiation doses are high.

Radiation doses and somatic risk to patients during cardiac radiological procedures

The radiation dose to a series of adult and paediatric patients undergoing cardiac catheterisations and adults having percutaneous transluminal coronary angioplasty has been measured/determined directly using lithium fluoride thermoluminescent dosemeters and indirectly using an air ionisation chamber which indicated exposure-area product. Somatic and genetic risks are estimated from the dosimetry results. It is suggested that the magnitude of the radiation hazard is negligible compared with other clinical hazards associated with these procedures.

Digital subtraction angiography in infants and children with congenital heart disease

Digital subtraction angiography was used as the sole imaging technique in 95 infants and children aged 13 hours to 16 years undergoing cardiac catheterisation for the investigation of congenital heart disease. Injections of diluted contrast medium were made selectively at central sites, and the images were obtained using continuous image intensification fluoroscopy at either 32.25 nC/kg/s (125 microR /s) or 129 nC/kg/s (500 microR /s). In all cases images adequate for diagnosis and management were obtained with appreciably less contrast medium and a lower radiation dose than in a comparable group of patients using conventional biplane cineangiography. Thus digital subtraction angiography is a viable alternative to biplane cineangiography for children with congenital heart disease.

Mucocutaneous lentigines, cardiomucocutaneous myxomas, and multiple blue nevi: the "LAMB" syndrome

We describe a 13-year-old girl with a cardiocutaneous syndrome characterized by an atrial myxoma, pigmented lesions of the skin and genital mucosa, and opalescent papules and dermal nodules of the skin and tongue. Her pigmented lesions included black macules of the face and vulva, brown macules of the lips and perioral skin, multiple blue nevi, and a congenital nevomelanocytic nevus. The black and brown macules of the face and vulva consisted of lentiginous proliferations of large, intensely dopa-reactive melanocytes. The opalescent papules and dermal nodules had histologic, ultrastructural, and histochemical characteristics of myxomas. During follow-up, the patient developed thyroid nodules, which were composed of mixed papillary and follicular hyperplasia. This case emphasizes the necessity of a cardiac evaluation for a potentially fatal (and surgically treatable) atrial myxoma in individuals with multiple melanocytic and myxomatous tumors of the skin and mucosa.

Digital angiography in the pediatric patient with congenital heart disease: comparison with standard methods

Digital subtraction angiography (DSA) permits high-resolution cardiac imaging with relatively low doses of contrast medium and reduced radiation exposure. These are potential advantages in children with congenital heart disease. Computer-based DSA (30 frames/sec) and conventional cutfilm angiography (6 frames/sec) or cineangiography (60 frames/sec) were compared in 42 patients, ages 2 months to 18 years (mean 7.8 years) and weighing 3.4 to 78.5 kg (mean 28.2 kg). There were 29 diagnoses that included valvular regurgitant lesions, obstructive lesions, various shunt abnormalities, and a group of miscellaneous anomalies. For injections made at a site distant from the lesion and on the right side of the circulation, the mean dose of contrast medium was 60% to 100% of the conventional dose given during standard angiography. With injections made close to the lesion and on the left side of the circulation, the mean dose of contrast medium was 27.5% to 42% of the conventional dose. Radiation exposure for each technique was markedly reduced in all age groups. A total of 92 digital subtraction angiograms were performed. Five studies were suboptimal because too little contrast medium was injected; in the remaining 87 injections, DSA and conventional studies resulted in identical diagnoses in 81 instances (p less than .001 vs chance). The remaining six injections made during DSA failed to confirm diagnoses made angiographically by standard cutfilm angiography or cineangiography. We conclude that DSA usually provides diagnostic information equivalent to that available from cutfilm angiography and cineangiography, but DSA requires considerably lower doses of contrast medium and less radiation exposure than standard conventional methods.

Radiation exposure to the child during cardiac catheterization

Few data are available regarding radiation exposure to children during cardiac catheterization. Using lithium fluoride thermoluminescent dosimeters, radiation exposure was measured during precatheterization chest roentgenography, fluoroscopy (hemodynamic assessment phase of catheterization) and cineangiography in 30 infants and children, ages 3 days to 21 years. Dosimeters were placed over the eyes, thyroid, anterior chest, posterior chest, anterior abdomen, posterior abdomen and gonads. Average absorbed chest doses were 24.5 mR during chest roentgenography, 5810 mR during catheterization fluoroscopy and 1592 mR during cineangiography. During the complete catheterization, average doses were 26 mR to the eyes, 431 mR to the thyroid area, 150 mR to the abdomen and 11 mR to the gonads. Radiation exposure during pediatric cardiac catheterization is low to the eyes and gonads but high to the chest and thyroid area. To decrease radiation dosage we suggest (1) low pulse-rate fluoroscopy; (2) substitution of contrast echocardiography for cineangiography; (3) large-plate abdominal/gonadal shielding; (4) a selective shield for thyroid area; (5) a very small field during catheter manipulation. Minimum radiation consistent with accurate diagnosis is optimal; however, erroneous or incomplete diagnosis is more dangerous than radiation-related hazards.

Radiation exposure to the pediatric patient during cardiac catheterization and angiocardiography. Emphasis on the thyroid gland

Thermoluminescent dosimetry was used to measure the radiation exposure to the skin, thyroid and gonads in 50 consecutive pediatric patients undergoing cardiac catheterization and angiocardiography using cine photofluorography. Average exposures were 17.1 R to the skin, 2.3 R to the thyroid and 0.1 R to the gonads. Fluoroscopy accounted for approximately 80% of the skin and thyroid exposure and cine photofluorography for 20-25%. Occasional primary-beam irradiation was the major contributor to gonad exposure. Internal scatter of the incident x-ray beam was primarily responsible for thyroid exposure, so that infants received relatively high exposures; one receiving 7.3 R. The thyroid was not frequently in the primary beam. The significance of high radiation exposure to the thyroid, and in particular its relationship to thyroid carcinoma, are discussed. The results are compared with other series in the literature and relative exposures of cine photofluorography and serial filming are contrasted.

Clinical applications of radionuclide lung scanning in infants and children

Krypton 81m ventilation and technetium 99m perfusion lung scans in anterior, posterior and oblique views in 86 children (age range 14 days to 15 years) with various paediatric problems were obtained. On reviewing these studies we found four main areas of clinical usefulness. (a) Establishing the diagnosis; in a relatively small number of patients the lung scan was essential for either establishing the exact diagnosis or directing attention to the abnormal area. (b) Refuting a diagnosis: the two main groups in this category include possible bronchiectasis and inhaled foreign body. (c) Establishing the extent of the disease; radionuclide studies enable one to assess and follow up the extent of the disease in children with lower respiratory problems; a lung scan may obviate the need for bronchography in bronchiectatics failing to respond to medical treatment and for whom surgery is being considered. Repeat studies are useful in following the natural history or the response to treatment of various lung conditions. (d) Assessing the success of surgical procedures on the heart and on abnormal pulmonary arteries. We indicate that 81Krm ventilation/99Tcm perfusion scanning are particularly useful in small children in whom tests of overall pulmonary function cannot be carried out because of lact of co-operation.

Papillary carcinoma of the thyroid in two brothers after chest fluoroscopy in childhood

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Thromboxane A2 in pregnancy and puerperium

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