Reduced radiation during cardiac catheterization of infants using acquisition zoom technology

Digital zoom is a useful, simple, and cost-effective method of reducing radiation exposure in percutaneous coronary intervention

Reducing radiation exposure is a very important issue in interventional cardiology techniques such as percutaneous coronary intervention. Although novel techniques to reduce radiation exposure are valuable, we should also reconsider older techniques. Digital zoom has been available in Japan from 2005. Digital zoom enlarges an 8-inch field of view (FOV) by 1.2 times, allowing visualization of a 6.7-inch FOV without FOV switching. We identified 2101 suitable cases of percutaneous intervention (PCI) and divided them into two groups according to the use of digital zoom; 1195 patients were included in the digital zoom group and 906 patients in the conventional group. We collected data regarding the reference air kerma (RAK) and dose-area product (DAP). We calculated RAK and DAP per minute fluoroscope time (RAK/min, DAP/min, respectively). There were intergroup differences in RAK, DAP, RAK/min, and DAP/min (digital zoom group vs conventional group; RAK, 1590 mGy [990-2410] vs 1850 [1220-2720], p < 0.01, RAK/min; 54.7 mGy/min [38.5-73.2] vs 71.2 [51.5-93.0], p < 0.01; DAP, 16,000 cGy × cm² [10,300-24,400] vs 20,700 [13,400-29,500], p < 0.001; DAP/min, 557 cGy × cm²/min [392-737] vs 782 [571-1010], p < 0.01, respectively). Because of baseline differences between the two groups, we performed propensity score matching. Even after score matching, there were intergroup differences in DAP, DAP/min, RAK, and RAK/min. Furthermore, the least squares method showed that digital zoom is a significant predictor of RAK (β = 0.14, p < 0.01) and DAP (β = 0.20, p < 0.01). Digital zoom is an older cost-effective technique that can significantly reduce radiation exposure in PCI.

Radiation doses from fluoroscopically guided cardiac catheterization procedures in children and young adults in the United Kingdom: a multicentre study

OBJECTIVE

To gather data on radiation doses from fluoroscopically guided cardiac catheterization procedures in patients aged under 22 years at multiple centres and over a prolonged period in the UK. To evaluate and explain variation in doses. To estimate patient-specific organ doses and allow for possible future epidemiological analysis of associated cancer risks.

METHODS

Patient-specific data including kerma area product and screening times from 10,257 procedures carried out on 7726 patients at 3 UK hospitals from 1994 until 2013 were collected. Organ doses were estimated from these data using a dedicated dosimetry system based on Monte Carlo computer simulations.

RESULTS

Radiation doses from these procedures have fallen significantly over the past two decades. The organs receiving the highest doses per procedure were the lungs (median across whole cohort, 20.5 mSv), heart (19.7 mSv) and breasts (13.1 mSv). Median cumulative doses, taking into account multiple procedures, were 23.2, 22.2 and 16.7 mSv for these organs, respectively. Bone marrow doses were relatively low (median per procedure, 3.2 mSv; cumulative, 3.6 mSv).

CONCLUSION

Most modern cardiac catheterizations in children are moderately low-dose procedures. Technological advances appear to be the single most important factor in the fall in doses. Patients undergoing heart transplants undergo the most procedures. An epidemiological assessment of cancer risks following these procedures may be possible, especially using older data when doses were higher.

ADVANCES IN KNOWLEDGE

This is the first large-scale, patient-specific assessment of organ doses from these procedures in a young population.

Radiation exposure in children during the current era of pediatric cardiac intervention

Cardiac catheterizations are among the X-ray procedures with the highest patient radiation dose and therefore are of great concern in pediatric settings. This study aimed to evaluate factors that influence variability of X-ray exposure in children with congenital heart diseases during cardiac catheterization. The study included 107 children who underwent either diagnostic (n = 46) or interventional (n = 61) procedures. A custom-made sheet for patient and procedural characteristics was designed. Data were collected, and different correlations were applied to determine factors that influence variability of X-ray exposure. The fluoroscopy time (FT) differed significantly between the diagnostic (8.9 ± 6.3 min) and intervention (12.8 ± 9.98 min) groups (P = 0.032). The mean dose-area product (DAP) differed significantly between the two groups (3.775 ± 2.5 Gy/cm(2) vs. 13.239 ± 15.4 Gy/cm(2); P = 0.003). The highest DAP was during left anterior oblique (LAO) cranial 30° angulation (2.8 Gy/cm(2)/4 s cine). The mean cumulative dose (CD) was 0.053 Gy in diagnostic cases and 0.48 Gy in intervention cases. The effective dose was 5.97 ± 7.05 mSv for therapeutic procedures compared with 3.42 ± 3.64 mSv for diagnostic procedures. The FT correlated significantly with both the DAP (r = 0.718; P < 0.001) and the CD (r = 0.701; P < 0.001). Other correlations were reported. An increasing number of therapeutic catheterization procedures are being performed for children. The justification for these procedures is evident because they avoid complicated surgery. However, the complexity of these procedures results in higher radiation exposures.

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.

Assessment of patient radiation doses during transcatheter closure of ventricular and atrial septal defects with Amplatzer devices

The purpose of this study was to estimate the radiation dose to which children are exposed during cardiac catheterizations for the treatment of ventricular and atrial septal defects. Radiation doses were estimated for 46 children aged 1-18 years. These children were treated for secundum atrial septal defects (ASD group) for perimembranous ventricular septal defects (VSD group) or underwent a routine diagnostic catheterization (diagnostic group). Thermoluminescent dosimeters (TLDs) were attached in locations, representing the lateral entrance dose, the posterior entrance dose, the thyroid dose, and the gonad dose, respectively. A dose area product (DAP) meter was also attached externally on the posterior-anterior (PA) tube to give a direct value in cGy cm(2) for each procedure. The patient's entrance dose from the PA field ranged from 1.5 to 185.0 mGy for all patients, while the lateral entrance dose varied from 0.9 to 204 mGy. Radiation exposure to the thyroid and the gonads was found to vary from 0.4 to 8.3 and 0.1 to 2.1 mGy, respectively. The DAP meter recorded DAP values for the posterior tube, between 46 and 3,700 cGy cm(2). The mean effective dose was found to be 7.7, 16.2, and 33.3 mSv for the diagnostic, the ASD, and the VSD group, respectively. Very strong correlation was found between the DAP values and the entrance radiation dose measured with TLDs. The mean entrance dose received from therapeutic cardiac catheterizations using the Amplatzer devices was found approximately twice the dose received from a diagnostic one. Even for the most complex procedures, the maximum entrance dose was at least 10 times lower than the threshold, associated with skin erythema.

Realtime Digital Magnification of the Fluoroscopic and Digital Subtraction Angiography Images: Randomized Prospective Study to Show Dose Reduction during Segmental Chemoembolization for Hepatocellular Carcinoma

PURPOSE

To show efficacy of realtime digital magnification of fluoroscopic and digital subtraction angiography images for dose reduction both of the medical personnel and the patient during segmental chemoembolization for hepatocellular carcinoma.

MATERIALS AND METHODS

Thirty patients were randomized into two groups; chemoembolization was performed with digital magnification (group A; n = 15) or with shorter field of view (group B; n = 15). Dose area product was used as a convenient and reasonable analog of the patient dose. Medical personnel dose and dose area product were compared.

RESULTS

Medical personnel dose and dose area product were 7.0 +/- 3.4 micro Sv and 71060 +/- 24653 cGy. cm(2)in group A, and 21.4 +/- 16.2 micro Sv and 110379 +/- 48065 cGy. cm(2) in group B, respectively. There were statistically significant differences in both the medical personnel dose (P =.002, Student t test) and the dose area product (P =.009, Student t test).

CONCLUSION

Digital magnification decreased the medical personnel dose by 67% and the patient dose by 36% during segmental chemoembolization for hepatocellular carcinoma.

Evaluation of patient-absorbed doses during coronary angiography and intervention by femoral and radial artery access

The aim of this study was to compare the radiation dose to patients during coronary angiography (CA) and coronary intervention (percutaneous transluminal coronary angioplasty, PTCA) by the femoral or radial artery access routes. A plane-parallel ionisation chamber, mounted on an under-couch X-ray tube (Siemens Coroskop TOP with an optional dose reduction system), recorded the dose-area product (DAP) to the patient from 40 coronary angiographies and 42 coronary interventions by the femoral route. The corresponding numbers for radial access were 36 and 24, respectively. Using a human-shaped phantom, conversion factors between maximum entrance surface dose and DAP were derived for CA and CA plus PTCA, respectively. The dose to the staff was measured with TL dosimeters for 22 examinations. Fluoroscopy time and DAP were significantly (p=0.003) larger using the radial access route for coronary angiography (7.5 min, 51 Gy cm2) than the corresponding values obtained from femoral access route (4.6 min, 38 Gy cm2). For CA plus PTCA the fluoroscopy time and DAP were larger for radial access (18.4 min, 75 Gy cm2) than for femoral access (12.5 min, 47 Gy cm2; p=0.013). In our experience, radial access did significantly prolong the fluoroscopy time and increase the patient doses.