The impact of cardiology on the collective effective dose in the North of England

Does cardiologist- or radiographer-operated fluoroscopy and image acquisition influence optimization of patient radiation exposure during routine coronary angiography?

The operator of radiation exposure during coronary angiography varies between different centres. The purpose of this study was to explore whether radiation dose was lower during cardiologist- or radiographer-controlled radiation exposure and to determine if the grade of cardiologist performing angiography influenced radiation dose. Patients were randomly allocated either to cardiologist- or radiographer-controlled radiation exposure during coronary angiography. Screening time and radiation dose during fluoroscopy and image acquisition, measured by dose-area product meter, were recorded. Mean radiation dose during cardiologist-controlled radiation exposure (n=176) of 15.6 Gy cm(2) (95% confidence interval (CI), 14.4-16.8) was significantly lower than that produced by the radiographer-controlled group (n=192) of 17.3 Gy cm(2) (95% CI, 16.2-18.6) (p<0.044). There was no significant difference in screening times produced by the two groups of radiation exposure operators. The difference in radiation dose produced by the two operator groups was principally owing to exposure produced at image acquisition. Irrespective of radiation exposure operator, consultant cardiologists produced significantly lower screening times and radiation doses compared with registrars. During routine coronary angiography, radiographer-controlled radiation exposure does not reduce screening time or radiation dose. Senior cardiologists produce the lowest radiation doses during coronary angiography when they are responsible for radiation exposure.

Usefulness of rotational spin for coronary angiography in patients with advanced renal insufficiency

Coronary angiography in patients with advanced renal insufficiency is typically restricted to cases of life-threatening circumstances such as acute myocardial infarction and unstable angina. To gather a large amount of visual information with a minimum number of cine runs, and consequently, with a minimum volume of contrast medium, we rotated the gantry at 40 degrees /s throughout an angle of 120 degrees, from the right toward the left anterior oblique positions. This technique of rotational spin during cinegraphic runs has not yet become established in invasive cardiology. Three experienced cardiologists independently evaluated all coronary segments in rotational versus standard coronary angiography modes for 15 patients, on the basis of an 11-point scale (0 = cardiac spin far better to 10 = standard mode far better). A score of 5 signified that there was no difference in quality between the 2 modes. The arithmetic mean of the assessment values was 4.9 +/- 0.3 for coronary segments, 5.4 +/- 1.3 for coronary lesions, 5.1 +/- 1.4 for bifurcations, and 5.0 +/- 0.1 for coronary flow. The arithmetic means for the volume of contrast medium (25 +/- 4 ml), for the overall dose area product (8.6 +/- 4.5 Gy x cm(2)), and for the number of cine graphic frames (203 +/- 65) for a diagnostic cardiac spin were significantly below published typical values in standard mode. Cardiac spin enables 3-dimensional coronary impression under conditions of adequate image quality and represents a new, useful, and beneficial method in invasive cardiology for applications involving the special indication of advanced renal insufficiency.

X-ray dose and associated risks from radiofrequency catheter ablation procedures

The objectives of this study were to quantify the ionizing radiation exposure to patient and operator during radiofrequency (RF) catheter ablation and to estimate the risks associated with this exposure. The study consisted of 50 RF ablation procedures, all performed in the same electrophysiology laboratory. Occupational dose to two cardiologists who performed the procedures was measured using film badges and extremity thermoluminescent dosemeters (TLDs). Absorbed dose to the patients' skin was measured using TLDs. Dose-area product (DAP) was also measured. The effective dose to the cardiologists was less than 0.15 mSv per month. The mean equivalent dose to the cardiologists' left hand and forehead was 0.24 mSv and 0.05 mSv, respectively, per RF ablation procedure, which was more than twice the mean dose for the other cardiology procedures carried out in the centre. Yearly occupational dose to the cardiologists was much lower than the relevant statutory dose limits. The mean skin dose, fluoroscopy time and DAP to patients were 0.81 Gy, 67 min and 123 Gycm(2), respectively, with a maximum of 3.2 Gy, 164 minutes and 430 Gycm(2), respectively. Mean effective dose to patients was 17 mSv, from which the excess risk of developing fatal cancer is 0.1%. Six of the patients (12%) received a skin dose above the threshold dose for radiation skin injury (2 Gy), but no skin injuries were reported. Patient skin dose and DAP were closely correlated and this allows DAP to be used to monitor patient skin dose in real-time. DAP levels were locally adopted as diagnostic reference levels (DRLs) that provide an indication during a procedure that a patient is at risk of suffering deterministic skin injury.

Skin radiation injuries in patients following repeated coronary angioplasty procedures

This study investigates the incidence of skin injuries and retrospectively estimates skin doses in a sample of patients who had multiple coronary angiographies and who underwent more than four percutaneous transluminal coronary angioplasties (PTCAs), performed primarily by the same team of cardiologists in a university hospital. A database of 7824 PTCAs performed during the last 14 years was analysed. Patients were selected and reviewed by a cardiologist and two radiotherapists with experience in radiation-induced skin injuries. A retrospective analysis of skin doses was performed using data from the patients' files and from the quality assurance (QA) programme of the hospital, which includes periodic patient dose measurements. 14 patients were included in the study. Each patient had undergone between 4 and 14 coronary angiographies and between 5 and 10 PTCAs, performed over a period of 2-10 years. The estimated mean dose-area product per procedure was 46 Gy cm(2) for coronary angiography and 82 Gy cm(2) for PTCA. Mean values of maximum skin dose per procedure were 217 mGy for the diagnostic studies and 391 mGy for the PTCAs. Only a slight radiation skin injury was clinically demonstrated in one patient with a history of 10 coronary angiographies and 10 PTCAs (estimated maximum skin dose 9.5 Gy). Another patient who underwent 14 coronary angiographies and 10 PTCAs (estimated maximum skin dose 7.3 Gy) showed a slight telangiectasia and discrete pigmentation. Another patient with a cutaneous lupus erythematosus showed pigmentation in the area of the radiation field following seven coronary angiographies and six PTCAs (estimated maximum skin dose 5.6 Gy), as expected bearing in mind that skin tolerance to high doses may be altered for patients with this pathology. Each of the remaining 11 patients with no skin injuries had undergone between 5 and 7 PTCAs and between 5 and 14 additional angiographies. None of the 14 patients reported acute skin injuries and no necrosis or radiodermatitis was observed.

Correlation of patient skin doses in cardiac interventional radiology with dose-area product

The use of X-rays in cardiac interventional radiology has the potential to induce deterministic radiation effects on the patient's skin. Guidelines published by official organizations encourage the recording of information to evaluate this risk, and the use of reference values in terms of the dose-area product (DAP). Skin dose measurements were made with thermoluminescent dosemeters placed at eight different locations on the body. In addition, DAP was recorded in 100 patients for four types of interventional radiology procedures. Mean, median and third quartile for these results are presented. Maximum skin dose values found were 412 mGy, 725 mGy, 760 mGy and 1800 mGy for coronary catheterization, coronary catheterization with left ventricle investigation, and percutaneous transluminal angiography without and with stenting, respectively. Median DAPs for these same procedures were, respectively, 5682 cGy cm2, 10,632 cGy cm2, 10,880 cGy cm2 and 13,161 cGy cm2. The relationship between DAP and skin dose was investigated. We found a poor correlation of DAP with maximum skin dose (r = 0.77) and skin dose indicator (r = 0.78). Using conversion factors derived from Monte Carlo simulations, skin dose distributions were calculated based on the measured DAPs. Agreement between the calculated skin dose distribution, using DAP values averaged over a group of patients who underwent coronary catheterization and left ventricle investigation, and the measured skin dose averaged over the same group of patients was very good. However, there were large differences between the calculated skin doses using the individual DAP data per patient and measured skin doses for individual patients (r = 0.66). Hence, calculation of individual skin doses based on the specific DAP data per patient is not reliable and therefore measuring skin dose is preferable.

Factors affecting patient radiation exposure during routine coronary angiography in a tertiary referral centre

Cardiac catheterization is carried out by an increasing number of operators from district hospitals as well as tertiary referral centres. Procedures are not standardized and are at the discretion of individual operators. The purpose of this study was to describe the pattern of patient radiation dose and screening times associated with diagnostic cardiac catheterization, and explore determinants of radiation dose to patients and staff. Data were collected from 1337 diagnostic procedures carried out in two cardiac catheterization laboratories from January to June 1998. Screening time and radiation dose measured by dose-area product (DAP) meter were recorded. Status of the operator and type of investigation were determined. 22 operators had performed at least 15 left ventriculograms with coronary angiography (total 944 procedures). The average (+/- SD) was 40 (+/- 22) per operator. Screening times for individual operators varied from 2.0 (+/- 1.3) min to 5.0 (+/- 4.3) min with no relationship between time and number of cases. Consultants and visiting physicians had longer screening times and greater patient DAP readings. In comparison with 115 cases of coronary angiography alone, left ventriculography increased DAP reading from 14.24 (+/- 11.7) Gy cm2 to 20.26 (+/- 0.47) Gy cm2 (p < 0.0001). In 106 cases of coronary artery bypass graft angiography, an aortogram (n = 53) did not add significantly to radiation dose or screening time. A right heart catheter added approximately 5 min to screening time (9.13 (+/- 0.63) min with right heart (n = 83) vs 3.96 (+/- 0.12) min without right heart (n = 1234)), but did not affect radiation dose significantly. There is a wide range of screening times and radiation doses related to diagnostic cardiac catheterization. Visiting and consultant staff use greater radiation doses. Left ventriculography adds significantly to patients' radiation exposure. Aortography does not add significantly to radiation dose in cases of graft angiography.

Patient dosimetry measurement methods

This article reviews patient dosimetry measurement methods applied to diagnostic radiology examinations. Various dose quantities and their relevance to patient dose surveys are described. When contemplating a patient dose survey it is important to develop a clear measurement strategy. This involves a detailed consideration of the most applicable dose measurement method for the intended survey. Various approaches to patient dosimetry are described and reviewed.