Broad-beam transmission data in lead for scattered radiation produced at diagnostic energies

Evaluation of the effectiveness of X-ray protective aprons in experimental and practical fields

Few practical evaluation studies have been conducted on X-ray protective aprons in workplaces. We examined the effects of exchanging the protective apron type with regard to exposure reduction in experimental and practical fields, and discuss the effectiveness of X-ray protective aprons. Experimental field evaluations were performed by the measurement of the X-ray transmission rates of protective aprons. Practical field evaluations were performed by the estimation of the differences in the transit doses before and after the apron exchange. A 0.50-mm lead-equivalent-thick non-lead apron had the lowest transmission rate among the 7 protective aprons, but weighed 10.9 kg and was too heavy. The 0.25 and 0.35-mm lead-equivalent-thick non-lead aprons differed little in the practical field of interventional radiology. The 0.35-mm lead apron had lower X-ray transmission rates and transit doses than the 0.25-mm lead-equivalent-thick non-lead apron, and each of these differences exceeded 8% in the experimental field and approximately 0.15 mSv/month in the practical field of computed tomography (p < 0.01). Therefore, we concluded that the 0.25-mm lead-equivalent-thick aprons and 0.35-mm lead apron are effective for interventional radiology operators and computed tomography nurses, respectively.

Occupational exposure in the electrophysiology laboratory: quantifying and minimizing radiation burden

Fluoroscopically guided procedures in the electrophysiology room, such as radiofrequency catheter ablation and implantation of cardiac resynchronization devices, may result in high radiation exposure of electrophysiologists and assisting staff. Our aim was to provide accurate and applicable data on occupational doses to the electrophysiology laboratory personnel. We exposed fluoroscopically an anthropomorphic phantom at three projections common in electrophysiology studies. For each exposure, scattered radiation was measured at 182 sites of the cardiology room at four body levels. Effective dose values, eye lens, skin and gonadal doses to the laboratory staff were calculated. Our study has shown that a procedure requiring 40 min of fluoroscopy yields a maximum effective dose of 129 microSv and a maximum value of gonadal dose of 56.8 microSv to staff using a 0.35 mm lead-equivalent apron. A conservative estimate of the electrophysiologist's annual maximum permissible workload is 155 procedures. Staff effective dose values vary by a factor of 40 due to positioning during fluoroscopy and by a factor of 11 due to radiation protection equipment. Undercouch protective shields may reduce gonadal doses up to 98% and effective dose up to 25%. Consequently, radiation levels in the electrophysiology room are not negligible. Mitigation of occupational exposure is feasible through good fluoroscopy and working practices.

Occupational radiation exposure from fluoroscopically guided percutaneous transhepatic biliary procedures

PURPOSE

The aim of this study was to determine occupational dose levels for projections commonly used in fluoroscopically guided percutaneous transhepatic biliary (PTB) drainage and stent placement procedures.

METHODS

Exposure data from 71 consecutive PTB examinations were analyzed to determine average examination parameters for biliary drainage and stent placement procedures. An anthropomorphic phantom was exposed at three projections common in PTB interventions according to the actual geometric parameters recorded in the patient study. Scattered air-kerma dose rates were measured for neck, waist, and gonad levels at various sites in the interventional radiology laboratory. To produce technique- and instrumentation-independent data, dose rate values were converted to dose-area product (DAP)-normalized air-kerma values. In addition, sets of thermoluminescent dosimetry crystals were placed in both hands of the interventional radiologist to monitor doses during all PTB procedures.

RESULTS

Isodose maps of DAP-normalized air-kerma doses in the interventional laboratory for projections commonly used in PTB procedures are presented. To facilitate effective dose estimation, normalized dosimetric data at the interventional radiologist's position are presented for left and right access drainage procedures, metallic stent placement only, and drainage and metallic stent placement in one-session procedures with and without under-couch shielding. Doses to the hands of interventional radiologists are presented for left and right transhepatic biliary access and metallic stent placement.

CONCLUSIONS

Body level-specific normalized air-kerma distributions from commonly used projections in PTB procedures may be useful to accurately quantify dose, maximum workloads, and possible radiogenic risks delivered to medical personnel working in the interventional radiology laboratory. Normalized dose data presented will enable occupational exposure estimation from other institutions.

Anticipation of Radiation Dose to the Conceptus from Occupational Exposure of Pregnant Staff During Fluoroscopically Guided Electrophysiological Procedures

Conceptus dose from occupational exposure.

INTRODUCTION

A female employee working in the electrophysiology suite has the right to know potential radiation hazards to the unborn child before she is pregnant or before she decides to formally declare her pregnancy. Moreover, the employer of a declared pregnant worker must evaluate the work situation and ensure that the conceptus dose is kept below the maximum permissible level during the remaining gestation period. The aim of this study was to develop a method for conceptus dose anticipation and determination of maximum workload allowed for the pregnant employee who participates in fluoroscopically guided electrophysiological procedures.

METHODS AND RESULTS

A C-arm fluoroscopy system, an anthropomorphic phantom, and a radiation meter were used to obtain scattered air kerma dose rates separately for each of the three fluoroscopic projections typically used in the electrophysiology suite. Air kerma to conceptus dose conversion factors for all trimesters of gestation were calculated using Monte Carlo simulation. A formula is presented for the anticipation of the conceptus dose from occupational exposure of pregnant staff during fluoroscopically guided electrophysiological procedures. Normalized data are provided for conceptus dose estimation from occupational exposure of pregnant staff working in any electrophysiology laboratory. A methodology for estimation of maximum workload allowed for each month of the remaining gestation period of a worker who declared her pregnancy is proposed, which ensures that the regulatory dose limits are not exceeded.

CONCLUSION

Data presented may be used for the implementation of a radiation protection program designed for pregnant staff working in an electrophysiological suite.

Image-guided reconstruction of femoral fractures: is the staff progeny safe?

The potential of adverse effects to progeny caused by preconceptual and fetal exposure to ionizing radiation is an issue of increasing concern to orthopaedic surgeons and assisting staff. Are these fears justified? How effectively is the embryo or fetus protected, and should pregnant staff alter their duties? In this study, an anthropomorphic phantom was exposed fluoroscopically at two geometries common in surgical reconstruction of proximal femur fractures. Scatter radiation was converted to gonadal dose and embryo or fetal dose with and without use of a protective apron. The genetic risk for the orthopaedic surgeon after 10 years of occupational exposure was estimated to be 16,000 times lower than the natural frequency of heritable disease. The excess risk of childhood cancer associated with the dose accumulated during gestation was at least 600 times lower than the corresponding natural frequency. A properly shielded pregnant orthopaedic surgeon is allowed to do 14 hours of hip fluoroscopy during gestation, whereas 2100 hours of fluoroscopy are required for the induction of gross malformation or mental retardation to the growing embryo or fetus. The supplementary dose constraints for pregnant staff provide adequate protection to the unborn child without affecting regular personnel duties.

Personnel and patient doses: are there ethical consequences to the use of X-rays?

Interventional cardiology has witnessed a period of great technological change. The introduction of new dedicated cardiology X-ray equipment, as well as advances in catheter and stent design, has revolutionised clinical practice in cardiology. As a consequence, the number, range and complexity of procedures have increased. This has meant that patients can be treated as outpatients without requiring hospitalisation for surgery. The public are aware of these benefits and demand greater access. However, these changes have had an impact on patient and staff doses and these are reviewed. Simple approaches to dose reduction for patients and staff are illustrated. There are a number of ethical issues concerning both patients and staff. For patients, these are related to informed consent. For staff, the ethical issues are associated with dose control. These issues will be discussed.

Occupational gonadal and embryo/fetal doses from fluoroscopically assisted surgical treatments of spinal disorders

STUDY DESIGN

Simulation of lumbar spine fluoroscopy used during surgical treatments of spinal disorders on a humanoid phantom and monitoring of the scattered radiation levels.

OBJECTIVES

To assess the potential of adverse effects to progeny due to the preconceptual and embryo/fetal exposure to ionizing radiation resulting from the parental occupational exposure to scattered radiation from lumbar fluoroscopy.

SUMMARY OF BACKGROUND DATA

There are no available data on embryo/fetal doses resulting from maternal occupational exposure in the orthopedic theater. Besides, studies on staff gonadal doses from fluoroscopically assisted spine surgery are scarce and their results are not generally applicable.

METHODS

Lumbar spine anterior-posterior and lateral fluoroscopy were performed on an anthropomorphic phantom. Scattered radiation within the orthopedic theater was recorded at the staff genitals and waist level. Gonadal, abdominal surface, and embryo/fetal doses normalized to the dose-area-product specific to each projection were calculated.

RESULTS

If the annual dose limits of occupational exposure are continuously exhausted for 10 years, the resulting radiogenic risk of congenital malformation in infants born to the orthopedic theater staff will be at least two orders of magnitude lower than the corresponding spontaneous probability. The occupational exposure of the pregnant mother bears a negligible contribution to the risk of hereditary effect on the newborn's progeny compared with the natural incidence rate.

CONCLUSIONS

Radiogenic genetic and embryo/fetal risks resulting from occupational exposure due to fluoroscopically assisted surgical treatments of spinal disorders are well within tolerance levels provided that rigorous confinement to all pertinent occupational dose constraints is established.

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.

The interdependence of staff and patient doses in interventional radiology

Staff doses arising from the use of X-rays are principally due to scattered radiation. This is related to the dose received by the patient expressed as the dose-area product (DAP). Doses to patients in interventional radiology are generally higher than for other fluoroscopically guided procedures. Doses to interventional radiologists are, therefore, amongst the highest associated with the use of diagnostic X-rays. The results of staff dose monitoring normalized to DAP should provide an indicator of those procedures which are associated with particularly high radiation exposures to staff, and should help to identify those radiologists whose practice may result in unnecessarily high doses to themselves. A study has been made of patient doses in two X-ray rooms used for interventional procedures associated with vascular and liver diseases. Doses to radiologists in these rooms were normalized to DAP. It was found that the average doses to the body, neck and hands were 0.05, 0.89 and 2.45 microSv/(Gy cm2), respectively for those radiologists with no significant involvement in hepatobiliary procedures. Higher doses were found for one radiologist whose workload included biliary drainage. The whole body dose was 0.17 microSv/(Gy cm2) or 5.8 mSv per year. It was shown that the doses to the neck and hands for the biliary drainage work was 6.59 and 29.0 microSv/(Gy cm2), respectively. This study has demonstrated the value of DAP as a measure of radiologist workload in respect of its significance in terms of staff dose.