An investigation into patient and staff doses from X-ray angiography during coronary interventional procedures

Effective Radiation Dose from Cone-Beam Computed Tomography Guidance during Bronchoscopic Tumour Ablation

INTRODUCTION

Endobronchial radiofrequency ablation (RFA) is a novel minimally invasive approach to management of peripheral non-small-cell lung cancer (NSCLC) in medically inoperable patients. Minimally invasive ablative techniques are generally delivered with cone-beam computed tomography (CBCT) guidance. CBCT requires a significant number of two dimensional imaging projections to be acquired which is then reconstructed as a three-dimensional cone-beam image. The objective of this study was to determine the radiation dosimetry consequent to use of CBCT guidance for bronchoscopic RFA.

METHODS

Post hoc analysis of data following bronchoscopic RFA of stage I biopsy-confirmed NSCLC performed with CBCT. Effective dose estimates for these patients were calculated using PCXMC2.0 software.

RESULTS

Ten patients underwent bronchoscopic RFA, with a median 3 (range 2-4) CBCT spins per procedure. Mean dose area product (DAP) per procedure was 7,778 μGy.m2 (±4,743) with an effective dose of 11.6 mSv (±7.4). The DAP per spin for these 10 patients varied from 83.8 to 8,625.6 μGy.m2 (effective dose range 0.15-13.81 mSv).

CONCLUSION

This is the first study to report radiation dosimetry consequent to CT guidance for bronchoscopic RFA procedures. Effective doses appear comparable to other CT fluoroscopic procedures.

Radiation Protection of the Eye Lens in Fluoroscopy-guided Interventional Procedures

The medical staff involved in fluoroscopy-guided procedures are at potential risks of radiation-induced cataract. Therefore, proper monitoring of the lens doses is critical, and radiation protection should be provided to the maximum extent that is reasonably achievable. The collar dosimeter is necessary to avoid underestimation of the lens dose, and the third dosimeter behind the protective eyewear would be helpful for those who are likely to exceed the dose limit. The reduction of the patient doses will correspondingly reduce the staff doses. Proper placement of the ceiling-mounted shields and minimization of the face-to-glass gap are the keys to effective shielding. The optimization of procedures and devices that help maintain a distance from the irradiated area and to prevent the looking-up posture will substantially reduce the lens dose.

A systematic review of conversion factors between kerma-area product and effective/organ dose for cardiac interventional fluoroscopy procedures performed in adult and paediatric patients

The aim of this systematic review is to undertake a critical appraisal of the evidence in the published literature concerning the conversion factors between kerma-area product (P KA) and effective/organ dose (DCED_PKA, DCHT_PKA) for cardiac interventional fluoroscopy procedures performed in adults and paediatric patients and to propose reference conversion factors to help standardize dose calculations. A search strategy utilizing MeSH headings in three databases identified 59 (adult) and 37 (paediatric) papers deemed eligible for the review. Exclusion criteria were adopted to select data only from publications which established DCED_PKA in patients using the ICRP 103 tissue weighting factors. A time restriction from January 2007 was introduced in the search to capture the evolving trends of utilization of fluoroscopy-guided intervention technologies only in recent years. The suggested DCED_PKA and DCHT_PKA were synthesized by calculating the weighted averages of the values reported by the authors with weights corresponding to the study sample size. Eighteen studies for both adult (9) and paediatric (9) patients matching the search terms fulfilled the inclusion criteria. The suggested value for DCED_PKA in adult patients amounts to 0.24 mSv Gy−1cm−2. The suggested values for DCHT_PKA ranged from a minimum of 0.15 mSv Gy−1cm−2 for the female breast to a maximum of 0.97 mSv Gy−1cm−2 for the lungs. The suggested values for DCED_PKA in paediatric patients ranged from 3.45 mSv Gy−1cm−2 for the new-born to 0.49 mSv Gy−1cm−2 in the 15 years age class. The suggested values for DCHT_PKA ranged from a minimum of 0.33 mSv Gy−1cm−2 for bone marrow in the 15 years age class to a maximum of 11.49 mSv Gy−1cm−2 for the heart in the new-born. To conclude, values of DCED_PKA/DCHT_PKA were provided for calculating effective/organ doses in cardiac interventional procedures. They can be useful for standardizing dose calculations, hence for comparison of the radiation detriment from different imaging procedures and in the framework of epidemiologic studies.

Monte Carlo evaluation of occupational exposure during uterine artery embolization

PURPOSE

Uterine fibroids affect women mainly of childbearing age, an alternative for the treatment of these fibroids is uterine artery embolization (UAE), a minimally invasive procedure which uses fluoroscopy, providing radiation doses often high, due to the fact that professionals remain in the room throughout the procedure. In this work, equivalent and effective doses were evaluated for the main physician, for the assistant and for the patient during the UAE procedure.

METHODS

Doses were calculated using computer simulation with the Monte Carlo Method, and virtual anthropomorphic phantoms, in a typical scenario of interventional radiology with field sizes of 20 × 20, 25 × 25 and 32 × 32 cm², tube voltages of 70, 80, 90 and 100 kV, and projections of LAO45, RAO45 and PA.

RESULTS

The results showed that the highest doses received by the professionals were for the LAO45 projection with 32 × 32 cm² field size and 100 kV tube voltage, which is in accordance with the existing literature. The highest equivalent doses, without the protective equipment, were in the eyes, skin, breast and stomach for the main physician, and for the assistant they were in the eyes, breast, thyroid and skin. When she used the protective equipment, the highest equivalent doses for the main physician were on the skin, brain, bone marrow and bone surface, and for the assistant they were on the skin, brain, red bone marrow and bone surface.

CONCLUSIONS

Effective doses increased up to 3186% for the main physician, and 2462% for the assistant, without protective equipment, thus showing their importance.

PATIENT SIZE INDICES AND DOSE IN FLUOROSCOPICALLY GUIDED LUMBAR DISCECTOMY AND FUSION: A PRELIMINARY STUDY

Patient dose values varied significantly during interventional procedures, mainly due to the patient size, operators' choices and clinical complexity. In this study, the effect of applying a previously described and validated size-correction method to normalise kerma-area product (KAP) and average KAP rate values of the whole procedure (KAP rate) and isolate variations in dose due to the patient size and complexity, during lumbar discectomy and fusion (LDF) procedures, was investigated. Fluoroscopy time (FT), KAP, KAP rate and patient size data (weight, height and equivalent diameter) were recorded, for 96 patients who underwent single or multilevel LDF procedures by three senior neurosurgeons, defining three different patient groups (surgeon 1, surgeon 2, surgeon 3). Simple linear regression and coefficients of determination were used to investigate the relationship between uncorrected and corrected KAP and KAP rate values and patient size indices in these groups. The results showed that the size correction decreased the influence of patient size and could contribute to the isolation of the variations in patient dose due to the patient size. From this point of view, dose surveys during lumbar spine interventions may include dosimetric data from all patients independently of their body size and not only for standard-sized patients, providing the advantage of accessible data collection for the establishment of local dose reference levels and optimisation purposes, within the framework of the radiation protection program in the Neurosurgery Department.

PRELIMINARY STAFF DOSE ASSESSMENT FOR COMMON FLUOROSCOPY GUIDED PROCEDURES AT KORLE-BU TEACHING HOSPITAL, ACCRA, GHANA

Preliminary studies on effective and eye lens doses of six Radiologists, four Cardiologists have been conducted for a period of 3 months. Electronic dosemeters positioned under and over lead apron of staff were used for the dosimetry. The estimated effective dose per month to Cardiologist and Radiologist were 0.01-0.07 mSv and 0.03-0.14 mSv, respectively. The estimated eye lens doses per month to Cardiologists and Radiologists were also 0.15-0.30 mSv and 0.53-3.39 mSv, respectively. The effective doses per month to staff were below the ICRP acceptable limit of 1.67 mSv/month but the upper limit of the range of estimated eye lens dose exceeded the ICRP acceptable limit by a factor of 2. Regular use of protective goggles and consistent eye lens dose monitoring is encouraged at the hospital for dose optimization.

Simulation of H p (10) and effective dose received by the medical staff in interventional radiology procedures

Interventional radiology and cardiology are widespread employed techniques for diagnosis and treatment of several pathologies because they avoid the majority of the side-effects associated with surgical treatments, but are known to increase the radiation exposure to patient and operators. In recent years many studies treated the exposure of the operators performing cardiological procedures. The aim of this work is to study the exposure condition of the medical staff in some selected interventional radiology procedures. The Monte Carlo simulations have been employed with anthropomorphic mathematical phantoms reproducing the irradiation scenario of the medical staff with two operators and the patient. A personal dosemeter, put on apron, was modelled for comparison with measurements performed in hospitals, done with electronic dosemeters, in a reduced number of interventional radiology practices. Within the limits associated to the use of numerical anthropomorphic models to mimic a complex interventional procedure, the personal dose equivalent, H _p (10), was evaluated and normalised to the simulated Kerma-Area Product, KAP, value, indeed the effective dose has been calculated. The H _p (10)/KAP_value of the first operator is about 10 μSv/Gy.cm², when ceiling shielding is not used. This value is calculated on the trunk and it varies of +/-30% moving the dosemeter to the waist or to the neck. The effective dose, normalised to the KAP value, varies between 0.03 and 0.4 μSv/Gy.cm². Considering all the unavoidable approximation of this kind of investigations, the comparisons with hospital measurement and literature data showed a good agreement allowing to use of the present results for dosimetric characterisation of interventional radiology procedures.

CHARACTERIZATION AND EXPERIMENTAL MEASUREMENTS OF SCATTER DOSE AT CARDIOLOGIST'S EYES DURING PAEDIATRIC INTERVENTIONAL CARDIOLOGY PROCEDURES IN COSTA RICA

This paper presents the results of the first characterization and experimental measurements of scatter dose at cardiologist's eyes for the only X-ray system that performs all paediatric Interventional cardiology procedures in Costa Rica. Entrance surface air kerma (ESAK) and the scatter dose values were measured on phantoms of 4-20 cm thicknesses of polymethyl methacrylate slabs. Image quality was evaluated using DICOM images of a test object Leeds TOR 18-FG, through the numerical parameters signal-to-noise ratio (SNR), high-contrast spatial resolution (HCSR) and figure of merit (FOM). When PMMA thickness is increased and during a move from low fluoroscopy to cine modes, ESAK, SNR, HCSR and FOM values range from 0.44 to 391.0 μGy fr-1; 2.8 to 14.89; 3.17 to 15.54 and 0.51 to 79.94, respectively. The highest scattered dose rates recorded during the simulations were 1.79 and 8.04 mSv h-1 for the high fluoroscopy and cine modes, respectively.

Optimisation of imaging protocols in interventional cardiology: impact on patient doses

The purpose of this work is to evaluate the impact of the imaging protocol as part of the optimisation of patient doses in interventional cardiology. This paper reports the results of an initial study to refine the existing fluoroscopy and cine settings, evaluates a new imaging protocol by measuring the image quality and phantom entrance air kerma values, and tests the clinical implementation of the new protocol in terms of the reduction in patient doses and the impact on clinical images. The initial study developed a new fluoroscopy mode using 7.5 frames s^-1 (instead of the previous 15 frames s^-1) with a similar dose/frame and a reduction of approximately 26% in dose/frame for the existing standard cine mode. For the new imaging protocol, the reduction in entrance air kerma was characterised for water depths of 16, 20, and 24 cm and the image quality was evaluated using a Leeds test object. A reduction in dose of around 50% was observed for the low fluoroscopy mode and an 18%-38% reduction was measured for cine. The image quality was unchanged in fluoroscopy mode and did not suffer noticeable alterations in cine mode. In the clinical implementation, cardiologists evaluated the new imaging protocol in clinical practice and cooperated with medical physicists to ensure full optimisation. The image quality criteria evaluated the ability to visualise the standard coronary arteries and small vessels (<2 mm), and the proper visualisation of the heart and diaphragm. A total of 1635 interventional cardiac procedures were assessed. The median kerma-area product exhibited a reduction of 37% for CA and 43% for PTCA examinations, and the quality of the clinical images was considered sufficient for standard clinical practice.

Towards Robot-Assisted Echocardiographic Monitoring in Catheterization Laboratories : Usability-Centered Manipulator for Transesophageal Echocardiography

This paper proposes a robotic Transesophageal Echocardiography (TOE) system concept for Catheterization Laboratories. Cardiovascular disease causes one third of all global mortality. TOE is utilized to assess cardiovascular structures and monitor cardiac function during diagnostic procedures and catheter-based structural interventions. However, the operation of TOE underlies various conditions that may cause a negative impact on performance, the health of the cardiac sonographer and patient safety. These factors have been conflated and evince the potential of robot-assisted TOE. Hence, a careful integration of clinical experience and Systems Engineering methods was used to develop a concept and physical model for TOE manipulation. The motion of different actuators of the fabricated motorized system has been tested. It is concluded that the developed medical system, counteracting conflated disadvantages, represents a progressive approach for cardiac healthcare.

PATIENT DOSIMETRY DURING INTERVENTIONAL CARDIAC PROCEDURES IN A DEDICATED CATHETERIZATION LABORATORY

Cardiac interventions often result in high radiation dose to patient's skin, so a reliable indicator in terms of a commonly used dose descriptor is required to monitor skin exposures. In the present study, Gafchromic XR-RV3 film was used to measure the peak skin dose (PSD) during 40 coronary angiography (CA) and 50 percutaneous transluminal coronary angioplasty (PTCA) procedures. Corresponding values of kerma-area product (PKA), fluoroscopy time (FT) and reference air-kerma (Ka,r) were recorded and correlated with PSD. Doses to patient's eyes and thyroid were also measured by using thermoluminescent dosimeters (TLDs) during PTCA procedures. The average dose to thyroid was about six times higher than the average dose to eyes. The mean values of PSD, PKA and FT were 1140 mGy, 97 Gy cm2 and 15.7 min for PTCA and 290 mGy, 21.1 Gy cm2 and 2.4 min for CA procedures, respectively. One in seven patients of PTCA procedure received PSD >2 Gy. With respect to FT, PKA may be used as a better predictor of skin exposures because the correlation of PSD with PKA was found better than with FT for both CA and PTCA procedures.

Occupational dose reduction in cardiac catheterisation laboratory: a randomised trial using a shield drape placed on the patient

The aim of this study was to evaluate the occupational radiation dose in interventional cardiology by using a shielding drape on the patient. A random study with and without the protective material was conducted. The following control parameters were registered: demographic data, number of stents, contrast media volume, fluoroscopy time, number of cine images, kerma-area product and cumulative air kerma. Occupational dose data were obtained by electronic active dosemeters. No statistically significant differences in the analysed control parameters were registered. The median dose value received by the interventional cardiologist was 50% lower in the group with a shielding drape with a statistically significant p-value <0.001. In addition, the median value of the maximum scatter radiation dose was 31% lower in this group with a statistically significant p-value <0.001. This study showed that a shielding drape is a useful tool for reducing the occupational radiation dose in a cardiac catheterisation laboratory.

Operator Radiation and the Efficacy of Ceiling-Suspended Lead Screen Shielding during Coronary Angiography: An Anthropomorphic Phantom Study Using Real-Time Dosimeters

Operator radiation and the radiation protection efficacy of a ceiling-suspended lead screen were assessed during coronary angiography (CA) in a catheterization laboratory. An anthropomorphic phantom was placed under the X-ray beam to simulate patient attenuation in eight CA projections. Using real-time dosimeters, radiation dose rates were measured on models mimicking a primary operator (PO) and an assistant. Subsequently, a ceiling-suspended lead screen was placed in three commonly used positions to compare the radiation protection efficacy. The radiation exposure to the PO was 2.3 to 227.9 (mean: 67.2 ± 49.0) μSv/min, with the left anterior oblique (LAO) 45°/cranial 25° and cranial 25° projections causing the highest and the lowest dose rates, respectively. The assistant experienced significantly less radiation overall (mean: 20.1 ± 19.6 μSv/min, P < 0.003), with the right anterior oblique (RAO) 30° and cranial 25° projections resulting in the highest and lowest exposure levels, respectively. Combined with table-side shielding, the ceiling-suspended lead screen reduced the radiation to the PO by 76.8%, 81.9% and 93.5% when placed close to the patient phantom, at the left side and close to the PO, respectively, and reduced the radiation to the assistant by 70.3%, 76.7% and 90.0%, respectively. When placed close to the PO, a ceiling-suspended lead screen provides substantial radiation protection during CA.

Operator Radiation Exposure in Cone-Beam Computed Tomography Guidance

Objectives:

Quantitative analysis of operator dose in cone-beam computed tomography guidance (CBCT-guidance) and the effect of protective shielding.

Methods:

Using a Rando phantom, a model was set-up to measure radiation dose for the operator hand, thyroid and gonad region. The effect of sterile radiation-absorbing drapes and ceiling/couch shielding was measured. Using this model we calculated the dose, based on relevant clinical parameters. The procedures were divided in thoracic and abdominal group. Furthermore, dosimetry measurements were performed during clinical cases to correlate with our calculations.

Results:

One hundred thirteen procedures were included between December 2007 and January 2010 (47 thoracic, 66 abdominal). The mean hand doses were 34.2 and 54.6 µSv (thoracic/abdominal respectively). The thyroid and gonad regions doses were 83.2 and 34.3 µSv in the thoracic, and 66.2 and 47.2 µSv in the abdominal group. Combined shielding reduced the dose by 98.2–98.9% (p<0.05). The radiation dose in clinical setting in the thoracic group (n=17) was 32.9 µSv (hand), 11.4 µSv (thyroid) and 16.0 µSv (gonad region). In the abdominal group (n=20) the doses were 43.4, 21.7 and 18.8 µSv respectively.

Conclusion:

The operator dose in CBCT-guidance without shielding is quite low, compared to the literature. Based on our data, between 375–830 cases can be performed staying below the yearly limit of 20 mSv effective whole-body dose.

Comparison of two angiographic systems in paediatric interventional cardiology

The aim of this work was to analyse the radiation dose for patients and staff between X-ray systems, a new biplane with flat-panel detectors (FDs) and a conventional system equipped with image intensifier (II). Entrance surface air kerma (ESAK) and scatter doses were measured on polymethyl methacrylate (PMMA) phantoms of different thicknesses (from 4 to 16 cm). The ESAK values for the different acquisition modes and PMMA thicknesses were higher for the II in comparison with FDs. For the II, the scatter dose rates ranged from 0.67 to 12.2 mSv h(-1) at the eye position of the cardiologist during fluoroscopy and cine modes. At the lower extremities, these values were 1.11 and 24.24 mSv h(-1). In the case of the FDs, these values ranged from 0.24 to 0.67 mSv h(-1) for eye lens and from 0.73 to 2.01 mSv h(-1) for the position of cardiologist's ankle. The newly installed X-ray system showed an average reduction factor of up to 9.7 times for ESAK values. For the staff with an average reduction factor of 15.9 times at the eye position during fluoroscopy and cine modes, no protective tools are used. At the lower extremities, this value was 7.6 times.

Reduction of occupational radiation dose in staff at the cardiac catheterisation laboratory by protective material placed on the patient

Reducing occupational radiation dose in cardiac catheterisation laboratories is one of the objectives of the radiation protection system because the procedures performed involve high levels of radiation compared with others in health care. Recommendations on protection methods used are referred to different structural types and personal protection tools. In this work, the effectiveness of a shielding drape above the patient in different geometric shapes for a standard procedure in interventional cardiology was evaluated. Values of personal dose equivalent Hp(10) obtained simultaneously with three active electronic semiconductor dosemeters located at the usual position of staff and at the C-arm have been used to show the usefulness of the shielding drape.

Preliminary results of an attempt to predict over apron occupational exposure of cardiologists from cardiac fluoroscopy procedures based on DAP (dose area product) values

This study is an effort to propose a mathematical relation between the occupational exposure measured by a dosimeter worn on a lead apron in the chest region of a cardiologist and the dose area product (DAP) recorded by a meter attached to the X-ray tube. We aimed to determine factors by which DAP values attributed to patient exposure could be converted to the over-apron entrance surface air kerma incurred by cardiologists during an angiographic procedure. A Rando phantom representing a patient was exposed by an X-ray tube from 77 pre-defined directions. DAP value for each exposure angle was recorded. Cardiologist exposure was measured by a Radcal ionization chamber 10X5-180 positioned on a second phantom representing the physician. The exposure conversion factor was determined as the quotient of over apron exposure by DAP value. To verify the validity of this method, the over-apron exposure of a cardiologist was measured using the ionization chamber while performing coronary angiography procedures on 45 patients weighing on average 75 ± 5 kg. DAP values for the corresponding procedures were also obtained. Conversion factors obtained from phantom exposure were applied to the patient DAP values to calculate physician exposure. Mathematical analysis of our results leads us to conclude that a linear relationship exists between two sets of data: (a) cardiologist exposure measured directly by Radcal & DAP values recorded by the X-ray machine system (R (2) = 0.88), (b) specialist measured and estimated exposure derived from DAP values (R (2) = 0.91). The results demonstrate that cardiologist occupational exposure can be derived from patient data accurately.

Comparison of radiation dose exposure in patients undergoing percutaneous coronary intervention vs. peripheral intervention

Introduction

Most endovascular techniques are associated with patient and personal exposure to radiation during the procedure. Ionising radiation can cause deterministic effects, such as skin injury, as well as stochastic effects, which increase the long-term risk of malignancy. Endovascular operators need to be aware of radiation danger and take all necessary steps to minimise the risk to patients and staff. Some procedures, especially percutaneous peripheral artery revascularisation, are associated with increased radiation dose due to time-consuming operations. There is limited data comparing radiation dose during percutaneous coronary intervention (PCI) with percutaneous transluminal angioplasty (PTA) of peripheral arteries.

Aim

To compare the radiation dose in percutaneous coronary vs. peripheral interventions in one centre with a uniform system of protection methods.

Material and methods

A total of 352 patients were included in the study. This included 217 patients undergoing PCI (single and multiple stenting) and 135 patients undergoing PTA (in lower extremities, carotid artery, renal artery, and subclavian artery). Radiation dose, fluoroscopy time, and total procedural time were reviewed. Cumulative radiation dose was measured in gray (Gy) units.

Results

The total procedural time was significantly higher in PTA (PCI vs. PTA: 60 (45–85) min vs. 75 (50–100) min), p < 0.001. The radiation dose for PCI procedures was significantly higher in comparison to PTA (PCI vs. PTA: 1.36 (0.83–2.23) Gy vs. 0.27 (0.13–0.46) Gy), p < 0.001. There was no significant difference in the fluoroscopy time (PCI vs. PTA: 12.9 (8.2–21.5) min vs. 14.4 (8.0–22.6) min), p = 0.6. The analysis of correlation between radiation dose and fluoroscopy time in PCI and PTA interventions separately shows a strong correlation in PCI group (r = 0.785). However, a weak correlation was found in PTA group (r = 0.317).

Conclusions

The radiation dose was significantly higher during PCI in comparison to PTA procedures despite comparable fluoroscopy time and longer total procedure time in PTA. Fluoroscopy time is a reliable parameter to control the radiation dose exposure in coronary procedures. The increasing complexity of endovascular interventions has resulted in the increase of radiation dose exposure during PCI procedures.

Assessment of physician and patient (child and adult) equivalent doses during renal angiography by Monte Carlo method

Renal angiography is one of the medical imaging methods in which patient and physician receive high equivalent doses due to long duration of fluoroscopy. In this research, equivalent doses of some radiosensitive tissues of patient (adult and child) and physician during renal angiography have been calculated by using adult and child Oak Ridge National Laboratory phantoms and Monte Carlo method (MCNPX). The results showed, in angiography of right kidney in a child and adult patient, that gall bladder with the amounts of 2.32 and 0.35 mSv, respectively, has received the most equivalent dose. About the physician, left hand, left eye and thymus absorbed the most amounts of doses, means 0.020 mSv. In addition, equivalent doses of the physician's lens eye, thyroid and knees were 0.023, 0.007 and 7.9E-4 mSv, respectively. Although these values are less than the reported thresholds by ICRP 103, it should be noted that these amounts are related to one examination.

An investigation of patient doses during coronary interventional procedures in China

The purpose of this study was to estimate patient doses during coronary angiography (CA) and different complex percutaneous transluminal coronary angioplasty (PTCA) procedures in China. Consecutive 290 patients (90 CA, 200 PTCA) with known or suspected coronary artery disease were enrolled prospectively into six groups. Differences in patient doses among the six groups were analysed, and the patient doses observed in this study were compared with the recent literature. The median dose area product values were 27.0 and 195.0 Gy cm(2) for CA and PTCA, respectively. The patient doses during CA were similar to those reported by other authors, while those during PTCA were higher. The differences in radiation doses depended on the complexity of the procedures. Enhanced knowledge of radiation doses may help cardiologists implement radiation-sparing procedures to minimise patient exposure.

Radiation doses to Norwegian heart-transplanted patients undergoing annual coronary angiography

Heart-transplanted patients in Norway undergo annual coronary angiography (CA). The aims of this study were to establish a conversion factor between dose-area product and effective dose for these examinations and to use this to evaluate the accumulated radiation dose and risks associated with annual CA. An experienced cardiac interventionist performed a simulated examination on an Alderson phantom loaded with thermoluminescence dosemeters. The simulated CA examination yielded a dose-area product of 17 Gy cm(2) and an effective dose of 3.4 mSv: the conversion factor between dose-area product and effective dose was 0.20 mSv Gy cm(-2). Dose-area product values from 200 heart-transplanted patients that had undergone 906 CA examinations between 2001 and 2008 were retrieved from the institutional database. Mean dose-area product from annual CA was 25 Gy cm(2), ranging from 2 to 140 Gy cm(2). Mean number of CA procedure was 8 (range, 1-23). Mean accumulated effective dose for Norwegian heart-transplanted patients between 2001 and 2008 was 34 mSv (range, 5-113 mSv). Doses and radiation risks for heart-transplanted patients are generally low, because most heart transplantations are performed on middle-aged patients with limited life expectancy. Special concern should however be taken to reduce doses for young heart-transplanted patients who are committed to lifelong follow-up of their transplanted heart.

DNA double-strand breaks as potential indicators for the biological effects of ionising radiation exposure from cardiac CT and conventional coronary angiography: a randomised, controlled study

OBJECTIVES

To prospectively compare induced DNA double-strand breaks by cardiac computed tomography (CT) and conventional coronary angiography (CCA).

METHODS

56 patients with suspected coronary artery disease were randomised to undergo either CCA or cardiac CT. DNA double-strand breaks were assessed in fluorescence microscopy of blood lymphocytes as indicators of the biological effects of radiation exposure. Radiation doses were estimated using dose-length product (DLP) and dose-area product (DAP) with conversion factors for CT and CCA, respectively.

RESULTS

On average there were 0.12 ± 0.06 induced double-strand breaks per lymphocyte for CT and 0.29 ± 0.18 for diagnostic CCA (P < 0.001). This relative biological effect of ionising radiation from CCA was 1.9 times higher (P < 0.001) than the effective dose estimated by conversion factors would have suggested. The correlation between the biological effects and the estimated radiation doses was excellent for CT (r = 0.951, P < 0.001) and moderate to good for CCA (r = 0.862, P < 0.001). One day after radiation, a complete repair of double-strand breaks to background levels was found in both groups.

CONCLUSIONS

Conversion factors may underestimate the relative biological effects of ionising radiation from CCA. DNA double-strand break assessment may provide a strategy for individualised assessments of radiation.

KEY POINTS

• Radiation dose causes concern for both conventional coronary angiography and cardiac CT. • Estimations of the biological effects of ionising radiation may become feasible. • Fewer DNA double-strand breaks are induced by cardiac CT than CCA. • Conversion factors may underestimate the relative effects of ionising radiation from CCA.

Personal dosimetry for interventional operators: when and how should monitoring be done?

OBJECTIVE

Assessment of the potential doses to the hands and eyes for interventional radiologists and cardiologists can be difficult. A review of studies of doses to interventional operators reported in the literature has been undertaken.

METHODS

Distributions for staff dose to relevant parts of the body per unit dose-area product and for doses per procedure in cardiology have been analysed and mean, median and quartile values derived. The possibility of using these data to provide guidance for estimation of likely dose levels is considered.

RESULTS

Dose indicator values that could be used to predict orders of magnitude of doses to the eye, thyroid and hands from interventional operator workloads have been derived, based on the third quartile values, from the distributions of dose results analysed.

CONCLUSION

Dose estimates made in this way could be employed in risk assessments when reviewing protection and monitoring requirements. Data on the protection provided by different shielding and technique factors have also been reviewed to provide information for risk assessments. Recommendations on the positions in which dosemeters are worn should also be included in risk assessments, as dose measurements from suboptimal dosemeter use can be misleading.

Risk for radiation-induced cataract for staff in interventional cardiology: is there reason for concern?

OBJECTIVES

To examine the prevalence of radiation-associated lens opacities among interventional cardiologists and nurses and correlate with occupational radiation exposure.

BACKGROUND

Interventional cardiology personnel are exposed to relatively high levels of X-rays and based on recent findings of radiation-associated lens opacities in other cohorts, they may be at risk for cataract without use of ocular radiation protection.

METHODS

Eyes of interventional cardiologists, nurses, and age- and sex-matched unexposed controls were screened by dilated slit lamp examination and posterior lens changes graded using a modified Merriam-Focht technique. Individual cumulative lens X-ray exposure was calculated from responses to a questionnaire and personal interview.

RESULTS

The prevalence of radiation-associated posterior lens opacities was 52% (29/56, 95% CI: 35-73) for interventional cardiologists, 45% (5/11, 95% CI: 15-100) for nurses, and 9% (2/22, 95% CI: 1-33) for controls. Relative risks of lens opacity was 5.7 (95% CI: 1.5-22) for interventional cardiologists and 5.0 (95% CI: 1.2-21) for nurses. Estimated cumulative ocular doses ranged from 0.01 to 43 Gy with mean and median values of 3.4 and 1.0 Gy, respectively. A strong dose-response relationship was found between occupational exposure and the prevalence of radiation-associated posterior lens changes.

CONCLUSIONS

These findings demonstrate a dose dependent increased risk of posterior lens opacities for interventional cardiologists and nurses when radiation protection tools are not used. While study of a larger cohort is needed to confirm these findings, the results suggest ocular radio-protection should be utilized.

Patient skin dose measurements during coronary interventional procedures using Gafchromic film

Interventional cardiology (IC) procedures are known to give high radiation doses to patients and cardiologists as they involve long fluoroscopy times and several cine runs. Patients' dose measurements were carried out at the cardiology department in a local hospital in Penang, Malaysia, using Gafchromic XR-RV2 films. The dosimetric properties of the Gafchromic film were first characterised. The film was energy and dose rate independent but dose dependent for the clinically used values. The film had reproducibility within ± 3% when irradiated on three different days and hence the same XR-RV2 dose-response calibration curve can be used to obtain patient entrance skin dose on different days. The increase in the response of the film post-irradiation was less than 4% over a period of 35 days. For patient dose measurements, the films were placed on the table underneath the patient for an under-couch tube position. This study included a total of 44 patients. Values of 35-2442 mGy for peak skin dose (PSD) and 10.9-344.4 Gy cm(2) for dose-area product (DAP) were obtained. DAP was found to be a poor indicator of PSD for PTCA procedures but there was a better correlation (R(2) = 0.7344) for CA + PTCA procedures. The highest PSD value in this study exceeded the threshold dose value of 2 Gy for early transient skin injury recommended by the Food and Drug Administration.

Evaluation of the dose to the patient and medical staff in interventional cardiology employing computational models

Interventional radiology, among guided X-rays procedures, is a methodology characterised by high level of doses, both for the patient and for the medical staff. The aim of the present study is to estimate the dose associated with coronary angiography procedures by means of numerical models (simplified and anthropomorphic) and MCNPX Monte Carlo code. Numerical estimates were supported by measurement performed with a dose area product meter that is commonly employed in such kind of studies. In the present work the main considerations and the preliminary results are presented.

Impact of biplane versus single-plane imaging on radiation dose, contrast load and procedural time in coronary angioplasty

Coronary angioplasties can be performed with either single-plane or biplane imaging techniques. The aim of this study was to determine whether biplane imaging, in comparison to single-plane imaging, reduces radiation dose and contrast load and shortens procedural time during (i) primary and elective coronary angioplasty procedures, (ii) angioplasty to the main vascular territories and (iii) procedures performed by operators with various levels of experience. This prospective observational study included a total of 504 primary and elective single-vessel coronary angioplasty procedures utilising either biplane or single-plane imaging. Radiographic and clinical parameters were collected from clinical reports and examination protocols. Radiation dose was measured by a dose-area-product (DAP) meter intrinsic to the angiography system. Our results showed that biplane imaging delivered a significantly greater radiation dose (181.4+/-121.0 Gycm(2)) than single-plane imaging (133.6+/-92.8 Gycm(2), p<0.0001). The difference was independent of case type (primary or elective) (p = 0.862), vascular territory (p = 0.519) and operator experience (p = 0.903). No significant difference was found in contrast load between biplane (166.8+/-62.9 ml) and single-plane imaging (176.8+/-66.0 ml) (p = 0.302). This non-significant difference was independent of case type (p = 0.551), vascular territory (p = 0.308) and operator experience (p = 0.304). Procedures performed with biplane imaging were significantly longer (55.3+/-27.8 min) than those with single-plane (48.9+/-24.2 min, p = 0.010) and, similarly, were not dependent on case type (p = 0.226), vascular territory (p = 0.642) or operator experience (p = 0.094). Biplane imaging resulted in a greater radiation dose and a longer procedural time and delivered a non-significant reduction in contrast load than single-plane imaging. These findings did not support the commonly perceived advantages of using biplane imaging in single-vessel coronary interventional procedures.

A review of radiology staff doses and dose monitoring requirements

Studies of radiation doses received during X-ray procedures by radiology, cardiology and other clinical staff have been reviewed. Data for effective dose (E), and doses to the eyes, thyroid, hands and legs have been analysed. These data have been supplemented with local measurements to determine the most exposed part of the hand for monitoring purposes. There are ranges of 60-100 in doses to individual tissues reported in the literature for similar procedures at different centres. While ranges in the doses per unit dose-area product (DAP) are between 10 and 25, large variations in dose result from differences in the sensitivity of the X-ray equipment, the type of procedure and the operator technique, but protection factors are important in maintaining dose levels as low as possible. The influence of shielding devices is significant for determining the dose to the eyes and thyroid, and the position of the operator, which depends on the procedure, is the most significant factor determining doses to the hands. A second body dosemeter worn at the level of the collar is recommended for operators with high workloads for use in assessment of effective dose and the dose to the eye. It is proposed that the third quartile values from the distributions of dose per unit DAP identified in the review might be employed in predicting the orders of magnitude of doses to the eye, thyroid and hands, based on interventional operator workloads. Such dose estimates could be employed in risk assessments when reviewing protection and monitoring requirements. A dosemeter worn on the little finger of the hand nearest to the X-ray tube is recommended for monitoring the hand.

A study on patients' radiation doses from interventional cardiac procedures in Tabriz, Iran

Interventional cardiac procedures produce a large amount of X-ray exposures to the patients in comparison with other conventional X-ray imaging procedures. In the current study, the exposure parameters of 580 patients referred to a cardiac angiography department were recorded. The mean values of total kerma-area product (KAP) were 18.6 Gy cm2 for coronary angiography (CA) and 55 Gy cm2 for percutaneous transluminal coronary angioplasty (PTCA). The mean fluoroscopy time was 3.2 and 11.6 min, respectively, for CA and PTCA. The patients' exposure parameters during electrophysiological studies were 15.5 min for mean fluoroscopy time and 33.9 Gy cm2 for total KAP. For paediatrics, the mean fluoroscopy time of 5.4 min and total KAP of 2 Gy cm2 were recorded. Comparing the proposed reference values, the authors think that the exposure level of patients in their department is at an acceptable level.