Patient dose values in interventional radiology

What are useful methods to reduce occupational radiation exposure among radiological medical workers, especially for interventional radiology personnel?

Protection against occupational radiation exposure in clinical settings is important. This paper clarifies the present status of medical occupational exposure protection and possible additional safety measures. Radiation injuries, such as cataracts, have been reported in physicians and staff who perform interventional radiology (IVR), thus, it is important that they use shielding devices (e.g., lead glasses and ceiling-suspended shields). Currently, there is no single perfect radiation shield; combinations of radiation shields are required. Radiological medical workers must be appropriately educated in terms of reducing radiation exposure among both patients and staff. They also need to be aware of the various methods available for estimating/reducing patient dose and occupational exposure. When the optimizing the dose to the patient, such as eliminating a patient dose that is higher than necessary, is applied, exposure of radiological medical workers also decreases without any loss of diagnostic benefit. Thus, decreasing the patient dose also reduces occupational exposure. We propose a novel four-point policy for protecting medical staff from radiation: patient dose Optimization, Distance, Shielding, and Time (pdO-DST). Patient dose optimization means that the patient never receives a higher dose than is necessary, which also reduces the dose received by the staff. The patient dose must be optimized: shielding is critical, but it is only one component of protection from radiation used in medical procedures. Here, we review the radiation protection/reduction basics for radiological medical workers, especially for IVR staff.

Niveles de referencia de dosis para adultos en procedimientos de cardiología intervencionista en Ecuador

Antecedents and objective

The knowledge of the reference levels for diagnoses and therapeutic studies is important, because it contributes to the optimization of the radiological protection of the patients, avoiding them to be exposed to unnecessarily high doses. However, there was no evidence of these levels in interventionist cardiology procedures in Ecuador, so the objective of this study was to estimate the diagnostic reference levels of dose at the entrance surface in adult patients undergoing interventional cardiology procedures (cinecoronariography, catheterization and coronary percutaneous interventionism) in the Unit of Hemodynamic of the Hospital of Specialties Carlos Andrade Marín in Ecuador.

Materials and methods

The measurements of product dose-area, dose in input surface, number of images and the time of fluoroscopy performed using the Axiom Artis angiographer, and the obtained data was tabulated and processed with the Excel computer program. For this study, 145 patients older than 18 years were selected, and the values obtained from diagnostic reference dose levels were compared with others reported in previous investigations and with the permissible limits for the appearance of deterministic effects on the skin.

Results

This study made it possible to establish reference levels for diagnosis in interventional cardiology procedures (coronary angiography, catheterization and percutaneous coronary intervention) in the Hemodynamics Unit of the Carlos Andrade Marín Specialty Hospital in Ecuador.

Conclusions

The results showed that the intake surface doses obtained were lower than the maximum levels recommended by the International Atomic Energy Agency.

An initial investigation of a wireless patient radiation dosimeter for use in interventional radiology

Radiation exposure during interventional radiology (IR) procedures is a critical issue. We have developed a wireless real-time dosimeter for IR patients that use nontoxic phosphor (four sensors). We evaluated the basic performance parameters (such as dose linearity, batch uniformity, reproducibility, and wireless-communication conditions) of the developed system using an IR X-ray system. Further, we investigated the influence of noise from other medical equipment on our wireless real-time dosimeter in the IR X-ray room. Overall, our wireless system exhibited excellent performance in terms of uniformity, reproducibility, and linearity; moreover, the wireless communication performance was better. The developed system enabled real-time visualization of patient radiation dose, without noise contamination from other medical equipment. In addition, the wireless system can be easily installed in a location where the PC screen (display) can be readily viewed by the IR physician. Hence, we developed a wireless system that can display the patient radiation dose data in real time; the system performed satisfactorily upon application in radiation dosimetry. Therefore, our wireless system will facilitate the real-time monitoring/management of patient radiation dose during IR.

ESTIMATION OF RADIATION EXPOSURE TO THE PATIENTS IN DIAGNOSTIC AND THERAPEUTIC INTERVENTIONAL PROCEDURES

The present work reports data of the radiation exposure to the patient in various diagnostic and therapeutic interventional radiological (IR) procedures. The study includes 260 diagnostic and 195 therapeutic exposure data in 455 IR procedures. All the IR procedures were performed on a biplane angiographic machine in a tertiary care hospital. The radiation exposure was estimated from dose-area product (DAP), fluoroscopy time (FT), number of fluoroscopic runs, number of images and cumulative dose (CD) value recorded during the procedure. The data reported in the present study show significant variability in DAP values in diagnostic and therapeutic IR procedures. In diagnostic procedures, the minimum median DAP value is 8.93 Gy cm2 for upper limb angiography with mean FT of 2.7 min and maximum DAP value is 108.8 Gy cm2 for inferior vena cava angiography with mean FT of 12.55 min. For therapeutic procedures, the median value of DAP ranges from 2.43 Gy cm2 for sclerotherapy with mean FT 0.65 min to 267.23 Gy cm2 for coiling of cerebral aneurysm with mean FT of 60.52 min. The DAP value for each procedure was also correlated with FT, number of fluoroscopic runs, number of images and CD. The reported DAP values in this study are within the range of earlier published results which suggest that our finding provides at least approximate applicability to other hospitals. The third quartile DAP values of the procedures having significant number of patient data (n ≥ 10) serves as provisional reference values for the optimization of procedure protocols.

Patient doses in endovascular and hybrid revascularization of the lower extremities

OBJECTIVE:

Hybrid surgical methods such as remote endarterectomy and endovascular revascularization are fluoroscopy-guided procedures successfully replacing conventional open surgery for treatment of peripheral artery disease (PAD). The aim of this study was to: (1) evaluate the dose parameters describing exposure of patients undergoing endovascular or hybrid revascularization of the lower limb (below the inguinal ligament); (2) compare the data available in the literature with the evaluations of patients' dose values and related factors for patients undergoing such procedures; (3) examine the correlation of doses with certain parameters; (4) estimate the peak skin dose and assess the potential for radiation-induced skin injuries during the procedures.

METHODS:

Data for 259 patients were extracted retrospectively and analyzed. The procedures were grouped by type of intervention, vascular approach, and level of complexity. The analyses included the correlation of dose values with the operating team.

RESULTS:

The air kerma-area product (KAP) and fluoroscopy time (FT) values greatly varied depending on the procedure type but also among patients undergoing the same procedure. The type of vascular access has the largest impact on patients' doses. The KAP and FT values for brachial artery were: 347 Gy.cm² and FT: NA; for contralateral common femoral artery (CFA) approach: 207 Gy.cm² and 153 s; e.g. significantly higher than for ipsilateral CFA: 96 Gy.cm² and 78 s; for hybrid surgery: 77 Gy.cm² and 41 s; and for ipsilateral retrograde popliteal approach: 61 Gy.cm² and 53 s. The same tendency is observed for the peak skin dose (PSD) values: the highest are for brachial artery (2053 mGy) and contralateral CFA (1325 mGy) approach, followed by the ipsilateral CFA (748 mGy), hybrid surgery (649 mGy), and ipsilateral retrograde popliteal approach (566 mGy).

CONCLUSION:

Registered dose values and FT for the different procedures do not exceed the International Atomic Energy Agency (IAEA) proposed trigger values for patients' follow-up for radiation-induced skin injuries. The type of vascular access has the highest negative impact on radiation dose levels and resultant KAP, PSD, and FT values. There is a significant increase of the dose values with increase of the number of inserted stents and the level of complexity. This should be considered in planning, especially for patients who undergo multiple diagnostic and therapeutic procedures.

ADVANCES IN KNOWLEDGE:

This study gives a systematic understanding for patient radiation exposure in endovascular and hybrid revascularization of the lower extremities, thus far absent in the literature.

DOSE MEASUREMENT USING GAFCHROMIC FILM FOR PATIENTS UNDERGOING INTERVENTIONAL CARDIOLOGY PROCEDURES

The aim of this study was to evaluate dose area product (DAP) and skin dose to patients undergoing coronary angiography (CA) and percutaneous transluminal coronary angioplasty (PTCA) using GafChromic XR film at King Khalid Hospital, Najran, Saudi Arabia. The entrance skin doses (ESDs) were calculated from DAP using GafChromic XR film placed on the patients back. The mean DAP obtained for patients undergoing CA and PTCA examinations were found to be 31.4 and 74.2 Gy cm2, respectively. The mean ESD using GafChromic XR film was found to be 0.264 and 0.596 Gy for CA and PTCA examinations, respectively.

Radiation Dose and Image Quality in Neuroangiography: Effects of Increased Tube Voltage, Added X-Ray Filtration and Antiscatter Grid Removal

During endovascular treatment the patient may be subject to fluoroscopy for long periods as well as multiple x-ray exposures. The radiation dose to the patient can be considerable, and cause local deterministic effects such as alopecia or even skin burn. The potential carcinogenic effects should also be noted, being especially important in the paediatric population.

We measured radiation doses to patients and personnel during neuroendovascular procedures and diagnostic neuroangiography. We also tried to reduce the radiation dose to the patient utilising increased tube voltage, additional primary X-ray filtration and by removing the antiscatter grid in front of the image intensifier, employing air gap technique.

We investigated radiation doses to patient and personnel during neuroangiographic procedures and optimized the examination technique with regard to radiation dose with maintained image quality.

Radiation exposure to patients and personnel was measured with thermoluminescent dosimeters and permanently mounted KermaDose-Area-Product meters in front of the X-ray tubes during 13 cerebral angiographies and six neuroendovascular procedures. We performed experiments with radiation dose measurements and evaluation of image quality with 80 and 90 kV tube voltage during image acquisition and 75 and 85 kV during fluoroscopy, as well as with different primary X-ray filtration.

Images from patient studies acquired with the original grid in front of the image intensifier were compared with images from patient studies acquired with the grid removed and air gap technique (30 cm).

Images from patient studies acquired with the original examination technique were compared to images from patient studies acquired with increased x-ray tube voltage, increased x-ray filtering and with the antiscatter grid removed using an airgap as scatter reduction method.

Radiation exposure to personnel was very low using standard protective devices. Measurable doses were recorded only on the hands and forehead of the neuroradiologist.

Maximum entrance skin dose was about 1 Gy on the side of the patientspatient's forehead during an endovascular procedure.

Increasing the tube voltage from 75 to 85 – 85 and 90 kV, exchanging the original 0.5 mm aluminium primary filtration for 0.2 mm copper and removing the antiscatter grid allowed us to reduce entrance skin dose to the patient by 70% with unchanged or slightly improved image quality.

An Evaluation of the Organ Dose Received by Cardiologists Arising From Angiography Examinations in Educational Hospital in Rasht

Interventional procedures, cine acquisitions and operation of fluoroscopic equipment in high-dose fluoroscopic modes, involve long fluoroscopic times which can lead to high staff doses. Also, Coronary angiography (CA) procedures require the cardiologist and assisting personnel to remain close to the patient, which is the main source of scattered radiation. Thus, radiation exposure is a significant concern for radiation workers and it is important to measure the radiation doses received by personnel and evaluate the parameters concerning total radiation burden. In this research, we investigated radiation doses to 10 cardiologists performing 120 CA procedures. Using thermo luminescent dosimeters doses to the wrists, thyroid and eyes per procedure were measured. Based on the measured dose values, maximum doses to the Left wrist, Right wrist, thyroid and eyes of cardiologist were measured 241.45 µSv, 203.17 µSv, 78.21 µSv and 44.58 µSv, respectively. The results of this study indicate that distance from the source, use of protective equipment's, procedure complexity, equipment performance, and cardiologist experience are the principal exposure-determining variables. It can be conclude that if adequate radiation protection approaches have been implemented, occupational dose levels to cardiologists would be within the regulated acceptable dose limits.

Patient doses in interventional cardiology procedures in Sudan

Radiation doses delivered to 461 patients were measured during the period of 12 months in a hospital in Khartoum, Sudan. Kerma Area Product, Cumulative Kerma and fluoroscopy time were registered during four selected procedures, namely coronary angiography (CA), percutaneous transluminal coronary angioplasty (PTCA), percutaneous transvenous mitral commissurotomy (PTMC) and pacemaker. For CA, PTCA, PTMC and pacemaker the mean and median kerma area product values in gray centimeter square were found to be (20, 17.9), (56.5, 50.3), (21.6, 19.6) and (15.3, 9.6), respectively. The obtained results for mean and median cumulative kerma in milli gray were (143.7, 120.5), (418.4, 371.4), (119.8, 102) and (88.7, 59.8) as measured for CA, PTCA, PTMC and pacemaker, respectively. The mean and median total fluoroscopy time in minutes were (5.2, 3.39), (17.6, 14.8), (18, 15) and (10.2, 7.16) as registered for CA, PTCA, PTMA and pacemaker, respectively. Maximum skin dose was estimated for 13 patients during PTCA and CA procedures. Dose exceeded 2 Gy in PTCA for one patient. In comparison with the guidelines for coronary examinations suggested by SENTINEL Consortium, a higher fluoroscopy time for PTCA procedure is reported in this study. It is realised that proper selection of irradiation area, technique modes, fluoroscopy time and conducting special training on radiation protection to the operators are the main factors for potential optimisation.

Evaluation of radiation dose to patients undergoing interventional radiology procedures at Ramathibodi Hospital, Thailand

PURPOSE

This study was carried out to assess the radiation dose to patients undergoing interventional radiology procedures at Ramathibodi Hospital, Bangkok, Thailand.

METHODS

Data were collected from 60 patients under transarterial oily-chemoembolisation (TOCE) and femoral angiography performed with the Toshiba Infinix model VC-i FPD single plane system. Data were also collected from 60 patients who underwent brain arteriovenous malformations (AVM) and dural-arteriovenous fistula (DAVF) embolisation, performed with the Toshiba Infinix model VF-i bi-plane systems. A built-in air kerma area product (KAP) meter calibrated in situ was used for the skin dose calculation.

RESULTS

The calibration coefficient of air kerma area product meter at tube voltage between 50 kV and 100 kV was found to vary within ± 5.07%, ± 7.2%, ± 4.86 % from calibration coefficient of 80 kV for a single-plane, tube 1 and tube 2 of bi-plane x-ray system, respectively. Mean air kerma area product values were 90.99 ± 52.89, 31.02 ± 17.92, 33.11 ± 23.99 (Frontal), 35.01 ± 19.10 (Lateral), 50.15 ± 44.76 (Frontal), 97.31 ± 44.12 (Lateral) Gy-cm(2) for transarterial oily-chemoembolisation, femoral angiography, diagnostic cerebral angiography, therapeutic cerebral angiography, respectively. The therapeutic cerebral angiography procedure was found to give the highest entrance dose, number of images and fluoroscopy time: 362.63 cGy (Lateral), 1015 images (Lateral) and 126 minutes, respectively. However, the highest air kerma area product value was from transarterial oily-chemoembolisation with 264.37 Gy-cm(2). There were 2 cases of therapeutic cerebral angiography, where the patient entrance dose was higher than 3 Gy in the frontal view, which reached the deterministic threshold for temporary epilation.

CONCLUSION

Very wide variationswere found in patient dose from different interventional procedures. There is a need for a dose record system to provide feedback to radiologists who perform the procedures; especially in cases where the dose exceeds the deterministic threshold.

Optimization and audit of radiation dose during percutaneous transluminal coronary angioplasty

The percutaneous transluminal coronary angioplasty (PTCA) is one of the interventional procedures which impart high radiation doses to patients compared to the other cardiologic procedures. This study intends to audit and optimize radiation dose imparted to patients undergoing PTCA. Forty-four patients who underwent PTCA involving single or multiple stent placement guided under cardiovascular X-ray machine were included in the study. Radiation doses were measured using dose area product (DAP) meter for patients undergoing single and multiple stent placements during PTCA. A dose reduction of 27-47% was achieved using copper filters and optimal exposure parameters. The mean DAP values before optimization were 66.16 and 122.68 Gy cm² for single and multiple stent placement respectively. These values were 48.67 and 65.44 Gy cm² respectively after optimization. In the present scenario, due to the increase in the number of PTCAs performed and the associated risk from radiation, periodical audit of radiation doses for interventional procedures are recommended.

Reduction of radiation doses to patients and staff during endoscopic retrograde cholangiopancreatography

BACKGROUND/AIM

Endoscopic retrograde cholangiopancreatography (ERCP) is associated with a considerable radiation exposure for patients and staff. While optimization of the radiation dose is recommended, few studies have been published. The purpose of this study has been to measure patient and staff radiation dose, to estimate the effective dose and radiation risk using digital fluoroscopic images. Entrance skin dose (ESD), organ and effective doses were estimated for patients and staff.

MATERIALS AND METHODS

Fifty-seven patients were studied using digital X-ray machine and thermoluminescent dosimeters (TLD) to measure ESD at different body sites. Organ and surface dose to specific radiosensitive organs was carried out. The mean, median, minimum, third quartile and the maximum values are presented due to the asymmetry in data distribution.

RESULTS

The mean ESD, exit and thyroid surface dose were estimated to be 75.6 mGy, 3.22 mGy and 0.80 mGy, respectively. The mean effective dose for both gastroenterologist and assistant is 0.01 mSv. The mean patient effective dose was 4.16 mSv, and the cancer risk per procedure was estimated to be 2 × 10(-5).

CONCLUSION

ERCP with fluoroscopic technique demonstrate improved dose reduction, compared to the conventional radiographic based technique, reducing the surface dose by a factor of 2, without compromising the diagnostic findings. The radiation absorbed doses to the different organs and effective doses are relatively low.

Proposed local diagnostic reference levels in angiography and interventional neuroradiology and a preliminary analysis according to the complexity of the procedures

The aim of this study was to propose local diagnostic reference levels (DRL) for exposure to radiation during diagnostic procedures and neuroradiological interventions such as cerebral angiography and embolisation of cerebral aneurysms (intra-cranial aneurysms and arteriovenous malformations). Hospitals should adopt the national DRLs for use locally or establish their own DRLs based on local practice, if sufficient local data are available. For this purpose we studied a sample of 113 cerebral angiography procedures and 82 embolisations of cerebral aneurysms. The data recorded included the kerma-area product (KAP), the fluoroscopy time and the number of frames for each procedure: third quartiles from the total dosimetric databank were calculated and proposed as provisional local DRL. Since the complexity of a procedure must be taken into account when evaluating the radiation dose, in the case of embolisation of aneurysms (intra-cranial), in this initial phase we assessed whether the complexity of the embolisation procedure is related to the size of the aneurysm and/or its site. We, therefore, re-calculated the DRL for only intra-cranial aneurysms, leaving aside the arteriovenous malformations. Considering that the DRL calculated for all the therapeutic procedures are similar to those calculated considering only intra-cranial aneurysms, at the moment we propose, besides the DRL for cerebral angiography, a single DRL for all interventional procedures, even when the clinical pictures are very different. Local preliminary DRLs were proposed as follows: 180 Gy cm(2), 12 min and 317 frames for cerebral angiography and 487 Gy cm(2), 46 min and 717 frames for interventional procedures (intra-cranial aneurysms and arteriovenous malformations).

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.

Patient radiation doses in the most common interventional cardiology procedures in Croatia: first results

Apart from its benefits, the interventional cardiology (IC) is known to generate high radiation doses to patients and medical staff involved. The European Union Medical Exposures Directive 97/43/Euroatom strongly recommend patient dosimetry in interventional radiology, including IC. IC patient radiation doses in four representative IC rooms in Croatia were investigated. Setting reference levels for these procedures have difficulties due to the large difference in procedure complexity. Nevertheless, it is important that some guideline values are available as a benchmark to guide the operators during these potentially high-dose procedures. Local and national diagnostic reference levels (DRLs) were proposed as a guidance. A total of 138 diagnostic (coronary angiography, CA) and 151 therapeutic (PTCA, stenting) procedures were included. Patient irradiation was measured in terms of kerma-area product (KAP), fluoroscopy time (FT) and number of cine-frames (F). KAP was recorded using calibrated KAP-meters. DRLs of KAP, FT and F were calculated as third quartile values rounded up to the integer. Skin doses were assessed on a selected sample of high skin dose procedures, using radiochromic films, and peak skin doses (PSD) were presented. A relative large range of doses in IC was detected. National DRLs were proposed as follows: 32 Gy cm(2), 6.6 min and 610 frames for CA and 72 Gy cm(2), 19 min and 1270 frames for PTCA. PSD <1 Gy were measured in 72 % and PSD >2 Gy in 8 % of selected patients. Measuring the patient doses in radiological procedures is required by law, but rarely implemented in Croatia. The doses recorded in the study are acceptable when compared with the literature, but optimisation is possible. The preliminary DRL values proposed may be used as a guideline for local departments, and should be a basis for radiation reduction measures and quality assurance programmes in IC in Croatia.

Radiation dose and radiation protection for patients and physicians during interventional procedure

Although the wide acceptance of interventional radiology (IVR) procedures has led to increasing numbers of interventions being performed, the radiation doses from IVR are higher. Increasing numbers of case reports of patient radiation injury resulting from IVR are being published. Therefore, radiation protection during IVR poses a very important problem. To protect against radiation injury, the evaluation of radiation dose is essential. The radiation dose must be evaluated for each IVR x-ray machine and each laboratory, because it varies greatly. To obtain this information easily, and to ensure practical use of the radiation information, good relationships between interventionists and medical physicists are essential.

Estimation of children's radiation dose from cardiac catheterisations, performed for the diagnosis or the treatment of a congenital heart disease using TLD dosimetry and Monte Carlo simulation

Entrance surface radiation doses were measured with thermoluminescent dosimeters for 98 children who were referred to a cardiology department for the diagnosis or the treatment of a congenital heart disease. Additionally, all the radiographic parameters were recorded and Monte Carlo simulations were performed for the estimation of entrance surface dose to effective dose conversion factors, in order to further calculate the effective dose for each child. For diagnostic catheterisations the values ranged from 0.16 to 14.44 mSv, with average 3.71 mSv, and for therapeutic catheterisations the values ranged from 0.38 to 25.01 mSv, with average value 5 mSv. Effective doses were estimated for diagnostic procedures and interventional procedures performed for the treatment of five different heart diseases: (a) atrial septal defect (ASD), (b) ventricular septal defect (VSD), (c) patent ductus arteriosus (PDA), (d) aorta coarctation and (e) pulmonary stenosis. The high levels of radiation exposure are, however, balanced with the advantages of cardiac catheterisations such as the avoidance of surgical closure and the necessity of shorter or even no hospitalisation.

A large-scale multicentre study of patient skin doses in interventional cardiology: dose-area product action levels and dose reference levels

For 318 patients in 8 different Belgian hospitals, the entire skin-dose distribution was mapped using a grid of 70 thermoluminescence dosimeters per patient, allowing an accurate determination of the maximum skin dose (MSD). Dose-area product (DAP) values, exposure parameters and geometry, together with procedure, patient and cardiologist characteristics, were also registered. Procedures were divided into two groups: diagnostic procedures (coronary angiography) and therapeutic procedures (dilatation, stent, combined procedures (e.g. coronary angiography + dilatation + stent)). The mean value of the MSD was 0.310 Gy for diagnostic and 0.699 Gy for therapeutic procedures. The most critical projection for receiving the MSD is the LAO90 (left anterior oblique) geometry. In 3% of cases, the MSD exceeded the 2 Gy dose threshold for deterministic effects. Action levels in terms of DAP values as the basis for a strategy for follow-up of patients for deterministic radiation skin effects were derived from measured MSD and cumulative DAP values. Two DAP action levels are proposed. A first DAP action level of 125 Gy cm(2) corresponding to the dose threshold of 2 Gy would imply an optional radiopathological follow-up depending on the cardiologist's decision. A second DAP action level of 250 Gy cm(2) corresponding to the 3 Gy skin dose would imply a systematic follow-up. Dose reference levels - 71.3 Gy cm(2) for diagnostic and 106.0 Gy cm(2) for therapeutic procedures - were derived from the 75 percentile of the DAP distributions. As a conclusion, we propose that total DAP is registered in patient's record file, as it can serve to improve the follow-up of patients for radiation-induced skin injuries.

Patient radiation doses in interventional cardiology procedures

Interventional cardiology procedures result in substantial patient radiation doses due to prolonged fluoroscopy time and radiographic exposure. The procedures that are most frequently performed are coronary angiography, percutaneous coronary interventions, diagnostic electrophysiology studies and radiofrequency catheter ablation. Patient radiation dose in these procedures can be assessed either by measurements on a series of patients in real clinical practice or measurements using patient-equivalent phantoms. In this article we review the derived doses at non-pediatric patients from 72 relevant studies published during the last 22 years in international scientific literature. Published results indicate that patient radiation doses vary widely among the different interventional cardiology procedures but also among equivalent studies. Discrepancies of the derived results are patient-, procedure-, physician-, and fluoroscopic equipmentrelated. Nevertheless, interventional cardiology procedures can subject patients to considerable radiation doses. Efforts to minimize patient exposure should always be undertaken.

Dose measurement on both patients and operators during neurointerventional procedures using photoluminescence glass dosimeters

BACKGROUND AND PURPOSE

Although radiation skin injuries associated with interventional radiology have been known as a critical issue, there are few reports mentioning direct measurement of the entrance skin dose (ESD). Thus, the purpose of this study was to clarify the regional distributions of ESDs in neurointervention.

MATERIALS AND METHODS

Using photoluminescence glass dosimeters (PLDs), we measured the ESDs in 32 patients with a median age of 61.5 years. Angiographic parameters, including exposure time, dose-area product (DAP), and the number of digital subtraction angiography (DSA) studies and frames, were recorded. The ESDs of operators were analyzed by the same method.

RESULTS

The maximum ESD of 28 therapeutic procedures was 1.8 +/- 1.3 Gy. Although the averaged ESD on the right temporo-occipital region was higher than that in other regions, disease-specific patterns were not observed. Statistically positive correlations were found between the maximum ESD and exposure time (r = 0.5283, P = .005), DAP (r = 0.7917, P < .001), the number of DSA studies (r = 0.5636, P = .002), and the number of DSA frames (r = 0.8583, P < .001). As for operators, ESDs to the left upper extremity were significantly higher than those to other regions. However, most of the ESDs were <0.2 mGy. Lead protective garments reduced the exposure doses to approximately one half to one tenth.

CONCLUSION

It was shown that the regional ESD could be measured by applying the PLD. This method should contribute to reducing the dose accumulation in patients as well as in operators.

Patient dose in neonatal units

Lung disease represents one of the most life-threatening conditions in prematurely born children. In the evaluation of the neonatal chest, the primary and most important diagnostic study is therefore the chest radiograph. Since prematurely born children are very sensitive to radiation, those radiographs may lead to a significant radiation detriment. Hence, knowledge of the patient dose is necessary to justify the exposures. A study to assess the patient doses was started at the neonatal intensive care unit (NICU) of the University Hospital in Leuven. Between September 2004 and September 2005, prematurely born babies underwent on average 10 X-ray examinations in the NICU. In this sample, the maximum was 78 X-ray examinations. For chest radiographs, the median entrance skin dose was 34 microGy and the median dose area product was 7.1 mGy.cm(2). By means of conversion coefficients, the measured values were converted to organ doses. Organ doses were calculated for three different weight classes: extremely low birth weight infants (<1000 g), low birth weight infants (1000-2500 g) and normal birth weight infants (>2500 g). The doses to the lungs for a single chest radiograph for infants with extremely low birth weights, low birth weights and normal birth weights were 24, 25 and 32 microGy, respectively.

Effective doses in radiology and diagnostic nuclear medicine: a catalog

Medical uses of radiation have grown very rapidly over the past decade, and, as of 2007, medical uses represent the largest source of exposure to the U.S. population. Most physicians have difficulty assessing the magnitude of exposure or potential risk. Effective dose provides an approximate indicator of potential detriment from ionizing radiation and should be used as one parameter in evaluating the appropriateness of examinations involving ionizing radiation. The purpose of this review is to provide a compilation of effective doses for radiologic and nuclear medicine procedures. Standard radiographic examinations have average effective doses that vary by over a factor of 1000 (0.01-10 mSv). Computed tomographic examinations tend to be in a more narrow range but have relatively high average effective doses (approximately 2-20 mSv), and average effective doses for interventional procedures usually range from 5-70 mSv. Average effective dose for most nuclear medicine procedures varies between 0.3 and 20 mSv. These doses can be compared with the average annual effective dose from background radiation of about 3 mSv.

Proposed preliminary diagnostic reference levels for three common interventional cardiology procedures in Ireland

This study has gathered data across Ireland to determine the range of radiation doses received during interventional cardiology (IC) investigations. Radiation doses for three common types of IC examinations where investigated: coronary angiography (CA), percutaneous coronary intervention (PCI) and pacemaker insertions (PPI). A total of 22 cardiac imaging suites participated in the study. Radiation dose was monitored for 1804 adult patients using dose area product (DAP) meters. Individual patient DAP values ranged from 136-23,101 cGy cm2, 475-41,038 cGy cm2 and 45-17,192 cGy cm2 for CA, PCI and PPI respectively, with third quartile values of 4654 cGy cm2, 10,650 cGy cm2 and 1686 cGy cm2. The importance of optimising radiation dose, while not compromising diagnostic efficacy is clear. Although setting reference levels for these complex procedures has some difficulties, it is important that some guideline values are available as a benchmark to guide the operators during these potentially high dose procedures. The third quartile values as described by this paper may offer such guidance.

Analysis of the frequency of interventional cardiology in various European countries

The contribution of interventional cardiology procedures to the population dose in Europe is poorly known. The estimation of the population dose from these procedures requires knowledge of both the typical dose received by patients and an estimate of the number of procedures undertaken annually. Data on the number of cardiology procedures in various European countries are available on the internet for a number of countries. However, this data set is incomplete or out of date. This paper describes the statistical analysis undertaken to estimate the number of interventional cardiology procedures in a number of European countries for 2007. Estimates of the number of procedures are given. On average, the number of cardiac catheterisations per million population is 5346, percutaneous transluminal coronary angioplasty is 1599 and 1214 stent procedures. In addition, there are an estimated 973 pacemaker insertions per million population.

Patient skin dose assessment during CT-guided interventional procedures

The purpose of this study was to investigate patient skin doses in the most frequent computed tomography-guided interventional radiology procedures. The study includes 14 abdominal biopsies and 15 radiofrequency (RF) ablations. Patient skin dose was assessed by slow verification films. The technical factors recorded were: tube kilovoltage (kVp), tube load (mAs), slice thickness and the total number of slices (S). The median value of maximum entrance skin dose (ESD(M)) in biopsy was 108 mGy (9.5-282 mGy). S had a range of 4-152 with a median of 44 slices. Significant correlation was found between S and dose (r = 0.80). Median ESD(M) in RF ablation was 238 mGy (104-500 mGy). S had a range of 108-175 with a median of 155 slices. No significant correlation was found between S and dose. The large range of results show that a more extensive investigation should be performed. In summary, diagnostic procedures such as biopsy present patient skin doses that are relatively low. On the other hand, patient skin dose in RF ablation can be high and can reach values higher than the value that a slow verification film is capable of measuring (1.2 Gy). For these procedures, an alternative method should be investigated.

A study of the correlation between dose area product and effective dose in vascular radiology

The purpose of the multi-centre study was to assess dose area product (DAP) and effective dose of patients undergoing angiography of the lower limbs in Belgium and to investigate the correlation between DAP and effective dose. DAP values were measured in 12 centres and compared with the national diagnostic reference levels (DRLs). The effective dose (E) was estimated by multiplying the DAP with case-specific conversion coefficients (CCs) that were calculated with Monte Carlo software MCNP5. As a model for the patient, a mathematical hermaphrodite phantom was used. Calculations showed that tube configurations and extra Cu filtration have a large influence on these CCs. Due to the use of Cu filtration, effective dose can be twice as high for comparable DAP values. Also the use of an over-couch tube configuration is a disadvantage when compared with the under-couch tube configuration. For centres working under-couch without the use of extra Cu-filtration, the DAP values correlate very well with effective dose (Spearman's rank correlation rho ; = 0.97). For these conditions, general CCs between DAP and E were calculated. They were 0.083 mSv Gy(-1) cm(-2) (ICRP 60) and 0.065 mSv Gy(-1) cm(-2) (ICRP 103).

Patient dose in interventional radiology: a European survey

Patient doses for a few common fluoroscopy-guided procedures in interventional radiology (IR) (excluding cardiology) were collected from a few radiological departments in 13 European countries. The major aim was to evaluate patient doses for the basis of the reference levels. In total, data for 20 procedures for about 1300 patients were collected. There were many-fold variations in the number of IR equipment and procedures per population, in the entrance dose rates, and in the patient dose data (total dose area product or DAP, fluoroscopy time and number of frames). There was no clear correlation between the total DAP and entrance dose rate, or between the total DAP and fluoroscopy time, indicating that a number of parameters affect the differences. Because of the limited number of patients, preliminary reference levels were proposed only for a few procedures. There is a need to improve the optimisation of IR procedures and their definitions and grouping, in order to account for their different complexities.

Diagnostic reference levels in angiography and interventional radiology: a Belgian multi-centre study

The purpose of this study was to determine diagnostic reference levels (DRLs) for common angiographic and interventional procedures in Belgium. Dose Area Product (DAP) measurements were performed on 21 systems, (13 angiography and 4 vascular surgery centres). Type of procedure, total DAP, patient weight and height were collected on a daily basis during 1 y. The 75th percentile of the distribution of DAP values was defined as DRL. Preliminary DRLs were calculated for the three most frequent procedures for the whole population, for a weight class of patients (65-80 kg) and normalised to the standard size patient. Among them, the DRL for angiography of the lower limbs (30% of the procedures) from the whole population was 74.6 and 63.2 Gycm2 for the size corrected. The mean DAP values of each room was then compared to these DRLs.

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

Radiation doses to patients from interventional coronary X-ray procedures are relatively high when compared with conventional radiographic procedures. These high patient doses can translate into high staff doses owing to scattered radiation. This study investigates patient doses by means of dose-area product (DAP) meters installed in six rooms in two hospitals. DAP measurements in each room ranged from 28.0-39.3 Gy cm2 for coronary angiography and from 61.3-92.8 Gy cm2 for percutaneous transluminal coronary angioplasty, with the mean effective doses calculated to range between 5.1-6.6 mSv and 11.2-17.0 mSv, respectively. These values are comparable with those found in recent literature. DAP measurements were found to correlate strongly (correlation coefficient of 79%) with patient weight. The non-uniform scatter radiation fields surrounding the irradiated area during coronary angiography were also investigated using a tissue equivalent phantom and an ionization chamber. Exposure rates of scattered radiation from digital acquisition were found to be around 16 times higher than those generated from fluoroscopy, and oblique-angled imaging led to greater amounts of scatter owing to the increase in related exposure factors. The distribution of scatter from oblique projections confirms that X-ray photons in the diagnostic energy range are preferentially scattered backwards, toward the X-ray tube. These concepts are a major consideration when training individuals working in the angiography suite in order to keep doses "as low as reasonably practicable".

Local organ dose conversion coefficients for angiographic examinations of coronary arteries

New organ dose conversion coefficients for coronary angiographic interventions are presented, as well as dose distributions and resulting maximal local dose conversion coefficients in the relevant organs. For the Monte Carlo based simulations, voxel models of the human anatomy were employed which represent the average Caucasian adult man and woman as defined by the International Commission on Radiological Protection. In the 21 investigated projections, the mean organ dose conversion coefficients vary from a few 0.01 to 2 mGy(Gy cm(2))(-1), depending on the projections. However, especially in portions of the lungs and the active bone marrow, the conversion coefficients can locally amount up to 10 mGy(Gy cm(2))(-1), which is half the average conversion coefficient of the skin at the field entrance. In addition to the dose conversion coefficients, the dependence of the patient dose on the projection has been estimated. It could be shown that the patient doses are highest for left anterior oblique views with strong caudal or cranial orientation. Nevertheless, for a large range of image-intensifier positions no significant dose differences could be found.

Radiation dose and risk from fluoroscopically guided percutaneous transluminal angioplasty and stenting in the abdominal region

The objective of this study was to estimate the radiation dose and associated risks resulting from fluoroscopically guided percutaneous transluminal angioplasty with or without stent placement in the abdominal region. Average examination parameters for renal and aortoiliac procedures were derived using data from 80 consecutive procedures performed in our institute. Organ and effective doses were estimated for endovascular procedures with the use of a Monte Carlo (MC) transport code and an adult mathematical phantom. Thermoluminescent dosimeters were used in an anthropomorphic phantom to verify MC calculations. Radiation-induced risks were estimated. Results are presented as doses normalized to dose area product, so that the patient dose from any technique and X-ray unit can be easily calculated for iliac and renal PTA/stenting sessions. The average effective dose varied from 75 to 371 microSv per Gycm(2) depending on the beam quality, procedure scheme and sex of the patient. Differences up to 17% were observed between MC-calculated data and data derived from thermoluminescent dosimetry. The radiation-induced cancer risk may be considerable for younger individuals undergoing transluminal angioplasty with stent placement.

Audit of radiation dose during balloon mitral valvuloplasty procedure

Radiation doses to patients during cardiological procedures are of concern in the present day scenario. This study was intended to audit the radiation dose imparted to patients during the balloon mitral valvuloplasty (BMV) procedure. Thirty seven patients who underwent the BMV procedure performed using two dedicated cardiovascular machines were included in the study. The radiation doses imparted to patients were measured using a dose area product (DAP) meter. The mean DAP value for patients who underwent the BMV procedure from one machine was 19.16 Gy cm(2) and from the other was 21.19 Gy cm(2). Optimisation of exposure parameters and radiation doses was possible for one machine with the use of appropriate copper filters and optimised exposure parameters, and the mean DAP value after optimisation was 9.36 Gy cm(2).

Variations of Patient Doses in Interventional Examinations at Different Angiographic Units

PURPOSE

We analyzed doses for various angiographic procedures using different X-ray systems in order to assess dose variations.

METHODS

Dose-area product (DAP), skin doses from thermoluminescent dosimeters and air kerma measurements of 308 patients (239 diagnostic and 69 interventional) were assessed for five different angiographic units. All fluoroscopic and radiographic exposure parameters were recorded online for single and multiprojection studies. Radiation outputs of each X-ray system were also measured for all the modes of exposure using standard protocols for such measurements.

RESULTS

In general, the complexity of the angiographic procedure was found to be the most important reason for high radiation doses. Skill of the radiologist, management of the exposure parameters and calibration of the system are the other factors to be considered. Lateral cerebral interventional studies carry the highest risk for deterministic effects on the lens of the eye. Effective doses were calculated from DAP measurements and maximum fatal cancer risk factors were found for carotid studies.

CONCLUSIONS

Interventional radiologists should measure patient doses for their examinations. If there is a lack of necessary instrumentation for this purpose, then published dose reports should be used in order to predict the dose levels from some of the exposure parameters. Patient dose information should include not only the measured quantity but also the measured radiation output of the X-ray unit and exposure parameters used during radiographic and fluoroscopic exposures.

Patient Doses from Noncardiac Diagnostic and Therapeutic Interventional Procedures

PURPOSE

To determine the patient doses during noncardiac diagnostic and therapeutic interventional procedures carried out in a dedicated angiographic unit.

MATERIALS AND METHODS

For 1,214 interventional procedures, the technique type, dose-area product (DAP), cumulative dose (CD), and fluoroscopy time were recorded. These procedures were classified into 23 categories (10 diagnostic and 13 therapeutic) that included nine to 259 patients each. For each category, descriptive statistical analysis was used to determine the characteristics of DAP, CD, and fluoroscopy time distributions. The statistical significance of the differences observed between categories in terms of DAP was assessed.

RESULTS

For the 23 categories studied, the median DAP values ranged from 0.2 to 176.8 Gycm(2). In comparison with the literature, the mean and median DAP values in this study were within reported ranges for eight categories, greater for three, and less for six, whereas for the remaining six categories no relevant data were found in the literature.

CONCLUSIONS

Overall, the results of this survey indicate that the techniques used by the interventionalists, the operation skills of radiation technologists, and the performance of the x-ray unit present no obvious deficiencies in terms of patient radiation protection. However, for those procedures in which lower DAP values were found in the literature, it should be further investigated whether patient doses could be reduced without degradation of the diagnostic and therapeutic outcomes.

Practice of ALARA in the pediatric interventional suite

As interventional procedures have become progressively more sophisticated and lengthy, the potential for high patient radiation dose has increased. Staff exposure arises from patient scatter, so steps to minimize patient dose will in turn reduce operator and staff dose. The practice of ALARA in an interventional radiology (IR) suite, therefore, requires careful attention to technical detail in order to reduce patient dose. The choice of imaging modality should minimize radiation when and where possible. In this paper practical steps are outlined to reduce patient dose. Further details are included that specifically reduce operator exposure. Challenges unique to pediatric intervention are reviewed. Reference is made to experience from modern pediatric interventional suites. Given the potential for high exposures, the practice of ALARA is a team responsibility. Various measures are outlined for consideration when implementing a quality assurance (QA) program for an IR service.

Patient radiation exposure measurements during interventional procedures: a prospective study

This is a prospective study with the purpose of assessing patient radiation dose and stochastic risk (risk for fatal cancer) in a patient population undergoing interventional radiological (IR) procedures. Measurements were performed on 36 consecutive patients undergoing percutaneous transluminal angioplasty (PTA, n=18), transjugular intrahepatic portosystemic shunt (TIPS, n=3), diagnostic angiography (DA, n=6), arterial embolization (AE, n=3), and hepatic neoplasm chemoembolization (HCE, n=6). Kerma area product (KAP) was used as a measure of x-ray exposure to the patient. Mean KAP value per procedure was 79+/-50 Gy cm for PTA, 139+/-55 Gy cm for TIPS, 110+/-44 Gy cm for DA, 325+/-145 Gy cm for AE, and 150+/-76 Gy cm for HCE. Forty-six percent of total KAP value was attributed to fluoroscopy. In conclusion, we showed that a linear correlation between effective dose and KAP was found (r=0.84), which could be used for estimating patient effective dose using KAP measurements. Small changes to the number of digital frames acquired result in substantial change of the total KAP in interventional radiological procedures. Stochastic risk from IR procedures is quite low for the patient. Measuring KAP is a simple and accurate method, which provides the interventional radiologist with a good estimation of the patient's relative risk for stochastic effects.