Roberto M. Sánchez

Patient Radiation Dose Management in the Follow-Up of Potential Skin Injuries in Neuroradiology

BACKGROUND AND PURPOSE: Radiation exposure from neurointerventional procedures can be substantial, with risk of radiation injuries. We present the results of a follow-up program applied to potential skin injuries in interventional neuroradiology based on North American and European guidelines. MATERIALS AND METHODS: The following guidelines approved in 2009 by SIR and CIRSE have been used over the last 2 years to identify patients with potential skin injuries requiring clinical follow-up: peak skin dose >3 Gy, air kerma at the patient entrance reference point >5 Gy, kerma area product >500 Gy · cm2, or fluoroscopy time >60 minutes. RESULTS: A total of 708 procedures (325 in 2009 and 383 in 2010) were included in the study. After analyzing each dose report, 19 patients (5.9%) were included in a follow-up program for potential skin injuries in 2009, while in 2010, after introducing several optimizing actions and refining the selection criteria, only 4 patients (1.0%) needed follow-up. Over the last 2 years, only 3 patients required referral to a dermatology service. CONCLUSIONS: The application of the guidelines to patient radiation dose management helped standardize the selection criteria for including patients in the clinical follow-up program of potential skin radiation injuries. The peak skin dose resulted in the most relevant parameter. The refinement of selection criteria and the introduction of a low-dose protocol in the x-ray system, combined with a training program focused on radiation protection, reduced the number of patients requiring clinical follow-up.

Realistic approach to estimate lens doses and cataract radiation risk in cardiology when personal dosimeters have not been regularly used.

AbstractInterventional fluoroscopic guided cardiac procedures lead to radiation exposure to the lenses of the eyes of cardiologists, which over time may be associated with an increased risk of cataracts. This study derives radiation doses to the lens of the eye in cardiac catheterization laboratories from measurements of individual procedures to allow for estimates of such doses for those cases when personal dosimeters have not been used regularly. Using active electronic dosimeters at the C-arm (at 95 cm from the isocenter), scatter radiation doses have been measured for cardiac procedures and estimated radiation doses to the lenses of the cardiologists for different groups of procedures (diagnostic, PTCAs, and valvular). Correlation factors with kerma area product included in the patient dose reports have been derived. The mean, median, and third quartile scatter dose values per procedure at the C-arm for 1,969 procedures were 0.99, 0.78 and 1.25 mSv, respectively; for coronary angiography, 0.51, 0.45, and 0.61 mSv, respectively; for PTCAs, 1.29, 1.07, and 1.56 mSv; and for valvular procedures, 1.64, 1.45, and 2.66 mSv, respectively. For all the procedures, the ratio between the scatter dose at the C-arm and the kerma area product resulted in between 10.3–11.3 &mgr;Sv Gy−1 cm−2. The experimental results of this study allow for realistic estimations of the dose to the lenses of the eyes from the workload of the cardiologists and from the level of use of radiation protection tools when personal dosimeters have not been regularly used.

Measurements of eye lens doses in interventional cardiology using OSL and electronic dosemeters

The purpose of this paper is to test the appropriateness of OSL and electronic dosemeters to estimate eye lens doses at interventional cardiology environment. Using TLD as reference detectors, personal dose equivalent was measured in phantoms and during clinical procedures. For phantom measurements, OSL dose values resulted in an average difference of -15 % vs. TLD. Tests carried out with other electronic dosemeters revealed differences up to ±20 % versus TLD. With dosemeters positioned outside the goggles and when TLD doses were >20 μSv, the average difference OSL vs. TLD was -9 %. Eye lens doses of almost 700 μSv per procedure were measured in two cases out of a sample of 33 measurements in individual clinical procedures, thus showing the risk of high exposure to the lenses of the eye when protection rules are not followed. The differences found between OSL and TLD are acceptable for the purpose and range of doses measured in the survey.

Staff Doses in Interventional Radiology: A National Survey

PURPOSE To present the results of occupational radiation doses investigated through a national survey promoted by the National Society of Interventional Radiology in Spain. MATERIALS AND METHODS The monthly dosimetric records of 28 interventional radiologists from 10 hospitals were analyzed and filtered to remove inconsistent dosimeter readings. The evaluation of the results includes different workloads as well as different radiation protection habits. RESULTS Poor use of personal dosimetry by some interventional radiologists was brought to light. Most professionals do not use an over-apron dosimeter as recommended by the International Commission on Radiological Protection. Ceiling-suspended protective screens are used irregularly in many cases. All interventionalists perform digital subtraction angiographic imaging from a control room in more than 80% of procedures. The maximum monthly doses recorded were 3.8 mSv under the apron, 20.2 mSv over the apron, and 63.1 mSv to the hands. CONCLUSIONS For under-apron and hand readings, extrapolated median values were below 30% of annual dose limits, but in the case of over-apron readings, the extrapolated median dose was higher than the newly recommended limit for the eye lens of 20 mSv per year. This study mainly highlights the need to use radiation protection tools and personal dosimeters to protect staff and monitor eye lens doses.

Influence of dosemeter position for the assessment of eye lens dose during interventional cardiology

The equivalent dose limit for the eye lens for occupational exposure recommended by the ICRP has been reduced to 20 mSv y(-1) averaged over defined periods of 5 y, with no single year exceeding 50 mSv. The compliance with this new requirement could not be easy in some workplace such as interventional radiology and cardiology. The aim of this study is to evaluate different possible approaches in order to have a good estimate of the eye lens dose during interventional procedures. Measurements were performed with an X-ray system Philips Allura FD-10, using a PMMA phantom to simulate the patient scattered radiation and a Rando phantom to simulate the cardiologist. Thermoluminescence (TL) whole-body and TL eye lens dosemeters together with Philips DoseAware active dosemeters were located on different positions of the Rando phantom to estimate the eye lens dose in typical cardiology procedures. The results show that, for the studied conditions, any of the analysed dosemeter positions are suitable for eye lens dose assessment. However, the centre of the thyroid collar and the left ear position provide a better estimate. Furthermore, in practice, improper use of the ceiling-suspended screen can produce partial protection of some parts of the body, and thus large differences between the measured doses and the actual exposure of the eye could arise if the dosemeter is not situated close to the eye.

Brain Radiation Doses to Patients in an Interventional Neuroradiology Laboratory

BACKGROUND AND PURPOSE: In 2011, the International Commission on Radiologic Protection established an absorbed-dose threshold to the brain of 0.5 Gy as likely to produce cerebrovascular disease. In this paper, the authors investigated the brain doses delivered to patients during clinical neuroradiology procedures in a university hospital. MATERIALS AND METHODS: The radiation dose delivered to the brain was investigated in 99 diagnostic and therapeutic interventional neuroradiology procedures. Brain doses were calculated in a mathematic model of an adult standard anthropomorphic phantom by using the technical and radiation dose data of an x-ray biplane system submitted to regular quality controls and calibration programs. RESULTS: For cerebral embolizations, brain doses resulted in a maximum value of 1.7 Gy, with an average value of 500 mGy. Median and third quartile resulted in 400 and 856 mGy, respectively. For cerebral angiography, the average dose in the brain was 100 mGy. CONCLUSIONS: This work supports the International Commission on Radiologic Protection recommendation on enhancing optimization when doses to the brain could be higher than 0.5 Gy. Radiation doses should be recorded for all patients and kept as low as reasonably achievable. For pediatric patients and young adults, an individual evaluation of brain doses could be appropriate.

A national programme for patient and staff dose monitoring in interventional cardiology

A national programme on patient and staff dose evaluation in interventional cardiology made in cooperation with the haemodynamic section of the Spanish Society of Cardiology has recently been launched. Its aim is to propose a set of national diagnostic reference levels (DRLs) for patients as recommended by the International Commission on Radiological Protection and to initiate several optimisation actions to improve radiological protection of both patients and staff. Six hospitals have joined the programme and accepted to submit their data to a central database. First to be acquired were the quality control data of the X-ray systems and radiation doses of patients and professionals. The results from 9 X-ray systems, 1467 procedures and staff doses from 43 professionals were gathered. Provisional DRLs resulted in 44 Gy cm(2) for coronary angiography and 78 Gy cm(2) for interventions. The X-ray systems varied up to a factor of 5 for dose rates in reference conditions. Staff doses showed that 50 % of interventional cardiologists do not use their personal dosemeters correctly.

Occupational eye lens doses in interventional cardiology. A multicentric study.

New European regulation regarding radiological protection of workers and more specifically the new occupational dose limit for the eye lens recently reduced to 20 mSv yr(-1) may affect interventional cardiologists. This paper presents a set of measurements of occupational doses performed in five interventional cardiology centres and then compared with the new dose limit. The measurement of occupational doses was performed over the apron at chest level using electronic dosemeters recording H p(10). In one of the centres, scatter dose at goggles was also measured with optically stimulated luminescence dosemeters calibrated in terms of H p(0.07). An average H p(10) over the apron of 46 μSv/procedure was measured for cardiologists. Lower doses were noted in other professionals like second cardiologists, nurses or anaesthetists. Procedures for valvular and other structural heart diseases involved the highest occupational doses, averaging over 100 μSv/procedure. Important differences in occupational doses among centres may be indicative of different radiation protection habits. The new occupational dose limit for the eye lens is likely to be exceeded by those among the interventionalists who do not use protection tools (ceiling suspended screen and/or goggles) even with standard workloads.

Estimation of staff lens doses during interventional procedures. Comparing cardiology, neuroradiology and interventional radiology

The purpose of this article is to estimate lens doses using over apron active personal dosemeters in interventional catheterisation laboratories (cardiology IC, neuroradiology IN and radiology IR) and to investigate correlations between occupational lens doses and patient doses. Active electronic personal dosemeters placed over the lead apron were used on a sample of 204 IC procedures, 274 IN and 220 IR (all performed at the same university hospital). Patient dose values (kerma area product) were also recorded to evaluate correlations with occupational doses. Operators used the ceiling-suspended screen in most cases. The median and third quartile values of equivalent dose Hp(10) per procedure measured over the apron for IC, IN and IR resulted, respectively, in 21/67, 19/44 and 24/54 µSv. Patient dose values (median/third quartile) were 75/128, 83/176 and 61/159 Gy cm(2), respectively. The median ratios for dosemeters worn over the apron by operators (protected by the ceiling-suspended screen) and patient doses were 0.36; 0.21 and 0.46 µSv Gy(-1) cm(-2), respectively. With the conservative approach used (lens doses estimated from the over apron chest dosemeter) we came to the conclusion that more than 800 procedures y(-1) and per operator were necessary to reach the new lens dose limit for the three interventional specialties.

Staff lens doses in interventional urology. A comparison with interventional radiology, cardiology and vascular surgery values.

The purpose of this work is to evaluate radiation doses to the lens of urologists during interventional procedures and to compare them with values measured during interventional radiology, cardiology and vascular surgery. The measurements were carried out in a surgical theatre using a mobile C-arm system and electronic occupational dosimeters (worn over the lead apron). Patient and staff dose measurements were collected in a sample of 34 urology interventions (nephrolithotomies). The same dosimetry system was used in other medical specialties for comparison purposes. Median and 3rd quartile values for urology procedures were: patient doses 30 and 40 Gy cm(2); personal dose equivalent Hp(10) over the apron (μSv/procedure): 393 and 848 (for urologists); 21 and 39 (for nurses). Median values of over apron dose per procedure for urologists resulted 18.7 times higher than those measured for radiologists and cardiologists working with proper protection (using ceiling suspended screens) in catheterisation laboratories, and 4.2 times higher than the values measured for vascular surgeons at the same hospital. Comparison with passive dosimeters worn near the eyes suggests that dosimeters worn over the apron could be a reasonable conservative estimate for ocular doses for interventional urology. Authors recommend that at least the main surgeon uses protective eyewear during interventional urology procedures.