Current status of diagnostic reference levels in interventional cardiology.

Interventional cardiology provides indisputable benefits for patients but uses a substantial amount of ionising radiation. The diagnostic reference level (DRL) is the tool recommended by the International Commission on Radiological Protection to optimise imaging procedures. In this work, a review of studies dealing with radiation dose or recommending DRL values for interventional cardiology since 2010 is presented, providing quantitative and qualitative results. There are many published papers on coronary angiography (CA) and percutaneous coronary intervention. The DRL values compiled for different continental regions are different: the DRL for CA is about 35 Gy cm2for Europe and 83 Gy cm2for North America. These differences emphasise the need to establish national DRLs considering different social and/or economic factors and the harmonisation of the survey methodology. Surveys with a large amount of data collected with the help of dose management systems provide more reliable information with less chance of statistical bias than those with a small amount of data. The complexity of procedures and improvements in technology are important factors that affect the radiation dose delivered to patients. There is a need for additional data on structural and electrophysiological procedures. The analysis of paediatric procedures is especially difficult because some studies present results split into age bands and others into weight bands. Diagnostic procedures are better described, but there is a great variety of therapeutic procedures with different DRL values (up to a factor of nine) and these require a dedicated review.

Benefits and limitations for the use of radiation dose management systems in medical imaging. Practical experience in a university hospital.

OBJECTIVES: Radiation dose management systems (DMS) are currently used to help improve radiation protection in medical imaging and interventions. This study presents our experience using a homemade DMS called DOLQA (Dose On-Line for Quality Assurance). METHODS: Our DMS is connected to 14 X-ray systems in a university hospital linked to the central data repository of a large network of 16 public hospitals in the Autonomous Community of Madrid, with 6.7 million inhabitants. The system allows us to manage individual patient dose data and groups of procedures with the same clinical indications, and compare them with diagnostic reference levels (DRLs). The system can also help to prioritise optimisation actions. RESULTS: This study includes results of imaging examinations from 2020, with 37,601 procedures and 286,471 radiation events included in the radiation dose structured reports (RDSR), for computed tomography (CT), interventional procedures, positron emission tomography-CT (PET-CT) and mammography. CONCLUSIONS: The benefits of the system include: automatic registration and management of patient doses, creation of dose reports for patients, information on recurrent examinations, high dose alerts, and help to define optimisation actions.The system requires the support of medical physicists and implication of radiologists and radiographers. DMSs must undergo periodic quality controls and audit reports must be drawn up and submitted to the hospital's quality committee.The drawbacks of DMSs include the need for continuous external support (medical physics experts, radiologists, radiographers, technical services of imaging equipment and hospital informatics services) and the need to include data on clinical indication for the imaging procedures. ADVANCES IN KNOWLEDGE: DMS perform automatic management of radiation doses, produces patient dose reports, and registers high dose alerts to suggest optimisation actions. Benefits and limitations are derived from the practical experience in a large university hospital.

Managing occupational doses with smartphones in interventional radiology.

PURPOSE: This study presents a prototype smartphone application for occupational dosimetry in interventional practices based on electronic personal dosimeters to assist in dose monitoring. METHODS: The prototype receives and records information from the occupational dose report containing the cumulative dose of electronic personal dosimeters worn over the apron at chest level and electronic area dosimeters located on C-arms (reference dosimeters), for each fluoroscopy-guided procedure. Using their smartphones, personnel involved in interventional practices can review and compare their occupational records with an investigation level, the dose limits, and their department colleagues (anonymously). The ratio between Hp (10) measured by the personal and the reference dosimeters at the C-arm is presented as an indicator of consistent use of suspended operator shield. Some general results extracted from the first months of use are presented. RESULTS: The reference dosimeter located at the C-arm (without lead protection and acting as an ambient dosimeter) recorded in one of the laboratories 217 mSv during 308 procedures over 5 months, showing an indication of the radiation risk present in an interventional laboratory. The ratio between the personal cumulative dose and the dose at a reference C-arm dosimeter ranged from 0.2% to 1.67% (a factor of 8.5) for different interventionalists. These differences suggest different protection habits among interventional operators, as well as a target for dose reduction. CONCLUSIONS: With this system, professionals have easy access to their occupational dosimetry records (including information on the workload) in the setting of their interventional departments, to thereby actively engage in the protection process.

High filtration in interventional practices reduces patient radiation doses but not always scatter radiation doses.

OBJECTIVES: In fluoroscopy-guided interventional practices, new dose reduction systems have proved to be efficient in the reduction of patient doses. However, it is not clear whether this reduction in patient dose is proportionally transferred to operators' doses. This work investigates the secondary radiation fields produced by two kinds of interventional cardiology units from the same manufacturer with and without dose reduction systems.Methods:Data collected from a large sample of clinical procedures over a 2-year period (more than 5000 procedures and 340,000 radiation events) and the DICOM radiation dose structured reports were analysed. RESULTS: The average cumulative Hp(10) per procedure measured at the C-arm was similar for the standard and the dose reduction systems (452 vs 476 µSv respectively). The events analysis showed that the ratio Hp(10)/KAP at the C-arm was (mean ± SD) 5 ± 2, 10 ± 4, 14 ± 4 and 14 ± 6 µSv·Gy-1·cm-2 for the beams with no added filtration, 0.1, 0.4 and 0.9 mm Cu respectively and suggested that the main cause for the increment of the ratio Hp(10)/KAP vs the "standard system" is the use of higher beam filtration in the "dose reduction" system. CONCLUSION: Dose reduction systems are beneficial to reduce KAP in patients and their use should be encouraged, but they may not be equally effective to reduce occupational doses. Interventionalists should not overlook their own personal protection when using new technologies with dose reduction systems. ADVANCES IN KNOWLEDGE: Dose reduction technology in interventional systems may increase scatter dose for operators. Personal protection should not be overlooked with dose reduction systems.

Percutaneous structural cardiology: are anaesthesiologists properly protected from ionising radiation?

During transcatheter aortic valve implantations (TAVI) and other percutaneous structural procedures, some patients may need close anesthesiological care, thus exposing the anaesthesiologist to x-rays. This work aims to investigate the radiation dose received by anaesthesiologists during these specific procedures in order to improve their radiological protection. Occupational radiation doses were measured prospectively during percutaneous structural procedures in several health professionals using electronic dosimeters worn over the apron at chest level. A sample of 49 procedures were recorded, where the anaesthesiologists' average dose per procedure resulted 13 times higher than that of interventional cardiologists. The average dose per procedure received over the protection apron during TAVIs by the anaesthesiologist was 0.13 mSv, with a maximum value of 0.69 mSv. Taking these figures as a conservative estimation of the eye lens dose, an anaesthesiologist could participate in around 150 procedures before reaching the regulatory annual dose limit for the lens of the eye in Europe (20 mSv). In those clinical procedures where patients need close anesthesiological care, the anaesthesiologists might receive high radiation doses increasing the risk for cataracts and the risk of stochastic radiation effects. The proper use of occupational dosimeters will help identify these situations. It is recommended to use a mobile shielding barrier to reduce radiation exposure to acceptable levels in these situations.

National Diagnostic Reference Levels for Endovascular Aneurysm Repair and Optimisation Strategies.

OBJECTIVE: The International Commission on Radiological Protection (ICRP) has highlighted the large number of medical specialties using fluoroscopy outside imaging departments without programmes of radiation protection (RP) for patients and staff. Vascular surgery is one of these specialties and endovascular aneurysm repair (EVAR) is one of the most challenging procedures requiring RP guidance and optimisation actions. The recent European Directive on Basic Safety Standards requires the use and regular update of diagnostic reference levels (DRL) for interventional procedures. The objective of the study was to know the doses of patients undergoing EVAR with mobile Xray systems and with hybrid rooms (fixed Xray systems), to obtain national DRLs and suggest optimisation actions. METHODS: The Spanish Chapter of Endovascular Surgery launched a national survey that involved hospitals for 10 autonomous communities representing the 77% of the Spanish population (46.7 million inhabitants). Patient dose values from mobile Xray systems were available from nine hospitals (sample of 165 EVAR procedures) and data from hybrid rooms, from seven hospitals, with dosimetric data from 123 procedures. The initial national DRLs have been obtained, as the third quartile of the median values from the different centres involved in the survey. RESULTS: The proposed national DRLs are 278 Gy cm2 for hybrid rooms and 87 Gy cm2 for mobile Xray systems, and for cumulative air kerma (cumulative AK) at the patient entrance reference point, 1403 mGy for hybrid rooms, and 292 mGy for mobile systems. CONCLUSION: An audit of patient doses for EVAR procedures to identify optimised imaging protocol strategies is needed. It is also appropriate to evaluate the diagnostic information required for EVAR procedures. The increase by a factor of 3.2 (for kerma area product) and 4.8 (for cumulative AK) in the DRLs needs to be justified when the procedures are performed in the hybrid rooms rather than with mobile Xray systems.

Conversion factors to estimate effective doses from kerma area product in interventional cardiology. Impact of added filtration.

There is a large variation in the factors used to estimate effective doses from kerma area product (KAP) for interventional cardiology. These factors are required to estimate population doses. This paper presents the results for this conversion factor for cardiac procedures using tissue weighting factors of ICRP-103 and the impact of the added copper filtration in the X-ray beam. The data from 925 cardiac procedures and 75,347 radiation events were collected from two angiography laboratories using the DICOM Radiation Dose Structured Reports (RDSR). Effective doses were calculated with Monte Carlo software and the dosimetric, technical and geometrical information included in the RDSR. In one laboratory, with an X-ray system without Cu filtration for the cine runs, a factor of 0.21 ± 0.05 mSv/(Gy·cm2) was obtained. In other laboratory, incorporating a patient dose reduction technique, and 0.4 mm of Cu filtration for cine runs, the conversion factor was 0.29 ± 0.05 mSv/(Gy·cm2). The analysis of the radiation events for the different Cu filtrations (0.0; 0.1; 0.4 and 0.9 mm) resulted in conversion factors of: 0.16; 0.27; 0.34 and 0.40 mSv/(Gy·cm2) respectively. The estimation of effective and population doses from KAP should take into account the Cu filtration in the X-ray beam. For the X-ray system with patient dose reduction technique, using 0.4 mm Cu for cine runs, the global conversion factor increased by 38%, from 0.21 to 0.29 mSv/(Gy·cm2) in comparison to the standard X-ray system with a protocol that did not include copper filtration for cine acquisitions.

Reducing the risk of skin injuries in cardiac catheterization procedures: Optimization proposal for obese patients.

PURPOSE: During interventional cardiology procedures, high doses of X-ray may be delivered to patients. This is especially critical in cases of obese patients and/or high obliquity projections. High dose rates can then be produced in patients' skin as well as insufficient image quality due to regulatory limitations in the X-ray tube output working in the fluoroscopy mode. In this paper, an optimization action is proposed to reduce patient entrance dose rate and preserve image quality in cases of thick patients. METHODS: The action is based on the evaluation of dose rate to the patient and image quality in a new fluoroscopy protocol with less frame rate (7.5 vs. 15 frames/s) and higher spectral shape filter (0.4 vs. 0.1 mm Cu). The new protocol is tested in an angiography room using a PMMA phantom and a test object. RESULTS: The new fluoroscopy protocol (7.5 fr/s and 0.4 mm Cu) reduces entrance surface air kerma in 70%-10% (depending on PMMA thickness), preserving the incident air kerma per frame at the image detector. While at lower PMMA thickness, the MTF measured with bar pattern is better for the default protocol; at PMMA thickness between 32 and 37 cm, the optimized protocol produces better image quality indicators. CONCLUSIONS: This work demonstrates that in the case of high thicknesses of PMMA (32-37 cm), increasing spectral beam filter and reducing frame rate may help improve image quality and maintain entrance surface air kerma so as to fulfil the regulatory requirements.

Strategies to optimise occupational radiation protection in interventional cardiology using simultaneous registration of patient and staff doses.

The International Commission on Radiological Protection recommends that occupational protection and patient protection be managed in an integrated approach. This paper describes the experience and the initial results of a system able to register and to process simultaneously staff and patient doses in interventional cardiology and the practical use of this system in the optimisation of occupational exposure. The system used simultaneously collects and manages patient and staff doses for all radiation events. The personal electronic dosimeters worn over the protective apron of health professionals working inside catheterisation laboratories can send (wireless) doses and dose rate values to an X-hub and provide the operators inside the catheterisation rooms with real-time information. Individual and global reports for all the health professionals may be periodically obtained from the system to help with the optimisation. The results for eight cardiologists, one fellow and four nurses for a total of 2468 interventional cardiology procedures and 3207 occupational dose values collected over one year are presented here. Annual doses Hp(10) measured over the apron for cardiologists ranged from 0.3 to 6.3 mSv. For the cardiologist, the ratio between occupational doses (over the apron) and patient doses ranged from 0.05 to 0.23 µSv Gy-1 cm-2, with a mean value of 0.12 µSv Gy-1 cm-2. The system allows defining optimisation strategies by comparing the results between the different operators while considering the workload and complexity of the procedures (based on the total Kerma Area Product managed by the different operators). The registration of the date and time of the occupational radiation doses allows auditing the use of the personal dosimeters worn by the various operators.

Evaluation of a real-time display for skin dose map in cardiac catheterisation procedures.

The purpose of this work was to validate a prototype designed to display skin dose maps in real time for clinicians that perform interventional cardiology procedures. Measurements using copper absorbers and three kinds of dosemeters (solid-state, radiochromic film and optically stimulated luminescence) were performed in a catheterisation laboratory. Some clinical results are also discussed. The system provides patient skin doses with acceptable accuracy, taking into account couch shifts, wedge compensation filters and collimation. The greatest source of uncertainty is that resulting from patient shape modelling. From a set of 374 patients recorded, it can be concluded that the peak skin dose (PSD) for patients with the same cumulative air kerma at the patient entrance reference point can be rather different. This real-time skin dose calculator has resulted easier to manage for measuring patient PSDs than other methods based on films or CR plates. As well as an improvement for patient safety, it could prove a useful training tool for clinicians.

Evaluation of an automated FDG dose infuser to PET-CT patients.

An experience with an automated infuser device at a university hospital is presented in this paper. Occupational doses at operators' fingertips were measured using optically stimulated luminescence dosemeters for two different scenarios: (i) using a semi-automatic system to prepare the fluorodesoxiglucose (FDG) injections that were delivered to the patient manually and (ii) using an automated infusion device that prepares and delivers the FDG dose. The accuracy of the activity prepared by the automatic system was also verified. Reductions in fingertip doses of 60 % using the fully automatic system have been measured. The difference between the programmed and the delivered activity was 2 %. The use of the automatic infuser in the authors' institution has led to a substantial reduction in hand radiation doses. But contamination risks, even though reduced, still exist; therefore, radioisotope manipulation should follow strict radiation protection rules to avoid incidents. Improved accuracy in dose delivery reduces chances of dose misadministration.

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.

Resultados iniciales de un programa nacional para el seguimiento de dosis de radiación en pacientes de cardiología intervencionista / Initial results from a national follow-up program to monitor radiation doses for patients in interventional cardiology

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

Interventional 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 µSv Gy cm. 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.

Dose assessment during the commissioning of flat detector imaging systems for cardiology.

Incident air kerma (IAK) and entrance surface air kerma (ESAK) have been measured for a range of copper (Cu) absorbers (1-10 mm) and polymethylmethacrylate (PMMA) slabs (12-28 cm) with kilovolt values ranging from 61 to 120 during the commissioning of an X-ray system equipped with a flat detector used in interventional cardiology procedures. Numerical parameters on image quality have also been measured for different X-ray beam qualities using the plastic wall of the ionisation chamber. When moving from 1 to 10 mm of Cu, IAK per frame increased to a factor of 38 for cine and 27 for fluoroscopy. A cine frame requires 60-116 times more IAK than a fluoroscopy frame. As for PMMA, when the backscatter factor is included (simulating real conditions with patients), and when moving from 12 to 28 cm, the increases in ESAK are 16 times for cine and 10 times for fluoroscopy. Because of the differences in X-ray beam quality for cine and fluoroscopy modes, the Cu thicknesses necessary to drive the generator to equivalent kilovolts resulted in the following values (cine and fluoroscopy, respectively): 12 cm of PMMA (1 and 1.5 mm Cu), 20 PMMA (2.5 and 3.5 mm Cu) and 28 cm PMMA (4.5 and 8.5 mm Cu). With the analysis of IAK, ESAK and image quality, one can verify the appropriate settings of the X-ray system and obtain baseline information for constancy checks and help cardiologists in the management of patient doses by knowing the dose increase factors and image quality changes when increasing patient thickness or using different C-arm projections.

Factor tubo peritoneal. Reversión de la oclusión tubaria / Tubo-peritoneal factor. Tabal occlusion reversion

Se analizan las técnicas de oclusión tubaria bilateral más empleadas y cuáles son las que tienen mayor potencialidad de reversión. Revisando 200 casos de pacientes con factor tuboperitoneal de esterilidad se encontró que 24 solicitaban recanalización tubaria por tener antecedente de salpingoclasia. En el perfil de estas pacientes, se obtuvo un promedio de 29.4 años, con un periodo de latencia entre la oclusión tubaria y la solicitud de reversión de 4.1 años teniendo un promedio de 2 hijos vivos. Los motivos de solicitud fueron las segundas nupcias 54%, hijos fallecidos 12.5%, OTB involuntaria 12.5% alteraciones psicológicas 12.5% e inestabilidad matrimonial 8.5%. La técnica OTB más empleada fué Pomeroy 70.8%. De las 24 pacientes estudiadas, cuatro se descartaron por no reunir los requisitos necesarios, de las 20 restantes dos desertaron en el periodo preoperatorio y dos están pendientes de efectuar la renalización. De las 16 operadas, tres desertaron y siete se embarazoron; lo que dá un cuadro de 53.8% de embarazos. Resultado que está dentro de los límites de éxito reportados por otros investigadores.

Factor tuboperitoneal. Clasificación y pronóstico de las adherencias por laparoscopia / Tubo-peritoneal factor. Classification and prognosis of adhesions by laparoscopy

Se revisaron 200 pacientes estériles con factor tuboperitoneal alterado. La enfermedad adhesiva anexial fue el factor más importante en la esterilidad. La mayor parte de los casos estaban en la tercera década de vida; 40.5% fue de enfermedad inflamatoria pélvica inespecífica que respondió bien al tratamiento con antibióticos y antiinflamatorios. A mayor grado e enfermedad anexial adhesiva, menor posibilidad de embarazo

Correlación de la histerosalpingografía, pruebas de Rubin y celiotomía con los diagnósticos laparoscópicos en la permeabilidad tubárica / Correlation of hysterosalpingography, Rubins test and celiotomy with laparoscopic diagnosis in tubal permeability

No se cuenta con un método único para el estudio integral de la trompa de falopio. Los métodos más utilizados: HSG, PR y cromotubación por Laparoscopia por ser ascendentes no son fisiológicos y no evalúan la función del endosalpinx. La PR debe seguirse utilizando por evaluar la contractibilidad del miosalpinx u ostium tubario; es barato, prácticamente inócuo y coincide más frecuentemente con la laparoscopia que con la HSG. La coincidencia de permeabilidad y obstrucción tubaria por HSG y Laparoscopia se obtuvo en 70.5% y en 29.5% no hubo correlación. Las obstrucciones tubarias evidenciadas por HSG pueden ser permables a la laparoscopia por quitarse el componente espasmo-dolor en esta última prueba. Las funciones de permeabilidad en la HSG que muestran oclusión en la laparoscopia pueden deberse a defecto de técnica, hidrocromotubación preferencial, proceso inflamatório evolutivo reactivo o inducido por el estudio radiográfico. Durante la HSG no sólo se debe analizar las imáges de permeabilidad y de oclusión tubaria, sino que es obligado analizar la distribución del material radiopaco en el Douglas y tratar de evidenciar la calidad de la relación fibrio-ovárica. La laparoscopia tiene mayor grado de confiabilidad y sólo 6.7% de error. Es un estudio parorámico y evaluativo de las condiciones del aparato genital interno, pero no evidencia la contractilidad ni la imagen de las cavidades uterotubaria. Los tres métodos deben utilizarse en el protocolo de estudio de la pareja estéril y complementarse entre sí, por la falta de correlación observada y para tener un diagnóstico integral de la patología existente

Salpingostomía y resección de adherencias tubarias por microcirugía / Salpingostomy and adhesions resection by microsorgery

Se estudiaron 32 pacientes sometidas a microcirugía tubaria (salpingoovariolisis y salpingostomía) en el lapso comprendido entre Enero de 1983 y Octubre de 1984, obteniéndose el 46.87% de embarazos. En las pacientes sometidas a salpingoovariolisis se obtuvo 54.16% de embarazos. En las pacientes sometidas a salpingostomía se obtuvo 25% embarazos. No se encontraron embarazos ectópicos ni abortos hasta la fecha del estudio. Todos los embarazos ocurrieron en un periodo menor de 18 meses. A la fecha del estudio de las 15 pacientes embarazadas, 73.3% de pacientes se encontraban gestantes y en 26.6% el embarazo había llegado a término y resultó en forma satisfatoria