Radiation Dose Structured Reports Research Articles

Feasibility study for the evaluation of doses received by organs during medical exposure for pediatric patient undergoing CT scan and estimation of the potential risk of radiation-induced cancers

Computed Tomography (CT) continues to contribute a significant portion of the total collective dose delivered to the public from medical procedures involving ionizing radiation. Children are considered to be at higher risk of developing radiation induced cancer due to the young age of exposure and increased tissue radio sensitivity. Organ dose estimation is essential for pediatric patient cancer risk assessment. The aim of this study was to evaluate the excess risk of radiation induced cancer following exposure to low-dose ionizing radiation from pediatric CT scans.We collected information from Radiation Dose Structured Report (RDSR) in 2 radiology department for 3 protocols and three (3) different age group in pediatric CT scan.We estimated the excess of cancer risk by using the Radiation Risk Assessment Tool RadRAT). For that, we calculate first the organ doses with National Cancer Institute for CT (NCICT). Effective dose and Size Specific Dose Estimate were also estimated, CTDI and DLP recorded from the RDSR were compared by the ones given by the software. The doses received by 30 organs including both inside and outside the scanning range were calculated and compared for the different age groups and protocols.The excess risk observed here range between 0.6 and 10.1‰ for respectively the thorax and Abdomen protocol in boy's cohort. This can be due to the significant dose variability observed among radiological protocols defined for the same CT scan and patient of the same age. For a head examination, a ratio of 2–4, depending on the age of the child, is estimated between the maximum and minimum doses delivered to the brain. For the other types of examination, this ratio is even greater: around 9 for chest examinations, 16 for abdominopelvic explorations.Careful justification of pediatric CT scans and dose optimization should be available in hospitals to minimize risks.

Effect of an optimized X-ray blanket design on operator radiation dose in cardiac catheterization based on real-world angiography.

There is increasing concern and focus in the interventional cardiology community on potential long term health issues related to radiation exposure and heavy wearable protection. Optimized shielding measures may reduce operator dose to levels where lighter radioprotective garments can safely be used, or even omitted. X-ray blankets (XRB) are commercially available but suffer from small size and lack of stability. A larger XRB may reduce operator dose but could hamper vascular access and visualization. The aim of this study is to assess shielding effect of an optimized XRB during cardiac catheterization and estimate the potential reduction in annual operator dose based on DICOM Radiation Dose Structured Report (RDSR) data reflecting everyday clinical practice. Data accumulated from 7681 procedures over three years in our RDSR repository was used to identify projection angles and radiation doses during cardiac catheterization. Using an anthropomorphic phantom and a scatter radiation detector, radiation dose to the operator (mSv) and patient (dose area product-DAP) was measured for each angiographic projection for three different shielding setups. Relative operator dose (mSv/DAP) was calculated and multiplied by DAP per projection to estimate effect on operator dose. Adding an optimized XRB to a standard shielding setup comprising a table- and ceiling-mounted shield resulted in a 94.9% reduction in estimated operator dose. The largest shielding effect was observed in left and cranial projections where the ceiling-mounted shield offered less protection. An optimized XRB is a simple shielding measure that has the potential to reduce operator dose.

Al2O3:C optically stimulated luminescence dosimetry for evaluation of potential factors contributing to entrance skin doses received by liver cancer patients undergoing Transarterial Chemoembolization

Transarterial Chemoembolization (TACE) has been accepted as an effective technique that can be practically used for liver cancer treatment due to its outstanding benefits for patients with large, infiltrative, and multifocal tumors that cannot be surgically removed. However, this invasive image-guided technique may potentially result in higher radiation doses than general diagnostic radiology. Radiation-induced skin injury caused by excessive exposure to X-rays during fluoroscopically guided procedures has been previously reported. Therefore, dose assessment during TACE examination is relevant to minimize radiological hazards and reduce patient distress.The study aims to 1) quantify the magnitude of radiation doses received in TACE treatments, 2) evaluate potential factors contributing to an increase of the entrance skin dose, and 3) demonstrate an improved image-guided procedure for reducing radiation doses while maintaining high X-ray image quality. The study was carried out employing an anthropomorphic phantom to determine radiation dose using a standard commercial optically stimulated luminescence dosimeter (OSLD). Experimental data was collected from 370 patients under three specific image-guided techniques. They include 1) abdomen frontal 3 fps procedure where a pathway of blood flow was created using an image acquisition rate of three frames per second (fps), 2) navigation where a blood vessel roadmap was created with subtraction of bones and organs, and 3) fluoroscopy where X-ray beams were continuously delivered to a target for creating real-time images with no interference removed. Analysis of variance was used to demonstrate the difference of the mean entrance skin doses (ESDs) among the three imaging techniques. A multiple regression model was also used to investigate potential factors contributing to the increased ESDs.The study confirms that the ESDs received by TACE patients using these three imaging techniques are not significantly different. Moreover, the statistical-based model shows that the five main factors obtained from the exposure parameters and patient dosimetric data contribute to the patient ESDs. They include 1) the dose area product (DAP), 2) fluoroscopy time, 3) X-ray tube voltage, 4) X-ray tube current, and 5) total diagnostic images. All information is reported based on the machine DICOM-RDSR (Digital Imaging and Communication in Medicine – Radiation Dose Structured Report) data after completed examinations. Finally, the ANOVA test confirms that this simplified model can be used to estimate the radiation doses received by TACE patients, accounting for a 95% confidence interval.

Effect of an optimized X-ray blanket design on operator radiation dose in cardiac catheterization based on real-world angiography

Abstract Background There is increasing concern and focus in the interventional cardiology community on potential long term health issues related to radiation exposure and heavy wearable protection. Optimized shielding measures may reduce operator dose to levels where lighter radioprotective garments can safely be used, or even omitted. X-ray blankets (XRB) are commercially available but suffer from small size and lack of stability. Purpose The aim of this study is to assess shielding effect of an optimized XRB during cardiac catheterization and estimate the potential reduction in annual operator dose based on DICOM Radiation Dose Structured Report (RDSR) data reflecting everyday clinical practice. Methods Data accumulated from 7681 procedures over three years in our RDSR repository was used to identify projection angles and radiation doses during cardiac catheterization. Using an anthropomorphic phantom and a scatter radiation detector, radiation dose to the operator (mSv) and patient (dose area product – DAP) was measured for each angiographic projection for three different shielding setups. Relative operator dose (mSv/DAP) was calculated and multiplied by DAP per projection to estimate effect on operator dose. Results Adding an optimized XRB to a standard shielding setup comprising a table- and ceiling-mounted shield resulted in a 94.9% reduction in estimated operator dose. The largest shielding effect was observed in left and cranial projections where the ceiling-mounted shield offered less protection. Conclusions An optimized XRB is a simple shielding measure that has the potential to reduce operator dose. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): Grieg Foundation

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

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). 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. 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. 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. 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.

Influence of Calculated Equivalent Doses and Effective Dose due to Differences in Software Version on Radiation Dose Management System

To verify the influence of the software version of the dose control system on the equivalent dose and effective dose calculation values. We performed chest CT and liver to pelvic CT imaging with a human phantom placed on a CT bed. After the imaging was completed, the radiation dose structured reports (RDSRs) generated by the equipment were transferred to several dose management systems with different software versions for equivalent dose and effective dose calculations. The equivalent and effective doses calculated from the same RDSR differed depending on the software version of the dose management system with a difference of approximately 2 times for the effective dose and up to 50 times for the equivalent dose. It is considered that the voxel phantom geometry and dose calculation algorithm may differ depending on the software version of the dose management system. Careful attention should be paid in handling the dose calculation values because the exposure explanations and risk assessments using the equivalent doses, and effective dose calculated by the dose management systems may be overestimated.

Estimation of patient skin dose in fluoroscopy: summary of a joint report by AAPM TG357 and EFOMP.

Physicians use fixed C-arm fluoroscopy equipment with many interventional radiological and cardiological procedures. The associated effective dose to a patient is generally considered low risk, as the benefit-risk ratio is almost certainly highly favorable. However, X-ray-induced skin injuries may occur due to high absorbed patient skin doses from complex fluoroscopically guided interventions (FGI). Suitable action levels for patient-specific follow-up could improve the clinical practice. There is a need for a refined metric regarding follow-up of X-ray-induced patient injuries and the knowledge gap regarding skin dose-related patient information from fluoroscopy devices must be filled. The most useful metric to indicate a risk of erythema, epilation or greater skin injury that also includes actionable information is the peak skin dose, that is, the largest dose to a region of skin. The report is based on a comprehensive review of best practices and methods to estimate peak skin dose found in the scientific literature and situates the importance of the Digital Imaging and Communication in Medicine (DICOM) standard detailing pertinent information contained in the Radiation Dose Structured Report (RDSR) and DICOM image headers for FGI devices. Furthermore, the expertise of the task group members and consultants have been used to bridge and discuss different methods and associated available DICOM information for peak skin dose estimation. The report contributes an extensive summary and discussion of the current state of the art in estimating peak skin dose with FGI procedures with regard to methodology and DICOM information. Improvements in skin dose estimation efforts with more refined DICOM information are suggested and discussed. The endeavor of skin dose estimation is greatly aided by the continuing efforts of the scientific medical physics community, the numerous technology enhancements, the dose-controlling features provided by the FGI device manufacturers, and the emergence and greater availability of the DICOM RDSR. Refined and new dosimetry systems continue to evolve and form the infrastructure for further improvements in accuracy. Dose-related content and information systems capable of handling big data are emerging for patient dose monitoring and quality assurance tools for large-scale multihospital enterprises.

A diagnostic medical physicist’s guide to the American College of Radiology Fluoroscopy Dose Index Registry

A diagnostic medical physicist’s guide to the American College of Radiology Fluoroscopy Dose Index Registry

Accuracy of skin dose mapping in interventional cardiology: Comparison of 10 software products following a common protocol.

Online and offline software products can estimate the maximum skin dose (MSD) delivered to the patient during interventional cardiology procedures. The capabilities and accuracy of several skin dose mapping (SDM) software products were assessed on X-ray systems from the main manufacturers following a common protocol. Skin dose was measured on four X-ray systems following a protocol composed of nine fundamental irradiation set-ups and three set-ups simulating short, clinical procedures. Dosimeters/multimeters with semiconductor-based detectors, radiochromic films and thermoluminescent dosimeters were used. Results were compared with up to eight of 10 SDM products, depending on their compatibility. The MSD estimates generally agreed with the measurements within±40% for fundamental irradiation set-ups and simulated procedures. Only three SDM products provided estimates within±40% for all tested configurations on at least one compatible X-ray system. No SDM product provided estimates within±40% for all combinations of configurations and compatible systems. The accuracy of the MSD estimate for lateral irradiations was variable and could be poor (up to 66% underestimation). Most SDM products produced maps which qualitatively represented the dimensions, the shape and the relative position of the MSD region. Some products, however, missed the MSD region when situated at the intersection of multiple fields, which is of radiation protection concern. It is very challenging to establish a common protocol for quality control (QC) and acceptance testing because not all information necessary for accurate MSD calculation is available or standardised in the radiation dose structured reports (RDSRs).

Vendor-independent skin dose mapping application for interventional radiology and cardiology.

PurposeThe purpose of this paper is to present and validate an originally developed application SkinCare used for skin dose mapping in interventional procedures, which are associated with relatively high radiation doses to the patient’s skin and possible skin reactions.MethodsSkinCare is an application tool for generating skin dose maps following interventional radiology and cardiology procedures using the realistic 3D patient models. Skin dose is calculated using data from Digital Imaging and Communications in Medicine (DICOM) Radiation Dose Structured Reports (RDSRs). SkinCare validation was performed by using the data from the Siemens Artis Zee Biplane fluoroscopy system and conducting “Acceptance and quality control protocols for skin dose calculating software solutions in interventional cardiology” developed and tested in the frame of the VERIDIC project. XR‐RV3 Gafchromic films were used as dosimeters to compare peak skin doses (PSDs) and dose maps obtained through measurements and calculations. DICOM RDSRs from four fluoroscopy systems of different vendors (Canon, GE, Philips, and Siemens) were used for the development of the SkinCare and for the comparison of skin dose maps generated using SkinCare to skin dose maps generated by different commercial software tools (Dose Tracking System (DTS) from Canon, RadimetricsTM from Bayer and RDM from MEDSQUARE). The same RDSRs generated during a cardiology clinical procedure (percutaneous coronary intervention—PCI) were used for comparison.ResultsValidation performed using VERIDIC's protocols for skin dose calculation software showed that PSD calculated by SkinCare is within 17% and 16% accuracy compared to measurements using XR‐RV3 Gafchromic films for fundamental irradiation setups and simplified clinical procedures, respectively. Good visual agreement between dose maps generated by SkinCare and DTS, RadimetricsTM and RDM was obtained.ConclusionsSkinCare is proved to be very convenient solution that can be used for monitoring delivered dose following interventional procedures.

Patient radiation dose from x-ray guided endovascular aneurysm repair: a Monte Carlo approach using voxel phantoms and detailed exposure information

Endovascular aneurysm repair (EVAR) is a well-established minimally invasive technique that relies on x-ray guidance to introduce a stent through the femoral artery and manipulate it into place. The aim of this study was to estimate patient organ and effective doses from EVAR procedures using anatomically realistic computational phantoms and detailed exposure information from radiation dose structured reports (RDSR). Methods: Lookup tables of conversion factors relating kerma area product (PKA) to organ doses for 49 different beam angles were produced using Monte Carlo simulations (MCNPX2.7) with International Commission on Radiological Protection (ICRP) adult male and female voxel phantoms for EVAR procedures of varying complexity (infra-renal, fenestrated/branched and thoracic EVAR). Beam angle specific correction factors were calculated to adjust doses according to x-ray energy. A MATLAB function was written to find the appropriate conversion factor in the lookup table for each exposure described in the RDSR, perform energy corrections and multiply by the respective exposure PKA. Using this approach, organ doses were estimated for 183 EVAR procedures in which RDSRs were available. A number of simplified dose estimation methodologies were also investigated for situations in which RDSR data are not available. Results: Mean estimated bone marrow doses were 57 (range: 2–247), 86 (2–328) and 54 (8–250) mGy for infra-renal, fenestrated/branched and thoracic EVAR, respectively. Respective effective doses were 27 (1–208), 54 (1–180) and 37 (5–167) mSv. Dose estimates using non-individualised, average conversion factors, along with those produced using the alternative Monte Carlo code PCXMC, yielded reasonably similar results overall, though variation for individual procedures could exceed 100% for some organs. In conclusion, radiation doses from x-ray guided endovascular aneurysm repairs are potentially high, though this must be placed in the context of the life sparing nature and high success rate for this procedure.

Age-specific and gender-specific radiation risks in paediatric angiography and interventional cardiology: conversion coefficients and risk reference values.

To estimate risk for exposure-induced cancer death (REID), organ-specific risks of exposure-induced cancer death (REIDHT) and associated conversion coefficients (CCREID:KAP=REID/kerma-area product (KAP), CCREIDHT:KAP=REIDHT/KAP) in paediatric cardiac catheterizations using data from radiation dose structured reports (RDSR). A novel risk surveillance tool consisting of age-specific and gender-specific risk reference values (RRVs) related to population cancer risk is suggested. The PCXMC v.2.0 code is used together with exposure-related information from RDSR from a cohort of 238 children to assess cancer risks and related conversion coefficients. The KAP corresponding to 1 in 1000 of increased REID is used to define age-specific and gender-specific KAP values to monitor risk in such patient cohorts, here denoted as RRVs. The REID estimates ranged from below 1 up to 300 in 100,000, and the RRVs for the different age groups and gender ranged from 0.77 Gycm2 and 2.1 Gycm2 for neonates (female, male) to 11 Gycm2 and 25 Gycm2 for 15-year-olds (female, male). The CCREID:KAP and CCREIDHT:KAP decreased biexponentially with increased age, being notably higher for female patients. Prominent risk contributing organs were the lungs and the (female) breast. The concept of age-specific and gender-specific RRVs related to population cancer risk is introduced and is intended to be used as a supporting tool for physicians performing such interventions. Age-related and gender-related conversion coefficients for radiation risk, CCREID:KAP and CCREIDHT:KAP, are introduced and a novel risk surveillance concept, the RRV, is suggested for paediatric cardiac catheterizations.

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.

Experimental evaluation of a radiation dose management system-integrated 3D skin dose map by comparison with XR-RV3 Gafchromic® films

ObjectiveTo assess the interactive Skin Dose Map® tool (SDMTool) integrated to the radiation dose management system (RDMS) DoseWatch® with Gafchromic® films for implementation in routine practice. MethodsA retrospective dose estimation software SDMTool was used to calculate Peak Skin Dose (PSD) and display the patient skin dose distribution. PSD was calculated with a triangle mesh of 0.055 cm2 resolution on ICRP 110 male anthropomorphic phantom and with a square ROI of 1 cm2 on flat phantom. The tool uses Radiation Dose Structured Reports (RDSR) data to model exposure events and calculate the PSD per event. The PSD and the skin dose distribution estimated with SDMTool were evaluated in comparison with Gafchromic® films positioned under the PMMA phantom (20 cm) for 13 configurations. Measurements were performed on a Philips system. Statistical analysis were carried out to compare PSDFilm and PSDSDM. ResultsAverage differences between PSDFilm and PSDSDM were 6% ± 6% (range from −3% to 22%) for flat phantom and 5% ± 7% (range from −3% to 25%) for ICRP phantom. Concordance was good between the measured PSDFilm and the estimated PSDSDM with Lin’s coefficient estimation and 95% Confidence Interval of 0.979 [0.875; 0.984] for flat phantom and 0.977 [0.877; 0.985] for ICRP phantom. Dose map representations are concordant for 11 of the 13 tests on PMMA phantom. Disparities arose from the limitations of the RSDR format: table displacement during fluoroscopy events and the use of wedge filter. ConclusionThe results found in this experimental evaluation show that the SDMTool is a suitable alternative to Gafchromic® film to calculate PSD.

A scalable database of organ doses for common diagnostic fluoroscopy examinations of children: procedures of current practice at the University of Florida

Of all the medical imaging modalities that utilize ionizing radiation, fluoroscopy proves to be the most difficult to assess values of patient organ dose owing to the dynamic and patient-specific nature of the irradiation geometry and its associated x-ray beam characteristics. With the introduction of the radiation dose structured report (RDSR) in the mid-2000s, however, computational tools have been developed to extract patient and procedure-specific data for each irradiation event of the study, and when coupled to a computational phantom of the patient, values of skin and internal organ dose may be assessed. Unfortunately, many legacy and even current diagnostic fluoroscopy units do not have RDSR reporting capabilities, thus limiting these dosimetry reporting advances. Nevertheless, knowledge of patient organ doses for patient care, as well as for radiation epidemiology studies, remains a research and regulatory priority. In this study, we created procedural outlines which document all radiation exposure information required for organ dose assessment, akin to a reference RDSR, for six common diagnostic fluoroscopy procedures performed at the University of Florida (UF) Shands Pediatric Hospital. These procedures include the voiding cystourethrogram, the gastrostomy-tube placement, the lower gastrointestinal study, the rehabilitation swallow, the upper gastrointestinal study, and the upper gastrointestinal study with follow through. These procedural outlines were used to develop an extensive database of organ doses for the 162-member UF/NCI (National Cancer Institute) library of pediatric hybrid phantoms, with each member varying combinations of sex, height, and weight. The organ dose assessment accounts for the varying x-ray fields, fluoroscopy time, relative concentration of x-ray contrast in the organs, and changes in the fluoroscope output due to patient size. Furthermore, we are also reporting organ doses normalized to total fluoroscopy time, reference point air kerma, and kerma-area product, effectively providing procedure dose coefficients. The extensive organ dose library produced in this study may be used prospectively for patient organ dose reporting or retrospectively in epidemiological studies of radiation-associated health risks.

Calculating organ and effective doses in paediatric interventional cardiac radiology based on DICOM structured reports – Is detailed examination data critical to dose estimates?

PurposeTo estimate effective dose (E), equivalent organ doses (HT) and associated conversion coefficients (CCE:KAP = E/KAP, CCHT:KAP = HT/KAP; KAP = Kerma-area product) in paediatric cardiac interventions, using detailed exposure data from radiation dose structured reports (RDSR). These “RDSR dose estimations” have been compared with estimations performed using the approach currently implemented in the clinic that is based on a simplified assumptions method (SAM). MethodsThe Monte Carlo system PCXMC, incorporated into a previously developed framework, was used to calculate E and HT for 202 children. The calculations were performed with input values from RDSR, and also using simplified assumptions, including fixed nominal values for the focus-skin distance, collimated beam size, irradiation geometry and patient size (age, weight and height). ResultsMean HT to critical organs were: 5–25 mSv (lungs), 5–8 mSv (breasts) and 5–22 mSv (heart), with the lower and upper end of the doses associated with the neonatal and 15 years group, respectively. The associated mean CCHT:KAP for the different age groups were: 9.4–1.6 mSv/Gycm2 (lungs), 8.9–0.54 mSv/Gycm2 (breasts) and 9.3–1.4 mSv/Gycm2 (heart). ConclusionsThe extension of the concept of a conversion coefficient for HT is introduced and CCHT:KAP values for paediatric cardiac interventions divided in age groups are presented. This method of linking the KAP to HT is intended for use in epidemiological/cohort studies or in clinics that do not have access to RDSR. Further, the population-averaged conversion coefficients for the critical organs estimated from RDSR, displayed no statistically significant difference compared with the SAM approach.

Benchmarking the DACS-integrated Radiation Dose Monitor® skin dose mapping software using XR-RV3 Gafchromic® films.

To perform a benchmark of a new DACS-integrated patient skin dose mapping solution using on-phantom measurements with Gafchromic® films. To calculate cumulative patient skin dose distribution with 1-cm2 resolution, a Radiation Dose Monitor (RDM, Medsquare), using the Radiation Dose Structured Report (RDSR), tabulated backscatter and mass energy absorption coefficients together with site-specific corrections for table, mattress attenuation, and air kerma calibration factor. Peak skin dose (PSD) and two-dimensional (2D) skin dose distributions calculated with RDM were compared against on-phantom measurements with XR-RV3 Gafchromic® films considering two widely used x-ray equipment. Seventeen different settings which include simple and multiple beam projections with extreme angulations (up to 75°), all available fields-of-view (FOVs 48-11cm), additional collimation, variable table height and lateral positions, and variable phantom thickness (12, 20, and 30cm) were involved. Due to a careful calibration of films using clinical beam qualities, 22.8% (k=2) overall measurement uncertainty was achieved. Calculated and measured PSD values agreed with an average difference of 10%±7% and 9%±7% for 34 test conditions performed on Siemens Artis Zee and GEMS Innova IGS interventional systems, respectively. Finally, RDM's 2D skin dose maps closely matched those registered on XR-RV3 films considering the 1-cm2 resolution. While RDM correctly reproduced beam overlapping due to variable tube projections, FOV, table positions, etc., few challenges were identified related to conversion of rectangular fields to square areas in the RDSR and a stair-step effect visible for large tube projections (>45°). The accuracy of RDM's DACS-integrated skin dose mapping software was acceptable considering measurement uncertainties associated with Gafchromic® films.

P023] Estimating patient peak skin dose with fluoroscopic procedures

Purpose Deterministic radiation induced patient skin injuries may be caused by time consuming and complex fluoroscopic procedures. Post-procedure dose analysis can provide valuable feedback for optimisation of exposures in interventional radiology and follow-up of individual patients. However, lack of accuracy when estimating patient peak skin dose (PSD) can lead to inappropriate action levels and follow-up routines. It is common to use action levels entirely based on the interventional reference point (IRP) cumulative Air kerma, spatially located 15 cm from the irradiation geometry isocentre. This metric lacks influence of physical effects needed to estimate PSD, e.g., specifics of the irradiation event, conversion of Air kerma to absorbed skin dose, scattered radiation, and pre-patient attenuation. Modern radiologic equipment commonly reports irradiation event details in a radiation dose structured report (RDSR), as described by the NEMA DICOM standard. For fluoroscopy equipment the RDSR contains important information, e.g., X-ray beam field size, IRP Air kerma, number of images, X-ray beam filtration and X-ray tube voltage. The RDSR is thus a useful data source for estimation of PSD with fluoroscopic procedures. Methods Pertinent correction methods and data for PSD estimation were summarized by literature review and beam quality- and geometry dependent functions were developed in the PythonTM programming language v3.6 (Python Software Foundation). The RDSR from two different fluoroscopic devices; Siemens Artis Zee (Siemens Healthineers, Erlangen, Germany) and Philips Allura Clarity (Philips, Amsterdam, Netherlands), were examined and information required as input for the developed functions was identified. Results This work resulted in an open source Python™ script for RDSR parsing and patient PSD estimation; including table-top and mattress attenuation, Air kerma to absorbed skin dose conversion, forward and back scatter. PSD estimates were verified and compared to IRP Air-kerma. Conclusions The estimation of patient PSD with fluoroscopic procedures is greatly assisted by information found in fluoroscopy device RDSR. With refined dose metrics the specificity of patient PSD estimates may be increased, e.g., compared to the IRP Air kerma. Combining RDSR information and novel methods for refining patient dose metrics found in the literature can improve the management of patients after interventional radiology procedures.

OA102] Correlation between cumulative dose and peak skin dose using gafchromic films for patients undergoing interventional cardiology procedures

Purpose During last years Interventional Cardiology (IC) procedures have increased in number and complexity thus the concern about radiation dose to patients and radiation damages is increasing too. The aim of the work is to examine the radiation exposure of patients undergoing IC procedures and evaluating the deterministic risk in terms of Peak Skin Dose (PSD). Methods 40 procedures involving adult patients undergoing Coronary Angiography (CA) and Percutaneous Transluminal Coronary Angioplasty (PTCA) were involved. The procedures were performed at our institution by means of an Allura Clarity and Axiom Artis angiographic system. PSD was measured in vivo using calibrated radiochromic GafChromic XR-RV3 films and Cumulative Dose at the Interventional Reference Point (CD), reported in the Radiation Dose Structured Reports (RDSR), was collected. Linear regression between measured PSD and CD was investigated for both the angiographic systems. Results The CD values are generally higher and more variable for PTCA than for CA, due to the different procedure complexity. Mean PSD was found (103 ± 64) Gy for CA, (526 ± 436) Gy for PTCA, respectively. For the same type of procedure, values result lower on Allura Clarity system, due to his powerful dose-reduction strategies. The correlation obtained between PSD and CD was found to be good (R2 = 0.76 for Axiom Artis, R2 = 0.83 for Allura Clarity). The CD values corresponding to a PSD of 2 Gy (threshold for deterministic skin effects) are 6.0 Gy for Axiom Artis and 3.5 Gy for Allura Clarity system, respectively. Conclusions The study confirmed that IC procedures can deliver high levels of radiation dose to patients, dose increases with the complexity of procedures and can significantly depend on the X-Rays system. The correlation between PSD and CD can effectively support clinicians in identifying and managing patients at risk for deterministic effects.

OA221] The dose to the lens of the eye for the heart team performing transcatheter aortic valve implementation (TAVI): Is there any concern for cataract?

Purpose To estimate and assess the lens doses to the heart team performing transcatheter aortic valve implementation (TAVI) from latest generation of interventional x-ray equipment and to establish correlations between the equivalent lens dose for each profession and the patient dose (dose-area product, DAP). Methods Thermoluminescence dosimeters (TLD) have been used to measure the lens dose without lead glasses, to the medical staff, in a cohort of 24 TAVI procedures. Detailed exam-specific dose-related data from radiation dose structured reports (RDSR) was used to analyze the components contributing to the operator’s eye lens dose. Results The mean annual dose (150 TAVI procedures) to the lens of the eye for the whole heart team (primary operator, secondary operator, anesthesiologist and the nurse) was 4.3 ± 1.5, 1.9 ± 0.68, 3.9 ± 1.4 and 1.1 ± 0.40 mSv. The mean DAP-value per procedure was 27 ± 19 Gycm2. The primary operator is exposed to the highest radiation dose with a conversion coefficient (equivalent dose to the lens/DAP) of 1.1 ± 0.27 μSv/Gycm2 of the left eye lens followed by the anesthesiologist, who was exposed for almost equally high lens doses but in both lenses, and the secondary operator with 0.48 ± 0.12 μSv/Gycm2 of the left eye lens. The nurse is located at a safe distance with the lowest conversion factor for the left eye lens (0.27 ± 0.069 μSv/Gycm2). Conclusions In modern interventional x-ray equipment, the TAVIs will contribute to radiation dose levels below the threshold value for cataract as long as a ceiling mounted shield is used. The information from the RDSR shows that the highest dose contribution to the primary operator’s lens is from the second half of the procedure due to the aortography section consisting of image acquisitions.