To help operators acknowledge patient dose during interventional procedures, EURADOS WG-12 focused on measuring patient skin dose using XR-RV3 gafchromic films, thermoluminescent detector (TLD) pellets or 2D TL foils and on investigating possible correlation to the on-line dose indicators such as fluoroscopy time, Kerma-area product (KAP) and cumulative air Kerma at reference point (CK). The study aims at defining non-centre-specific European alert thresholds for skin dose in three interventional procedures: chemoembolization of the liver (CE), neuroembolization (NE) and percutaneous coronary interventions (PCI). Skin dose values of >3 Gy (ICRP threshold for skin injuries) were indeed measured in these procedures confirming the need for dose indicators that correlate with maximum skin dose (MSD). However, although MSD showed fairly good correlation with KAP and CK, several limitations were identified challenging the set-up of non-centre-specific European alert thresholds. This paper presents preliminary results of this wide European measurement campaign and focuses on the main challenges in the definition of European alert thresholds.
- MeSH
- absorpce radiace MeSH
- fyziologie kůže účinky záření MeSH
- intervenční radiografie metody MeSH
- kardiovaskulární chirurgické výkony metody MeSH
- kůže radiografie MeSH
- lidé MeSH
- maximální přípustná koncentrace MeSH
- radiometrie přístrojové vybavení metody MeSH
- rentgenové záření * MeSH
- reprodukovatelnost výsledků MeSH
- senzitivita a specificita MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- multicentrická studie MeSH
- srovnávací studie MeSH
PURPOSE: Point detectors are frequently used to measure patient's maximum skin dose (MSD) in fluoroscopically-guided interventional procedures (IP). However, their performance and ability to detect the actual MSD are rarely evaluated. The present study investigates the sampling uncertainty associated with the use of grids of point detectors to measure MSD in IP. METHOD: Chemoembolisation of the liver (CE), percutaneous coronary intervention (PCI) and neuroembolisation (NE) procedures were studied. Spatial dose distributions were measured with XR-RV3 Gafchromic(®) films for 176 procedures. These distributions were used to simulate measurements performed using grids of detectors such as thermoluminescence detectors, with detector spacing from 1.4 up to 10 cm. RESULTS: The sampling uncertainty was the highest in PCI and NE procedures. With 40 detectors covering the film area (36 cm × 44 cm), the maximum dose would be on average 86% and 63% of the MSD measured with Gafchromic(®) films in CE and PCI procedures, respectively. In NE procedures, with 27 detectors covering the film area (14 cm × 35 cm), the maximum dose measured would be on average 82% of the MSD obtained with the Gafchromic(®) films. CONCLUSION: Thermoluminescence detectors show good energy and dose response in clinical beam qualities. However the poor spatial resolution of such point-like dosimeters may far outweigh their good dosimetric properties. The uncertainty from the sampling procedure should be estimated when point detectors are used in IP because it may lead to strong underestimation of the MSD.
PURPOSE: To investigate the optimal use of XR-RV3 GafChromic(®) films to assess patient skin dose in interventional radiology while addressing the means to reduce uncertainties in dose assessment. METHODS: XR-Type R GafChromic films have been shown to represent the most efficient and suitable solution to determine patient skin dose in interventional procedures. As film dosimetry can be associated with high uncertainty, this paper presents the EURADOS WG 12 initiative to carry out a comprehensive study of film characteristics with a multisite approach. The considered sources of uncertainties include scanner, film, and fitting-related errors. The work focused on studying film behavior with clinical high-dose-rate pulsed beams (previously unavailable in the literature) together with reference standard laboratory beams. RESULTS: First, the performance analysis of six different scanner models has shown that scan uniformity perpendicular to the lamp motion axis and that long term stability are the main sources of scanner-related uncertainties. These could induce errors of up to 7% on the film readings unless regularly checked and corrected. Typically, scan uniformity correction matrices and reading normalization to the scanner-specific and daily background reading should be done. In addition, the analysis on multiple film batches has shown that XR-RV3 films have generally good uniformity within one batch (<1.5%), require 24 h to stabilize after the irradiation and their response is roughly independent of dose rate (<5%). However, XR-RV3 films showed large variations (up to 15%) with radiation quality both in standard laboratory and in clinical conditions. As such, and prior to conducting patient skin dose measurements, it is mandatory to choose the appropriate calibration beam quality depending on the characteristics of the x-ray systems that will be used clinically. In addition, yellow side film irradiations should be preferentially used since they showed a lower dependence on beam parameters compared to white side film irradiations. Finally, among the six different fit equations tested in this work, typically used third order polynomials and more rational and simplistic equations, of the form dose inversely proportional to pixel value, were both found to provide satisfactory results. Fitting-related uncertainty was clearly identified as a major contributor to the overall film dosimetry uncertainty with up to 40% error on the dose estimate. CONCLUSIONS: The overall uncertainty associated with the use of XR-RV3 films to determine skin dose in the interventional environment can realistically be estimated to be around 20% (k = 1). This uncertainty can be reduced to within 5% if carefully monitoring scanner, film, and fitting-related errors or it can easily increase to over 40% if minimal care is not taken. This work demonstrates the importance of appropriate calibration, reading, fitting, and other film-related and scan-related processes, which will help improve the accuracy of skin dose measurements in interventional procedures.
The article reports results from the largest international dose survey in paediatric computed tomography (CT) in 32 countries and proposes international diagnostic reference levels (DRLs) in terms of computed tomography dose index (CTDI vol) and dose length product (DLP). It also assesses whether mean or median values of individual facilities should be used. A total of 6115 individual patient data were recorded among four age groups: <1 y, >1-5 y, >5-10 y and >10-15 y. CTDIw, CTDI vol and DLP from the CT console were recorded in dedicated forms together with patient data and technical parameters. Statistical analysis was performed, and international DRLs were established at rounded 75th percentile values of distribution of median values from all CT facilities. The study presents evidence in favour of using median rather than mean of patient dose indices as the representative of typical local dose in a facility, and for establishing DRLs as third quartile of median values. International DRLs were established for paediatric CT examinations for routine head, chest and abdomen in the four age groups. DRLs for CTDI vol are similar to the reference values from other published reports, with some differences for chest and abdomen CT. Higher variations were observed between DLP values, based on a survey of whole multi-phase exams. It may be noted that other studies in literature were based on single phase only. DRLs reported in this article can be used in countries without sufficient medical physics support to identify non-optimised practice. Recommendations to improve the accuracy and importance of future surveys are provided.
- MeSH
- dávka záření MeSH
- dítě MeSH
- internacionalita MeSH
- kojenec MeSH
- lidé MeSH
- mladiství MeSH
- monitorování radiace normy statistika a číselné údaje MeSH
- novorozenec MeSH
- pediatrie normy MeSH
- počítačová rentgenová tomografie normy statistika a číselné údaje MeSH
- předškolní dítě MeSH
- průzkumy zdravotní péče MeSH
- radiační expozice normy statistika a číselné údaje MeSH
- referenční hodnoty MeSH
- Check Tag
- dítě MeSH
- kojenec MeSH
- lidé MeSH
- mladiství MeSH
- mužské pohlaví MeSH
- novorozenec MeSH
- předškolní dítě MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
The purpose of this work was an evaluation of organ doses and effective doses from three verification techniques in Image-Guided Radiotherapy: from kilovoltage (kV) cone beam computed tomography (CBCT) scans, from two orthogonal kV images and from two orthogonal megavoltage (MV) images for two different treatment sites: pelvis and head and neck (H&N). For comparison reasons, organ doses and effective doses from prostate and H&N radiotherapy were also evaluated. Measurements of organ doses were performed in a male anthropomorphic Rando phantom by means of thermoluminescent dosemeters. In this investigation, measured organ doses from one CBCT scan, from two MV images and from two kV images of pelvis represent typically 1-6, 1-10 and 0.05-1 %, respectively, of organ doses resulting from one fraction of prostate radiotherapy. The maximum effective doses from CBCT scans, kV images and MV images of pelvis are 5.6, 0.8 and 11.9 mSv, respectively.
- MeSH
- celková dávka radioterapie MeSH
- fantomy radiodiagnostické MeSH
- hlava radiografie MeSH
- krk radiografie MeSH
- lidé MeSH
- nádory prostaty radiografie radioterapie MeSH
- pánev radiografie MeSH
- počítačová tomografie s kuželovým svazkem MeSH
- radioterapie řízená obrazem MeSH
- termoluminiscenční dozimetrie MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
In this study, skin dosimetry of patients undergoing interventional cardiology procedures is presented. Three hospitals were included. Two methods were used for skin dosimetry--radiochromic dosimetry films and reconstruction of skin dose distribution based on examination protocol. Maximum skin doses (MSD) obtained from both methods were compared for 175 patients. For patients for whom the film MSD was >1 Gy, the reconstruction MSD differed from the film MSD in the range of ± 50 % for 83 % of patients. For remaining patients, the difference was higher and it was caused by longer fluoroscopy time. For 59 patients for whom the cumulative dose was known, the cumulative dose was compared with the film MSD. Skin dosimetry with radiochromic films is more accurate than the reconstruction method, but films do not include X-ray fields from lateral projections whilest reconstructions do.
- MeSH
- dávka záření MeSH
- filmová dozimetrie přístrojové vybavení metody MeSH
- intervenční radiografie MeSH
- kůže účinky záření radiografie MeSH
- lidé MeSH
- retrospektivní studie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- multicentrická studie MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Česká republika MeSH
