- Email: [email protected]
Tackling the commissioning of a digital radiography AEC system
E. Keavey et al. / Physica Medica 52 (2018) 165–182
the project will be explored and the salient findings will be presented. In conclusion, a novel adaptation of an industry standard DQE technique developed by our group is shown to be appropriate for use in a clinical environment. https://doi.org/10.1016/j.ejmp.2018.06.060
Poster Session P28 Independent assessment of MRI-induced temperature change and SAR distributions in phantoms Niall Colgan a,*, James Blackwell a, Wil Van der Putten b, Brendan Tuohy b a
Department of Physics, National University of Ireland Galway, Galway, Ireland b Medical Physics and Bioengineering, Galway University Hospital, Galway, Ireland E-mail address: [email protected] Background. During an MR procedure, most of the transmitted RF power is transformed into heat referred to as the specific energy absorption rate(SAR). EU directive(IEC60602-3-33) mandates all scanners must measure SAR and provide safeguards for tissuelimits. Accurate estimation of SAR is critical in safeguarding vulnerable patients. Modern MRI systems can easily exceed safe SAR levels and our aim is to develop a protocol to verify patient specific SAR using a MR phantom heated solely by the RF fields. Methods. Our phantom is a non-perfused material simplifying pennes-bioheat equation. The SAR at discreet points in the observation plane is determined by SARC_agar DT=Dt[Wnkg] Where C_agar is 4200 J/kg.K, DT is the change in temperature and Dt is the change in time. DT was determined via Proton Resonance Frequency Shift (PRF) thermometry. DT ¼ ð/ / 0Þ/(acB_0 TE) Where. https://doi.org/10.1016/j.ejmp.2018.06.061
Poster Session P29 Tackling the commissioning of a digital radiography AEC system Aisling McMahon, Edward Ranahan, James McCullagh Cork University Hospital, Ireland E-mail address: [email protected] AEC devices aim to maintain a consistent level of clinical image quality despite variations in patient body habitus and imaging method. The assessment of AEC performance has undergone significant revision with the advent of digital radiography and challenges still remain. Verification of manufacturers’ target detector air kerma (DAK) values with differing AEC testing protocols can be problematic, particularly when the system has been configured with integrated direct digital radiography (DDR) detectors. In addition, there is a need for comparative dose information from current DDR technology to be made available to the wider Medical Physics community. AEC testing was performed on 4 recently-installed Carestream DRX Evolution Plus digital radiographic systems as part of their commissioning tests. AEC calibration was assessed using 3 IPEMrecommended parameters; DAK, image pixel value and detector dose indicator (DDI). Testing was performed with both free and
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scatter-free configurations and with and without antiscatter grid. A mixture of exit dose and in-bucky measurements were performed with the assistance of a field service engineer (FSE) for both free and integrated detectors. Results from the AEC testing of the four Carestream digital radiographic systems are presented for different testing conditions along with hints and tips on assessing the AEC dose levels when commissioning the systems. DAK results are compared to the manufacturers target values and to Bowden et al.’s (2011) published results on other DDR systems. These results could be used as initial AEC reference values against which others can compare their results when commissioning comparable systems. https://doi.org/10.1016/j.ejmp.2018.06.062
Poster Session P30 Breast dose audit of a symptomatic service James McCullagh, Aisling McMahon Cork University Hospital, Ireland E-mail address: [email protected] Monitoring breast dose is as important for the estimation of the radiation risk in a symptomatic service as it is in a national screening programme. The view generally held that special resources are needed to perform breast dose surveys has limited this service and others like it, from compliance with patient radiation safety legislation. In fact any medical physics department providing a support service to a breast imaging unit should be able to carry out a dose survey. This poster is a presentation of the results obtained from a dose survey of the symptomatic breast service provided in this hospital. Using a combination of commonly available software, exposure data from the examinations of 50 patients per mammography X-ray machine was compiled to perform the survey. It was found that the average breast MGD in the unit was 1.52 and 1.7 mGy for the CC and OB views, respectively. There are three digital mammography systems in the unit and the average MGD values for an OB view of compressed thickness 61 ± 5 mm on each unit was 1.59, 1.45 and 1.51 mGy. The breast dose performance of individual mammography Xray machines were commensurate with results reported in a previous survey of symptomatic services. The overall dose performance was compliant with dose reference levels established by both the national screening programme and a national dose survey of symptomatic services. This work has demonstrated the possibility of any symptomatic service utilising commonly available resources to assess breast dose performance in its own unit. https://doi.org/10.1016/j.ejmp.2018.06.063
Poster Session P31 Clinical performance of digital mammography systems in a breast screening programme – An update Elizabeth Keavey, Niall Phelan, Patricia Fitzpatrick BreastCheck, The National Screening Service, Ireland E-mail address: [email protected] The purpose of this research was to compare the clinical performance of three individual digital mammography (DM) systems
the project will be explored and the salient findings will be presented. In conclusion, a novel adaptation of an industry standard DQE technique developed by our group is shown to be appropriate for use in a clinical environment. https://doi.org/10.1016/j.ejmp.2018.06.060
Poster Session P28 Independent assessment of MRI-induced temperature change and SAR distributions in phantoms Niall Colgan a,*, James Blackwell a, Wil Van der Putten b, Brendan Tuohy b a
Department of Physics, National University of Ireland Galway, Galway, Ireland b Medical Physics and Bioengineering, Galway University Hospital, Galway, Ireland E-mail address: [email protected] Background. During an MR procedure, most of the transmitted RF power is transformed into heat referred to as the specific energy absorption rate(SAR). EU directive(IEC60602-3-33) mandates all scanners must measure SAR and provide safeguards for tissuelimits. Accurate estimation of SAR is critical in safeguarding vulnerable patients. Modern MRI systems can easily exceed safe SAR levels and our aim is to develop a protocol to verify patient specific SAR using a MR phantom heated solely by the RF fields. Methods. Our phantom is a non-perfused material simplifying pennes-bioheat equation. The SAR at discreet points in the observation plane is determined by SARC_agar DT=Dt[Wnkg] Where C_agar is 4200 J/kg.K, DT is the change in temperature and Dt is the change in time. DT was determined via Proton Resonance Frequency Shift (PRF) thermometry. DT ¼ ð/ / 0Þ/(acB_0 TE) Where. https://doi.org/10.1016/j.ejmp.2018.06.061
Poster Session P29 Tackling the commissioning of a digital radiography AEC system Aisling McMahon, Edward Ranahan, James McCullagh Cork University Hospital, Ireland E-mail address: [email protected] AEC devices aim to maintain a consistent level of clinical image quality despite variations in patient body habitus and imaging method. The assessment of AEC performance has undergone significant revision with the advent of digital radiography and challenges still remain. Verification of manufacturers’ target detector air kerma (DAK) values with differing AEC testing protocols can be problematic, particularly when the system has been configured with integrated direct digital radiography (DDR) detectors. In addition, there is a need for comparative dose information from current DDR technology to be made available to the wider Medical Physics community. AEC testing was performed on 4 recently-installed Carestream DRX Evolution Plus digital radiographic systems as part of their commissioning tests. AEC calibration was assessed using 3 IPEMrecommended parameters; DAK, image pixel value and detector dose indicator (DDI). Testing was performed with both free and
179
scatter-free configurations and with and without antiscatter grid. A mixture of exit dose and in-bucky measurements were performed with the assistance of a field service engineer (FSE) for both free and integrated detectors. Results from the AEC testing of the four Carestream digital radiographic systems are presented for different testing conditions along with hints and tips on assessing the AEC dose levels when commissioning the systems. DAK results are compared to the manufacturers target values and to Bowden et al.’s (2011) published results on other DDR systems. These results could be used as initial AEC reference values against which others can compare their results when commissioning comparable systems. https://doi.org/10.1016/j.ejmp.2018.06.062
Poster Session P30 Breast dose audit of a symptomatic service James McCullagh, Aisling McMahon Cork University Hospital, Ireland E-mail address: [email protected] Monitoring breast dose is as important for the estimation of the radiation risk in a symptomatic service as it is in a national screening programme. The view generally held that special resources are needed to perform breast dose surveys has limited this service and others like it, from compliance with patient radiation safety legislation. In fact any medical physics department providing a support service to a breast imaging unit should be able to carry out a dose survey. This poster is a presentation of the results obtained from a dose survey of the symptomatic breast service provided in this hospital. Using a combination of commonly available software, exposure data from the examinations of 50 patients per mammography X-ray machine was compiled to perform the survey. It was found that the average breast MGD in the unit was 1.52 and 1.7 mGy for the CC and OB views, respectively. There are three digital mammography systems in the unit and the average MGD values for an OB view of compressed thickness 61 ± 5 mm on each unit was 1.59, 1.45 and 1.51 mGy. The breast dose performance of individual mammography Xray machines were commensurate with results reported in a previous survey of symptomatic services. The overall dose performance was compliant with dose reference levels established by both the national screening programme and a national dose survey of symptomatic services. This work has demonstrated the possibility of any symptomatic service utilising commonly available resources to assess breast dose performance in its own unit. https://doi.org/10.1016/j.ejmp.2018.06.063
Poster Session P31 Clinical performance of digital mammography systems in a breast screening programme – An update Elizabeth Keavey, Niall Phelan, Patricia Fitzpatrick BreastCheck, The National Screening Service, Ireland E-mail address: [email protected] The purpose of this research was to compare the clinical performance of three individual digital mammography (DM) systems