- Email: [email protected]
3D image acquisition in scoliosis correction surgery: Radiation exposure of a paediatric patient cohort
D. Murphy, S. McCoubrey / Physica Medica 52 (2018) 165–182
NEMA Cardiology Phantom and a homemade linear motion phantom were used to investigate the impact of Motion Recursive Filtering on image quality in LDA. Systems assessed were: Philips Alura FD 20, Alura Clarity FD 10 and Siemens Artis Zee systems. All systems using LDA demonstrated different levels of Temporal Ghosting. The Intensity and spacing of the ghost images was dependent on system type, protocol and pulse rate. The impact of temporal ghosting impinges on the effective optimisation of clinical systems. The impact of temporal ghosts should be assessed during the commissioning and optimisation stages for all digital angiography systems. https://doi.org/10.1016/j.ejmp.2018.06.046
Poster Session P14 Challenges and opportunities for a CAMPEP-accredited medical physics graduate program Christoph Kleefeld a, Mark Foley b
175
Photosensitive acrylate polymers can be spatially patterned to produce layers of alternating optical contrast using multi-beam interference patterns of laser light. This technology is widely used for the fabrication of photonic devices including optical sensors and holographic elements [1,2]. Here, the use of photonic Bragg structures fabricated in a pressure-sensitive photopolymer [3] for the calibration of therapeutic ultrasound pressure output is presented. On exposure to ultrasound pressure waves, the Bragg structure is compressed, inducing a change in the spacing of the periodic layers of varying optical contrast and, thus, changing the devices readout wavelength i.e. colour. The device colour change due to pressure can either be visually assessed or spectroscopically interrogated for more accurate pressure quantification. This technology offers a fast, straight-forward and low-cost method for regular mapping and calibration of ultrasound pressure output. This is crucial for quality assurance of therapeutic ultrasound scanners used in Extracorporeal Shock Wave Lithotripsy and High Intensity Focused Ultrasound. To date, the photopolymer composition and Bragg device structure has been optimised for MPa range pressures. Results from the optimisation and characterisation of the pressure-sensitive devices are presented.
a
University Hospital Galway, Ireland National University of Ireland Galway, Ireland E-mail address: [email protected] b
A long running MSc in Medical Physics program, delivered by a close university – hospital collaboration, was awarded CAMPEP accreditation in 2015. This presentation will give an outline of the current program structure and will identify challenges likely affecting the areas of teaching, research and course administration. Strategies to address these challenges will be discussed. Challenges evolve from the accreditation itself, the adjustment of the existing course curriculum where modules were only partially compliant, from the transposition of the EU council directive into Irish law, and from policies of the host university. Since the accreditation the number of students enrolled in the program increased from 8 in 2015/16 and 16 in 2016/17 to 21 in 2017/18. The number of non-EU students in these cohorts was 2, 5, and 4, respectively. The total number of applicants averages at approximately 50 per year. A further increase in student intake has been advocated but might impact negatively on the quality of the clinical training which forms a vital part of the program. Students are given access to clinical systems for laboratory exercises as well as for pursuing research projects, gaining some clinical experience which will increase their employability. However, local clinical access has to be limited. In order to mitigate the situation, the program cooperates with medical physics departments nationwide, thus contributing to an active Irish research landscape. A related issue, the mismatch between the number of available residency positions and the number of graduates, will be further expanded on. https://doi.org/10.1016/j.ejmp.2018.06.047
Poster Session P15 A novel calibration device for quality assurance of therapeutic ultrasound Dervil Cody a, Tatsiana Mikulchyk a, Jacinta Browne b, Sabad-e Gul a, Izabela Naydenova a a
Centre for Industrial and Engineering Optics, School of Physics and Clinical and Optometric Sciences, Dublin Institute of Technology, Ireland b Medical Physics and Ultrasound Group, School of Physics and Clinical and Optometric Sciences, Dublin Institute of Technology, Ireland E-mail address: [email protected]
References 1. Zawadzka M, Mikulchyk T, Cody D, Martin S, Mihaylova E, Yetisen AK, et al.. Photonic materials for holographic sensing. Springer; 2016. 2. Akbari H, Naydenova I, Martin S. Using acrylamide based photopolymers for fabrication of holographic optical elements in solar energy applications. Appl. Opt. 2014;53:1343–53. 3. Mihaylova E, Cody D, Naydenova I, Martin S, Toal V. A Holographic Recording Composition. WO2016001108 A1; 7th Jan 2016. https://doi.org/10.1016/j.ejmp.2018.06.048
Poster Session P16 3D image acquisition in scoliosis correction surgery: Radiation exposure of a paediatric patient cohort Dara Murphy, Siobhan McCoubrey Our Lady’s Children’s Hospital, Crumlin, Ireland E-mail address: [email protected] 3D spine imaging has become a popular technique in orthopaedic surgery to assist with the placement of screws and rods for the treatment of scoliosis. It is most often used in combination with navigation software to reduce the risk of surgical-induced patient paralysis. One way to acquire this type of imaging is to use an X-ray c-arm that rotates around the patient, mimicking a cone beam CT acquisition. Although this technique has been successfully implemented in many centres, there is a deficit of information in the literature with regard to the consequent patient radiation exposure, in particular, where an eccentric or noncircular orbit is utilised. This information is particularly important for paediatric patients, as they are the most likely candidates for this type of surgery. Our study estimates the radiation dose to paediatric patients who have undergone scoliosis correction surgery, using the proprietary non-circular orbit employed by a Ziehm Vision RFD 3D C-arm. We estimate and compare patient organ doses using this eccentric orbit with one where a simple circular orbit is assumed. We further compare our calculated organ doses with those imparted by traditional 2D fluoroscopic techniques, and calculate the risk of future radiation induced cancer for this patient cohort. The doses presented here will be useful
176
N. McWilliams et al. / Physica Medica 52 (2018) 165–182
to other centres in establishing diagnostic reference levels for this increasingly common technique. https://doi.org/10.1016/j.ejmp.2018.06.049
Poster Session P17 Quantitative MRI volumetry in the detection of mesial temporal sclerosis in patients with refractory epilepsy Michael O’Neill Beaumont Hospital, Ireland E-mail address: [email protected] One third of patients who suffer from epilepsy are resistant to anti-epileptic medication, known as refractory epilepsy. These patients may be considered for surgical resection, where a portion of brain tissue which is believed to be involved in the seizure onset is removed. In the most common form of epilepsy, temporal lobe epilepsy (TLE), structures such as the hippocampus are often found to be involved. An indicator that the hippocampus may be related to the seizure onset is the presence of mesial temporal sclerosis (mTS), which is noted by a loss of internal architecture, reduced hippocampal volume and hyperintensity on T2-weighted MRI. The published literature indicates that a radiological evaluation of mTS supported by hippocampal volumetry can indicate a better postoperative outcome for patients. This project evaluates the use of software packages to produce volumetric estimates of these TL structures. These estimates were obtained for patients whose radiological reports indicate the presence and/or suspicion of mTS and a normal cohort. A comparison between Freesurfer and more specific hippocampal volumetric software packages was made. A database of normal MRI scans was compiled, this is age and gender matched for robust comparison and to reduce systematic error associated with comparing volumetric data. The software packages showed concordance with radiological reports by indicating a reduced hippocampal volume. Following on from this work and further validation of semi-automated volumetric analyses, it is hoped that this approach will be integrated into the pre-surgical evaluation workflow with the aim of improving the postoperative prognosis for patients. https://doi.org/10.1016/j.ejmp.2018.06.050
Poster Session P18 Risk and radiation exposure – An information poster for patients, parents and guardians Dara Murphy, Siobhan McCoubrey Our Lady’s Children’s Hospital, Crumlin, Ireland E-mail address: [email protected] We present an information poster detailing the risks associated with a variety of examinations employing ionising radiation in a paediatric radiology department. The poster aims to explain to patients, parents and guardians, the radiation doses associated with common radiology examinations and contextualise the risk in terms that can be understood by a non-medical audience. https://doi.org/10.1016/j.ejmp.2018.06.051
Poster Session P19 Comparison of 2D and 3D dosimetry parameters for breast planning Louise Fahy a, Maryam Alanazi b, James Murphy a a
University Hospital Galway, Ireland National University Ireland Galway, Ireland E-mail address: [email protected] b
Historically, external beam radiotherapy (EBRT) breast/chest wall treatment planning was a 2D process using breast contour and X-ray imaging, and the depth of the lung or heart in the treatment field was used to estimate the risk to these organs. Over the last two decades, the use of 3D CT imaging for breast treatment planning has become widespread but many centres still use Depth-in-Field for organ at risk (OAR) estimation. This is a retrospective study of breast cancer patients treated at our centre. The DVH parameters for lung and heart will be compared with the depth in the treatment field to investigate which of these parameters should be used in the clinic for plan evaluation. The treatment plans of 60 left-breast cancer patients treated with a prescription dose of 50 Gy in 25 fractions were reviewed. The results illustrated that there was a strong correlation between DVH parameters for the heart and the depth in field. Also, there was a strong correlation between DVH parameters and the lung depth in two field tangential plans. However, no correlation existed for plans with a third field to treat the supraclavicular area. There was not enough data to analyse the relation between the V107% of prescription dose and the depth in the treatment field. Moreover, comparing the results with clinical trials indicated that the mean dose and V20 Gy for heart and mean dose and V40 Gy for lung are valid parameters to look at when estimating the risk to heart and lung. https://doi.org/10.1016/j.ejmp.2018.06.052
Poster Session P20 Determining Diagnostic Reference Levels (DRLs) for Radiography and Fluorsocopy Procedures in a University Based Teaching Hospital Nina McWilliams a, Emerald House b, Matthew Donoghue b, Brendan Tuohy b a BreastCheck, Western Unit, National Screening Service, Newcastle Rd., Galway, Ireland b Dept. of Medical Physics and Clinical Engineering, University Hospital, Newcastle Rd., Galway, Ireland E-mail address: [email protected]
The introduction of the latest basic safety standard (BSS) into Irish legislation in 2018 will aid optimisation, justification and correction of high or low levels of radiation delivery as part of diagnostic procedures. Establishment and implementation of Local Diagnostic Reference Levels (LDRLs) play an important role in this optimisation process within Radiology Departments. This research focused on a review of LDRLs for both radiography and fluoroscopy procedures in a University based teaching hospital. LDRLs were based on the most commonly performed procedures in each room for adult patients (P18 years). As a retrospective dose audit, data acquisition was both manual, using the DICOM header information of individual images, and automatic using, Siemens CareAnalytics software. Dose-area product (DAP) data was acquired from fitted
NEMA Cardiology Phantom and a homemade linear motion phantom were used to investigate the impact of Motion Recursive Filtering on image quality in LDA. Systems assessed were: Philips Alura FD 20, Alura Clarity FD 10 and Siemens Artis Zee systems. All systems using LDA demonstrated different levels of Temporal Ghosting. The Intensity and spacing of the ghost images was dependent on system type, protocol and pulse rate. The impact of temporal ghosting impinges on the effective optimisation of clinical systems. The impact of temporal ghosts should be assessed during the commissioning and optimisation stages for all digital angiography systems. https://doi.org/10.1016/j.ejmp.2018.06.046
Poster Session P14 Challenges and opportunities for a CAMPEP-accredited medical physics graduate program Christoph Kleefeld a, Mark Foley b
175
Photosensitive acrylate polymers can be spatially patterned to produce layers of alternating optical contrast using multi-beam interference patterns of laser light. This technology is widely used for the fabrication of photonic devices including optical sensors and holographic elements [1,2]. Here, the use of photonic Bragg structures fabricated in a pressure-sensitive photopolymer [3] for the calibration of therapeutic ultrasound pressure output is presented. On exposure to ultrasound pressure waves, the Bragg structure is compressed, inducing a change in the spacing of the periodic layers of varying optical contrast and, thus, changing the devices readout wavelength i.e. colour. The device colour change due to pressure can either be visually assessed or spectroscopically interrogated for more accurate pressure quantification. This technology offers a fast, straight-forward and low-cost method for regular mapping and calibration of ultrasound pressure output. This is crucial for quality assurance of therapeutic ultrasound scanners used in Extracorporeal Shock Wave Lithotripsy and High Intensity Focused Ultrasound. To date, the photopolymer composition and Bragg device structure has been optimised for MPa range pressures. Results from the optimisation and characterisation of the pressure-sensitive devices are presented.
a
University Hospital Galway, Ireland National University of Ireland Galway, Ireland E-mail address: [email protected] b
A long running MSc in Medical Physics program, delivered by a close university – hospital collaboration, was awarded CAMPEP accreditation in 2015. This presentation will give an outline of the current program structure and will identify challenges likely affecting the areas of teaching, research and course administration. Strategies to address these challenges will be discussed. Challenges evolve from the accreditation itself, the adjustment of the existing course curriculum where modules were only partially compliant, from the transposition of the EU council directive into Irish law, and from policies of the host university. Since the accreditation the number of students enrolled in the program increased from 8 in 2015/16 and 16 in 2016/17 to 21 in 2017/18. The number of non-EU students in these cohorts was 2, 5, and 4, respectively. The total number of applicants averages at approximately 50 per year. A further increase in student intake has been advocated but might impact negatively on the quality of the clinical training which forms a vital part of the program. Students are given access to clinical systems for laboratory exercises as well as for pursuing research projects, gaining some clinical experience which will increase their employability. However, local clinical access has to be limited. In order to mitigate the situation, the program cooperates with medical physics departments nationwide, thus contributing to an active Irish research landscape. A related issue, the mismatch between the number of available residency positions and the number of graduates, will be further expanded on. https://doi.org/10.1016/j.ejmp.2018.06.047
Poster Session P15 A novel calibration device for quality assurance of therapeutic ultrasound Dervil Cody a, Tatsiana Mikulchyk a, Jacinta Browne b, Sabad-e Gul a, Izabela Naydenova a a
Centre for Industrial and Engineering Optics, School of Physics and Clinical and Optometric Sciences, Dublin Institute of Technology, Ireland b Medical Physics and Ultrasound Group, School of Physics and Clinical and Optometric Sciences, Dublin Institute of Technology, Ireland E-mail address: [email protected]
References 1. Zawadzka M, Mikulchyk T, Cody D, Martin S, Mihaylova E, Yetisen AK, et al.. Photonic materials for holographic sensing. Springer; 2016. 2. Akbari H, Naydenova I, Martin S. Using acrylamide based photopolymers for fabrication of holographic optical elements in solar energy applications. Appl. Opt. 2014;53:1343–53. 3. Mihaylova E, Cody D, Naydenova I, Martin S, Toal V. A Holographic Recording Composition. WO2016001108 A1; 7th Jan 2016. https://doi.org/10.1016/j.ejmp.2018.06.048
Poster Session P16 3D image acquisition in scoliosis correction surgery: Radiation exposure of a paediatric patient cohort Dara Murphy, Siobhan McCoubrey Our Lady’s Children’s Hospital, Crumlin, Ireland E-mail address: [email protected] 3D spine imaging has become a popular technique in orthopaedic surgery to assist with the placement of screws and rods for the treatment of scoliosis. It is most often used in combination with navigation software to reduce the risk of surgical-induced patient paralysis. One way to acquire this type of imaging is to use an X-ray c-arm that rotates around the patient, mimicking a cone beam CT acquisition. Although this technique has been successfully implemented in many centres, there is a deficit of information in the literature with regard to the consequent patient radiation exposure, in particular, where an eccentric or noncircular orbit is utilised. This information is particularly important for paediatric patients, as they are the most likely candidates for this type of surgery. Our study estimates the radiation dose to paediatric patients who have undergone scoliosis correction surgery, using the proprietary non-circular orbit employed by a Ziehm Vision RFD 3D C-arm. We estimate and compare patient organ doses using this eccentric orbit with one where a simple circular orbit is assumed. We further compare our calculated organ doses with those imparted by traditional 2D fluoroscopic techniques, and calculate the risk of future radiation induced cancer for this patient cohort. The doses presented here will be useful
176
N. McWilliams et al. / Physica Medica 52 (2018) 165–182
to other centres in establishing diagnostic reference levels for this increasingly common technique. https://doi.org/10.1016/j.ejmp.2018.06.049
Poster Session P17 Quantitative MRI volumetry in the detection of mesial temporal sclerosis in patients with refractory epilepsy Michael O’Neill Beaumont Hospital, Ireland E-mail address: [email protected] One third of patients who suffer from epilepsy are resistant to anti-epileptic medication, known as refractory epilepsy. These patients may be considered for surgical resection, where a portion of brain tissue which is believed to be involved in the seizure onset is removed. In the most common form of epilepsy, temporal lobe epilepsy (TLE), structures such as the hippocampus are often found to be involved. An indicator that the hippocampus may be related to the seizure onset is the presence of mesial temporal sclerosis (mTS), which is noted by a loss of internal architecture, reduced hippocampal volume and hyperintensity on T2-weighted MRI. The published literature indicates that a radiological evaluation of mTS supported by hippocampal volumetry can indicate a better postoperative outcome for patients. This project evaluates the use of software packages to produce volumetric estimates of these TL structures. These estimates were obtained for patients whose radiological reports indicate the presence and/or suspicion of mTS and a normal cohort. A comparison between Freesurfer and more specific hippocampal volumetric software packages was made. A database of normal MRI scans was compiled, this is age and gender matched for robust comparison and to reduce systematic error associated with comparing volumetric data. The software packages showed concordance with radiological reports by indicating a reduced hippocampal volume. Following on from this work and further validation of semi-automated volumetric analyses, it is hoped that this approach will be integrated into the pre-surgical evaluation workflow with the aim of improving the postoperative prognosis for patients. https://doi.org/10.1016/j.ejmp.2018.06.050
Poster Session P18 Risk and radiation exposure – An information poster for patients, parents and guardians Dara Murphy, Siobhan McCoubrey Our Lady’s Children’s Hospital, Crumlin, Ireland E-mail address: [email protected] We present an information poster detailing the risks associated with a variety of examinations employing ionising radiation in a paediatric radiology department. The poster aims to explain to patients, parents and guardians, the radiation doses associated with common radiology examinations and contextualise the risk in terms that can be understood by a non-medical audience. https://doi.org/10.1016/j.ejmp.2018.06.051
Poster Session P19 Comparison of 2D and 3D dosimetry parameters for breast planning Louise Fahy a, Maryam Alanazi b, James Murphy a a
University Hospital Galway, Ireland National University Ireland Galway, Ireland E-mail address: [email protected] b
Historically, external beam radiotherapy (EBRT) breast/chest wall treatment planning was a 2D process using breast contour and X-ray imaging, and the depth of the lung or heart in the treatment field was used to estimate the risk to these organs. Over the last two decades, the use of 3D CT imaging for breast treatment planning has become widespread but many centres still use Depth-in-Field for organ at risk (OAR) estimation. This is a retrospective study of breast cancer patients treated at our centre. The DVH parameters for lung and heart will be compared with the depth in the treatment field to investigate which of these parameters should be used in the clinic for plan evaluation. The treatment plans of 60 left-breast cancer patients treated with a prescription dose of 50 Gy in 25 fractions were reviewed. The results illustrated that there was a strong correlation between DVH parameters for the heart and the depth in field. Also, there was a strong correlation between DVH parameters and the lung depth in two field tangential plans. However, no correlation existed for plans with a third field to treat the supraclavicular area. There was not enough data to analyse the relation between the V107% of prescription dose and the depth in the treatment field. Moreover, comparing the results with clinical trials indicated that the mean dose and V20 Gy for heart and mean dose and V40 Gy for lung are valid parameters to look at when estimating the risk to heart and lung. https://doi.org/10.1016/j.ejmp.2018.06.052
Poster Session P20 Determining Diagnostic Reference Levels (DRLs) for Radiography and Fluorsocopy Procedures in a University Based Teaching Hospital Nina McWilliams a, Emerald House b, Matthew Donoghue b, Brendan Tuohy b a BreastCheck, Western Unit, National Screening Service, Newcastle Rd., Galway, Ireland b Dept. of Medical Physics and Clinical Engineering, University Hospital, Newcastle Rd., Galway, Ireland E-mail address: [email protected]
The introduction of the latest basic safety standard (BSS) into Irish legislation in 2018 will aid optimisation, justification and correction of high or low levels of radiation delivery as part of diagnostic procedures. Establishment and implementation of Local Diagnostic Reference Levels (LDRLs) play an important role in this optimisation process within Radiology Departments. This research focused on a review of LDRLs for both radiography and fluoroscopy procedures in a University based teaching hospital. LDRLs were based on the most commonly performed procedures in each room for adult patients (P18 years). As a retrospective dose audit, data acquisition was both manual, using the DICOM header information of individual images, and automatic using, Siemens CareAnalytics software. Dose-area product (DAP) data was acquired from fitted