- Email: [email protected]
Personalised dosimetry for benign thyroid radioiodine therapy – An update
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J. McFadden, M. Donoghue / Physica Medica 52 (2018) 165–182
c Dept. of Radiotherapy Physics, Galway Clinic, Ireland E-mail address: [email protected]
Modern radiation therapy treatment techniques and delivery methods introduce new challenges to existing dosimetry systems. As a result, much research has been conducted on the development of a radiation dosimetry system based on scintillating optical fibre. They offer many advantages over the currently employed dosimeters for real time dosimetry. Optical Fibre dosimeters (OFD) have small dimensions, are immune to electromagnetic fields and can be used to remotely monitor radiation in real time. For this study a novel OFD based on an inorganic scintillating material for external beam radiotherapy was developed. The dosimeter was constructed using a PMMA (polymethyl methacrylate) plastic optical fibre. The core of the PMMA was micro machined to make a 700 lm diameter and 7 mm deep cavity. The scintillating material, terbium doped gadolinium oxysulphide (Gd2O2S:Tb) was filled in the cavity and sealed with an epoxy. The scintillation material fluoresces on exposure to ionising radiation and the resultant emitted fluorescent light is detected using a multi-pixel photon counting module. Measurements to date using the novel dosimeter demonstrate very good repeatability and reproducibility with only a maximum of 0.17% and 0.68% difference from the average value, respectively. The results also show excellent linearity of the output signal with radiation doses and the dosimeter response was independent of dose rate. However, the percentage depth dose measurements showed an over response of the OFD compared to an ionization chamber. These differences are being investigated by means of Monte Carlo simulations.
stimulation the pressure stayed low and the motility showed increase in amplitude. During both tests the pylorus showed higher pressure and lack of motility waves at maximum probe distention. The pylorus seems to acts as a sphincter at low distention but when further dilated starts acting as a pump. Fully distended the pyloric motility disappears and the pressure remains high, suggesting that a stent with high radial force might show less migration. https://doi.org/10.1016/j.ejmp.2018.06.058
Poster Session P26 Personalised dosimetry for benign thyroid radioiodine therapy – An update Jennie Cooke a, Marie-Louise Healy b, Niamh Phelan b, Khaled Al Janaee b a
Medical Physics and Bioengineering, St. James’s Hospital, Dublin 8, Ireland b Dept of Endocrinology, St. James’s Hospital, Dublin 8, Ireland E-mail address: [email protected] At IAPM 2017 an overview of the dosimetry protocol for outpatient I-131 therapy which was in the process of being implemented in St. James’s Hospital was presented. A year on, 25 patients have now been treated using dosimetry, and here we present an overview of our experience and treatment outcomes for this small cohort. https://doi.org/10.1016/j.ejmp.2018.06.059
https://doi.org/10.1016/j.ejmp.2018.06.057
Poster Session P25 Exploring pyloric dynamics in stenting – Using a distensibility technique Barry McMahon a, Stephen Bligh a, Jorge Alberto Arroyo Vázquez b, Maria Bergstrom b, Per-Ola Park b a
MPCE, Tallaght Hospital, Ireland South Alvsborg Hospital, Boras, Sweden E-mail address: [email protected] b
Perforated duodenal ulcers can be treated with a stent. Stent migration is a severe complication, sometimes requiring surgery. Pyloric physiology during stent-treatment has not been studied and mechanisms for migration are unknown. To investigate the pyloric response to distention, mimicking stent-treatment, using the EndoFLIP, a non-survival study in five pigs was carried out, followed by a pilot study in one volunteer. Animals were gastroscoped during anaesthesia and the EndoFLIP was placed straddling the pylorus. Baseline distensibility readings were performed at stepwise balloon distentions to 20 ml, 30 ml, 40 ml and 50 ml, measuring pyloric Cross Sectional Area and pressure. Measurements were repeated after administration of a pro-kinetic drug and after a liquid meal. In the human study readings were performed in conscious sedation at baseline and after stimulation with metoclopramide. During baseline readings the pylorus was shown to open more with increasing distention together with higher amplitude motility waves. Reaching maximum distention-volume (50 ml), pyloric pressure increased significantly (p = 0.016) and motility waves disappeared. After pro-kinetic stimulation the pressure decreased and the motility waves increased in frequency and amplitude. After food
Poster Session P27 The development and implementation of the detective quantum efficiency metric in a clinical environment John McFadden a, Matthew Donoghue b a
University of Manchester, UK HSE, UK E-mail address: [email protected] b
Development and application of a practical DQE protocol for routine use by medical physicists during assessment of digital radiography systems. J. McFadden, M. Donoghue, E House, B. Tuohy. Measurement of the Detective Quantum Efficiency (DQE) of a DR detector provides a more quantitative assessment of the imaging performance of a system in comparison to the very subjective assessments traditionally used by medical physicists ‘‘in the field”. Although commonly used by the system manufacturers, the method has yet to be widely incorporated into quality assurance (QA) protocols in Irish hospitals. We will report in this paper on the findings from a project which aimed to adapt the IEC-62220 industrial DQE standard for a clinical environment. Results from our studies on the influence of DQE software algorithm chosen, variations in image acquisition and processing methods will be presented and explored. Development of the technique involved a compromise between the Industry standard IEC method and the practical limitations of time and equipment availability experienced by medical physicists in the field. Following adaptation of the Industry standard DQE approach, a practical methodology, which can be applied to any general radiography DR detector, allows medical physicists in the field to incorporate DQE assessment in their annual DR system assessment. A number of problems and challenges encountered during
J. McFadden, M. Donoghue / Physica Medica 52 (2018) 165–182
c Dept. of Radiotherapy Physics, Galway Clinic, Ireland E-mail address: [email protected]
Modern radiation therapy treatment techniques and delivery methods introduce new challenges to existing dosimetry systems. As a result, much research has been conducted on the development of a radiation dosimetry system based on scintillating optical fibre. They offer many advantages over the currently employed dosimeters for real time dosimetry. Optical Fibre dosimeters (OFD) have small dimensions, are immune to electromagnetic fields and can be used to remotely monitor radiation in real time. For this study a novel OFD based on an inorganic scintillating material for external beam radiotherapy was developed. The dosimeter was constructed using a PMMA (polymethyl methacrylate) plastic optical fibre. The core of the PMMA was micro machined to make a 700 lm diameter and 7 mm deep cavity. The scintillating material, terbium doped gadolinium oxysulphide (Gd2O2S:Tb) was filled in the cavity and sealed with an epoxy. The scintillation material fluoresces on exposure to ionising radiation and the resultant emitted fluorescent light is detected using a multi-pixel photon counting module. Measurements to date using the novel dosimeter demonstrate very good repeatability and reproducibility with only a maximum of 0.17% and 0.68% difference from the average value, respectively. The results also show excellent linearity of the output signal with radiation doses and the dosimeter response was independent of dose rate. However, the percentage depth dose measurements showed an over response of the OFD compared to an ionization chamber. These differences are being investigated by means of Monte Carlo simulations.
stimulation the pressure stayed low and the motility showed increase in amplitude. During both tests the pylorus showed higher pressure and lack of motility waves at maximum probe distention. The pylorus seems to acts as a sphincter at low distention but when further dilated starts acting as a pump. Fully distended the pyloric motility disappears and the pressure remains high, suggesting that a stent with high radial force might show less migration. https://doi.org/10.1016/j.ejmp.2018.06.058
Poster Session P26 Personalised dosimetry for benign thyroid radioiodine therapy – An update Jennie Cooke a, Marie-Louise Healy b, Niamh Phelan b, Khaled Al Janaee b a
Medical Physics and Bioengineering, St. James’s Hospital, Dublin 8, Ireland b Dept of Endocrinology, St. James’s Hospital, Dublin 8, Ireland E-mail address: [email protected] At IAPM 2017 an overview of the dosimetry protocol for outpatient I-131 therapy which was in the process of being implemented in St. James’s Hospital was presented. A year on, 25 patients have now been treated using dosimetry, and here we present an overview of our experience and treatment outcomes for this small cohort. https://doi.org/10.1016/j.ejmp.2018.06.059
https://doi.org/10.1016/j.ejmp.2018.06.057
Poster Session P25 Exploring pyloric dynamics in stenting – Using a distensibility technique Barry McMahon a, Stephen Bligh a, Jorge Alberto Arroyo Vázquez b, Maria Bergstrom b, Per-Ola Park b a
MPCE, Tallaght Hospital, Ireland South Alvsborg Hospital, Boras, Sweden E-mail address: [email protected] b
Perforated duodenal ulcers can be treated with a stent. Stent migration is a severe complication, sometimes requiring surgery. Pyloric physiology during stent-treatment has not been studied and mechanisms for migration are unknown. To investigate the pyloric response to distention, mimicking stent-treatment, using the EndoFLIP, a non-survival study in five pigs was carried out, followed by a pilot study in one volunteer. Animals were gastroscoped during anaesthesia and the EndoFLIP was placed straddling the pylorus. Baseline distensibility readings were performed at stepwise balloon distentions to 20 ml, 30 ml, 40 ml and 50 ml, measuring pyloric Cross Sectional Area and pressure. Measurements were repeated after administration of a pro-kinetic drug and after a liquid meal. In the human study readings were performed in conscious sedation at baseline and after stimulation with metoclopramide. During baseline readings the pylorus was shown to open more with increasing distention together with higher amplitude motility waves. Reaching maximum distention-volume (50 ml), pyloric pressure increased significantly (p = 0.016) and motility waves disappeared. After pro-kinetic stimulation the pressure decreased and the motility waves increased in frequency and amplitude. After food
Poster Session P27 The development and implementation of the detective quantum efficiency metric in a clinical environment John McFadden a, Matthew Donoghue b a
University of Manchester, UK HSE, UK E-mail address: [email protected] b
Development and application of a practical DQE protocol for routine use by medical physicists during assessment of digital radiography systems. J. McFadden, M. Donoghue, E House, B. Tuohy. Measurement of the Detective Quantum Efficiency (DQE) of a DR detector provides a more quantitative assessment of the imaging performance of a system in comparison to the very subjective assessments traditionally used by medical physicists ‘‘in the field”. Although commonly used by the system manufacturers, the method has yet to be widely incorporated into quality assurance (QA) protocols in Irish hospitals. We will report in this paper on the findings from a project which aimed to adapt the IEC-62220 industrial DQE standard for a clinical environment. Results from our studies on the influence of DQE software algorithm chosen, variations in image acquisition and processing methods will be presented and explored. Development of the technique involved a compromise between the Industry standard IEC method and the practical limitations of time and equipment availability experienced by medical physicists in the field. Following adaptation of the Industry standard DQE approach, a practical methodology, which can be applied to any general radiography DR detector, allows medical physicists in the field to incorporate DQE assessment in their annual DR system assessment. A number of problems and challenges encountered during