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Validation of a Molecular Radiotherapy (MRT) dosimetry system requires imaging data for which an accompanying "ground truth" pharmacokinetic model and absorbed dose calculation are known. METHODS: We present a methodology for production of a validation dataset for image based 177Lu dotatate dosimetry calculations. A pharmacokinetic model is presented with activity concentrations corresponding to common imaging timepoints. Anthropomorphic 3D printed phantoms, corresponding to the organs at risk, have been developed to provide SPECT/CT and Whole Body imaging with known organ activities corresponding to common clinical timepoints. RESULTS: Results for the accuracy of phantom filling reproduce the activity concentrations from the pharmacokinetic model for all timepoints and organs within measurement uncertainties, with a mean deviation of 0.6(8)%. The imaging dataset, ancillary data and phantoms designs are provided as a source of well characterized input data for the validation of clinical MRT dosimetry systems. CONCLUSIONS: The combination of pharmacokinetic modelling with the use of anthropomorphic 3D printed phantoms are a promising procedure to provide data for the validation of Molecular Radiotherapy Dosimetry systems, allowing multicentre comparisons.
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Radiometría , Tomografía Computarizada por Tomografía Computarizada de Emisión de Fotón Único , Radiometría/métodos , Fantasmas de ImagenRESUMEN
Accurate image quantification requires accurate calibration of the detector and is vital if dosimetry is to be performed in molecular radiotherapy. A dependence on the position of calibration has been observed in single photon emission computed tomography images when attenuation correction (AC) and scatter correction are applied. This work investigates the origin of this dependence in single photon emission computed tomography scans of phantom inserts filled with Lu solution. A 113 ml sphere and inserts representing a mathematical model of a spleen and an anatomical model of a patient spleen were imaged at the centre and edge of elliptical phantoms. For these inserts, the difference in calibration factor between the positions was around 10% for images reconstructed with AC and triple energy window scatter correction. A combination of experimental imaging and Monte Carlo simulation was used to isolate possible causes due to imaging or reconstruction in turn. Inconsistent application of AC between different reconstruction systems was identified as the origin of the positional dependence.
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Procesamiento de Imagen Asistido por Computador , Tomografía Computarizada de Emisión de Fotón Único , Calibración , Dispersión de RadiaciónRESUMEN
The optimised delivery of Molecular Radiotherapy requires individualised calculation of absorbed dose to both targeted lesions and neighbouring healthy tissue. To achieve this, accurate quantification of the activity distribution in the patient by external detection is vital. METHODS: This work extends specific anatomy-related calibration to true organ shapes. A set of patient-specific 3D printed organ inserts based on a diagnostic CT scan was produced, comprising the liver, spleen and both kidneys. The inserts were used to calculate patient-specific calibration factors for 177Lu. These calibration factors were compared with previously reported calibration factors for corresponding organ models based on the Cristy and Eckerman phantom series and for a comparably sized sphere. Monte Carlo calculations of the patient-specific radiation dose were performed for comparison with current clinical dosimetry methods for these data. RESULTS: Patient-specific calibration factors are shown to be dependent on the volume, shape and position of the organ containing activity with a corresponding impact on the calculation of the dose to the patient. The impact of organ morphology on calculated dose is reduced when the dominant contributor to dose is beta particles. This is due to the small range of beta particles in tissue. Overestimations of recovered activity and hence dose of up to 135% are observed. CONCLUSION: For accurate quantification to be performed calibration factors accounting for organ size, shape and position must be used. Such quantification is vital if accurate, patient-specific dosimetry is to be achieved.
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Radiometría/métodos , Radioterapia , Calibración , Humanos , Método de Montecarlo , Fantasmas de Imagen , Dosis de Radiación , Tomografía Computarizada por Rayos XRESUMEN
INTRODUCTION: This is the first study reporting the application of Enhanced Recovery Principles (ERP) to revision arthroplasty. METHOD: Retrospective series of 132 revision hip and knee replacements treated with ERP. RESULTS: Infiltration was associated with reduced LOS in knees (6 vs 8.5 days), lower PCA usage and incidence of transfusion in knees (2 vs 3 days) and hips (1 vs 6 days). Revisions for infection had a longer LOS (5.4 vs 11.5 days p = 0.001), a greater use of PCA and a higher incidence of transfusion (5 vs 0) in both knees and hips. DISCUSSION: The application of ERPs to revision arthroplasty is safe. Infiltration appears to be an important factor in improving outcome measures.
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AIMS: To review the perinatal outcomes for prenatally diagnosed exomphalos from a single geographical region. METHODS: Retrospective review of cases of prenatally identified exomphalos in the state of Western Australia in the ten-year period 1998-2007 using the medical databases of the sole tertiary obstetric and paediatric hospitals. RESULTS: Ninety-four cases of prenatally identified exomphalos comprise this consecutive case series. Culture-proven karyotypic abnormalities occurred in 40 (42.6%) fetuses. No karyotypically abnormal fetus survived the neonatal period, with 33 of 40 (82.5%) pregnancies interrupted, five of 40 (12.5%) resulting in fetal demise and two (5%) neonatal deaths. For the 49 (52.1%) fetuses with a normal karyotype, 26 (53.1%) had associated abnormalities with termination occurring in 22 (84.6%). Prenatally isolated exomphalos was present in 23 cases (24.5%), with live birth in 15 cases (30.6% of euploid fetuses). Fourteen (93.3%) of the liveborn prenatally isolated exomphalos cases survived with no postoperative deaths, although four (28.5%) had significant abnormalities detected postdelivery and most have experienced childhood morbidity. CONCLUSIONS: In the the majority of cases of prenatally detected exomphalos the pregnancy was interrupted secondary to chromosomal or structural abnormalities. In only 10.6% of prenatally recognised fetuses with exomphalos was the disorder truly isolated with neonatal survival occurring.