Ali Mohammed Ali1, Peter Hogg2, Safora Johansen3, Andrew England4. 1. School of Health Sciences, University of Salford, Salford, M6 6PU, United Kingdom. Electronic address: a.h.m.a.mohammedali@edu.salford.ac.uk. 2. School of Health Sciences, University of Salford, Salford, M6 6PU, United Kingdom. Electronic address: P.Hogg@salford.ac.uk. 3. Oslo Metropolitan University, Faculty of Health Sciences, Norway; Department of Oncology, Division of Cancer Medicine, Surgery and Transplantation, Oslo University Hospital, Radiumhospitalet, Oslo, Norway. Electronic address: saferajo@oslomet.no. 4. School of Health Sciences, University of Salford, Salford, M6 6PU, United Kingdom. Electronic address: A.England@salford.ac.uk.
Abstract
PURPOSE: Imaging phantoms can be cost prohibitive, therefore a need exists to produce low cost alternatives which are fit for purpose. This paper describes the development and validation of a low cost paediatric pelvis phantom based on the anatomy of a 5-year-old child. METHODS: Tissue equivalent materials representing paediatric bone (Plaster of Paris; PoP) and soft tissue (Poly methyl methacrylate; PMMA) were used. PMMA was machined to match the bony anatomy identified from a CT scan of a 5-year-old child and cavities were created for infusing the PoP. Phantom validation comprised physical and visual measures. Physical included CT density comparison between a CT scan of a 5-year old child and the phantom and Signal to Noise Ratio (SNR) comparative analysis of anteroposterior phantom X-ray images against a commercial anthropomorphic phantom. Visual analysis using a psychometric image quality scale (face validity). RESULTS: CT density, the percentage difference between cortical bone, soft tissue and their equivalent tissue substitutes were -4.7 to -4.1% and -23.4%, respectively. For SNR, (mAs response) there was a strong positive correlation between the two phantoms (r > 0.95 for all kVps). For kVp response, there was a strong positive correlation between 1 and 8 mAs (r = 0.85), this then decreased as mAs increased (r = -0.21 at 20 mAs). Psychometric scale results produced a Cronbach's Alpha of almost 0.8. CONCLUSIONS: Physical and visual measures suggest our low-cost phantom has suitable anatomical characteristics for X-ray imaging. Our phantom could have utility in dose and image quality optimisation studies.
PURPOSE: Imaging phantoms can be cost prohibitive, therefore a need exists to produce low cost alternatives which are fit for purpose. This paper describes the development and validation of a low cost paediatric pelvis phantom based on the anatomy of a 5-year-old child. METHODS: Tissue equivalent materials representing paediatric bone (Plaster of Paris; PoP) and soft tissue (Poly methyl methacrylate; PMMA) were used. PMMA was machined to match the bony anatomy identified from a CT scan of a 5-year-old child and cavities were created for infusing the PoP. Phantom validation comprised physical and visual measures. Physical included CT density comparison between a CT scan of a 5-year old child and the phantom and Signal to Noise Ratio (SNR) comparative analysis of anteroposterior phantom X-ray images against a commercial anthropomorphic phantom. Visual analysis using a psychometric image quality scale (face validity). RESULTS: CT density, the percentage difference between cortical bone, soft tissue and their equivalent tissue substitutes were -4.7 to -4.1% and -23.4%, respectively. For SNR, (mAs response) there was a strong positive correlation between the two phantoms (r > 0.95 for all kVps). For kVp response, there was a strong positive correlation between 1 and 8 mAs (r = 0.85), this then decreased as mAs increased (r = -0.21 at 20 mAs). Psychometric scale results produced a Cronbach's Alpha of almost 0.8. CONCLUSIONS: Physical and visual measures suggest our low-cost phantom has suitable anatomical characteristics for X-ray imaging. Our phantom could have utility in dose and image quality optimisation studies.