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Bebbington NA, Jørgensen T, Dupont E, Micheelsen MA. Validation of CARE kV automated tube voltage selection for PET-CT: PET quantification and CT radiation dose reduction in phantoms. EJNMMI Phys 2021; 8:29. [PMID: 33743091 PMCID: PMC7981373 DOI: 10.1186/s40658-021-00373-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 02/25/2021] [Indexed: 11/20/2022] Open
Abstract
Background Applied tube voltage (kilovolts, kV) and tube current (milliampere seconds, mAs) affect CT radiation dose and image quality and should be optimised for the individual patient. CARE kV determines the kV and mAs providing the lowest dose to the patient, whilst maintaining user-defined reference image quality. Given that kV changes affect CT values which are used to obtain attenuation maps, the aim was to evaluate the effect of kV changes on PET quantification and CT radiation dose using phantoms. Method Four phantoms (‘Lungman’, ‘Lungman plus fat’, ‘Esser’ and ‘NEMA image quality’ (NEMA IQ)) containing F-18 sources underwent 1 PET and 5 CT scans, with CARE kV on (automatic kV selection and mAs modulation) and in semi mode with specified tube voltages of 140, 120, 100 and 80 kV (mAs modulation only). A CARE kV image quality reference of 120 kV/50 mAs was used. Impact on PET quantification was determined by comparing measured activity concentrations for PET reconstructions from different CT scans with the reconstruction using the 120 kV reference, and dose (DLP, CTDIvol) differences calculated by comparing doses from all kV settings with the 120 kV reference. Results CARE kV-determined optimal tube voltage and CARE kV ‘on’ dose (DLP) savings compared with the 120 kV reference were: Lungman, 100 kV, 2.0%; Lungman plus fat, 120 kV, 0%; Esser, 100 kV, 9.3%; NEMA IQ, 100 kV, 3.4%. Using tube voltages in CARE kV ‘semi’ mode which were not advised by CARE kV ‘on’ resulted in dose increases ≤ 65% compared with the 120 kV reference (greatest difference Lungman plus fat, 80 kV). Clinically insignificant differences in PET activity quantification of up to 0.7% (Lungman, 100 kV, mean measured activity concentration) were observed when using the optimal tube voltage advised by CARE kV. Differences in PET quantification of up to 4.0% (Lungman, 140 kV, maximum measured activity concentration) were found over the full selection of tube voltages in semi mode, with the greatest differences seen at the most suboptimal kV for each phantom. However, most differences were within 1%. Conclusions CARE kV on can provide CT radiation dose savings without concern over changes in PET quantification.
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Affiliation(s)
- Natalie A Bebbington
- Siemens Healthcare A/S, Bredskifte Alle 15, 8210, Aarhus V, Denmark. .,Department of Clinical Medicine, Aalborg University, Søndre Skovvej 15, 9000, Aalborg, Denmark.
| | - Troels Jørgensen
- Department of Nuclear Medicine, Zealand University Hospital, Køge, Denmark
| | - Erik Dupont
- Department of Biomedical Engineering, Region Zealand, Roskilde, Denmark
| | - Mille A Micheelsen
- Department of Nuclear Medicine, Zealand University Hospital, Køge, Denmark
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Hansen SL, Bebbington NA. Estimation of CARE Dose 4D quality reference mAs conversion factors for child to adult reference patient in child protocols on Siemens Symbia SPECT-CT systems. Nucl Med Commun 2021; 42:107-112. [PMID: 33079892 PMCID: PMC7725139 DOI: 10.1097/mnm.0000000000001312] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 09/15/2020] [Indexed: 11/28/2022]
Abstract
OBJECTIVES CARE Dose 4D modulates mAs through several mechanisms according to patient size and shape, whilst maintaining user-defined reference image quality on Siemens Symbia single-photon emission computed tomography (SPECT)-computed tomography (CT) systems. A 20 kg child reference was used in child protocols prior to software version VB10 and a 75 kg adult thereafter. Quality reference mAs conversion factors are estimated for delivering equivalent mAs to children between two comparable SPECT-CT systems using adult and child references for topogram-based patient-size-related dose level adaptations. METHODS A child phantom was scanned using child protocols on a Siemens Symbia T16 (child reference) and a Siemens Symbia Intevo Bold (adult reference). On each system, scans of the thorax, abdomen and pelvis were acquired with arms up and down, at 80 and 110 kVp. Quality reference mAs settings of 10-50 were used on the Symbia T16 and 40-200 on the Symbia Intevo Bold. These data were used to propose quality reference mAs (adult/child reference) conversion factors according to scan range, arm position and tube voltage. RESULTS Quality reference mAs for child protocols using the adult reference should multiply the child quality reference mAs by the following factors, to give comparable delivered mAs: arms up 80 kV: 3.8 (thorax), 3.8 (abdomen), 4.3 (pelvis); arms up at 110 kV: 3.8 (thorax), 4.1 (abdomen), 4.6 (pelvis); arms down at 80 kV: 4.0 (thorax), 3.7 (abdomen), 3.9 (pelvis); arms down at 110 kV: 4.3 (thorax), 4.0 (abdomen), 4.2 (pelvis). CONCLUSION Conversion factors for child to adult dose modulation references are proposed, allowing comparable delivered mAs to a child.Video abstract: http://links.lww.com/NMC/A178.
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Affiliation(s)
- Sofie L. Hansen
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, Copenhagen
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Bebbington NA, Haddock BT, Bertilsson H, Hippeläinen E, Husby EM, Tunninen VI, Söderberg M. A Nordic survey of CT doses in hybrid PET/CT and SPECT/CT examinations. EJNMMI Phys 2019; 6:24. [PMID: 31845047 PMCID: PMC6915162 DOI: 10.1186/s40658-019-0266-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 11/28/2019] [Indexed: 11/30/2022] Open
Abstract
Background Computed tomography (CT) scans are routinely performed in positron emission tomography (PET) and single photon emission computed tomography (SPECT) examinations globally, yet few surveys have been conducted to gather national diagnostic reference level (NDRL) data for CT radiation doses in positron emission tomography/computed tomography (PET/CT) and single photon emission computed tomography/computed tomography (SPECT/CT). In this first Nordic-wide study of CT doses in hybrid imaging, Nordic NDRL CT doses are suggested for PET/CT and SPECT/CT examinations specific to the clinical purpose of CT, and the scope for optimisation is evaluated. Data on hybrid imaging CT exposures and clinical purpose of CT were gathered for 5 PET/CT and 8 SPECT/CT examinations via designed booklet. For each included dataset for a given facility and scanner type, the computed tomography dose index by volume (CTDIvol) and dose length product (DLP) was interpolated for a 75-kg person (referred to as CTDIvol,75kg and DLP75kg). Suggested NDRL (75th percentile) and achievable doses (50th percentile) were determined for CTDIvol,75kg and DLP75kg according to clinical purpose of CT. Differences in maximum and minimum doses (derived for a 75-kg patient) between facilities were also calculated for each examination and clinical purpose. Results Data were processed from 83 scanners from 43 facilities. Data were sufficient to suggest Nordic NDRL CT doses for the following: PET/CT oncology (localisation/characterisation, 15 systems); infection/inflammation (localisation/characterisation, 13 systems); brain (attenuation correction (AC) only, 11 systems); cardiac PET/CT and SPECT/CT (AC only, 30 systems); SPECT/CT lung (localisation/characterisation, 12 systems); bone (localisation/characterisation, 30 systems); and parathyroid (localisation/characterisation, 13 systems). Great variations in dose were seen for all aforementioned examinations. Greatest differences in DLP75kg for each examination, specific to clinical purpose, were as follows: SPECT/CT lung AC only (27.4); PET/CT and SPECT/CT cardiac AC only (19.6); infection/inflammation AC only (18.1); PET/CT brain localisation/characterisation (16.8); SPECT/CT bone localisation/characterisation (10.0); PET/CT oncology AC only (9.0); and SPECT/CT parathyroid localisation/characterisation (7.8). Conclusions Suggested Nordic NDRL CT doses are presented according to clinical purpose of CT for PET/CT oncology, infection/inflammation, brain, PET/CT and SPECT/CT cardiac, and SPECT/CT lung, bone, and parathyroid. The large variation in doses suggests great scope for optimisation in all 8 examinations.
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Affiliation(s)
| | - Bryan T Haddock
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen University Hospital, Ndr. Ringvej 57, 2600, Glostrup, Denmark
| | | | - Eero Hippeläinen
- HUS Medical Imaging Center, Clinical Physiology and Nuclear Medicine, Nuclear Medicine Unit, Meilahti Hospital, University of Helsinki and Helsinki University Hospital, Tukholmankatu 8 F, PL 442, 00029 HUS, Helsinki, Finland
| | - Ellen M Husby
- Department of Diagnostic Physics, Gaustad Hospital, Oslo University Hospital, Building 20, P.O. Box 4959, N-0424, Nydalen, Oslo, Norway
| | - Virpi I Tunninen
- Department of Nuclear Medicine, Satakunta Central Hospital, Sairaalantie 3, 28500, Pori, Finland
| | - Marcus Söderberg
- Medical Radiation Physics, Department of Translational Medicine, Lund university, Inga Marie Nilssons gata 49, 20502, Malmö, Sweden.,Radiation Physics, Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Inga Marie Nilssons gata 49, 20502, Malmö, Sweden
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Crabtree NJ, Shaw NJ, Bishop NJ, Adams JE, Mughal MZ, Arundel P, Fewtrell MS, Ahmed SF, Treadgold LA, Högler W, Bebbington NA, Ward KA. Amalgamated Reference Data for Size-Adjusted Bone Densitometry Measurements in 3598 Children and Young Adults-the ALPHABET Study. J Bone Miner Res 2017; 32:172-180. [PMID: 27490028 PMCID: PMC5453244 DOI: 10.1002/jbmr.2935] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 07/28/2016] [Accepted: 08/02/2016] [Indexed: 01/24/2023]
Abstract
The increasing use of dual-energy X-ray absorptiometry (DXA) in children has led to the need for robust reference data for interpretation of scans in daily clinical practice. Such data need to be representative of the population being studied and be "future-proofed" to software and hardware upgrades. The aim was to combine all available pediatric DXA reference data from seven UK centers to create reference curves adjusted for age, sex, ethnicity, and body size to enable clinical application, using in vivo cross-calibration and making data back and forward compatible. Seven UK sites collected data on GE Lunar or Hologic Scanners between 1996 and 2012. Males and females aged 4 to 20 years were recruited (n = 3598). The split by ethnic group was white 2887; South Asian 385; black Afro-Caribbean 286; and mixed heritage 40. Scans of the total body and lumbar spine (L1 to L4 ) were obtained. The European Spine Phantom was used to cross-calibrate the 7 centers and 11 scanners. Reference curves were produced for L1 to L4 bone mineral apparent density (BMAD) and total body less head (TBLH) and L1 to L4 areal bone mineral density (aBMD) for GE Lunar Prodigy and iDXA (sex- and ethnic-specific) and for Hologic (sex-specific). Regression equations for TBLH BMC were produced using stepwise linear regression. Scans of 100 children were randomly selected to test backward and forward compatibility of software versions, up to version 15.0 for GE Lunar and Apex 4.1 for Hologic. For the first time, sex- and ethnic-specific reference curves for lumbar spine BMAD, aBMD, and TBLH aBMD are provided for both GE Lunar and Hologic scanners. These curves will facilitate interpretation of DXA data in children using methods recommended in ISCD guidelines. The databases have been created to allow future updates and analysis when more definitive evidence for the best method of fracture prediction in children is agreed. © 2016 American Society for Bone and Mineral Research.
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Affiliation(s)
- Nicola J Crabtree
- Department of Endocrinology and Diabetes, Birmingham Children's Hospital, Birmingham, UK
| | - Nicholas J Shaw
- Department of Endocrinology and Diabetes, Birmingham Children's Hospital, Birmingham, UK
| | - Nicholas J Bishop
- Academic Unit of Child Health, University of Sheffield, Sheffield, UK
| | - Judith E Adams
- Radiology and Manchester Academic Health Science Centre, Manchester Royal Infirmary, Central Manchester University Hospitals NHS Foundation Trust and University of Manchester, Manchester, UK
| | - M Zulf Mughal
- Department of Endocrinology, Central Manchester University Hospitals NHS Foundation Trust and University of Manchester, Manchester, UK
| | - Paul Arundel
- Academic Unit of Child Health, University of Sheffield, Sheffield, UK
| | - Mary S Fewtrell
- Childhood Nutrition Research Centre, University College London, Institute of Child Health, London, UK
| | - S Faisal Ahmed
- Developmental Endocrinology Research Group, School of Medicine, University of Glasgow, Royal Hospital for Sick Children, Glasgow, UK
| | - Laura A Treadgold
- Division of Biomedical Imaging, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Wolfgang Högler
- Department of Endocrinology and Diabetes, Birmingham Children's Hospital, Birmingham, UK
| | - Natalie A Bebbington
- Department of Endocrinology and Diabetes, Birmingham Children's Hospital, Birmingham, UK
| | - Kate A Ward
- Nutrition and Bone Health, MRC Human Nutrition Research, Cambridge, UK.,MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton, UK
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Crabtree NJ, Bebbington NA, Chapman DM, Wahid YS, Ayuk J, Boivin CM, Cooper MS, Gittoes NJL. Impact of UK National Guidelines based on FRAX®--comparison with current clinical practice. Clin Endocrinol (Oxf) 2010; 73:452-6. [PMID: 20626412 DOI: 10.1111/j.1365-2265.2010.03844.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To assess whether clinician-determined treatment intervention thresholds are in line with the assessment of fracture risk provided by FRAX® and treatment recommendations provided by UK guidelines produced by the National Osteoporosis Guidelines Group (NOGG). DESIGN, PATIENTS AND MEASUREMENTS This was a retrospective cohort analysis of 288 patients consecutively referred for dual-energy X-ray absorptiometry (DXA) scanning from primary care immediately prior to the introduction of the FRAX® algorithm. In addition to DXA assessment, patients completed a clinical risk factor questionnaire which included risk factors used in the FRAX® algorithm. Initial risk assessment and treatment decisions were performed after DXA. FRAX® was used, retrospectively, with femoral neck T-score, to estimate fracture risk which was applied to NOGG to generate guidance on treatment intervention. Clinician- and NOGG-determined outcomes were audited for concordance. RESULTS There was concordance between clinician and NOGG treatment decisions in 215 (74.6%) subjects. Discordance was observed in 73 (25.3%) subjects. In the discordant group, seven subjects were given lifestyle advice when NOGG recommended treatment, 42 given treatment when NOGG recommended lifestyle advice only, and 24 were referred to a metabolic bone clinic for further evaluation. The reasons for treatment differences in subjects recommended treatment by clinician but not NOGG were largely (90.2%) attributed to the use of lumbar spine bone mineral density (BMD). CONCLUSIONS There is high concordance between clinician-determined and FRAX®-NOGG intervention. The absence of spine BMD from FRAX® is the primary source of discrepancy. This study provides some assurance of the validity of the treatment thresholds generated from FRAX®-NOGG in 'real-world' usage.
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Affiliation(s)
- N J Crabtree
- Bone Densitometry Endocrinology, Queen Elizabeth Hospital Birmingham, and University of Birmingham, Edgbaston, Birmingham, UK.
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