Synchrotron CT dosimetry at the IMBL for low wiggler magnetic field strength and spatial modulation with bow tie filters

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dc.contributor.authorMidgley, Sen_AU
dc.contributor.authorSchleich, Nen_AU
dc.contributor.authorStevenson, AWen_AU
dc.contributor.authorMerchant, Aen_AU
dc.date.accessioned2023-10-06T03:46:37Zen_AU
dc.date.available2023-10-06T03:46:37Zen_AU
dc.date.issued2021-11-26en_AU
dc.date.statistics2023-04-24en_AU
dc.description.abstractSynchrotron CT dose reduction was investigated for the IMBL wiggler source operated at lower magnetic field strength and for beam modulation with spatial filters placed upstream from the sample. Beam quality at 25-30 KeV for 1.4-3.0 T was assessed using transmission measurements with copper to quantify the influence of third harmonic radiation. The low energy operational limit is 24-28 KeV for 0.1-1% transmission by added filters, 2 mm path length through silicon and 25 m of air. The upper limit is near 80 KeV for wiggler field 1.4 T, approximately 100 keV for 2.0 T and extend beyond 100 keV for 3.0-4.2 T. The harmonic radiation contribution is reduced for lower field strengths. Measured dose rates suggest the influence of harmonics is insignificant above approximately 26 keV at 1.4 T and above 33 keV at 2.0 T. Relative to 3 T operation, the mean dose rate in air is reduced to approximately 12% at 2 T and 4% at 1.4 T. Spatial filters were constructed from blocks of perspex with circular voids of diameter matching the CT dosimetry test objects. A calibrated ion chamber integrated absorbed dose to the phantom during 360o rotation. CT dose indices (CTDI) were measured at 25-100 KeV for 3.0T only, at the centre and periphery for 35-160 mm diameter perspex phantoms. Beam shaping filters offer protection to the sample by reducing the peripheral and volumetric CTDI by about 10% for small objects and 20-30% for the larger samples. © 2021 The Authorsen_AU
dc.identifier.articlenumber211en_AU
dc.identifier.citationMidgley, S., Schleich, N., Stevenson, S. W., & Merchant. A., (2021). Synchrotron CT dosimetry at the IMBL for low wiggler magnetic field strength and spatial modulation with bow tie filters. Presentation to the ANSTO User Meeting, Online, 24-26 November 2021. Retrieved from: https://events01.synchrotron.org.au/event/146/contributions/4254/contribution.pdfen_AU
dc.identifier.conferenceenddate2021-11-26en_AU
dc.identifier.conferencenameANSTO User Meeting 2021en_AU
dc.identifier.conferenceplaceOnlineen_AU
dc.identifier.conferencestartdate2021-11-24en_AU
dc.identifier.urihttps://events01.synchrotron.org.au/event/146/contributions/4254/contribution.pdfen_AU
dc.identifier.urihttps://apo.ansto.gov.au/handle/10238/15140en_AU
dc.language.isoenen_AU
dc.publisherAustralian Nuclear Science and Technology Organisationen_AU
dc.relation.urihttps://events01.synchrotron.org.au/event/146/contributions/4254/contribution.pdfen_AU
dc.subjectSyncrotronsen_AU
dc.subjectDosimetryen_AU
dc.subjectWiggler magnetsen_AU
dc.subjectFiltersen_AU
dc.subjectModulationen_AU
dc.subjectDose ratesen_AU
dc.subjectRadiation dosesen_AU
dc.subjectBeamsen_AU
dc.titleSynchrotron CT dosimetry at the IMBL for low wiggler magnetic field strength and spatial modulation with bow tie filtersen_AU
dc.typeConference Presentationen_AU
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