SPECT-CT/VQ has high sensitivity and specificity for diagnosing PE compared with CTPA, even among patients with pre-existing lung disease, with lower radiation doses.

(18)F-FDG-PET/CT imaging should be performed as late as reasonably possible after tracer administration in order to increase tumour-to-background contrast and thereby improve the sensitivity of demonstrating additional sites of disease. Dual-time-point (18)FDG-PET/CT may be of benefit in the evaluation of intra-abdominal lesions but does not improve the overall evaluation of pulmonary lesions.

A table of conversion factors, independent of the isotope, was generated for the estimation of dose rates from injected patients at various distances. An isotope-specific conversion table was also generated. The effectiveness of the lead aprons within the department was also successfully measured and assessed and recommendations were passed on to staff regarding their use.

. (2013). Measurement of multislice computed tomography dose profile with the Dose Magnifying Glass and the MOSkin radiation dosimeter. Radiation Measurements, 55 51-55. Measurement of multi-slice computed tomography dose profile with the Dose Magnifying Glass and the MOSkin radiation dosimeter AbstractThis study describes the application of two in-house developed dosimeters, the Dose Magnifying Glass (DMG) and the MOSkin dosimeter at the Centre for Medical Radiation Physics, University of Wollongong, Australia, for the measurement of CT dose profiles for a clinical diagnostic 16-slice MSCT scanner. Two scanner modes were used; axial mode and helical mode, and the effect of varying beam collimation and pitch was studied. With an increase in beam collimation in axial mode and an increase of CT pitch in helical mode, cumulative point dose at scanner isocentre decreased while FWHM increased. There was generally good agreement to within 3% between the acquired dose profiles obtained by the DMG and the film except at dose profile tails, where film over-responded by up to 30% due to its intrinsic depth dose dependence at low doses. AbstractThis study describes the application of two in-house developed dosimeters, the Dose Magnifying Glass (DMG) and the MOSkin dosimeter at the Centre for Medical Radiation Physics, University of Wollongong, Australia, for the measurement of CT dose profiles for a clinical diagnostic 16-slice MSCT scanner. Two scanner modes were used; axial mode and helical mode, and the effect of varying beam collimation and pitch was studied.With an increase in beam collimation in axial mode and an increase of CT pitch in helical mode, cumulative point dose at scanner isocentre decreased while FWHM increased. There was generally good agreement to within 3% between the acquired dose profiles obtained by the DMG and the film except at dose profile tails, where film over-responded by up to 30% due to its intrinsic depth dose dependence at low doses.

This study reports on the application of the MOSkin™ dosimeter in MSCT imaging for the real-time measurement of absorbed organ point doses in a tissue-equivalent female anthropomorphic phantom. MOSkin™ dosimeters were placed within the phantom to measure absorbed point organ doses for 2 commonly applied clinical scan protocols, namely the renal calculus scan and the pulmonary embolus scan. Measured organ doses in the imaged field of view were found to be in the dose range 4.7-9.5 mGy and 16.2-27.4 mGy for the renal calculus scan and pulmonary scan protocols respectively. For the derivation of effective dose, using the more recent ICRP 103 tissue weighting factors (w T) compared to that of the ICRP 60 wT resulted in a difference in the derived effective dose by up to 0.8 mSv (-20%) in the renal calculus protocol and up to 1.8 mSv (18%) in the pulmonary embolus protocol. This difference is attributed to the reduced radiosensitivity of the gonads and the increased radiosensitivity of breast tissue in the latest ICRP 103 assigned wT. The results of this study show that the MOSkin™ dosimeter is a useful real-time tool for the direct assessment of organ doses in clinical MSCT examinations.

Quantitative accuracy and constancy of Siemens xSPECT Bone quantitative reconstruction algorithm (xBone) can be monitored using activity-filled hollow spheres, which could be 3D printed (3DP-S) and increases accessibility to phantoms. One concern is that 3D prints can have air gaps in the walls which may pose issues for attenuation correction and xBone tissue zone mapping. This study assessed the feasibility of using 3DP-S with materials PLA, PETG and Resin as substitutes for commercial hollow spheres (C-S). Phantom preparation and acquisition parameters were based on the white paper. A Jaszczak phantom was fitted with six 99mTc- and contrast-filled 3DP-S. SPECT/CT acquisitions were performed on the Siemens Intevo T6 and reconstructed with xBone. Regions-of-interest for activity concentration measurements were drawn to the internal diameter of the spheres. PLA and PETG printed via filament freeform fabrication resulted in minute air gaps mainly at steep overhang however did not impact xBone zone maps. Activity concentration recovery of the 3DP-S were within +/-5% of C-S when sufficient projection angles are used. Resin printed via masked stereolithography experienced minor resin pooling and increased wall thickness – the smallest sphere was not usable. Resin printing achieved the best watertightness and transparency. PLA and PETG were most affordable but was labour intensive in construction. PLA performed best overall in print reproducibility and quantitative accuracy. Similarly printed hollow spheres can be used for quality control of xBone accuracy where C-S are not available. While 3D printing increases accessibility to phantoms, close oversight is required of printing conditions.

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