A Method for Validating PET and SPECT Cameras for Quantitative Clinical Imaging Trials Using Novel Radionuclides.

Our aim is to report methodology that has been developed to calibrate and verify PET and SPECT quantitative image accuracy and quality assurance for use with nonstandard radionuclides, especially with longer half-lives, in clinical imaging trials. Procedures have been developed for quantitative PET and SPECT image calibration for use in clinical trials. The protocol uses a 3-step approach: check quantitative accuracy with a previously calibrated radionuclide in a simple geometry, check the novel trial radionuclide in the same geometry, and check the novel radionuclide in a more challenging, complex geometry (the National Electrical Manufacturers Association [NEMA] NU-2 International Electrotechnical Commission [IEC] image-quality phantom).

Evolving SPECT-CT technology.

Both hardware and software developments have seen single photon emission computed tomography (SPECT)/X-ray computed tomography (CT) technology grow at a rapid rate. Such growth has been fuelled by the need for clinical applications and has provided inspiration for clinical developments, particularly with the expanding role of theranostics. Developments such as whole-body quantitative reconstructions, digital detectors, and recent multidetector 3D geometry have allowed SPECT to become comparable to PET on a number of fronts, with a particularly powerful role in biodistribution and dosimetry studies for both planning and evaluating radionuclide therapy.

A practical method for assessing quantitative scanner accuracy with long-lived radionuclides: The ARTnet insert.

Objectives: To address the problem of using large volumes of long-lived radionuclides in test phantoms to check calibration accuracy of PET and SPECT systems we have developed a test object which (a) contains less radioactivity, (b) has a low total volume, and (c) is easier to store than currently used phantoms, while still making use of readily-available "standardised" test objects.

Methods: We have designed a hollow acrylic cylindrical insert compatible with the NEMA/IEC PET Body Image Quality (IQ) phantom used in NU 2 performance testing of PET systems. The insert measures 90 mm internal diameter and 70 mm internal height and so is sufficiently large to not be subject to partial volume effects in PET or SPECT imaging.

Investigation and optimization of PET-guided SPECT reconstructions for improved radionuclide therapy dosimetry estimates.

Introduction: To investigate and optimize the SPECTRE (Single Photon Emission Computed Theranostic REconstruction) reconstruction approach, using the hybrid kernelised expectation maximization (HKEM) algorithm implemented in the software for tomographic image reconstruction (STIR) software library, and to demonstrate the feasibility of performing algorithm exploration and optimization in 2D. Optimal SPECTRE parameters were investigated for the purpose of improving SPECT-based radionuclide therapy (RNT) dosimetry estimates.

Materials And Methods: Using the NEMA IEC body phantom as the test object, SPECT data were simulated to model an early and late imaging time point following a typical therapeutic dose of 8 GBq of Lu.

Transition to Fast Whole-Body SPECT/CT Bone Imaging: An Assessment of Image Quality.

Objective: To investigate the impact of reduced SPECT acquisition time on reconstructed image quality for diagnostic purposes.

Method: Data from five patients referred for a routine bone SPECT/CT using the standard multi-bed SPECT/CT protocol were reviewed. The acquisition time was 900 s using gating technique; SPECT date was resampled into reduced data sets of 480 s, 450 s, 360 s and 180 s acquisition duration per bed position.

Cu Treatment Planning and Cu Therapy with Radiolabeled [Cu/Cu]MeCOSar-Octreotate in Subjects with Unresectable Multifocal Meningioma: Initial Results for Human Imaging, Safety, Biodistribution, and Radiation Dosimetry.

Our aim was to report the use of Cu and Cu as a theranostic pair of radionuclides in human subjects. An additional aim was to measure whole-organ dosimetry of Cu and Cu attached to the somatostatin analog octreotate using the sarcophagine MeCOSar chelator (SARTATE) in subjects with somatostatin receptor-expressing lesions confined to the cranium, thereby permitting normal-organ dosimetry for the remainder of the body. Pretreatment PET imaging studies were performed up to 24 h after injection of [Cu]Cu-SARTATE, and normal-organ dosimetry was estimated using OLINDA/EXM.

Towards personalised dosimetry in patients with liver malignancy treated with Y-SIRT using in vivo-driven radiobiological parameters.

Background: The prediction of response is one of the major challenges in radiation-based therapies. Although the selection of accurate linear-quadratic model parameters is essential for the estimation of radiation response and treatment outcome, there is a limited knowledge about these radiobiological parameters for liver tumours using radionuclide treatments.

Methods: The "clinical radiobiological" parameters ([Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text]) for twenty-five patients were derived using the generalised linear-quadratic model, the diagnostic ([F] FDG PET/CT) and therapeutic ([Y]-SIR-Spheres PET/CT) images to compute the biological effective dose and tumour control probability (TCP) for each patient.

AN UNUSUAL CAUSE OF GAMMA CAMERA CONTAMINATION.

This report is of an unusual case of radioactive contamination of a gamma camera after scanning two individuals who had been treated 3 days prior with ablative doses of radioiodine (I) for thyroid cancer. A combination of observed half-life and pulse-height spectroscopy were employed to identify the radio-contaminant. The source of the contamination was eventually found to be a single human hair, presumably contaminated by the individual sucking her hair while waiting for the scan to start.

Optimization of Tc whole-body SPECT/CT image quality: A phantom study.

Investigate the impact of acquisition time and reconstruction parameters on single-photon emission computed tomography/computed tomography (SPECT/CT) image quality with the ultimate aim of finding the shortest possible acquisition time for clinical whole-body SPECT/CT (WB-SPECT/CT) while maintaining image quality METHODS: The National Electrical Manufacturers Association (NEMA) image quality measurements were performed on a SPECT/CT imaging system using a NEMA International Electrotechnical Commission (IEC) phantom with spherical inserts of varying diameter (10-37 mm), filled with Tc in activity sphere-to-background concentration ratio of 8.5:1. A gated acquisition was acquired and binned data were summed to simulate acquisitions of 15, 8, and 3 s per projection angle.

Individualised dosimetry and safety of SIRT for intrahepatic cholangiocarcinoma.

Background: The aim of this study was to investigate the safety and efficacy of selective internal radiation therapy (SIRT) with Y resin microspheres for the treatment of Intrahepatic Cholangiocarcinoma (ICC). A total of 23 SIRT procedures from 18 ICC subjects were analysed to determine a lesion-based dose/response relationship with absorbed dose measures from Y PET and metabolic response as measured on [F]FDG PET. Average absorbed dose (D), minimum dose to 70% of the volume (D), volume receiving at least 50 Gy (V), biological effective dose (BED) and equivalent uniform dose (EUD), were compared to changes in metabolic volume, maximum standardised uptake value (SUV) and total lesion glycolysis (TLG).

Overlooked potential of positrons in cancer therapy.

Positron (β) emitting radionuclides have been used for positron emission tomography (PET) imaging in diagnostic medicine since its development in the 1950s. Development of a fluorinated glucose analog, fluorodeoxyglucose, labelled with a β emitter fluorine-18 (F-FDG), made it possible to image cellular targets with high glycolytic metabolism. These targets include cancer cells based on increased aerobic metabolism due to the Warburg effect, and thus, F-FDG is a staple in nuclear medicine clinics globally.

Quantitative PET in the 2020s: a roadmap.

Positron emission tomography (PET) plays an increasingly important role in research and clinical applications, catalysed by remarkable technical advances and a growing appreciation of the need for reliable, sensitive biomarkers of human function in health and disease. Over the last 30 years, a large amount of the physics and engineering effort in PET has been motivated by the dominant clinical application during that period, oncology. This has led to important developments such as PET/CT, whole-body PET, 3D PET, accelerated statistical image reconstruction, and time-of-flight PET.

Quantifying the effects of absorbed dose from radioembolisation on healthy liver function with [Tc]TcMebrofenin.

Purpose: To quantify the effects of absorbed radiation dose on healthy liver parenchyma following radioembolisation (RE) using [Tc]TcMebrofenin to analyse both global and regional liver function.

Methods: Patients having RE to treat hepatic disease underwent a [Tc]TcMebrofenin hepatobilliary scintigraphy (HBS) study at both baseline and 8 weeks following treatment. Changes in global liver uptake rate were compared with healthy liver absorbed dose measures derived from the post-treatment Y PET/CT, including average dose, minimum dose to 70% of the volume (D70) and volume receiving at least 50 Gy (V50).

Performance evaluation of quantitative SPECT/CT using NEMA NU 2 PET methodology.

Although PET is routinely evaluated using NEMA NU2 as standard in the clinic, standard methodology for evaluating the performance of quantitative SPECT systems has not been established. In this study, the quantitative performance of the Symbia Intevo SPECT/CT was evaluated for two common isotopes (Tc, Lu) and benchmarked against the performance of a PET/CT. A further aim was to demonstrate the utility of adapting NEMA NU2 PET measurements to SPECT.

Diagnostic reference levels for F-FDG whole body PET/CT procedures: Results from a survey of 12 centres in Australia and New Zealand.

Introduction: The aim of this work is to report diagnostic reference levels (DRLs) for hybrid positron emission tomography and x-ray computed tomography (PET/CT) exams in Australia (AU) for Queensland (QLD) and Western Australia (WA) (AU QLD/WA) and New Zealand (NZ).

Methods: Two-structured booklets were designed to collect dose information, patient demographics, equipment details and acquisition protocols for fluoride-18 fluorodeoxyglucose ( F-FDG) PET/CT procedures, and any additional diagnostic CT routinely performed as part of F-FDG whole-body examination. The DRL was reported based on the 75 percentile and achievable dose for F-FDG, CT dose index volume (CTDI ) and dose length product (DLP).

An Australian local diagnostic reference level for paediatric whole-body F-FDG PET/CT.

Objective:: The aim of this study is to report a local diagnostic reference level (DRL) for paediatric whole-body (WB) fludeoxyglucose (F-FDG) positron emission tomography (PET) CT examinations.

Methods:: The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) national DRL (NDRL) age category (0-4 years and 5-14 years), the International Commission on Radiological Protection age category (ICRP age) (<1, >1-5, >5-10, and >10-15 years), and European guideline weight category ( EG weight) (<5, 5-<15, 15-<30, 30-<50, and 50-<80 kg) were used to determine a local DRL for WB F FDG PET/CT studies. Two-structured questionnaires were designed to collect dose data, patient demographics, equipment details, and acquisition protocols for WB F-FDG PET/CT procedures.

Feasibility and accuracy of single time point imaging for renal dosimetry following Lu-DOTATATE ('Lutate') therapy.

Background: This study aims to assess both feasibility and accuracy of renal dosimetry imaging protocols in patients receiving Lutate therapy for neuroendocrine tumours (NETs), when data acquisition over multiple days is not possible on all cycles.

Method: Patients who had received a full 4 cycles of Lutate therapy with complete imaging at each cycle were included. Imaging consisted of quantitative SPECT/CT of the kidneys at 4, 24 and 96-120 h post injection.

Results of a Prospective Phase 2 Pilot Trial of Lu-PSMA-617 Therapy for Metastatic Castration-Resistant Prostate Cancer Including Imaging Predictors of Treatment Response and Patterns of Progression.

Background: Lu-PSMA-617 (Lu-PSMA) is an emerging therapy in men with metastatic castration-resistant prostate cancer. Paired theranostic agents have the potential to visually identify phenotypes that will respond to targeted therapy. This study examined the value of Ga-HBEDD PSMA-11; prostate-specific membrane antigen (PSMA) positron emission tomography (PET) in predicting treatment response and disease progression in Lu-PSMA therapy within the context of a phase 2 prospective pilot trial.

Comparison of radiobiological parameters for Y radionuclide therapy (RNT) and external beam radiotherapy (EBRT) in vitro.

Background: Dose rate variation is a critical factor affecting radionuclide therapy (RNT) efficacy. Relatively few studies to date have investigated the dose rate effect in RNT. Therefore, the aim of this study was to benchmark Y RNT (at different dose rates) against external beam radiotherapy (EBRT) in vitro and compare cell kill responses between the two irradiation processes.

Determining and updating PET/CT and SPECT/CT diagnostic reference levels: A systematic review.

The aim of this systematic review is to investigate the national diagnostic reference level (NDRL) methods for positron emission tomography/computed tomography (PET/CT) and single photon emission tomography/computed tomography (SPECT/CT) procedures. A search strategy was based on the preferred, reporting items for systematic review and meta-analysis (PRISMA). Relevant articles retrieved from Medline, Scopus, Web of Science, Embase, Cinahl, and Google Scholar published up to October 2017.

A Comparison of 2D and 3D Kidney Absorbed Dose Measures in Patients Receiving Lu-DOTATATE.

Objectives: To investigate and compare quantitative accuracy of kidney absorbed dose measures made from both 2D and 3D imaging in patients receiving Lu-DOTATATE (Lutate) for treatment of neuroendocrine tumours (NETs).

Methods: Patients receiving Lutate therapy underwent both whole body planar imaging and SPECT/CT imaging over the kidneys at time points 0.5, 4, 24, and 96-120 hours after injection.

Changing Therapeutic Paradigms: Predicting mCRC Lesion Response to Selective Internal Radionuclide Therapy (SIRT) based on Critical Absorbed Dose Thresholds: A Case Study.

A 65 year old male with metastatic colorectal cancer (mCRC) in the liver was referred for selective internal radionuclide therapy (SIRT) following a history of extensive systemic chemotherapy. Y PET imaging was performed immediately after treatment and used to confirm lesion targeting and measure individual lesion absorbed doses. Lesion dosimetry was highly predictive of eventual response in the follow-up FDG PET performed 8 weeks after therapy.