Illusory implications: incidental exposure to ideas can induce beliefs.

Numerous psychological findings have shown that incidental exposure to ideas makes those ideas seem more true, a finding commonly referred to as the 'illusory truth' effect. Under many accounts of the illusory truth effect, initial exposure to a statement provides a metacognitive feeling of 'fluency' or familiarity that, upon subsequent exposure, leads people to infer that the statement is more likely to be true. However, genuine beliefs do not only affect truth judgements about individual statements, they also imply other beliefs and drive decision-making.

Addressing lung truncation in Tc-MAA SPECT/CT for Y microsphere radioembolization treatment planning.

Background: Prior studies have established that macroaggregated albumin (MAA)-SPECT/CT offers more robust lung shunt fraction (LSF) and lung mean absorbed dose (LMD) estimates in Y radioembolization in comparison to planar imaging. However, incomplete SPECT/CT coverage of the lungs is common due to clinical workflows, complicating its potential use for LSF and LMD calculations. In this work, lung truncation in MAA-SPECT/CT was addressed via correction strategies to improve Y treatment planning.

Arterial hypoperfusion as a negative predictive marker for primary hepatic malignancies treated with Y-90 glass microsphere transarterial radioembolization.

Background: Radioembolization with yttrium-90 (Y-90) is utilized to treat primary liver malignancies. The efficacy of this intra-arterial therapy in arterially hypoperfused tumors is not known.

Methods: We reviewed data of patients with primary liver tumors treated with Y-90 prescription doses of at least 150 Gy.

PET/CT-Based Absorbed Dose Maps in Y Selective Internal Radiation Therapy Correlate with Spatial Changes in Liver Function Derived from Dynamic MRI.

Functional liver parenchyma can be damaged from treatment of liver malignancies with Y selective internal radiation therapy (SIRT). Evaluating functional parenchymal changes and developing an absorbed dose (AD)-toxicity model can assist the clinical management of patients receiving SIRT. We aimed to determine whether there is a correlation between Y PET AD voxel maps and spatial changes in the nontumoral liver (NTL) function derived from dynamic gadoxetic acid-enhanced MRI before and after SIRT.

Linear Boltzmann equation solver for voxel-level dosimetry in radiopharmaceutical therapy: Comparison with Monte Carlo and kernel convolution.

Background: With recent interest in patient-specific dosimetry for radiopharmaceutical therapy (RPT) and selective internal radiation therapy (SIRT), an increasing number of voxel-based algorithms are being evaluated. Monte Carlo (MC) radiation transport, generally considered to be the most accurate among different methods for voxel-level absorbed dose estimation, can be computationally inefficient for routine clinical use.

Purpose: This work demonstrates a recently implemented grid-based linear Boltzmann transport equation (LBTE) solver for fast and accurate voxel-based dosimetry in RPT and SIRT and benchmarks it against MC.

Stereotactic body radiation therapy (SBRT) following Yttrium-90 (Y) selective internal radiation therapy (SIRT): a feasibility planning study usingY delivered dose.

.Y selective internal radiation therapy (SIRT) treatment of hepatocellular carcinoma (HCC) can potentially underdose lesions, as identified on post-therapy PET/CT imaging. This study introduces a methodology and explores the feasibility for selectively treating SIRT-underdosed HCC lesions, or lesion subvolumes, with stereotactic body radiation therapy (SBRT) following post-SIRT dosimetry.

Intra- and inter-operator variability in MRI-based manual segmentation of HCC lesions and its impact on dosimetry.

Purpose: The aim was to quantify inter- and intra-observer variability in manually delineated hepatocellular carcinoma (HCC) lesion contours and the resulting impact on radioembolization (RE) dosimetry.

Methods: Ten patients with HCC lesions treated with Y-90 RE and imaged with post-therapy Y-90 PET/CT were selected for retrospective analysis. Three radiologists contoured 20 lesions manually on baseline multiphase contrast-enhanced MRIs, and two of the radiologists re-contoured at two additional sessions.

A Multicenter Study on Observed Discrepancies Between Vendor-Stated and PET-Measured Y Activities for Both Glass and Resin Microsphere Devices.

Dosimetry-guided treatment planning in selective internal radiation therapy relies on accurate and reproducible measurement of administered activity. This 4-center, 5-PET-device study compared the manufacturer-declared Y activity in vials with quantitative Y PET/CT assessment of the same vials. We compared Y PET-measured activity (A) for 56 Y-labeled glass and 18 Y-labeled resin microsphere vials with the calibrated activity specified by the manufacturer (A).

Experimental validation of Monte Carlo dosimetry for therapeutic beta emitters with radiochromic film in a 3D-printed phantom.

Purpose: Validation of dosimetry software, such as Monte Carlo (MC) radiation transport codes used for patient-specific absorbed dose estimation, is critical prior to their use in clinical decision making. However, direct experimental validation in the clinic is generally not performed for low/medium-energy beta emitters used in radiopharmaceutical therapy (RPT) due to the challenges of measuring energy deposited by short-range particles. Our objective was to design a practical phantom geometry for radiochromic film (RF)-based absorbed dose measurements of beta-emitting radionuclides and perform experiments to directly validate our in-house developed Dose Planning Method (DPM) MC code dedicated to internal dosimetry.

The American Brachytherapy Society consensus statement for permanent implant brachytherapy using Yttrium-90 microsphere radioembolization for liver tumors.

Purpose: To develop a multidisciplinary consensus for high quality multidisciplinary implementation of brachytherapy using Yttrium-90 (Y) microspheres transarterial radioembolization (Y TARE) for primary and metastatic cancers in the liver.

Methods And Materials: Members of the American Brachytherapy Society (ABS) and colleagues with multidisciplinary expertise in liver tumor therapy formulated guidelines for Y TARE for unresectable primary liver malignancies and unresectable metastatic cancer to the liver. The consensus is provided on the most recent literature and clinical experience.

A Pipeline for Automated Voxel Dosimetry: Application in Patients with Multi-SPECT/CT Imaging After Lu-Peptide Receptor Radionuclide Therapy.

Patient-specific dosimetry in radiopharmaceutical therapy (RPT) is impeded by the lack of tools that are accurate and practical for the clinic. Our aims were to construct and test an integrated voxel-level pipeline that automates key components (organ segmentation, registration, dose-rate estimation, and curve fitting) of the RPT dosimetry process and then to use it to report patient-specific dosimetry in Lu-DOTATATE therapy. An integrated workflow that automates the entire dosimetry process, except tumor segmentation, was constructed.

DblurDoseNet: A deep residual learning network for voxel radionuclide dosimetry compensating for single-photon emission computerized tomography imaging resolution.

Purpose: Current methods for patient-specific voxel-level dosimetry in radionuclide therapy suffer from a trade-off between accuracy and computational efficiency. Monte Carlo (MC) radiation transport algorithms are considered the gold standard for voxel-level dosimetry but can be computationally expensive, whereas faster dose voxel kernel (DVK) convolution can be suboptimal in the presence of tissue heterogeneities. Furthermore, the accuracies of both these methods are limited by the spatial resolution of the reconstructed emission image.

Pretreatment Levels of Soluble Tumor Necrosis Factor Receptor 1 and Hepatocyte Growth Factor Predict Toxicity and Overall Survival After Y Radioembolization: Potential Novel Application of Biomarkers for Personalized Management of Hepatotoxicity.

Liver function may be negatively affected by radiation for treatment of hepatic malignancy. Pretreatment blood cytokine levels are biomarkers for prediction of toxicity and survival after external-beam radiation therapy. We hypothesized that cytokines may also predict outcomes after radioembolization, enabling a biomarker-driven personalized approach to treatment.

Y-90 SIRT: evaluation of TCP variation across dosimetric models.

Introduction: Much progress has been made in implementing selective internal radiation therapy (SIRT) as a viable treatment option for hepatic malignancies. However, there is still much need for improved options for calculating the amount of activity to be administered. To make advances towards this goal, this study examines the relationship between predicted biological outcomes of liver tumors via tumor control probabilities (TCP) and parenchyma via normal tissue complication probabilities (NTCP) given variations in absorbed dose prescription methodologies.

Development and comprehensive commissioning of an automated brachytherapy plan checker.

Purpose: To present on the commissioning of an automated brachytherapy plan checker (BPC) for the evaluation of high-dose-rate brachytherapy treatment plans in support of standardized workflows and patient safety.

Methods And Materials: A BPC was developed using an applications programming interface in a commercial treatment planning system based on different inputs (e.g.

Transarterial Radioembolization for Hepatocellular Carcinoma and Hepatic Metastases: Clinical Aspects and Dosimetry Models.

Transarterial radioembolization (TARE) with Yttrium-90 (Y) microspheres is a liver-directed therapy for primary and metastatic disease. This manuscript provides a review of the clinical literature on TARE indications and efficacy with overviews of patient-selection and toxicity. Current dosimetry models used in practice are safe, relatively simple, and easy for clinicians to use.

Silicon Photomultipliers for Deep Tissue Cerenkov Emission Detection During External Beam Radiotherapy.

Cerenkov Emission (CE) during external beam radiation therapy (EBRT) from a linear accelerator (Linac) has been demonstrated as a useful tool for radiotherapy quality assurance and potentially other applications for online tracking of tumors during treatment delivery. However, some of the current challenges that are impacting the potential of CE are related to the limited detection sensitivity and the lack of flexible tools to fit into an already complex treatment delivery environment. Silicon photomultiplier (SiPM) solid-state devices are new promising tools for low light detection due to their extreme sensitivity that mirrors photomultiplier tubes and yet have a form factor that is similar to silicon photodiodes, allowing for improved flexibility in device design that may help in the process of wider clinical applicability.

Prediction of Tumor Control in Y Radioembolization by Logit Models with PET/CT-Based Dose Metrics.

The aim of this work was to develop models for tumor control probability (TCP) in radioembolization with Y PET/CT-derived radiobiologic dose metrics. Patients with primary liver cancer or liver metastases who underwent radioembolization with glass microspheres were imaged with Y PET/CT for voxel-level dosimetry to determine lesion absorbed dose (AD) metrics, biological effective dose (BED) metrics, equivalent uniform dose, and equivalent uniform BED for 28 treatments (89 lesions). The lesion dose-shrinkage correlation was assessed on the basis of RECIST and, when available, modified RECIST (mRECIST) at first follow-up.

Assessing Spatial Concordance Between Theranostic Pairs Using Phantom and Patient-Specific Acceptance Criteria: Application to Tc-MAA SPECT/Y-Microsphere PET.

Purpose: Predictive 3-dimensional dosimetry requires spatial concordance between diagnostic and therapeutic activity distributions. We assess similarity between theranostic pairs (Tc-macroaggregated albumin [MAA] single photon emission computed tomography [SPECT] and Y microsphere positron emission tomography [PET]) in patients using criteria that account for spatial resolution differences and misregistration.

Methods And Materials: Phantom-based acceptance criteria were determined using a liver phantom filled with Tc and YCl and scanned with SPECT/computed tomography [CT] and PET/CT, respectively.

Impact of Y PET gradient-based tumor segmentation on voxel-level dosimetry in liver radioembolization.

Background: The purpose was to validate Y PET gradient-based tumor segmentation in phantoms and to evaluate the impact of the segmentation method on reported tumor absorbed dose (AD) and biological effective dose (BED) in Y microsphere radioembolization (RE) patients. A semi-automated gradient-based method was applied to phantoms and patient tumors on the Y PET with the initial bounding volume for gradient detection determined from a registered diagnostic CT or MR; this PET-based segmentation (PS) was compared with radiologist-defined morphologic segmentation (MS) on CT or MRI. AD and BED volume histogram metrics (D90, D70, mean) were calculated using both segmentations and concordance/correlations were investigated.

Dose volume histogram-based optimization of image reconstruction parameters for quantitative Y-PET imaging.

Purpose: Y-microsphere radioembolization or selective internal radiation therapy is increasingly being used as a treatment option for tumors that are not candidates for surgery and external beam radiation therapy. Recently, volumetric Y-dosimetry techniques have been implemented to explore tumor dose-response on the basis of 3D Y-activity distribution from PET imaging. Despite being a theranostic study, the optimization of quantitative Y-PET image reconstruction still uses the mean activity concentration recovery coefficient (RC) as the objective function, which is more relevant to diagnostic and detection tasks than is to dosimetry.

Hepatocellular Carcinoma Tumor Dose Response After Y-radioembolization With Glass Microspheres Using Y-SPECT/CT-Based Voxel Dosimetry.

Purpose: To investigate hepatocellular carcinoma tumor dose-response characteristics based on voxel-level absorbed doses (D) and biological effective doses (BED) using quantitative Y-single-photon emission computed tomography (SPECT)/computed tomography (CT) after Y-radioembilization with glass microspheres. We also investigated the relationship between normal liver D and toxicities.

Methods And Materials: Y-radioembolization activity distributions for 34 patients were based on quantitative Y-bremsstrahlung SPECT/CT.

The value of Tc-MAA SPECT/CT for lung shunt estimation in Y radioembolization: a phantom and patient study.

Background: A major toxicity concern in radioembolization therapy of hepatic malignancies is radiation-induced pneumonitis and sclerosis due to hepatopulmonary shunting of Y microspheres. Currently, Tc macroaggregated albumin (Tc-MAA) imaging is used to estimate the lung shunt fraction (LSF) prior to treatment. The aim of this study was to evaluate the accuracy/precision of LSF estimated from Tc planar and SPECT/CT phantom imaging, and within this context, to compare the corresponding LSF and lung-absorbed dose values from Tc-MAA patient studies.

The impact of a high-definition multileaf collimator for spine SBRT.

Purpose: Advanced radiotherapy delivery systems designed for high-dose, high-precision treatments often come equipped with high-definition multi-leaf collimators (HD-MLC) aimed at more finely shaping radiation dose to the target. In this work, we study the effect of a high definition MLC on spine stereotactic body radiation therapy (SBRT) treatment plan quality and plan deliverability.

Methods And Materials: Seventeen spine SBRT cases were planned with VMAT using a standard definition MLC (M120), HD-MLC, and HD-MLC with an added objective to reduce monitor units (MU).

Effects of image noise, respiratory motion, and motion compensation on 3D activity quantification in count-limited PET images.

The aims of this study were to evaluate the effects of noise, motion blur, and motion compensation using quiescent-period gating (QPG) on the activity concentration (AC) distribution-quantified using the cumulative AC volume histogram (ACVH)-in count-limited studies such as Y-PET/CT. An International Electrotechnical Commission phantom filled with low F activity was used to simulate clinical Y-PET images. PET data were acquired using a GE-D690 when the phantom was static and subject to 1-4 cm periodic 1D motion.