Prostate diffusion-weighted imaging (DWI) in MR-guided radiotherapy: Reproducibility assessment on 1.5 T MR-Linac and 1.5 T MR-simulator.

Purpose: Diffusion-weighted imaging (DWI) holds promise for image-guided radiotherapy (MRgRT) in prostate cancer. However, challenges persist due to image distortion, artifacts, and apparent diffusion coefficient (ADC) reproducibility issues. This study aimed to assess DWI image quality and ADC reproducibility on both a 1.

A study of Bayesian deep network uncertainty and its application to synthetic CT generation for MR-only radiotherapy treatment planning.

Background: The use of synthetic computed tomography (CT) for radiotherapy treatment planning has received considerable attention because of the absence of ionizing radiation and close spatial correspondence to source magnetic resonance (MR) images, which have excellent tissue contrast. However, in an MR-only environment, little effort has been made to examine the quality of synthetic CT images without using the original CT images.

Purpose: To estimate synthetic CT quality without referring to original CT images, this study established the relationship between synthetic CT uncertainty and Bayesian uncertainty, and proposed a new Bayesian deep network for generating synthetic CT images and estimating synthetic CT uncertainty for MR-only radiotherapy treatment planning.

Magnetic field induced dose effects in radiation therapy using MR-linacs.

MR-guided radiotherapy (MRgRT) is one of the most significant advances in radiotherapy in recent years. The hybrid systems were designed to visualize patient anatomical and physiological changes during the course of radiotherapy, enabling more precise treatment. However, before MR-linacs reach their full potential in delivering safe and accurate treatments to patients, the radiotherapy team must understand how a magnetic field alters the dosimetric properties of the radiation beam and its potential impact on treatment quality and clinical outcomes.

A pilot study of MRI radiomics for high-risk prostate cancer stratification in 1.5 T MR-guided radiotherapy.

Purpose: To investigate the potential value of MRI radiomics obtained from a 1.5 T MRI-guided linear accelerator (MR-LINAC) for D'Amico high-risk prostate cancer (PC) classification in MR-guided radiotherapy (MRgRT).

Methods: One hundred seventy-six consecutive PC patients underwent 1.

Determining the reliable feature change in longitudinal radiomics studies: A methodological approach using the reliable change index.

Purpose: Determination of reliable change of radiomics feature over time is essential and vital in delta-radiomics, but has not yet been rigorously examined. This study attempts to propose a methodological approach using reliable change index (RCI), a statistical metric to determine the reliability of quantitative biomarker changes by accounting for the baseline measurement standard error, in delta-radiomics. The use of RCI was demonstrated with the MRI data acquired from a group of prostate cancer (PCa) patients treated by 1.

Clinical implementation of kVCT-guided tomotherapy with ClearRT.

A helical fan-beam kilovoltage computed tomography (kVCT) was recently introduced into Tomotherapy units. This study aims to share the initial experience of kVCT in clinical workflow, compare its performance with that of the existing megavoltage computed tomography (MVCT), and explore its potential in adaptive planning. We retrospectively enrolled 23 patients who underwent both MVCT and kVCT scans.

A Prospective Study of Stereotactic Body Radiotherapy (SBRT) with Concomitant Whole-Pelvic Radiotherapy (WPRT) for High-Risk Localized Prostate Cancer Patients Using 1.5 Tesla Magnetic Resonance Guidance: The Preliminary Clinical Outcome.

Background: Conventionally fractionated whole-pelvic nodal radiotherapy (WPRT) improves clinical outcome compared to prostate-only RT in high-risk prostate cancer (HR-PC). MR-guided stereotactic body radiotherapy (MRgSBRT) with concomitant WPRT represents a novel radiotherapy (RT) paradigm for HR-PC, potentially improving online image guidance and clinical outcomes. This study aims to report the preliminary clinical experiences and treatment outcome of 1.

Proton Therapy for Prostate Cancer: Challenges and Opportunities.

The dosimetric advantages of proton therapy (PT) treatment plans are demonstrably superior to photon-based external beam radiotherapy (EBRT) for localized prostate cancer, but the reported clinical outcomes are similar. This may be due to inadequate dose prescription, especially in high-risk disease, as indicated by the ASCENDE-RT trial. Alternatively, the lack of clinical benefits with PT may be attributable to improper dose delivery, mainly due to geometric and dosimetric uncertainties during treatment planning, as well as delivery procedures that compromise the dose conformity of treatments.

Analysis of online plan adaptation for 1.5T magnetic resonance-guided stereotactic body radiotherapy (MRgSBRT) of prostate cancer.

Purpose: To analyze and characterize the online plan adaptation of 1.5T magnetic resonance-guided stereotactic body radiotherapy (MRgSBRT) of prostate cancer (PC).

Methods: PC patients (n = 107) who received adaptive 1.

A narrative review of MRI acquisition for MR-guided-radiotherapy in prostate cancer.

Magnetic resonance guided radiotherapy (MRgRT), enabled by the clinical introduction of the integrated MRI and linear accelerator (MR-LINAC), is a novel technique for prostate cancer (PCa) treatment, promising to further improve clinical outcome and reduce toxicity. The role of prostate MRI has been greatly expanded from the traditional PCa diagnosis to also PCa screening, treatment and surveillance. Diagnostic prostate MRI has been relatively familiar in the community, particularly with the development of Prostate Imaging - Reporting and Data System (PI-RADS).

3D-T2W-TSE radiotherapy treatment planning MRI using compressed sensing acceleration for prostate cancer: Image quality and delineation value.

Purpose: To assess the image quality and delineation value of compressed sensing (CS)-accelerated 3D T2W turbo-spin-echo (TSE) sequence for radiotherapy treatment planning (RTP) of prostate cancer.

Methods: An optimized CS-accelerated 3D-T2W-TSE was determined by volunteer imaging and applied for clinical RTP-MRI. This optimized CS-accelerated planning MRI and the standardized adaptive MRI acquired at 1.

1.5T Magnetic Resonance-Guided Stereotactic Body Radiotherapy for Localized Prostate Cancer: Preliminary Clinical Results of Clinician- and Patient-Reported Outcomes.

Background: Magnetic resonance-guided stereotactic body radiotherapy (MRgSBRT) offers the potential for achieving better prostate cancer (PC) treatment outcomes. This study reports the preliminary clinical results of 1.5T MRgSBRT in localized PC, based on both clinician-reported outcome measurement (CROM) and patient-reported outcome measurement (PROM).

3D T1-weighted turbo spin echo contrast-enhanced MRI at 1.5 T for frameless brain metastases radiotherapy.

Purpose: Performance of 3D-T1W-TSE has been proven superior to 3D-MP-GRE at 3 T on brain metastases (BM) contrast-enhanced (CE) MRI. However, its performance at 1.5 T is largely unknown and sparsely reported.

Quantitative assessment of acquisition imaging parameters on MRI radiomics features: a prospective anthropomorphic phantom study using a 3D-T2W-TSE sequence for MR-guided-radiotherapy.

Background: MRI pulse sequences and imaging parameters substantially influence the variation of MRI radiomics features, thus impose a critical challenge on MRI radiomics reproducibility and reliability. This study aims to prospectively investigate the impact of various imaging parameters on MRI radiomics features in a 3D T2-weighted (T2W) turbo-spin-echo (TSE) pulse sequence for MR-guided-radiotherapy (MRgRT).

Methods: An anthropomorphic phantom was scanned using a 3D-T2W-TSE MRgRT sequence at 1.

Effects on skin dose from unwanted air gaps under bolus in an MR-guided linear accelerator (MR-linac) system.

Bolus is commonly used in MV photon radiotherapy to increase superficial dose and improve dose uniformity for treating shallow lesions. However, irregular patient body contours can cause unwanted air gaps between a bolus and patient skin. The resulting dosimetric errors could be exacerbated in MR-Linac treatments, as secondary electrons generated by photons are affected by the magnetic field.

Reliability of radiomics features due to image reconstruction using a standardized T -weighted pulse sequence for MR-guided radiotherapy: An anthropomorphic phantom study.

Purpose: To prospectively investigate the impact of image reconstruction on MRI radiomics features.

Methods: An anthropomorphic phantom was scanned at 1.5 T using a standardized sequence for MR-guided radiotherapy under SENSE and compressed-SENSE reconstruction settings.

Longitudinal acquisition repeatability of MRI radiomics features: An ACR MRI phantom study on two MRI scanners using a 3D T1W TSE sequence.

Purpose: The purpose of this study was to quantitatively assess the longitudinal acquisition repeatability of MRI radiomics features in a three-dimensional (3D) T1-weighted (T1W) TSE sequence via a well-controlled prospective phantom study.

Methods: Thirty consecutive daily datasets of an ACR-MRI phantom were acquired on two 1.5T MRI simulators using a 3D T1W TSE sequence.

A pilot study of highly accelerated 3D MRI in the head and neck position verification for MR-guided radiotherapy.

Background: To evaluate the performance of a highly accelerated 3D MRI on inter-fractional positional measurement for MR-guided radiotherapy (MRgRT) in the head and neck (HN).

Methods: Fourteen healthy volunteers received 159 scans on a 1.5 T MR-sim to simulate MRgRT fractions.

A novel method for monitoring the constancy of beam path accuracy in CyberKnife.

The aim of current work was to present a novel evaluation procedure implemented for checking the constancy of beam path accuracy of a CyberKnife system based on ArcCHECK. A tailor-made Styrofoam with four implanted fiducial markers was adopted to enable the fiducial tracking during beam deliveries. A simple two-field plan and an isocentric plan were created for determining the density override of ArcCHECK in MultiPlan and the constancy of beam path accuracy respectively.

Performance evaluation of the CyberKnife system in real-time target tracking during beam delivery using a moving phantom coupled with two-dimensional detector array.

The aim of the current study was to evaluate the tracking error of the Synchrony Respiratory Tracking system by conducting beam-by-beam analyses to determine the variation in the tracking beams measured during target motion. A moving phantom of in-house design coupled with a two-dimensional (2D) detector array was used to simulate respiratory motion in the superoinferior (SI) and anteroposterior (AP) direction. A styrofoam block with four implanted fiducial markers was placed on top of the detector to enable the fiducial-based respiratory tracking.