Assessing suitability and stability of materials for a head and neck anthropomorphic multimodality (MRI/CT) phantoms for radiotherapy.

This study aims to identify and evaluate suitable and stable materials for developing a head and neck anthropomorphic multimodality phantom for radiotherapy purposes. These materials must mimic human head and neck tissues in both computed tomography (CT) and magnetic resonance imaging (MRI) and maintain stable imaging properties over time and after radiation exposure, including the high levels associated with linear accelerator (linac) use.Various materials were assessed by measuring their CT numbers and T1 and T2 relaxation times.

Automated confidence estimation in deep learning auto-segmentation for brain organs at risk on MRI for radiotherapy.

Purpose: We have built a novel AI-driven QA method called AutoConfidence (ACo), to estimate segmentation confidence on a per-voxel basis without gold standard segmentations, enabling robust, efficient review of automated segmentation (AS). We have demonstrated this method in brain OAR AS on MRI, using internal and external (third-party) AS models.

Methods: Thirty-two retrospectives, MRI planned, glioma cases were randomly selected from a local clinical cohort for ACo training.

A systematic review of 4D magnetic resonance imaging techniques for abdominal radiotherapy treatment planning.

Background And Purpose: Four-dimensional magnetic resonance imaging (4DMRI) has gained interest as an alternative to the current standard for motion management four-dimensional tomography (4DCT) in abdominal radiotherapy treatment planning (RTP). This review aims to assess the 4DMRI literature in abdomen, focusing on technical considerations and the validity of using 4DMRI for patients within radiotherapy protocols.

Materials And Methods: The review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

Dosimetric impact of contour editing on CT and MRI deep-learning autosegmentation for brain OARs.

Purpose: To establish the clinical applicability of deep-learning organ-at-risk autocontouring models (DL-AC) for brain radiotherapy. The dosimetric impact of contour editing, prior to model training, on performance was evaluated for both CT and MRI-based models. The correlation between geometric and dosimetric measures was also investigated to establish whether dosimetric assessment is required for clinical validation.

Deep learning MRI-only synthetic-CT generation for pelvis, brain and head and neck cancers.

Background And Purpose: MRI-only planning relies on dosimetrically accurate synthetic-CT (sCT) generation to allow dose calculation. Here we validated the dosimetric accuracy of sCTs generated using a deep learning algorithm for pelvic, brain and head and neck (H&N) cancer sites using variable MRI data from multiple scanners.

Methods: sCT generation models were trained using a cycle-GAN algorithm, using paired MRI-CT patient data.

Geometric evaluations of CT and MRI based deep learning segmentation for brain OARs in radiotherapy.

Deep-learning auto-contouring (DL-AC) promises standardisation of organ-at-risk (OAR) contouring, enhancing quality and improving efficiency in radiotherapy. No commercial models exist for OAR contouring based on brain magnetic resonance imaging (MRI). We trained and evaluated computed tomography (CT) and MRI OAR autosegmentation models in RayStation.

The role and potential of using quantitative MRI biomarkers for imaging guidance in brain cancer radiotherapy treatment planning: A systematic review.

Background And Purpose: Improving the accuracy of brain tumour radiotherapy (RT) treatment planning is important to optimise patient outcomes. This systematic review investigates primary studies providing clinical evidence for the integration of quantitative magnetic resonance imaging (qMRI) biomarkers and MRI radiomics to optimise brain tumour RT planning.

Materials And Methods: PubMed, Scopus, Embase and Web of Science databases were searched for all years until June 21, 2022.

Treatment plan optimisation for reirradiation.

Background: The STRIDeR (Support Tool for Re-Irradiation Decisions guided by Radiobiology) project aims to create a clinically viable re-irradiation planning pathway within a commercial treatment planning system (TPS). Such a pathway should account for previously delivered dose, voxel-by-voxel, taking fractionation effects, tissue recovery and anatomical changes into account. This work presents the workflow and technical solutions in the STRIDeR pathway.

The impact of a metal artefact reduction algorithm on treatment planning for patients undergoing radiotherapy of the pelvis.

Background And Purpose: Metallic implants cause artefacts in computed tomography (CT) images and can introduce significant errors to structure visualisation and dosimetric calculation within the radiotherapy planning process. This study evaluated an orthopaedic metal artefact reduction algorithm and its effect on the CT number, image noise, structure delineation, and treatment dose.

Methods: Raw CT data were reconstructed using standard filtered back projection and an artefact reduction algorithm to create 'standard' and 'corrected' images.

Assessment of CBCT-based synthetic CT generation accuracy for adaptive radiotherapy planning.

Purpose: Cone-beam CT (CBCT)-based synthetic CT (sCT) dose calculation has the potential to make the adaptive radiotherapy (ART) pathway more efficient while removing subjectivity. This study assessed four sCT generation methods using 15 head-and-neck rescanned ART patients. Each patient's planning CT (pCT), rescan CT (rCT), and CBCT post-rCT was acquired with the CBCT deformably registered to the rCT (dCBCT).

Volumetric and dosimetric impact of post-surgical MRI-guided radiotherapy for glioblastoma: A pilot study.

Objectives: Glioblastoma (GBM) radiotherapy (RT) target delineation requires MRI, ideally concurrent with CT simulation (pre-RT MRI). Due to limited MRI availability, <72 h post-surgery MRI is commonly used instead. Whilst previous investigations assessed volumetric differences between post-surgical and pre-RT delineations, dosimetric impact remains unknown.

Harmonisation of scanner-dependent contrast variations in magnetic resonance imaging for radiation oncology, using style-blind auto-encoders.

Background And Purpose: Magnetic Resonance Imaging (MRI) exhibits scanner dependent contrast, which limits generalisability of radiomics and machine-learning for radiation oncology. Current deep-learning harmonisation requires paired data, retraining for new scanners and often suffers from geometry-shift which alters anatomical information. The aim of this study was to investigate style-blind auto-encoders for MRI harmonisation to accommodate unpaired training data, avoid geometry-shift and harmonise data from previously unseen scanners.

The benefit of MR-only radiotherapy treatment planning for anal and rectal cancers: A planning study.

Introduction: Limited evidence exists showing the benefit of magnetic resonance (MR)-only radiotherapy treatment planning for anal and rectal cancers. This study aims to assess the impact of MR-only planning on target volumes (TVs) and treatment plan doses to organs at risks (OARs) for anal and rectal cancers versus a computed tomography (CT)-only pathway.

Materials And Methods: Forty-six patients (29 rectum and 17 anus) undergoing preoperative or radical external beam radiotherapy received CT and T2 MR simulation.

Dose summation and image registration strategies for radiobiologically and anatomically corrected dose accumulation in pelvic re-irradiation.

Background: Re-irradiation (reRT) is a promising technique for patients with localized recurrence in a previously irradiated area but presents major challenges. These include how to deal with anatomical change between two courses of radiotherapy and integration of radiobiology when summating original and re-irradiation doses. The Support Tool for Re-Irradiation Decisions guided by Radiobiology (STRIDeR) project aims to develop a software tool for use in a commercial treatment planning system to facilitate more informed reRT by accounting for anatomical changes and incorporating radiobiology.

Patient position verification in magnetic-resonance imaging only radiotherapy of anal and rectal cancers.

Background And Purpose: Magnetic resonance (MR)-only treatment pathways require either the MR-simulation or synthetic-computed tomography (sCT) as an alternative reference image for cone beam computed tomography (CBCT) patient position verification. This study assessed whether using T2 MR or sCT as CBCT reference images introduces systematic registration errors as compared to CT for anal and rectal cancers.

Materials And Methods: A total of 32 patients (18 rectum,14 anus) received pre-treatment CT- and T2 MR- simulation.

Ten-year longitudinal health-related quality of life following iodine-125 brachytherapy monotherapy for localized prostate cancer.

Purpose: This prospective longitudinal study quantifies health-related quality of life (HRQoL) up to 10 years following permanent iodine-125 (I) prostate brachytherapy alone for localized prostate cancer.

Material And Methods: In total, 120 patients completed a validated expanded prostate cancer index composite (EPIC) questionnaire pre-treatment and at 8 time points after treatment (6 weeks, 6, 10, 18 months, and 2, 3, 5, 10 years). At each time point, clinically relevant small, moderate, and severe declines in HRQoL were defined as 0.

Multicentre, deep learning, synthetic-CT generation for ano-rectal MR-only radiotherapy treatment planning.

Background And Purpose: Comprehensive dosimetric analysis is required prior to the clinical implementation of pelvic MR-only sites, other than prostate, due to the limited number of site specific synthetic-CT (sCT) dosimetric assessments in the literature. This study aims to provide a comprehensive assessment of a deep learning-based, conditional generative adversarial network (cGAN) model for a large ano-rectal cancer cohort. The following challenges were investigated; T2-SPACE MR sequences, patient data from multiple centres and the impact of sex and cancer site on sCT quality.

Audit feasibility for geometric distortion in magnetic resonance imaging for radiotherapy.

Background And Purpose: Magnetic Resonance Imaging (MRI) is increasingly being used in radiotherapy (RT). However, geometric distortions are a known challenge of using MRI in RT. The aim of this study was to demonstrate feasibility of a national audit of MRI geometric distortions.

Efficacy and toxicity outcomes for patients treated with focal salvage high dose rate brachytherapy for locally recurrent prostate cancer.

Introduction: Isolated local recurrence of prostate cancer following primary radiotherapy or brachytherapy may be treated with focal salvage high dose rate brachytherapy, although there remains an absence of high quality evidence to support this approach.

Methods: Men with prostate cancer treated consecutively between 2015 and 2018 using 19 Gy in a single fraction high dose rate brachytherapy (HDR) for locally recurrent prostate cancer were identified from an institutional database. Univariable analysis was performed to evaluate the relationship between patient, disease and treatment factors with biochemical progression free survival (bPFS).

A comparison of outcomes for patients with intermediate and high risk prostate cancer treated with low dose rate and high dose rate brachytherapy in combination with external beam radiotherapy.

Introduction: There is evidence to support use of external beam radiotherapy (EBRT) in combination with both low dose rate brachytherapy (LDR-EBRT) and high dose rate brachytherapy (HDR-EBRT) to treat intermediate and high risk prostate cancer.

Methods: Men with intermediate and high risk prostate cancer treated using LDR-EBRT (treated between 1996 and 2007) and HDR-EBRT (treated between 2007 and 2012) were identified from an institutional database. Multivariable analysis was performed to evaluate the relationship between patient, disease and treatment factors with biochemical progression free survival (bPFS).

A Systematic Review of the Clinical Implementation of Pelvic Magnetic Resonance Imaging-Only Planning for External Beam Radiation Therapy.

The use of magnetic resonance (MR) imaging scans alone for radiation therapy treatment planning (MR-only planning) has been highlighted as one method of improving patient outcomes. Recent technologic advances have meant that introducing MR-only planning to the clinic is becoming a reality, with several specialist radiation therapy clinics using this technique for treatment. As such, substantial efforts are being made to introduce this technique into wide-spread clinical implementation.

Real-time in vivo dosimetry in high dose rate prostate brachytherapy.

Background And Purpose: Single fraction treatments of 15Gy or 19Gy are common in HDR prostate brachytherapy. In vivo dosimetry (IVD) is therefore important to ensure patient safety. This study assesses clinical IVD and investigates error detection thresholds for real-time treatment monitoring.

Hybrid (CT/MRI based) vs. MRI only based image-guided brachytherapy in cervical cancer: Dosimetry comparisons and clinical outcome.

Purpose: Limited access to MRI has restricted implementation of MRI-based image-guided brachytherapy (IGBT) in line with GEC-ESTRO guidelines in many centers. This work reports our experience using an alternative CT/MRI based (hybrid) approach for IGBT, dosimetry comparisons, and its impact on long-term clinical outcome and major toxicity.

Methods And Materials: Seventy-six patients diagnosed with locally advanced cervical cancer between May 2008 and May 2012 treated with IGBT were analyzed.