Definition and requirements for stereotactic radiotherapy: a systematic review.

Background And Purpose: This systematic review aimed to consolidate current definitions of stereotactic radiotherapy, identify commonly proposed quality standards and address inconsistencies in international practices despite its extensive use.

Materials And Methods: This systematic literature review followed the PRISMA methodology, conducting searches across PubMed, Embase, Cochrane, Scopus, and Epistemonikos databases between January 2001 and April 2024. Eligible articles included those explicitly defining stereotactic radiotherapy or providing detailed implementation criteria.

Dose-Escalated Stereotactic Versus Conventional Radiotherapy for Painful Bone Metastases (ROBOMET): A Multicenter, Patient-Blinded Randomized Clinical Trial.

Purpose: To test whether dose-escalated single fraction (SF) stereotactic body radiotherapy (SBRT) of 20 Gy to painful bone metastases is superior to conventional SF three-dimensional (3D) conformal radiotherapy (RT) to a standard dose of 8 Gy in achieving complete pain response (CR).

Methods: A single-blind, randomized, controlled, phase III trial (ROBOMET) included 126 patients with up to three painful bone metastases, randomly assigned between April 2019 and October 2022 at multiple centers in Belgium. Inclusion criteria were uncomplicated painful bone metastases (worst pain score ≥2 on a 0-10 pain scale) arising from a solid tumor.

A commissioning protocol for portal imaging-based radiotherapy in vivo dosimetry systems.

Background And Purpose: With the availability of commercial electronic portal imaging detector-based in vivo dosimetry (EPID-based IVD) solutions, many radiotherapy departments are adopting this technology. However, comprehensive commissioning guidance is lacking. This study aims to provide a protocol for testing the accuracy and sensitivity of EPID-based IVD systems.

Coverage with evidence development program on stereotactic body radiotherapy in Belgium (2013-2019): a nationwide registry-based prospective study.

Background: Although stereotactic body radiotherapy (SBRT) was progressively adopted in clinical practice in Belgium, a reimbursement request in 2011 was not granted because of remaining clinical and economic uncertainty. A coverage with evidence development (CED) program on SBRT started in 2013, with the aim to assess clinical and technical patterns-of-care in Belgium and monitor survival per indication, in view of supporting inclusion in the reimbursement system.

Methods: The Belgian National Institute for Health and Disability Insurance (NIHDI) initiated this prospective observational registry.

Automated determination of the ion-recombination correction factor (k) in ultra-high dose rate electron radiation therapy.

Background: Plane-parallel ionization chambers are the recommended secondary standard systems for clinical reference dosimetry of electrons. Dosimetry in high dose rate and dose-per-pulse (DPP) is challenging as ionization chambers are subject to ion recombination, especially when dose rate and/or DPP is increased beyond the range of conventional radiotherapy. The lack of universally accepted models for correction of ion recombination in UDHR is still an issue as it is, especially in FLASH-RT research, which is crucial in order to be able to accurately measure the dose for a wide range of dose rates and DPPs.

Multi-institutional generalizability of a plan complexity machine learning model for predicting pre-treatment quality assurance results in radiotherapy.

Background And Purpose: Treatment plans in radiotherapy are subject to measurement-based pre-treatment verifications. In this study, plan complexity metrics (PCMs) were calculated per beam and used as input features to develop a predictive model. The aim of this study was to determine the robustness against differences in machine type and institutional-specific quality assurance (QA).

Long-Term Results of a Phase 1 Dose Escalation Trial of Ablative Stereotactic Body Radiation Therapy.

Purpose: Stereotactic body radiation therapy is increasingly used for oligometastatic disease as well as palliation, but treatment protocols for nonspine bone and nodal metastases are lacking, with a wide variety of schedules applied.

Methods And Materials: A prospective dose-escalation trial was initiated, involving 90 patients, among whom 52 (58%) had primary prostate tumors, 13 had breast tumors (14%), and 25 (28%) had other primary tumor types. All visible lymph node or nonspine bone oligometastases were treated in 3 consecutive cohorts: 5 × 7.

A geometry and dose-volume based performance monitoring of artificial intelligence models in radiotherapy treatment planning for prostate cancer.

Background And Purpose: Clinical Artificial Intelligence (AI) implementations lack ground-truth when applied on real-world data. This study investigated how combined geometrical and dose-volume metrics can be used as performance monitoring tools to detect clinically relevant candidates for model retraining.

Materials And Methods: Fifty patients were analyzed for both AI-segmentation and planning.

Optically stimulated luminescence system as an alternative for radiochromic film for 2D reference dosimetry in UHDR electron beams.

Radiotherapy is part of the treatment of over 50% of cancer patients. Its efficacy is limited by the radiotoxicity to the healthy tissue. FLASH-RT is based on the biological effect that ultra-high dose rates (UHDR) and very short treatment times strongly reduce normal tissue toxicity, while preserving the anti-tumoral effect.

The use of in-vivo dosimetry to identify head and neck cancer patients needing adaptive radiotherapy.

Background And Purpose: Head and neck cancer (HNC) patients experiencing anatomical changes during their radiotherapy (RT) course may benefit from adaptive RT (ART). We investigated the sensitivity of an electronic portal imaging device (EPID)-based in-vivo dosimetry (EIVD) system to detect patients that require ART and identified its limitations.

Materials And Methods: A retrospective study was conducted for 182 HNC patients: laryngeal cancer without elective lymph nodes (group A), postoperative RT (group B) and primary RT including elective lymph nodes (group C).

Assessing the impact of adaptations to the clinical workflow in radiotherapy using transit in vivo dosimetry.

Background And Purpose: Currently in-vivo dosimetry (IVD) is primarily used to identify individual patient errors in radiotherapy. This study investigated possible correlations of observed trends in transit IVD results, with adaptations to the clinical workflow, aiming to demonstrate the possibility of using the bulk data for continuous quality improvement.

Materials And Methods: In total 84,100 transit IVD measurements were analyzed of all patients treated between 2018 and 2022, divided into four yearly periods.

Characterisation and Quenching Correction for an AlO:C Optical Fibre Real Time System in Therapeutic Proton, Helium, and Carbon-Charged Beams.

Real time radioluminescence fibre-based detectors were investigated for application in proton, helium, and carbon therapy dosimetry. The AlO:C probes are made of one single crystal (1 mm) and two droplets of micro powder in two sizes (38 μm and 4 μm) mixed with a water-equivalent binder. The fibres were irradiated behind different thicknesses of solid slabs, and the Bragg curves presented a quenching effect attributed to the nonlinear response of the radioluminescence (RL) signal as a function of linear energy transfer (LET).

Parameterisation of Respiratory Impedance in Lung Cancer Patients From Forced Oscillation Lung Function Test.

Objective: This study aims to analyze the contribution and application of forced oscillation technique (FOT) devices in lung cancer assessment. Two devices and corresponding methods can be feasible to distinguish among various degrees of lung tissue heterogeneity.

Methods: The outcome respiratory impedance Z (in terms of resistance R and reactance X) is calculated for FOT and is interpreted in physiological terms by being fitted with a fractional-order impedance mathematical model (FOIM).

Point scintillator dosimetry in ultra-high dose rate electron "FLASH" radiation therapy: A first characterization.

FLASH radiation therapy is a novel technique combining ultra-high dose rates (UHDR) with very short treatment times to strongly decrease normal tissue toxicity while preserving the anti-tumoral effect. However, the radiobiological mechanisms and exact conditions for obtaining the FLASH-effect are still under investigation. There are strong indications that parameters defining the beam structure, such as dose per pulse, instantaneous dose rate and pulse repetition frequency (PRF) are of importance.

Postgraduate education in radiation oncology during the COVID-19 pandemic - What did we learn?

Introduction: During the COVID-19 pandemic the ESTRO School who provides international non-profit postgraduate education in Radiation Oncology and related disciplines, including Medical Physics and Radiation Technology, had to close down all live educational activities and turn online, although having only limited experience. The paper describes the experience, discusses the limitations and benefits of online education and suggests directions for the future.

Materials And Methods: Data about format and feedback from attendees and faculty members from the course activities held in 2019, 2020 and 2021 were made available from the ESTRO School.

Quality Assurance for AI-Based Applications in Radiation Therapy.

Recent advancements in artificial intelligence (AI) in the domain of radiation therapy (RT) and their integration into modern software-based systems raise new challenges to the profession of medical physics experts. These AI algorithms are typically data-driven, may be continuously evolving, and their behavior has a degree of (acceptable) uncertainty due to inherent noise in training data and the substantial number of parameters that are used in the algorithms. These characteristics request adaptive, and new comprehensive quality assurance (QA) approaches to guarantee the individual patient treatment quality during AI algorithm development and subsequent deployment in a clinical RT environment.

Machine learning-based treatment couch parameter prediction in support of surface guided radiation therapy.

Purpose: A fully independent, machine learning-based automatic treatment couch parameters prediction was developed to support surface guided radiation therapy (SGRT)-based patient positioning protocols. Additionally, this approach also acts as a quality assurance tool for patient positioning.

Materials/methods: Setup data of 183 patients, divided into four different groups based on used setup devices, was used to calculate the difference between the predicted and the acquired treatment couch value.

A new solution for UHDP and UHDR (Flash) measurements: Theory and conceptual design of ALLS chamber.

Ultra-High dose-per-pulse regimens (UHDP), necessary to trigger the "FLASH" effect, still pose serious challenges to dosimetry. Dosimetry plays a crucial role, both to significantly improve the accuracy of the radiobiological experiments necessary to fully understand the mechanisms underlying the effect and its dependencies on the beam parameters, and to be able to translate such effect into clinical practice. The standard ionization chamber in UHDP region is significantly affected by the effects of the electric field generated by the enormous density of charges produced by the dose pulse.

Precision of image-guided spinal stereotactic ablative radiotherapy and impact of positioning variables.

Background And Purpose: Spinal stereotactic ablative body radiotherapy (SABR) requires high precision. We evaluate the intrafraction motion during cone-beam computed tomography (CBCT) guided SABR with different immobilization techniques.

Material And Methods: Fifty-seven consecutive patients were treated for 62 spinal lesions with SABR with positioning corrected in six degrees of freedom.

Application of a novel diamond detector for commissioning of FLASH radiotherapy electron beams.

Purpose: A diamond detector prototype was recently proposed by Marinelli et al. (Medical Physics 2022, https://doi.org/10.

Comparing treatment uncertainty for ultra- vs. standard-hypofractionated breast radiation therapy based on in-vivo dosimetry.

Background And Purpose: Postoperative ultrahypofractionated radiation therapy (UHFRT) in 5 fractions (fx) for breast cancer patients is as effective and safe as conventionally hypofractionated RT (HFRT) in 15 fx, liberating time for higher-level daily online Image-Guided Radiation Therapy (IGRT) corrections. In this retrospective study, treatment uncertainties occurring in patients treated with 5fx (5fx-group) were evaluated using electronic portal imaging device (EPID)-based in-vivo dosimetry (EIVD) and compared with the results from patients treated with conventionally HFRT (15fx-group) to validate the new technique and to evaluate if the shorter treatment schedule could have a positive effect on the treatment uncertainties.

Materials And Methods: EPID-based integrated transit dose images were acquired for each treatment fraction in the 5fx-group (203 patients) and on the first 3 days of treatment and weekly thereafter in the 15fx-group (203 patients).

Machine learning-based detection of aberrant deep learning segmentations of target and organs at risk for prostate radiotherapy using a secondary segmentation algorithm.

The output of a deep learning (DL) auto-segmentation application should be reviewed, corrected if needed and approved before being used clinically. This verification procedure is labour-intensive, time-consuming and user-dependent, which potentially leads to significant errors with impact on the overall treatment quality. Additionally, when the time needed to correct auto-segmentations approaches the time to delineate target and organs at risk from scratch, the usability of the DL model can be questioned.