Quality assurance and other challenges in paediatric radiotherapy: Accurate delivery of craniospinal radiotherapy.

Introduction: Cranio-spinal radiotherapy (CSI) is used to treat central nervous system malignancies in paediatric, adolescent/young adult (AYA), and adult patients. Its delivery in the paediatric/AYA population is particularly challenging across different age groups. This study aims to assess the setup variations and dosimetric impact of CSI in paediatric and AYA patients.

Cardiac substructure delineation in radiation therapy - A state-of-the-art review.

Delineation of cardiac substructures is crucial for a better understanding of radiation-related cardiotoxicities and to facilitate accurate and precise cardiac dose calculation for developing and applying risk models. This review examines recent advancements in cardiac substructure delineation in the radiation therapy (RT) context, aiming to provide a comprehensive overview of the current level of knowledge, challenges and future directions in this evolving field. Imaging used for RT planning presents challenges in reliably visualising cardiac anatomy.

The rationale for a carbon ion radiation therapy facility in Australia.

Australia has taken a collaborative nationally networked approach to achieve particle therapy capability. This supports the under-construction proton therapy facility in Adelaide, other potential proton centres and an under-evaluation proposal for a hybrid carbon ion and proton centre in western Sydney. A wide-ranging overview is presented of the rationale for carbon ion radiation therapy, applying observations to the case for an Australian facility and to the clinical and research potential from such a national centre.

Open-source, fully-automated hybrid cardiac substructure segmentation: development and optimisation.

Radiotherapy for thoracic and breast tumours is associated with a range of cardiotoxicities. Emerging evidence suggests cardiac substructure doses may be more predictive of specific outcomes, however, quantitative data necessary to develop clinical planning constraints is lacking. Retrospective analysis of patient data is required, which relies on accurate segmentation of cardiac substructures.

Infrastructure platform for privacy-preserving distributed machine learning development of computer-assisted theragnostics in cancer.

Introduction: Emerging evidence suggests that data-driven support tools have found their way into clinical decision-making in a number of areas, including cancer care. Improving them and widening their scope of availability in various differing clinical scenarios, including for prognostic models derived from retrospective data, requires co-ordinated data sharing between clinical centres, secondary analyses of large multi-institutional clinical trial data, or distributed (federated) learning infrastructures. A systematic approach to utilizing routinely collected data across cancer care clinics remains a significant challenge due to privacy, administrative and political barriers.

A novel method to determine linac mechanical isocenter position and size and examples of specific QA applications.

The most important geometric characteristic of stereotactic treatment is the accuracy of positioning the target at the treatment isocenter and the accuracy of directing the radiation beam at the treatment isocenter. Commonly, the radiation isocenter is used as the reference for the treatment isocenter, but its method of localization is not strictly defined, and it depends on the linac-specific beam steering parameters. A novel method is presented for determining the linac mechanical isocenter position and size based on the localization of the collimator axis of rotation at arbitrary gantry angle.

Towards zero radiation isocentre size: minimising radiation beam isocentricity on Elekta linear accelerators by means of optimising look-up tables.

The most important geometric characteristics of SRS/SBRT treatments are precise target localisation and precise aiming of the radiation beam at the target. The AAPM-RSS Medical Physics Practice Guideline 9.a.

Practical beam steering of X-ray beams on Elekta accelerators: The effect of focal spot alignment on beam (symmetry and position) and radiation isocentre (size and position).

Acceptance and commissioning of a linear accelerator is the process of preparing it for clinical use. One of the initial important dosimetric tasks for X-ray beam set-up and use is to optimise the trajectory of the electron beam before it hits the target (focal spot). The main purpose of this study is to characterise the effect of the focal spot position (offset) on the photon beam symmetry and centre position, as well as on linac radiation isocentre size and position for an Elekta Synergy® linac.

Assessment of error in the MV radiation isocenter position calculated with the Elekta XVI software.

The assessment of the coincidence of imaging and radiation isocenters is an important task of regular quality assurance of medical linear accelerators (linacs) as recommended in national and international quality assurance guidelines. A previously reported investigation of the accuracy of the Elekta XVI software to localize the linac radiation isocenter, by comparing statistically with other independent software, has shown some discrepancies at the sub-mm level. A further investigation is carried out here using a set of reference images and mathematical operations to observe how the Elekta XVI software analyses them.

Assessing the dependency of the uncertainties in the Elekta Agility MLC calibration procedure on the focal spot position.

The effectiveness of radiotherapy treatments depends on the accuracy of the dose delivery process. The majority of radiotherapy courses are delivered on linear accelerators with a Multi Leaf Collimator (MLC) in 3D conformal Radiation Therapy, Intensity Modulated Radiation Therapy (IMRT) or Volumetric Modulated Arc Therapy (VMAT) modes that require accurate MLC positioning. This study investigates the MLC calibration accuracy, following manufacturer procedures for an Elekta Synergy linac with the Agility head, against the radiation focal spot offset (alignment with the collimator axis of rotation).

Testing the methodology for a dosimetric end-to-end audit of IMRT/VMAT: results of IAEA multicentre and national studies.

Within an International Atomic Energy Agency (IAEA) co-ordinated research project (CRP), a remote end-to-end dosimetric quality audit for intensity modulated radiation therapy (IMRT)/ volumetric arc therapy (VMAT) was developed to verify the radiotherapy chain including imaging, treatment planning and dose delivery. The methodology as well as the results obtained in a multicentre pilot study and national trial runs conducted in close cooperation with dosimetry audit networks (DANs) of IAEA Member States are presented. A solid polystyrene phantom containing a dosimetry insert with an irregular solid water planning target volume (PTV) and organ at risk (OAR) was designed for this audit.

Changes in Brain Metastasis During Radiosurgical Planning.

Purpose: To determine whether there are any changes in brain metastases or resection cavity volumes between planning magnetic resonance imaging (MRI) and radiosurgery (RS) treatment and whether these led to a change in management or alteration in the RS plan.

Methods And Materials: Patients undergoing RS for brain metastasis or tumor resection cavities had a standardized planning MRI (MRI-1) performed and a repeat verification MRI (MRI-2) 24 hours before RS. Any change in management, including replanning based on MRI-2, was recorded.

Beam focal spot position determination for an Elekta linac with the Agility head; practical guide with a ready-to-go procedure.

A novel phantomless, EPID-based method of measuring the beam focal spot offset of a linear accelerator was proposed and validated for Varian machines. In this method, one set of jaws and the MLC were utilized to form a symmetric field and then a 180 collimator rotation was utilized to determine the radiation isocenter defined by the jaws and the MLC, respectively. The difference between these two isocentres is directly correlated with the beam focal spot offset of the linear accelerator.

Patient education using virtual reality increases knowledge and positive experience for breast cancer patients undergoing radiation therapy.

Purpose: Improved access to technology in the radiation therapy (RT) workforce education has resulted in opportunities for innovative patient education methods. This study investigated the impact of a newly developed education tool using the Virtual Environment for Radiotherapy Training (VERT) system on patients' RT knowledge and anxiety.

Method: Breast cancer patients were recruited into a control group (CG) (n = 18) who underwent the standard pre-RT education package at a targeted cancer therapy centre, followed by a VERT group (VG) (n = 19).

A multinational audit of small field output factors calculated by treatment planning systems used in radiotherapy.

Background And Purpose: An audit methodology for verifying the implementation of output factors (OFs) of small fields in treatment planning systems (TPSs) used in radiotherapy was developed and tested through a multinational research group and performed on a national level in five different countries.

Materials And Methods: Centres participating in this study were asked to provide OFs calculated by their TPSs for 10 × 10 cm, 6 × 6 cm, 4 × 4 cm, 3 × 3 cm and 2 × 2 cm field sizes using an SSD of 100 cm. The ratio of these calculated OFs to reference OFs was analysed.

Interprofessional education: evaluation of a radiation therapy and medical physics student simulation workshop.

Introduction: Interprofessional education (IPE) involves two or more professions engaged in learning with, from and about each other. An initiative was undertaken to explore IPE for radiation therapy (RT) and medical physics (MP) students through a newly developed workshop based around simulated learning. The aims of this study were to explore RT and MP students' perceptions of working as part of a collaborative team and of their own and the other group's professional roles.

Quantifying the effects of positional uncertainties and estimating margins for Gamma-Knife fractionated radiosurgery of large brain metastases.

Purpose: Besides conventional single fraction stereotactic radiosurgery (SRS), the newer Gamma Knife® (Elekta Instruments, AB, Sweden) (GK) models, Perfexion™ and Icon™, also allow the option of hypofractionated SRS, to widen the treatment range, reduce toxicity and provide flexibility. With fractionation, set-up uncertainties are introduced to the treatment. The question of what margin is required to cover set-up uncertainties arises.

Multi-institutional comparison of simulated treatment delivery errors in ssIMRT, manually planned VMAT and autoplan-VMAT plans for nasopharyngeal radiotherapy.

Purpose: To quantify the impact of simulated errors for nasopharynx radiotherapy across multiple institutions and planning techniques (auto-plan generated Volumetric Modulated Arc Therapy (ap-VMAT), manually planned VMAT (mp-VMAT) and manually planned step and shoot Intensity Modulated Radiation Therapy (mp-ssIMRT)).

Methods: Ten patients were retrospectively planned with VMAT according to three institution's protocols. Within one institution two further treatment plans were generated using differing treatment planning techniques.

Investigating the impact of treatment delivery uncertainties on treatment effectiveness for lung SABR.

To quantify the impact of treatment delivery uncertainties on lung stereotactic ablative body radiotherapy (SABR) plans for step-and-shoot intensity-modulated radiotherapy (ssIMRT) and volumetric modulated arc therapy (VMAT). Baseline ssIMRT and VMAT treatment plans were generated for a cohort of 18 lung SABR patients. Modified plans were generated for each baseline plan by systematically varying gantry and collimator angles between - 5 and + 5 degrees, as well as multi-leaf collimator (MLC) leaf position errors of magnitude between 1 and 5 mm in both directions (i.