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This was a comparative treatment planning study for posterior choroidal melanoma (CM) using four stereotactic approaches: Brainlab iPlan dynamic conformal arc therapy (DCAT), Brainlab Elements modulated arcs (BE), Varian Eclipse HyperArc modulated arcs (HA) and Gamma Knife ICON Leksell GammaPlan (GK). The clinical goal was to reduce dose to normal brain whilst maintaining other treatment planning goals. Thirteen CM cases over 3 years (2015-2018) treated with DCAT prescribed 50 Gy in 5 fractions were selected. The DCAT technique involved a forward planning method whereas semi-automated methods were used in BE, HA and GK. Target coverage and dose to critical organs were evaluated and compared across all approaches with the same set of structures used for each. Volume of brain receiving 10 Gy was DCAT 0.93 cc and 0.00 cc for GK, BE, HA (p < 0.001). Brain D GK 5.52 Gy, HA 6.41 Gy, BE 7.28 Gy, DCAT 13.73 Gy (p = 0.001). The median Gradient Index (GI) was GK 2.79, DCAT 6.39, BE 5.07, HA 6.00 (p < 0.001) with GK significantly different from each of the other approaches for PTV parameters. Further statistical significance was recorded for the lacrimal gland, contralateral lens and ipsilateral optic nerves. Modulation tools in HA and BE enabled clinically meaningful reduction in dose to brain compared with DCAT whilst maintaining dose to PTV. GK produced highest PTV coverage with superior gradient index, however current methods for eye immobilisation and treatment delivery only allow for single fraction treatment with GK.

Purpose The aim of this study was to provide a comprehensive assessment of patient intrafraction motion in linac‐based frameless stereotactic radiosurgery (SRS) and radiotherapy (SRT). Methods A retrospective review was performed on 101 intracranial SRS/SRT patients immobilized with the Klarity stereotactic thermoplastic mask (compatible with the Brainlab frameless stereotactic system) and aligned on a 6 Degree of Freedom (DoF) couch with the Brainlab ExacTrac image guidance system. Both pretreatment and intrafraction correction data are provided as observed by the ExacTrac system. The effects of couch angle and treatment duration on positioning outcomes are also explored. Results Initial setup data for patients is shown to vary by up to ±4.18 mm, ±2.97°, but when corrected with a single x‐ray image set with ExacTrac, patient positions are corrected to within ±2.11 mm, ±2.27°. Intrafraction patient motion is shown to be uniformly random and independent of both time and couch angle. Patient motion was also limited to within approximately 3 mm, 3° by the thermoplastic mask. Conclusions Our results indicate that since patient intrafraction motion is unrelated to couch rotation and treatment duration, intrafraction patient monitoring in 6 DoF is required to minimize intracranial SRS/SRT margins.

IntroductionIn 2020, the Australian Medical Services Advisory Committee (MSAC) recommended new proton beam therapy (PBT) item numbers be added to the Medicare Benefits Schedule. During the MSAC 1638 application process, MSAC recognised the uncertainties inherent in the cost-utility modelling of PBT. To address these uncertainties, MSAC proposed the establishment of a national registry with the intention to gather evidence to validate the claim of PBT’s superior toxicity outcomes and cost-effectiveness compared with conventional photon radiation therapy.Methods and analysisThe Australian Particle Therapy Clinical Quality Registry is a prospective, observational, longitudinal registry collecting national data on paediatric, adolescent young adult and adult patients with rare tumours receiving any form of radiation therapy for a defined group of diseases, specified by the MSAC 1638 Public Summary Document. Eligible patients undergoing radiation therapy at participating institutions will be provided with information about the registry, including the opt-out procedure. The registry has no enrolment cap and will persist either indefinitely or until the conclusion of the study.The study design was informed by the Australian Metadata Online Repository and contains a core set of minimum data elements. Representing baseline participant demographics, assessment, diagnosis and treatment; incorporating radiation and systemic therapies, with a specific focus on long-term follow-up, treatment toxicities and specific organ-at-risk testing.Ethics and disseminationThere will be no identifying data used in any reports or presentations of data. Additionally, all identifiable data will be safeguarded according to standard practices and available only to the host institution submitting the data to the registry. Aggregated data for the purposes of research will be stripped of identifiers. The registry has been approved under the National Mutual Agreement by the Central Adelaide Local Health Network Human Research Ethics Committee—HREC: 2021/HRE00394.Trial registration numberAustralian and New Zealand Clinical Trials Registry (ANZCTR): ACTRN12622000026729p.

This correspondence is in response to the Letter to the Editor “Evaluating Proton Versus Photon Therapy: A Call for Nuanced Decision‐Making”. A balanced evidence‐based approach that is patient‐centred is needed when deciding between proton versus photon radiotherapy.

Background Accurate and standardized descriptions of organs at risk (OARs) are essential in radiation therapy for treatment planning and evaluation. Traditionally, physicians have contoured patient images manually, which, is time-consuming and subject to inter-observer variability. This study aims to a) investigate whether customized, deep-learning-based auto-segmentation could overcome the limitations of manual contouring and b) compare its performance against a typical, atlas-based auto-segmentation method organ structures in liver cancer. Methods On - contrast computer tomography image sets of 70 liver cancer patients were used, and four OARs (heart, liver, kidney, and stomach) were manually delineated by three experienced physicians as reference structures. Atlas and deep learning auto-segmentations were respectively performed with MIM Maestro 6.5 (MIM Software Inc., Cleveland, OH) and, with a deep convolution neural network (DCNN). The Hausdorff distance (HD) and, dice similarity coefficient (DSC), volume overlap error (VOE), and relative volume difference (RVD) were used to quantitatively evaluate the four different methods in the case of the reference set of the four OAR structures. Results The atlas-based method yielded the following average DSC and standard deviation values (SD) for the heart, liver, right kidney, left kidney, and stomach: 0.92 ± 0.04 (DSC ± SD), 0.93 ± 0.02, 0.86 ± 0.07, 0.85 ± 0.11, and 0.60 ± 0.13 respectively. The deep-learning-based method yielded corresponding values for the OARs of 0.94 ± 0.01, 0.93 ± 0.01, 0.88 ± 0.03, 0.86 ± 0.03, and 0.73 ± 0.09. The segmentation results show that the deep learning framework is superior to the atlas-based framwork except in the case of the liver. Specifically, in the case of the stomach, the DSC, VOE, and RVD showed a maximum difference of 21.67, 25.11, 28.80% respectively. Conclusions In this study, we demonstrated that a deep learning framework could be used more effectively and efficiently compared to atlas-based auto-segmentation for most OARs in human liver cancer. Extended use of the deep-learning-based framework is anticipated for auto-segmentations of other body sites.

Proton beam therapy (PBT) is increasingly used to treat cancers, especially in the paediatric and adolescent and young adult (AYA) population. As PBT becomes more accessible, determining when PBT should be used instead of photon irradiation can be difficult. There is a need to balance patient, tumour and treatment factors when making this decision. Comparing the dosimetry between these two modalities plays an important role in this process. PBT can reduce low to intermediate doses to organs at risk (OAR), but photon irradiation has its dosimetric advantages. We present two cases with brain tumours, one paediatric and one AYA, in which treatment plan comparison between photons and protons showed dosimetric advantages of photon irradiation. The first case was an 18‐month‐old child diagnosed with posterior fossa ependymoma requiring adjuvant radiotherapy. Photon irradiation using volumetric modulated arc therapy (VMAT) had lower doses to the hippocampi but higher doses to the pituitary gland. The second case was a 21‐year‐old with an optic pathway glioma. There was better sparing of the critical optic structures and pituitary gland using fractionated stereotactic radiation therapy over PBT. The dosimetric advantages of photon irradiation over PBT have been demonstrated in these cases. This highlights the role of proton‐to‐photon comparative treatment planning to better understand which patients might benefit from photon irradiation versus PBT. This report describes two paediatric/adolescent and young adult (AYA) brain tumour cases demonstrating the dosimetric advantages of photon irradiation over proton beam therapy. This highlights the role of proton‐to‐photon comparative treatment planning to better understand which patients might benefit from photon irradiation versus proton beam therapy.

Proton‐beam therapy (PBT) is a cutting‐edge radiation therapy modality that is currently not available in Australia. Comparative photon‐proton (CPP) planning is required for the medical treatment overseas programme (MTOP) and will be required for access to PBT in Australia in the future. Comparative planning brings professional development benefits to all members of the radiation therapy team. This service was also created to support future proposals for a PBT facility in Victoria. We report our experience developing an in‐house CPP service at Peter MacCallum Cancer Centre. A set of resources to support CPP planning was established. Training of relevant staff was undertaken after which an in‐house training programme was developed. A standard protocol for PBT planning parameters was established. All CPP plans were reviewed. Future goals for the CPP planning programme were described. In total, 62 cases were comparatively planned over 54 months. Of these, 60% were paediatric cases, 14% were adolescents and young adults (15–25 years) and 26% were adults. The vast majority (over 75%) of patients comparatively planned required irradiation to the central nervous system including brain and cranio‐spinal irradiation. A variety of proton plans were reviewed by international PBT experts to confirm their deliverability. Our team at Peter MacCallum Cancer Centre has gained significant experience in CPP planning and will continue to develop this further. Local expertise will help support decentralisation of patient selection for proton treatments in the near future and the PBT business case in Victoria. Comparative planning brings professional development benefits to all members of the radiation therapy team. This service was also created to support future proposals for a Proton‐beam therapy facility in Victoria. We report our experience developing an in‐house comparative photon‐proton planning service at Peter Mac.

Introduction: Additive manufacturing or 3-dimensional printing has become a widespread technology with many applications in medicine. We have conducted a systematic review of its application in radiation oncology with a particular emphasis on the creation of phantoms for image quality assessment and radiation dosimetry. Traditionally used phantoms for quality assurance in radiotherapy are often constraint by simplified geometry and homogenous nature to perform imaging analysis or pretreatment dosimetric verification. Such phantoms are limited due to their ability in only representing the average human body, not only in proportion and radiation properties but also do not accommodate pathological features. These limiting factors restrict the patient-specific quality assurance process to verify image-guided positioning accuracy and/or dose accuracy in “water-like” condition. Methods and Results: English speaking manuscripts published since 2008 were searched in 5 databases (Google Scholar, Scopus, PubMed, IEEE Xplore, and Web of Science). A significant increase in publications over the 10 years was observed with imaging and dosimetry phantoms about the same total number (52 vs 50). Key features of additive manufacturing are the customization with creation of realistic pathology as well as the ability to vary density and as such contrast. Commonly used printing materials, such as polylactic acid, acrylonitrile butadiene styrene, high-impact polystyrene and many more, are utilized to achieve a wide range of achievable X-ray attenuation values from −1000 HU to 500 HU and higher. Not surprisingly, multimaterial printing using the polymer jetting technology is emerging as an important printing process with its ability to create heterogeneous phantoms for dosimetry in radiotherapy. Conclusion: Given the flexibility and increasing availability and low cost of additive manufacturing, it can be expected that its applications for radiation medicine will continue to increase.

Purpose Patient‐specific quality assurance (PSQA) for vertebra stereotactic body radiation therapy (SBRT) presents challenges due to highly modulated small fields with high‐dose gradients between the target and spinal cord. This study aims to explore the use of the SRS MapCHECK® (SRSMC) for vertebra SBRT PSQA. Methods Twenty vertebra SBRT treatment plans including prescriptions 20 Gy/1 fraction and 24 Gy/2 fractions were selected for each of Millennium (M)‐Multileaf Collimator (MLC), and high‐definition (HD)‐MLC. All 40 plans were measured using Gafchromic EBT3 film (film) and SRSMC, using the StereoPHAN phantom. Plan complexity was assessed using modulation complexity score (MCS), edge metric (EM) (mm−1), modulation factor (MU/cGy), and average leaf pair opening (ALPO) (mm) and its correlation with gamma‐pass rate was investigated. The high dose gradient between the target and the spinal cord was analyzed for film and SRSMC and compared against the treatment planning system (TPS). Applying the methodology proposed by AAPM TG‐218, action and tolerance values specific to the SRSMC for vertebra SBRT were determined for β values ranging from 5 to 8. Results Film and SRSMC gamma‐pass rates showed no correlation (p > 0.05). A moderate negative correlation (R = ‐0.57, p = 0.01) is present between EM and SRSMC 3%/1 mm gamma‐pass rate for HD‐MLC plans. Both film and SRSMC accurately measured high dose gradients between the target and the spinal cord (R2 > 0.86, p ≤ 0.05). Notably, dose‐gradient of HD‐MLC plans is 22% steeper and has a smaller standard deviation to M‐MLC plans (p ≤ 0.05). Applying TG‐218, the film tolerance limit was 96% with action limit 95% for 5%/1 mm (β = 6) and for the SRSMC tolerance limit was 97% with an action limit of 96% for 4%/1 mm (β = 6). Conclusion Our findings suggest that universal TG‐218 limits may not be suitable for vertebra SBRT PSQA. This study demonstrates that SRSMC is a viable tool for vertebra SBRT PSQA, supported by TG‐218 implementation of process‐based tolerance and action limits.

The additive manufacturing (AM) process plays an important role in enabling cross-disciplinary research in engineering and personalised medicine. Commercially available clinical tools currently utilised in radiotherapy are typically based on traditional manufacturing processes, often leading to non-conformal geometries, time-consuming manufacturing process and high costs. An emerging application explores the design and development of patient-specific clinical tools using AM to optimise treatment outcomes among cancer patients receiving radiation therapy. In this review, we: highlight the key advantages of AM in radiotherapy where rapid prototyping allows for patient-specific manufacture explore common clinical workflows involving radiotherapy tools such as bolus, compensators, anthropomorphic phantoms, immobilisers, and brachytherapy moulds; and investigate how current AM processes are exploited by researchers to achieve patient tissue-like imaging and dose attenuations. Finally, significant AM research opportunities in this space are highlighted for their future advancements in radiotherapy for diagnostic and clinical research applications.