INTRODUCTION:In carbon ion radiation therapy, the Local Effect Model (LEM) predicts higher value of Relative Biological Effectiveness (RBE) with respect to the Microdosimetric Kinetic Model (MKM) in most clinical situations. This work aims at comparing the MKM-based RBE-weighted dose calculated from experimental microdosimetric quantities against the RBE-weighted dose computed by a Treatment Planning System (TPS) using the LEM version I. METHODS:The Silicon-On-Insulator (SOI) 3D mushroom microdosimeter, developed by the Centre for Medical Radiation Physics (CMRP), Wollongong (Australia), was placed in an RW3 phantom and was irradiated with carbon ions with different plans at the Centro Nazionale di Adroterapia Oncologica (CNAO), Pavia (Italy), acquiring microdosimetric spectra along the beam direction and calculating the corresponding RBE10 with the MKM model applied for Human Salivary Gland (HSG) cells. RESULTS:A good agreement between experiment and Monte Carlo simulation was found, obtaining RBE10 values ranging between 1.2 and 2.8. The prescribed LEM I-based RBE-weighted dose of 3.0 GyE in a cubic SOBP showed to be 33 % larger than the MKM-based RBE-weighted dose, consistently with other results found in literature. CONCLUSION:This work confirms the reliable use of the 3D SOI microdosimeters as a quality assurance tool for RBE prediction in particle therapy. In addition, the presented outcomes represents a validation through experimental measurements of previous works found in literature on the MKM and LEM RBE-weighted dose comparison based on TPS calculations and Monte Carlo simulations.

BackgroundImage guided radiotherapy (IGRT) with cone-beam computed tomography (CBCT) is limited by the sub-optimal soft-tissue contrast and spatial resolution of energy-integrating flat panel detectors (FPDs) which produce quasi-quantitative CT numbers. Spectral CT with high resolution photon-counting detectors (PCDs) could improve tumor delineation by enhancing the soft-tissue contrast, spatial resolution, dose-efficiency, and CT number accuracy.PurposeThis study presents the first linac-mounted PCD. On the journey to developing spectral cone-beam CT for IGRT, the planar image quality of a linac-mounted PCD is first fundamentally characterized and compared to an FPD in terms of the 2D spatial resolution, noise, and contrast.MethodsA Medipix3RX-based PCD was mounted to the kV FPD of an x-ray volume imaging (XVI) system on an Elekta linac and the PCD acquisition was synchronized with the pulsed kV source. The energy calibration of the Medipix3RX was determined with various radioisotope gamma emissions up to 60 keV. To compare the 2D spatial resolution and noise between the PCD and FPD, the pre-sampling modulation transfer function (MTF) and normalized noise power spectrum (NPS) were measured using an RQA5 spectrum and a fluoroscopy phantom was imaged to determine the limiting resolution of line pairs. Spectral planar images of phantom inserts containing two different concentrations of calcium (60 and 240 mg/cc) and iodine (5 and 15 mg/cc) were optimally energy weighted to maximize the contrast using tube voltages of 60, 80, 100, and 120 kV. To account for drifts in the sensor temperature, the PCD was dynamically translated in and out of the insert shadow during acquisitions to obtain flat field corrections per frame. The raw contrast of the resultant planar images was compared to the energy-integrating FPD.ResultsThe energy calibration of the Medipix3RX was observed to be linear up to 60 keV. The limiting resolution observed on the fluoroscopy phantom was 2 lp/mm for the FPD and 5 lp/mm for the PCD. The pre-sampling MTF was higher across all frequencies comparing the PCD to the FPD. The normalized NPS of the PCD did not vary with frequency, whereas the spectrum for the FPD decreased monotonically and was lower than the PCD noise power across most of the spatial frequency range studied due to optical light spreading. Optimal energy weights were applied to the dynamically acquired PCD images and the raw contrast of the 60 mg/cc calcium insert increased by factors of 1.12 +/- 0.09$1.12\pm 0.09$ and 1.52 +/- 0.22$1.52\pm 0.22$ at 60 and 120 kV respectively compared to the FPD.ConclusionsA Medipix3RX-based PCD was successfully integrated with the kilovoltage imaging system on an Elekta linac. The initial planar image quality characterization indicated improvements in the MTF and energy-weighted contrast compared to the FPD. Future work will focus on obtaining linac-mounted spectral CBCT images with a translate-rotate geometry, however this initial study indicates that variations in the PCD sensor response during acquisitions must be addressed to realise the full potential of linac-mounted spectral CBCT.

BACKGROUND:This paper describes the protocol for the Nano X Image Guidance (Nano X IG) trial, a single-institution, clinical imaging study. The Nano X is a prototype fixed-beam radiotherapy system developed to investigate the feasibility of a low-cost, compact radiotherapy system to increase global access to radiation therapy. This study aims to assess the feasibility of volumetric image guidance with cone beam computed tomography (CBCT) acquired during horizontal patient rotation on the Nano X radiotherapy system.METHODS:In the Nano X IG study, we will determine whether radiotherapy image guidance can be performed with the Nano X radiotherapy system where the patient is horizontally rotated while scan projections are acquired. We will acquire both conventional CBCT scans and Nano X CBCT scans for 30 patients aged 18 and above and receiving radiotherapy for head/neck or upper abdomen cancers. For each patient, a panel of experts will assess the image quality of Nano X CBCT scans against conventional CBCT scans. Each patient will receive two Nano X CBCT scans to determine the image quality reproducibility, the extent and reproducibility of patient motion and assess patient tolerance.DISCUSSION:Fixed-beam radiotherapy systems have the potential to help ease the current shortfall and increase global access to radiotherapy treatment. Advances in image guidance could facilitate fixed-beam radiotherapy using horizontal patient rotation. The efficacy of this radiotherapy approach is dependent on our ability to image and adapt to motion due to rotation and for patients to tolerate rotation during treatment.TRIAL REGISTRATION:ClinicalTrials.gov, NCT04488224. Registered on 27 July 2020.

The 2019 peanut crop was the worst year in recent history for aflatoxin contamination in finished lots of shelled runner peanuts. This was largely due to excessive heat and late season drought in the southeastern US. The industry estimated that approximately 30% of finished lots failed to meet the USDA aflatoxin specifications for edible peanuts causing increased costs due to re-milling, material loss, and diversion to low value markets such as crushing for oil. As a result, the peanut industry formed the Aflatoxin Working Group at the 2020 American Peanut Council’s Winter Conference to (1) evaluate the state of the art in production, transportation, handling, storage, and processing, (2) identify the gaps in knowledge, and (3) prioritize the importance of the knowledge gaps in relation to risk of aflatoxin contamination. As a means toward meeting these objectives, the Aflatoxin Task Force organized a Peanut Quality Symposium held in Tifton, Georgia on November 29-30, 2021. This symposium was open to all interested stakeholders. This article is a synopsis of the symposium.

PURPOSE: Effective periprocedural analgesia is an important aspect of cervical brachytherapy delivery, with implications for patient comfort and attendance for subsequent fractions. We com-pared the efficacy and safety of three analgesic modalities: intravenous patient-controlled analgesia (IV-PCA), continuous epidural infusion (CEI) and programmed-intermittent epidural bolus with patient-controlled epidural analgesia (PIEB-PCEA).METHODS AND MATERIALS: Ninety-seven brachytherapy episodes involving 36 patients be-tween July 2016 and June 2019 in a single tertiary center were retrospectively reviewed. Episodes were divided into two key phases: Phase 1 (while applicator remained in situ) and Phase 2 (fol-lowing applicator removal until discharge or 4 h). For the primary endpoint, pain scores were retrieved and analyzed by analgesic modality with respect to median score and an internally de-fined "unacceptable" pain experience ( > 20% of scores being >= 4/10; i.e., moderate or greater). Total nonepidural oral morphine equivalent dose (OMED) and toxicity/complication events were reported as secondary endpoints.RESULTS: In Phase 1, there was a significantly higher median pain score ( p < 0.001) and more episodes with unacceptable pain scores (46%) in the IV-PCA group compared with either epidural modality (6-14%; p < 0.001). In Phase 2, we observed a greater median pain score ( p = 0.007) and higher proportion of patient episodes with unacceptable pain scores (38%) in the CEI group compared with both the IV-PCA (13%) and PIEB-PCEA (14%) groups ( p = 0.001). There was a significant difference in median OMED used throughout all phases across the PIEB-PCEA (0 mg), IV-PCA (70 mg), and CEI (15 mg) groups ( p < 0.001).CONCLUSIONS: PIEB-PCEA is safe and offers superior analgesia compared to IV-PCA or CEI for pain control after applicator placement in cervical brachytherapy.(c) 2023 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

Abstract BackgroundThis paper describes the protocol for the Nano X Image Guidance (Nano X IG), a single-institution, clinical imaging study. The Nano X is a prototype fixed-beam radiotherapy system developed to investigate the feasibility of a low cost, compact radiotherapy system to increase global access to radiation therapy. This study aims to assess the feasibility of volumetric image guidance with Cone Beam Computed Tomography (CBCT) acquired during horizontal patient rotation on the Nano X radiotherapy system.MethodsIn the Nano X IG study we will determine whether image guidance can be performed with the Nano X radiotherapy system, to a clinically acceptable and usable standard for radiotherapy. We will acquire both conventional CBCT scans and Nano X CBCT scans, where the patient is horizontally rotated while scan projections are acquired, for 30 patients. For each patient a panel of experts will assess the image quality of Nano X CBCT scans against conventional CBCT scans. Each patient will receive two Nano X CBCT scans to determine the image quality reproducibility, the extent and reproducibility of patient motion and assess patient tolerance.DiscussionFixed-beam radiotherapy systems have the potential to help ease the current shortfall and increase global access to radiotherapy treatment. Advances in image guidance could facilitate fixed-beam radiotherapy using horizontal patient rotation. The efficacy of this radiotherapy approach is dependent on our ability to image and adapt to motion due to rotation and for patients to tolerate rotation during treatment.Trial registrationThis study was registered on ClinicalTrials.gov on 27 July 2020. The identifier is: NCT04488224.

Objective. To better serve women with gynaecological cancers, we need a sound understanding of their health, wellbeing and needs. This study sought to explore these issues in a sample of Australian women before commencing curative radiotherapy.Methods. We undertook a secondary analysis of baseline data from a supportive care trial (n = 311). Descrip-tive statistics were used to summarise responses to measures of wellbeing, general psychological distress, symp-tom distress, sexual function and vaginal changes, and supportive care needs. Pre-specified regression models were used to examine sources of variation in wellbeing and sexual function.Results. Women reported lower emotional, functional and physical wellbeing than population norms (all p < 0.001). The prevalence of general psychological distress was 31% (95% CI 26-36%). Distress caused by physical symptoms was typically low. Health system and information needs comprised eight of the top ten moderate -to-high supportive care needs. Most women reported no change in interest for physical contact or sex compared to pre-diagnosis, but some sexually active women (16-24%) reported smaller vaginal size, increased dryness, and more pain on intercourse. General psychological distress was a robust marker of poorer wellbeing and sexual function.Conclusions. Before radiotherapy, a substantial minority of women with gynaecological cancers experience general psychological distress, reduced wellbeing and moderate-to-high health system and information needs. A model of comprehensive care incorporating assessment of unmet needs, general psychological distress, and sexual issues is recommended. Healthcare providers may require training to elicit and respond to a constellation of interrelated issues and access relevant services for women requiring additional support. CrownCopyright (c) 2022 Published by Elsevier Inc. All rights reserved.

Alpha particle therapy, such as diffusing alpha-emitters radiation therapy (DaRT) and targeted alpha-particle therapy (TAT), exploits the short range and high linear energy transfer (LET) of alpha particles to destroy cancer cells locally with minimal damage to surrounding healthy cells. Dosimetry for DaRT and TAT is challenging, as their radiation sources produce mixed radiation fields of $\alpha $ particles, $\beta $ particles, and $\gamma $ rays. There is currently no dosimeter for real-time in vivo dosimetry of DaRT or TAT. Metal-oxide-semiconductor field-effect transistors (MOSFETs) have features that are ideal for this scenario. They can be read out in real-time nondestructively, store information permanently, and their sensitivity to radiation can be varied by changing the bias on the gate during irradiation. Moreover, owing to their compactness, MOSFETs can fit into fine-gauge needle applicators, such as those used to carry radioactive seeds into the tumor. This study characterized the response of MOSFETs designed at the Centre for Medical and Radiation Physics, University of Wollongong. Irradiations were performed with a mono-energetic helium ion beam (He 2+ ) of 5.5 MeV and an Americium-241 ( 241 Am) source, for MOSFETs with three different gate oxide thicknesses (0.55, 0.68, and 1.0 $\mu \text{m}$ ). The results showed that the response was linear with alpha dose up to 25 Gy. Also, it was found that a gate bias of between 15 and 60 V would optimize the sensitivity to alpha particles with energy of 5.5 MeV.

The fi rst Australasian survey on brachytherapy training experience is published in JMIRO. 1 It was written by a largely Australian group of authors who sent a question-naire to all College trainees and Fellows who had quali- fi ed since 2015. The response rate was 24% (40/161 trainees, 30/126 recent fellows) and of the 70 respon-dents, 50 (71%), 38 (54%) and 43 (61%) reported to have received formal brachytherapy teaching from radiation oncologists, radiation therapists and physicists, respectively. Two-thirds of trainees and all fellows had performed at least one gynaecology brachytherapy pro-cedure. Prostate brachytherapy exposure was more lim-ited – by the end of the training, 27% and 13% of fellows did not have exposure to LDR and HDR prostate brachytherapy. The authors listed the barriers to training as including lack of caseload, perceived decreasing role of brachytherapy, low level of competency requirements and lack of formal teaching which may give the impres-sion that brachytherapy is not highly valued by the RANZCR. This gives a useful insight into the state of brachytherapy training and raises concerns about the future of brachytherapy in Australia and New Zealand. However, the survey is self-reported and has a low response rate. One can speculate that the responders maybe those with a greater interest in and more exposure

Abstract Introduction Radiation therapy is a common cancer treatment, requiring timely information to help patients prepare for treatment. We pilot tested a low literacy, psycho‐educational talking book (written booklet, with accompanying audio recording) to examine (i) the effect of the tool on knowledge, anxiety and communication; (ii) acceptability, and (iii) how it was used in appointments. Methods A pre‐post design was employed. Patients scheduled to receive radiation therapy for any cancer were recruited from two hospitals in Sydney, Australia. Participants were sent the talking book before treatment planning and completed baseline and follow‐up surveys, before and after the intervention. Results Forty participants were recruited, and 39 completed all study assessments. Overall, knowledge increased after receiving the talking book by 3.8 points from 13.9 to 17.7/20 (95% confidence interval (CI) 2.7, 4.8, P < 0.001). Anxiety and concerns were significantly lower after receiving the talking book (P = 0.015 and P = 0.004, respectively). Nearly half of participants (s = 17, 48%) reported using the book during appointments. Most reported finding it easier to communicate (n = 31, 89%) and to ask more questions (n = 21, 62%). Conclusion The talking book shows promise in improving knowledge, reducing anxiety and enhancing communication. Strategies to support the implementation of the talking book are required. Further studies to translate the book into different languages are also planned.

A feasibility study is presented on a newly developed microdosimetry system named Octobox, for its application in low dose rate, mixed radiation environments. A full characterization of the device was performed at the Heavy Ion Medical Accelerator in Chiba (HIMAC), Japan, out-of-field of various heavy ion radiation fields - 290 MeV/u C-12, 230 MeV/u and 490 MeV/u Si-28 and 400 MeV/u Ne-20 ions, as well as a low dose rate Rn-222 environment at the Australian Nuclear Sciences and Technology Organization (ANSTO). The device was shown to collect adequate statistics in a short period of time when compared to the MicroPlus probe with a single microdosimeter, while accurately measuring microdosimetric quantities and the corresponding average quality factor ((Q) over bar) and dose equivalent (H) of the mixed radiation field. Good agreement of the microdosimetric spectra was also shown with Geant4 simulations for all presented ion fields. Based on the findings in this study, the Octobox is capable of being applied in mixed, low dose rate, radiation environments such as those encountered in space and aviation, as well as in underground mines for radiation protection purposes.

AbstractPurposeStereotactic radiosurgery (SRS) can be delivered with a standard linear accelerator (linac). At institutions having more than one linac, beam matching is common practice. In the literature, there are indications that machine central axis (CAX) matching for broad fields does not guarantee matching of small fields with side ≤2 cm. There is no indication on how matching for broad fields on axis translates to matching small fields off axis. These are of interest to multitarget single‐isocenter (MTSI) SRS planning and the present work addresses that gap in the literature.MethodsWe used 6 MV flattening filter free (FFF) beams from four Elekta VersaHD® linacs equipped with an Agility™ multileaf collimator (MLC). The linacs were strictly matched for broad fields on CAX. We compared output factors (OPFs) and effective field size, measured concurrently using a novel 2D solid‐state dosimeter “Duo” with a spatial resolution of 0.2 mm, in square and rectangular static fields with sides from 0.5 to 2 cm, either on axis or away from it by 5 to 15 cm.ResultsAmong the four linacs, OPF for fields ≥1 × 1 cm2 ranged 1.3% on CAX, whereas off axis a maximum range of 1.9% was observed at 15 cm. A larger variability in OPF was noted for the 0.5 × 0.5 cm2 field, with a range of 5.9% on CAX, which improved to a maximum of 2.3% moving off axis. Two linacs showed greater consistency with a range of 1.4% on CAX and 2.2% at 15 cm off axis. Between linacs, the effective field size varied by <0.04 cm in most cases, both on and off axis. Tighter matching was observed for linacs with a similar focal spot position.ConclusionsVerification of small‐field consistency for matched linacs used for SRS is an important task for dosimetric validation. A significant benefit of concurrent measurement of field size and OPF allowed for a comprehensive assessment using a novel diode array. Our study showed the four linacs, strictly matched for broad fields on CAX, were still matched down to a field size of 1 x 1 cm2 on and off axis.

PurposeA 5 and 10 μm thin silicon on insulator (SOI) 3D mushroom microdosimeter was used to characterize both the in‐field and out‐of‐field of a 62 MeV proton beam.MethodsThe SOI mushroom microdosimeter consisted of an array of cylindrical sensitive volumes (SVs), developed by the Centre for Medical Radiation Physics, University of Wollongong, was irradiated with 62 MeV protons at the CATANA (Centro di AdroTerapia Applicazioni Nucleari Avanzate) facility in Catania, Italy, a facility dedicated to the radiation treatment of ocular melanomas. Dose mean lineal energy, (), values were obtained at various depths in PMMA along a pristine and spread out Bragg peak (SOBP). The measured microdosimetric spectra at each position were then used as inputs into the modified Microdosimetric Kinetic Model (MKM) to derive the RBE for absorbed dose in a middle of the SOBP 2Gy (RBED). Microdosimetric spectra were obtained with both the 5 and 10 μm 3D SOI microdosimeters, with a focus on the distal part of the BP. The in‐field and out‐of‐field measurement configurations along the Bragg curve were modeled in Geant4 for comparison with experimental results. Lateral out‐of‐field measurements were performed to study secondary particles’ contribution to normal tissue’s dose, up to 12 mm from the edge of the beam field, and quality factor and dose equivalent results were obtained.ResultsComparison between experimental and simulation results showed good agreement between one another for both the pristine and SOBP beams in terms of and RBED. Though a small discrepancy between experiment and simulation was seen at the entrance of the Bragg curve, where experimental results were slightly lower than Geant4. The dose equivalent value measured 12 mm from the edge of the target volume was 1.27 ± 0.15 mSv/Gy with a value of 2.52 ± 0.30, both of which agree within uncertainty with Geant4 simulation.ConclusionsThese results demonstrate that SOI microdosimeters are an effective tool to predict RBED in‐field as well as dose equivalent monitoring out‐of‐field to provide insight to probability of second cancer generation.

Fixed-gantry radiation therapy has been proposed as a low-cost alternative to the conventional rotating-gantry radiation therapy, that may help meet the rising global treatment demand. Fixed-gantry systems require gravitational motion compensated reconstruction algorithms to produce cone-beam CT (CBCT) images of sufficient quality for image guidance. The aim of this work was to adapt and investigate five CBCT reconstruction algorithms for fixed-gantry CBCT images. The five algorithms investigated were Feldkamp-Davis-Kress (FDK), prior image constrained compressed sensing (PICCS), gravitational motion compensated FDK (GMCFDK), motion compensated PICCS (MCPICCS) (a novel CBCT reconstruction algorithm) and simultaneous motion estimation and iterative reconstruction (SMEIR). Fixed-gantry and rotating-gantry CBCT scans were acquired of 3 rabbits, with the rotating-gantry scans used as a reference. Projections were sorted into rotation bins, based on the angle of rotation of the rabbit during image acquisition. The algorithms were compared using the structural similarity index measure root mean square error, and reconstruction time. Evaluation of the reconstructed volumes showed that, when compared with the reference rotating-gantry volume, the conventional FDK algorithm did not accurately reconstruct fixed-gantry CBCT scans. Whilst the PICCS reconstruction algorithm reduced some motion artefacts, the motion estimation reconstruction methods (GMCFDK, MCPICCS and SMEIR) were able to greatly reduce the effect of motion artefacts on the reconstructed volumes. This finding was verified quantitatively, with GMCFDK, MCPICCS and SMEIR reconstructions having RMSE 17%-19% lower and SSIM 1% higher than a conventional FDK. However, all motion compensated fixed-gantry CBCT reconstructions had a 56%-61% higher RMSE and 1.5% lower SSIM than FDK reconstructions of conventional rotating-gantry CBCT scans. The results show that motion compensation is required to reduce motion artefacts for fixed-gantry CBCT reconstructions. This paper further demonstrates the feasibility of fixed-gantry CBCT scans, and the ability of CBCT reconstruction algorithms to compensate for motion due to horizontal rotation.

PURPOSE:A radiotherapy system with a fixed treatment beam and a rotating patient positioning system could be smaller, more robust and more cost effective compared to conventional rotating gantry systems. However, patient rotation could cause anatomical deformation and compromise treatment delivery. In this work, we demonstrate an image-guided treatment workflow with a fixed beam prototype system that accounts for deformation during rotation to maintain dosimetric accuracy. METHODS:The prototype system consists of an Elekta Synergy linac with the therapy beam orientated downward and a custom-built patient rotation system (PRS). A phantom that deforms with rotation was constructed and rotated within the PRS to quantify the performance of two image guidance techniques: motion compensated cone-beam CT (CBCT) for pre-treatment volumetric imaging and kilovoltage infraction monitoring (KIM) for real-time image guidance. The phantom was irradiated with a 3D conformal beam to evaluate the dosimetric accuracy of the workflow. RESULTS:The motion compensated CBCT was used to verify pre-treatment position and the average calculated position was within -0.3 ± 1.1 mm of the phantom's ground truth position at 0°. KIM tracked the position of the target in real-time as the phantom was rotated and the average calculated position was within -0.2 ± 0.8 mm of the phantom's ground truth position. A 3D conformal treatment delivered on the prototype system with image guidance had a 3%/2 mm gamma pass rate of 96.3% compared to 98.6% delivered using a conventional rotating gantry linac. CONCLUSIONS:In this work, we have shown that image guidance can be used with fixed-beam treatment systems to measure and account for changes in target position in order to maintain dosimetric coverage during horizontal rotation. This treatment modality could provide a viable treatment option when there insufficient space for a conventional linear accelerator or where the cost is prohibitive.

For the last 30 years at the Royal Hospital for Women, unifocal vulvar squamous cancers have been treated by radical local excision, aiming to achieve a histopathological margin of ≥8 mm, equating to a surgical margin of 1 cm. The need for a margin of this width has recently been challenged. We aimed to determine the long-term outcome following this conservative approach, and the relationship between vulvar recurrences and surgical margins. Data were obtained retrospectively on 345 patients treated primarily with surgery for squamous vulvar cancer between 1987 and 2017. Median follow-up was 93 months. Five-year disease-specific survival was 86%. Of 78 vulvar recurrences, 33 (42.3%) were at the primary site and 45 (57.7%) at a remote site. In multivariable analysis, a margin <5 mm showed a higher risk of all vulvar (Hazard ratio (HR), 2.29; CI, 1.12−4.70), and primary site recurrences (subdistribution hazard ratio (SHR), 15.20; CI, 5.21−44.26), while those with a margin of 5 to <8 mm had a higher risk of a primary site recurrence (SHR, 8.92; CI, 3.26−24.43), and a lower risk of remote site recurrence. Excision margins <8 mm treated by re-excision or radiation therapy had a significantly decreased risk of recurrence. Guidelines should continue to recommend a surgical margin of 1 cm.