PURPOSE:To characterize global practice patterns in prostate brachytherapy (BT) and evaluate variation in practice, identifying alignment with guidelines and opportunities for harmonization. METHODS AND MATERIALS:A 75-item survey was distributed via international BT societies. One response per institution was requested, completed by a radiation oncologist and medical physicist. Domains included departmental characteristics, BT utilization, prescriptions, imaging, planning, verification, and salvage practices. Data were summarized descriptively. RESULTS:A total of 116 institutions responded (64.1%), mainly from North America and Europe. Most had >10 years' experience, though case volumes were modest (11-50 de novo; <10 salvage annually). High-dose-rate (HDR) BT was most used for combination and salvage, while HDR and low-dose-rate BT were evenly used for monotherapy. Prescription regimens were heterogeneous, particularly for HDR monotherapy and salvage. Androgen-deprivation therapy duration varied across risk groups. Transrectal ultrasound was the primary planning modality; only 46% used fused diagnostic imaging for intraprostatic lesion definition. Most used ≤3 mm margins and standard coverage metrics, though organ-at-risk constraints varied. Focal BT use was increasing, particularly in salvage settings. CONCLUSIONS:Substantial international variability exists across BT practice. While core technical principles are consistent, heterogeneity highlights the need for harmonized guidelines, prospective studies, and global collaboration.

High‑dose‑rate (HDR) brachytherapy is an important treatment modality for prostate cancer, used as monotherapy for low‑ and favorable intermediate‑risk patients and as a boost for those with higher‑risk disease. It also remains a key option for patients with radio‑recurrent localized prostate cancer. HDR offers several advantages, including real-time image guidance for catheter placement, dynamic treatment plan optimization, precise dose customization, and lower radiation exposure for staff. As HDR brachytherapy becomes increasingly integrated into clinical practice, trainees are expected to acquire the knowledge and procedural proficiency necessary for independent practice by the completion of residency.Despite this expectation, few institutions offer formal brachytherapy training or fellowships, and there is limited guidance outlining the specific competencies required for HDR prostate brachytherapy. Existing documents, including guidelines from the American Brachytherapy Society (ABS) and GEC‑ESTRO, provide high‑level recommendations but are not HDR-specific competencies. The objective of this manuscript is to summarize current prostate HDR guidelines from ABS and GEC‑ESTRO and to establish a structured competency framework that training programs can adopt to ensure residents and fellows achieve proficiency in HDR prostate brachytherapy.

PURPOSE:The primary aim was to evaluate the accuracy of the generated Mid-Ventilation (MidV) Gross Tumour Volume (GTV) and Planning Target Volume (PTV) using three Deformable Image Registration (DIR) algorithms (Eclipse DIR, MIM DIR, Velocity DIR) and two starting phases for contour propagation (0% vs. 20%), compared with inter-observer variation (IOV). METHODS:27 stereotactic ablative radiotherapy (SABR) lung datasets were analysed. For each patient, three contours and a consensus reference contour was created. This reference contour was used to generate six DIR-based 4D contours (three algorithms with two starting phases). Performance was assessed using contour agreement metrics (mean distance to agreement [MDA)], Dice similarity coefficient [DSC], Hausdorff distance [HD], and volume ratio). Non-inferiority tests (one-sided, Dunnett-adjusted) evaluated DIR performance relative to IOV. RESULTS:DIR with a 20% starting phase outperformed 0% predominantly. Eclipse and Velocity DIR-20% met all published tolerances (MDA within 2 mm, DSC more than 0.8, and volume ratio within 10%) and were non-inferior to IOV. Secondary analyses showed improved consistency in MidV phase determination, MidV to Mid-position (MidP) centroid deviation (within 1 mm), 4D motion estimation (<1 mm), and PTV margin calculation (<1 mm difference). CONCLUSION:DIR algorithms using a 20% starting phase demonstrated superior performance compared with a 0% starting phase. Commercial DIR algorithms can support MidV contouring for lung SABR when initiated from the 20% starting phase. DIR-20% produced contour accuracy comparable to IOV with robust performance across MidV subprocesses.

BACKGROUND:Diffusing alpha-emitters Radiation Therapy (DaRT) is a brachytherapy treatment modality that utilizes the diffusing progeny of 224 R a ${}^{224}Ra$ to treat solid tumors with therapeutic alpha radiation. The treatment is very complex, with comprehensive dosimetry, micro- and nanodosimetry, and detector studies requiring temporal modelling of the entire 224 R a ${}^{224}Ra\;$ decay chain, diffusion, energy-transfer physics, and the implementation of boundary conditions for both desorbed and source-bound nuclides. PURPOSE:To present and validate a 3D Monte Carlo (MC) model that combines the full 224 R a ${}^{224}Ra\;$ decay chain, radionuclide diffusion, and particle energy-transfer physics, to enable temporal DaRT dosimetry for both source-bound and diffusing nuclides. METHODS:Using the Geant4 toolkit, a multi-stage Monte Carlo model (MSMCM) was developed to combine radioactive decay, Brownian motion, and particle energy-transfer physics into a single framework. Using this framework we performed three simulations, with different boundary condition variants, for point, single, and multi-source model configurations, with the dose distributions validated against published analytical models. The MSMCM's potential application for use in multi-source in-vivo detector analyses was also assessed. RESULTS:The MSMCM was successfully able to produce spatial and temporal dose distributions for all source types: point, single, and multi-source. Additionally, for the single source model, we produced full-spectrum dosimetry, dose-buildup, and dose-rate curves over clinically relevant timeframes. Comparing the MSMCMs benchmark models, we found that the measured dose depositions of point- and radial-source scenarios were within 5%. We also found that boundary conditions had a marked impact on the axial depth-dose for realistic source geometries. CONCLUSIONS:The MSMCM provides a flexible particle-by-particle solution to modelling DaRT, producing spatial and temporal dosimetry consistent with current analytical models. Given the MSMCM's capacity to model the complete 224 R a ${}^{224}Ra\;$ decay chain, diffusion, track-level energy depositions, and complex boundaries in a single framework, it is suitable for micro- and nanodosimetry, multi-source in-vivo dosimetry, and detector analysis studies.

Purpose: Real-time tracking of source position during high-dose-rate (HDR) brachytherapy remains limited in routine clinical practice, despite its importance for treatment accuracy and patient safety. This study investigates the feasibility of using a CsI(Tl)-based fibre-optic dosimeter for real-time HDR source tracking using a stem-inclusive calibration framework that avoids suppression of non-scintillation optical signals. Methods: A single fibre-optic detector incorporating a CsI(Tl) scintillator was used with an Ir-192 brachytherapy source. A calibration model accounting for all optical signal contributions was applied to relate measured detector voltage to source geometry. Real-time source tracking was performed by comparing the averaged measured voltages with modelled responses to reconstruct the source position. Tracking performance was evaluated for step sizes of 3 mm and 5 mm, dwell times from 5.0 s to 0.5 s, and source-detector separations up to approximately 50 mm. Results: The detector response showed close agreement with the calibration model, with deviations within approximately 4% of the peak signal across the tracking range. Reconstructed source positions closely followed planned dwell locations for all tested configurations. Tracking errors remained within 1.51 mm for most conditions and increased to 2.6 mm only at the largest source-detector separations. Stable localisation performance was maintained across all dwell times, with no clear degradation as dwell time decreased. Conclusions: Real-time HDR source tracking was achieved using a single CsI(Tl)-based fibre-optic detector and a stem-inclusive calibration approach. Millimetre-scale localisation accuracy was obtained without stem signal suppression, additional detectors, or hardware modification, supporting calibration-driven signal interpretation for HDR source position verification.

BACKGROUND:Single-isocenter multiple-target stereotactic radiosurgery (SIMT SRS) has emerged as an efficient treatment for multiple brain metastases. However, this technique demands exceptional geometric accuracy, particularly off-axis, to ensure optimal dose delivery while sparing healthy tissue. Traditional quality assurance (QA) methods require adaptation for SIMT SRS, highlighting the need for robust testing protocols. PURPOSE:This study aimed to evaluate the long-term off-axis targeting accuracy of three Varian TrueBeam linear accelerators using a dedicated off-axis Winston-Lutz test (OAWLT) and to investigate correlations with routine varian machine performance check (MPC) results. MATERIALS & METHODS:Weekly OAWLT measurements were performed over a 6-month period on three TrueBeam linacs using the Sun Nuclear StereoPHAN phantom and MultiMet-WL cube. The test delivered 6 MV flattening filter-free beams to multiple off-axis targets via eight beam orientations, simulating clinical SIMT SRS workflows. Concurrently, daily MPC assessments evaluated geometric parameters including isocenter size, kV isocenter offset, beam center, and couch radiation-induced offset. RESULTS:Median OAWLT errors were 0.38, 0.44, and 0.59 mm for the three linacs included in this study, with maximum errors of 1.12, 1.08, and 1.54 mm. Notably, off-axis errors increased with target off-axis distance, with the worst performance observed at 7 cm off-axis. CONCLUSION:Routine OAWLT is an effective and sensitive QA tool for monitoring off-axis targeting accuracy in SIMT SRS. Despite the convenience of daily MPC, it cannot substitute for a dedicated OAWLT. The study supports implementing weekly OAWLT in clinical practice to ensure high-quality, consistent treatment delivery for SIMT SRS treatments.

Deformable image registration (DIR) has proven to be an invaluable tool to maximize the clinical benefits of multimodality imaging in radiation oncology. In contrast to rigid image registration (RIR), which is employed at all stages of diagnosis and treatment, the uptake of DIR has been constrained by concerns over the potential for unsafe use. The AAPM Task Group 132 (TG132) published a report on the use of image registration, including many recommendations on clinical integration of registration in treatment planning and delivery. There is a remaining uncertainty on incorporating registration uncertainties into treatment margins (Sect. 6.A, TG 132), a challenge in clinical practice. The aim of this work was to report our experience in implementing a practical, patient specific quality assurance process based on the AAPM Task Group 132 report recommendations. This work includes refining our process of target contouring using PET with deformable image registration based on our experience of addressing vulnerabilities identified during implementation. A multidisciplinary team created a flowchart for patient specific quality assurance for image registration (RIR or DIR) based on use cases defined in the AAPM TG132 Report on the use of image registration in radiotherapy. Vulnerabilities identified from this implementation were assessed relative to AAPM TG132 recommendations. These findings were used to adapt our patient specific quality assurance to mitigate vulnerabilities. The main vulnerabilities were identified in the last steps of image registration. There was potential for inappropriate use of the registration for clinical use, such as target contouring where the image registration accuracy level was poor. Vulnerabilities were addressed by an adaptation in our quality assurance process. A new physics image registration QA task was introduced that independently checks registration accuracy and appropriateness of target contouring, addressing the vulnerability in the last steps of the AAPM TG132 flowchart. A multi-disciplinary team implemented the image registration process outlined by AAPM TG132. An improved patient specific quality assurance process was developed by introducing an independent physics image registration review that considers the acceptable registration uncertainty for the specific clinical use case in question.

PURPOSE:We introduce the next generation of "MagicPlate" 2D monolithic pixelated semiconductor detectors - MagicPlate-976 (MP976). It features a larger array area, higher spatial resolution, and does not require external triggering. We perform a comprehensive characterization for small-field steep-dose-gradient dosimetry applications in radiation therapy focusing on x-ray beams used in stereotactic treatments. METHODS:The MP976, developed by the Centre for Medical Radiation Physics, consists of 976 ion-implanted diodes on a thin n-type epitaxial silicon substrate with a total array area of 58 × 58 mm2. The central region has "small" diodes with an area of 0.2 × 0.2 mm2 and 1 mm pitch and the peripheral region has "large" diodes with an area of 0.6 × 0.6 mm2 and 2 mm pitch. The detector was primed with 10 kGy (Co-60) and tested using a Varian TrueBeam linear accelerator for sensitivity change and dose linearity, and variations in response due to dose-per-pulse and beam incidence angle. Output factors, depth dose, and beam profiles were measured and compared with reference data. RESULTS:After the 10 kGy, the sensitivity declined by (74 ± 5)% for "large" diodes and by (78 ± 7)% for the "small" ones, the dose-per-pulse (DPP) dependence was in the range of commercially available diodes, however, a difference in the DPP dependence between the "large" and "small" diodes of (8.4 ± 0.2)% was found in the studied DPP range from 0.131-1.111 mGy/pulse. The minimum angular response was at 90° for 6 MV and 100° for 10 MV flattened beams (76% and 82%, respectively). The output factors and depth dose response showed agreement with the reference within 3.1% and 1%, respectively. Deviation in small field 80%/20% penumbra measurements was within 0.5 mm for 6 MV FF and 0.3 mm for 10 MV FFF. Full width at half maximum (FWHM) for the beam profiles agreed within 0.5 mm for both beam qualities. CONCLUSION:The new MagicPlate-976 detector system is shown to be suitable for dosimetry in small fields and steep dose gradients. It provides 1 mm spatial resolution in the central region and 2 mm on the periphery and has no dependence on the field size. The system's high spatial and temporal resolution opens new opportunities for trigger-less, film-less, and time-resolved verification and error identification for complex stereotactic treatment plans.

The aim of this study is to evaluate the feasibility of using CsI(Tl)-based fiber-optic dosimetry system for TG-43 dosimetric characterization of the Flexisource 192Ir HDR brachytherapy source. The investigation focuses on anisotropy and radial dose function measurements and assesses the impact of fluorescence and Cherenkov radiation on signal accuracy, with validation through TOPAS Monte Carlo simulations. Thallium Doped-Cesium Iodide (CsI(Tl)) scintillation crystals were used within a custom-designed PMMA phantom. The experiment, conducted with a Flexitron afterloader and 192Ir Flexisource, involved measurements at distances of 1.5-6 cm and polar angles of 20 degrees-155 degrees, with increments matching those in the published studies. Comprehensive dosimetric data were collected, revealing the influence of fluorescence and Cherenkov radiation on anisotropy function measurements. The radial dose function showed good agreement with simulation, with minor deviations attributed to limitations in the treatment planning. TOPAS Monte Carlo simulations demonstrated consistent agreement with experimental results, yielding a maximum absolute difference of 0.035 in the experimental data and a maximum deviation of 2.6% in anisotropy function validation against published reference data, further confirming the reliability of both the experimental approach and the simulation model. These findings underscore the importance of accounting for fluorescence and Cherenkov radiation in detector signal response. Unlike earlier approaches that primarily focused on signal removal or hardware suppression techniques, this study demonstrates the integration of these contributions directly into calibration models to improve dosimetric precision. By refining these calibration methods, fiber-optic detectors may be further developed into simple, accurate, and clinically viable tools for brachytherapy applications.

Purpose: Even with modern immobilisation devices, some amount of intrafraction patient motion is likely to occur during stereotactic radiosurgery (SRS) delivery. The aim of this work was to investigate how robustness of plans to intrafraction motion is affected by plan geometry and complexity. Methods: In 2018, the Trans-Tasman Radiation Oncology Group conducted a multiple-target SRS international planning challenge, the data from which was utilised in this study. Patient geometry included five intracranial targets with a prescription of 20 Gy. A previously validated in-house algorithm was used to simulate realistic intrafraction patient motion for these plans. Three scenario types were simulated: translational intrafraction motion; rotational motion; and simultaneous rotational and translational motion. Dosimetric impact was assessed using: dose covering 98 % of planning target volume, dose covering 99 % of gross tumour volume (GTV D99%), volume of normal brain receiving 12 Gy and maximum dose covering 0.03 cc brainstem. Results: GTV D99% was reduced by up to 70 %, with the strongest correlations between planning factors and robustness to intrafraction motion found for plan complexity. Despite only moderate correlation strength at r = 0.4, lower complexity plans had, on average, 5 % - 9 % less intrafraction motion scenarios with failing targets compared to the highest complexity plans. Conclusions: SRS plans with lower complexity, in particular larger mean multi-leaf collimator (MLC) gap and MLC aperture irregularity, were shown to improve plan robustness to intrafraction patient motion.

Very-high-energy electrons, coupled with ultra-high dose rates, are being explored for their potential use in radiotherapy to treat deep-seated tumours. The dose per pulse needed to achieve ultra-high dose rates far exceeds the limit of current medical linear accelerator capabilities. A high dose per pulse has been observed as the limiting factor for many existing dosimeters, resulting in saturation at doses far below what is required. The MOSkin, an existing clinical quality assurance dosimeter, has previously been demonstrated as dose rate independent but has not been subjected to a high dose per pulse. Within this study, the MOSkins dose-per-pulse response was tested for linearity, with a dose per pulse as high as 23 Gy within 200 ns at the ANSTO Australian Synchrotron’s Pulsed Energetic Electrons for Research facility. While using EBT-XD film as a reference dosimeter, a dose rate dependence of the EBT-XD was discovered. Once confirmed and a correction factor established, EBT-XD was used as an independent reference measurement. This work presents confirmation of the MOSkin suitability for ultra-high dose-rate environments with an electron energy of 100 MeV, and a theoretical discussion of its dose-rate and dose-per-pulse independence; the MOSkin is the only detector suitable for both clinical quality assurance, and ultra-high dose-rate measurements in its standard, unmodified form.

Introduction:The Mid-Ventilation (MidV) approach is an alternative to internal target volume (ITV) for generating a planning target volume (PTV) in lung stereotactic ablative radiotherapy (SABR). It has been shown to reduce PTV and volume of normal lung tissue irradiated, whilst maintaining high local control rates. However, this approach has not been widely adopted due to difficulties in determining the MidV phase in commercially available treatment planning systems. We hypothesised that a fully integrated MidV workflow could be developed and validated within a single vendor platform, producing accurate contours and dosimetric improvements compared with the ITV based method. Methods:A MidV workflow was implemented using Eclipse/Aria, incorporating deformable image registration (DIR) of 4DCT images, automated 4D contour statistics for MidV phase selection and an embedded PTV margin calculation spreadsheet. Ten patients from a multi-centre Phase II lung SABR study were retrospectively analysed. The following metrics were used to compare the DIR method with the manually contoured iGTV: mean distance to agreement (MDA), dice similarity coefficient (DSC) and accurate selection of the MidV Phase (±10 %). Corresponding ITV and MidV PTV based plans were generated and compared using absolute PTV volumes, mean lung dose (MLD) and V20Gy. Results:DIR generated iGTVs demonstrated high geometric accuracy (mean MDA 0.86 mm; DSC 0.86). MidV phase selection aligned with manual selection in all patients. MidV based planning produced smaller PTVs than ITV based in 8/10 cases (mean 47.0 cm3 vs 54.6 cm3). Lung dose metrics improved consistently: MLD decreased by 14 % (3.46 Gy to 2.97 Gy) and V20Gy by 16 % (3.78 % to 3.19 %). Conclusion:A streamlined, vendor integrated MidV workflow was successfully developed and validated, producing accurate DIR based contours and meaningful dosimetric reductions compared with ITV based method. These findings support broader clinical implementation of MidV based lung SABR.

This work investigates the response of specially developed silicon p-i-n diodes with a long base as sensors to measure displacement damage dose (DDD) in silicon. Measurements of DDD are based on the forward voltage shift (Delta V-F ) of irradiated p-i-n diodes. In this work the p-i-n diodes were irradiated in the following radiation fields: i) 20 MeV electrons from a medical LINAC (linear accelerator); ii) 200 MeV, 150 MeV, 100 MeV protons at the Groningen proton therapy facility and; iii) 4.63 MeV and 15.3 MeV quasi-monoenergetic neutrons at the Czech Technical University, Prague. It was demonstrated that the calibration factor (alpha), that is the response of the p-i-n diode in terms of DDD obtained using 20 MeV electrons, can be used to predict the p-i-n diode response for protons and neutrons as mentioned above (within experimental error). However, the p-i-n diodes response related to 100 MeV protons has a 70% higher response than predicted that requires further investigation. Overall, the 20 MeV electrons from a medical LINAC were found to be suitable for p-i-n diodes calibration in terms of the non-ionizing energy losses (NIEL) and is widely available in contrast to 1 MeV electrons, fast neutrons and protons.

Accurate contouring is crucial for optimal treatment outcomes, whether for nonadaptive radiotherapy with single images or adaptive radiotherapy (ART) with multiple images. For ART there are 2 common approaches for automated segmentation: deformable image registration (DIR) propagation of prior contours from a previous image to a newer replanning image or (ii) deep learning (DL) generated by models trained with datasets. The accuracy of the latter approach is impacted by the size, diversity and quality of the training dataset while the accuracy of the former approach depends on the quality of prior contours, the image contrast between image pairs, and the DIR algorithm used. This study assesses the accuracy of a commercially available pretrained DL model (Mirada DLC04, DLC13, DLC14) and DIR tools (Velocity, MIM, Eclipse) for generating contours in replanning scenarios for adaptive replanning in the head and neck region. Datasets from adaptive replanning in the head and neck region (n = 9 patients) included CTs (n = 18) with clinically approved contours and doses. Manual contour data were compared against deep learning models (Mirada DLC04, DLC13, DLC14) and image registration propagated contours (rigid, deformable with MIM, Velocity, and Eclipse). Evaluation involved (a) contour clinical relevance scores, (b) contour grading scores, (c) assessment of manual and DL contouring style by a Radiation Oncologist Consultant against the Brouwer contouring guideline and (d) accuracy assessment based on geometric and dosimetric metrics, These metrics included dice similarity coefficient (DSC), mean distance to agreement (MDA), Hausdorff distance(HD), volume ratio, and dose ratio. Contours were shortlisted for statistical analysis based on (i) contour relevance (ii) manual contour grading scores and (iii) existing contouring data. Statistical analysis assessed geometric and dosimetric metrics, with the Velocity DIR as the comparator. Contour relevancy scores were highest for spinal cord, parotids, oral cavity, mandible, larynx, and brainstem. Contour grading scores indicated most contours were clinically acceptable contours with minor edits for both manual and DL contours, except for brachial plexus and oral cavity with variation in contouring style described by the Radiation Oncologist. The brainstem and parotid were shortlisted for statistical analysis, with data indicating that: (i) no statistical evidence (all p > 0.1) of dosimetric difference between DL and DIR contours; (ii) geometrically, the DIR algorithm (Velocity) was superior to the DL model (Mirada DLCExpert) in terms of MDA (p = 0.014) and HD (p < 0.001) for parotids, volume difference for brainstem (p = 0.045); (iii) no statistical evidence (all p > 0.1) of geometric or dose difference for parotids and brainstem amongst rigid or deformable registrations. In our study of DL and DIR based contouring for adaptive radiotherapy in the head and neck region, DIR-based contours demonstrated superior geometric accuracy for the parotid glands and brainstem compared to the DL model (Mirada DLCexpert). Among DIR algorithms, no significant differences were observed, except for the MIM DIR volume ratio for brainstem. Our study found no significant dosimetric differences among DIR or DL contouring methods.

PURPOSE:The purpose of this study was to compare the effect of catheter shift errors and determine patient specific error thresholds (PSETs) for different high dose rate prostate brachytherapy (HDRPBT) plans generated by different forms of inverse optimization. METHODS:Three plans were generated for 50 HDRPBT patients and PSETs were determined for each of the 3 plans. Plan 1 was the original Oncentra Prostate (v4.2.2.4, Elekta Brachytherapy, Veenendaal, The Netherlands) plan, the second plan used the graphical processor unit multi-criteria optimization (gMCO) algorithm, and plan 3 used gMCO but had a robustness parameter as an additional optimization criterion (gMCOr). gMCO and gMCOr plans were selected from a pool of 2000 pareto optimal plans. gMCO plan selection involved increasing prostate V100% and reducing rectum Dmax/urethra D01.cc progressively until only 1 plan remained. The gMCOr plan was the most robust plan (using robustness parameter) that met the clinical DVH criteria (V100% ≥ 95%, rectum Dmax ≤ 80%, urethra D0.1cc ≤ 118%). PSETs were determined using catheter shift software. RESULTS:The initial dose volume histogram (DVH) characteristics showed all 50 patient plans met a prostate V100% > 95% and resulted in significant reduction in rectum Dmax and urethra D0.1cc for gMCO and gMCOr plans. No single plan showed benefits in PSETs for all shift directions compared to the other plans, however gMCO and gMCOr plans exhibit the best initial DVH characteristics assuming no errors occur. The robustness parameter showed no significant impact when considered in plan optimization. CONCLUSIONS:PSETs were found to be equivalent regardless of optimization method. Indicating, no single optimization method can significantly increase the patient specific thresholds.

Quality assurance (QA) ensures the accurate and safe delivery of radiation treatment. However, there are several challenges for advanced radiotherapy techniques, such as stereotactic radiosurgery (SRS), where substantial doses of radiation with multi-directional beams and variable dose rates are delivered to specific areas. Current dosimeters lack high precision, exhibiting issues with dependency on the angle of measurement and the dose rate. This study investigates the characterization of a two-dimensional edgeless silicon diode array for QA in SRS. This detector underwent evaluation of its dose linearity, percentage depth dose (PDD), output factors (OFs), dose rate variability, and angular dependence with megavoltage linear accelerator beams. The edgeless array demonstrated a linear response in the direct detection of MV therapeutic X-rays with sensitivity of 6.95 × 10−3 ± 2.3 × 10−5 Gy/nC, and the percentage differences for PDD and OF measurements were found to be within 2% compared to the reference detector. A dose per pulse dependence of ±2% was demonstrated across the range of 0.12 to 0.39 mGy/pulse. The angular dependence was within 2% variation for irradiation angles greater than 80° and smaller than 120°; however, a maximum of 4% variation was observed with some diodes for angles between 80° and 120°. The improved performance of the edgeless array is likely to overcome limitations of the current dosimeters for SRS QA by operating without the need of any corrections.

Focal boost to intra-prostatic lesions (IPLs) in radiotherapy could enhance treatment efficacy. Brachytherapy (BT), delivering highly conformal dose with sharp dose gradients emerges as a potentially optimal approach for precise dose escalation to IPLs. This study aims to consolidate clinical and planning studies that implemented whole gland prostate BT and focal dose escalation to IPLs, with the view to synthesize evidence on the strategy’s effectiveness and variability. In this review, we identified nine clinical studies and ten planning/simulation studies focusing on whole gland prostate BT with IPL dose escalation. From the clinical studies, the use of whole gland prostate BT with focal dose escalation in combination with external beam radiotherapy (EBRT) appears to be a safe and effective 21 form of treatment for men with T1b – T2c prostate cancer with average five-year biochemical failure22 free survival (BFFS) of 94 % (range 81.1 %−100 %) and minimal grade three toxicities reported. Both clinical and planning studies exemplified the high level of focal dose escalation achievable using BT with a mean IPL D90 % of 132 % and 146 %, respectively (expressed as a % of the whole gland prescription dose). There was considerable variation in the reporting of clinical and technical data in the identified studies. To facilitate a more widespread and uniform adoption of the technique, recommendations on essential and desirable items to be included in future studies incorporating whole gland prostate BT with focal boost to IPLs are provided.