This work calculates the microdosimetric spectra and evaluates the relative biological effectiveness (RBE10) of oxygen and carbon ions using Monte Carlo simulation. This study presents a fast, reliable radiation field characterisation and accurate biological dose prediction tool in charged particle therapy for heavy-ion beams using the Bridge silicon-on-insulator (SOI) microdosimeter via Tool for Particle Simulation (TOPAS)-based simulations toolkit.

The study used the TOPAS simulation to model the Bridge SOI microdosimeter and study its response to carbon beams with an energy of 290 MeV/u and oxygen beams with an energy of 345 MeV/u. Dose-mean lineal energy values $(\overline {{y_D})\;} $and RBE10 values were evaluated using microdosimetric lineal energy spectra with the MKM model.

The results demonstrate that oxygen ion beams have an advantage for cancer treatment as they provide higher RBE10 values and occur at the same positions as the maximum physical dose (Bragg peak), compared to carbon ion beams. The study provides new understanding of RBE for carbon and oxygen ions, as well as the relationship between physical doses and RBE.

This study aimed to investigate the influence of calibration field size on the gamma passing rate (GPR) in patient-specific quality assurance (PSQA).

Two independent detectors, PTW OCTAVIUS 4D (4DOCT) and Arc Check, were utilised in volumetric modulated arc therapy plans for 26 patients (14 with Arc Check and 12 with 4DOCT). Plans were administered using Varian Unique machine (with 4DOCT) and Varian TrueBeam (with Arc Check), each employing different calibration factors (CFs): 4 × 4, 6 × 6, 8 × 8, 10 × 10, 12 × 12 and 15 × 15 cm2 field sizes. Gamma analysis was conducted with 2%2mm, 2%3mm and 3%3mm gamma criteria.

GPR exhibited variations across different CFs. GPR demonstrated an increasing trend below 10 × 10 cm² CFs, while it displayed a decreasing trend above 10 × 10 cm². Both detectors exhibited similar GPR patterns. The correlation between 4DOCT and Arc Check was strong in tighter criteria (2%2mm) with an R² value of 0·9957, moderate criteria (2%3mm) with an R² value of 0·9868, but reduced in liberal criteria (3%3mm) with an R² value of 0·4226.

This study demonstrates that calibration field sizes significantly influence GPR in PSQA. This study recommends the plan specific calibration field must obtain to calibrate the QA devices for modulated plans.

This study aimed to assess the perception of radiographers on the difficulties encountered during the delineation of organs at risk (OARs) for radiotherapy planning and the methods that could be used to facilitate this process.

A self-designed questionnaire was distributed to all radiographers (n = 29) employed at the radiotherapy department in Malta. The survey assessed the challenges faced by the radiographers during the delineation of various OARs and inquired about the perceived effectiveness of specific measures that could be used to facilitate the delineation process using a Likert scale ranging from 1 (not difficult/effective) to 5 (very difficult/effective).

The response rate was 79%. Overall, the delineation of OARs was rated as slightly difficult (mean score 1.95 ± 0.33). Nevertheless, some OARs, such as the parotid, stomach and brain stem, were deemed more difficult to contour with a mean score of 3 or higher. The implementation of peer review was perceived as the most influential factor in reducing delineation difficulty (mean score 4.59 ± 0.58), followed by contouring training (mean score 4.48 ± 0.58) and training on artificial intelligence (AI) (mean score 4.35 ± 0.48).

The introduction of peer review, training and AI could facilitate the delineation of OARs.

While paediatric arteriovenous malformations (AVMs) often require aggressive therapeutic intervention due to their high bleeding incidence, choosing a course of treatment for deep and eloquent areas and asymptomatic cases is difficult. Sequelae are a concern in children, as they survive for longer after treatment. The authors have long recommended and implemented staged Gamma Knife radiosurgery (GKRS) in their treatment guidelines to maximise therapeutic effects.

Fifty-eight paediatric patients with AVM and ≤15 years old who underwent GKRS under general anesthesia from 2002 to 2020 were followed up for an average of 81·5 months. Obliteration dynamics and clinical outcomes were analysed.

The mean patient age was 10·5 years. The mean nidus volume was 6·6 cm3, the complete occlusion rate was 69%, the annual post-irradiation bleeding rate was 2·19% and nine (16%) cases had transient radiation-induced changes. One (1·7%) patient had sequela, and three (5·1%) developed encapsulated hematomas and cysts. Additionally, the 3- and 5-year cumulative occlusion rates were 39·0% and 53·3%, respectively. Multivariate analysis showed significantly higher occlusion rates in patients ≤12 years old and with a nidus volume of ≤4 cm3.

GKRS is a useful treatment for paediatric AVM; however, its use poses some challenges.

The main goal of radiation therapy is to eradicate all cancer cells and minimize the damage to healthy tissues around the tumour. Treatment planning systems are used to predict the outcome of the treatment in terms of dose distribution prior to the treatment. One of the most reliable dose calculation algorithms is Monte Carlo. The aim of this study is to evaluate the performance of automated external contouring tool on dose calculation using Monte Carlo algorithm.

The external contour of thorax phantom was created by automated tools of Monaco treatment planning system, and then, the IAEA-TECDOC-1583 quality assurance tests were created. Then, the treatment plans were delivered to the phantom, and the dose was measured by the Farmer ionization chamber at specific points. The external contour was corrected according to the source surface distances (SSD) which are mentioned in TECDOC-1583, and the dose was re-calculated. Finally, a comparison was made between the results.

Dosimetric tests of TECDOC-1583 showed the errors ranged from −2·8% to +2·5%. In case of editing external contour and omitting fluctuations, the errors were decreased. The comparisons indicated that the most significant variation occurred in test 4 and the least changes were related to the tests 1 and 3.

The results of the study showed that the fluctuations of the external contour affect the calculated volume of the phantom and thus the dose. In order to obtain correct results, automated external contouring tools should be used with the correct instructions and re-checked before treatment planning.

The miniaturized conical cones for stereotactic radiosurgery (SRS) make it challenging in measurement of dosimetric data needed for commissioning of treatment planning system. This study aims at validating dosimetric characteristics of conical cone collimator manufactured by Varian using Monte Carlo (MC) simulation technique.

Percentage depth dose (PDD), tissue maximum ratio (TMR), lateral dose profile (LDP) and output factor (OF) were measured for cones with diameters of 5mm, 7·5mm, 10mm, 12·5 mm, 15 mm and 17·5 mm using EDGE detector for 6MV flattening filter-free (FFF) beam from Truebeam linac. Similarly, MC modelling of linac for 6MVFFF beam and simulation of conical cones were performed in PRIMO. Subsequently, measured beam data were validated by comparing them with results obtained from MC simulation.

The measured and MC-simulated PDDs or TMRs showed close agreement within 3% except for cone of 5mm diameter. Deviations between measured and simulated PDDs or TMRs were substantially higher for 5mm cone. The maximum deviations at depth of 10cm, 20cm and at range of 50% dose were found 4·05%, 7·52%, 5·52% for PDD and 4·04%, 7·03%, 5·23% for TMR with 5mm cone, respectively. The measured LDPs acquired for all the cones showed close agreement with MC LDPs except in penumbra region around 80% and 20% dose profile. Measured and MC full-width half maxima of dose profiles agreed with nominal cone size within ± 0·2 mm. Measured and MC OFs showed excellent agreement for cone sizes ≥10 mm. However, deviation consistently increases as the size of the cone gets smaller.

MC model of conical cones for SRS has been presented and validated. Very good agreement was found between experimentally measured and MC-simulated data. The dosimetry dataset obtained in this study validated using MC model may be used to benchmark beam data measured for commissioning of SRS for cone planning.

A 53-year-old female presented with a large (945 cc) unresectable leiomyosarcoma of the uterus, with metastasis in the lungs, significant abdominal/pelvic pain and evidence of hydronephrosis secondary to obstruction caused by the mass. In an effort to palliate symptoms, radiation was recommended.

Given the size of the lesion, the patient was treated with crossfire GRID, a type of spatially fractionated radiotherapy (18 Gy × 1), followed four weeks later by a short course of external beam radiation (4 Gy × 5).

The patient experienced significant symptom relief. Her abdominal/pelvic pain resolved, and a stent was placed to relieve her hydronephrosis. The tumour volume had decreased significantly (5·5 months post-treatment 276 cc, 8·5 months post-treatment 17 cc). Unfortunately, at 9 months post-treatment, the patient died from progression of her metastatic disease in the lungs.

The use of GRID radiotherapy resulted in effective and sustained palliation of a large uterine leiomyosarcoma in this patient’s case.

Intracavitary brachytherapy (ICBT) is essential in managing locally advanced cervical cancer. Brachytherapy as a modality has the advantage of a higher dose to the tumour with a dose fall off at the periphery as per the inverse square law. The dose per fraction is much higher than external beam radiotherapy. So proper application and dosimetry are of paramount importance to reduce late toxicity.

A retrospective analysis of 69 patients who underwent three ICBT applications of 7 Gray in each fraction was done. The factors under consideration were the type of pain management (spinal anaesthesia (SA) versus conscious sedation (CS)), the initial size of the disease (bulky and non-bulky) and subsequent fractions (first fraction versus third fraction). The dosimetric parameters analysed were the doses received by points A, B and P and that of the critical organs (bladder, rectum and sigmoid colon).

The dose received by critical organs was comparable concerning all the factors under consideration. The dose to point P on the left side was significantly lower in the CS group than in the SA group (p-value = 0·031). Also, the dose to point P on the right side was significantly lower in the third fraction compared with the first fraction (p-value = 0·016).

ICBT under spinal anaesthesia resulted in a higher dose to the pelvic wall. The initial size of the tumour or the subsequent fractions does not significantly affect the dose received by critical organs.

The aim of this study was to develop a method for accurately measuring the intra-fraction motion in cine electronic portal imaging device (EPID) images of tangential breast irradiation.

The cine EPID images were acquired for 18 breast cancer patients during medial tangential breast radiotherapy. The skin surface and the chest wall were segmented separately in each EPID image using an automated MATLAB algorithm to obtain the magnitude of intra-fraction motion.

The patients had an average age of 55 years (range 43–69 years), with the highest observed displacement at 3·50 mm. The mean intra-fraction motion due to respiration for the skin surface and chest wall was 1·04 ± 0·24 mm and 1·10 ± 0·27 mm, respectively. The amount of intra-fraction motion showed no significant association with either the patient’s age or the side of the breast receiving the treatment.

In this study, by utilising cine EPID technology and the automated MATLAB algorithm, the intra-fraction motion during breast radiotherapy treatment was accurately measured and analysed. Results indicate minimal skin surface and chest wall motion (approximately 1 mm), confirming negligible intra-fraction motions during conformal radiotherapy in breast cancer patients.

Radiation dermatitis (RD) is a frequent toxicity during radiotherapy (RT) for head and neck cancer (HNC). We report the first use of KeraStat® Cream (KC), a topical, keratin-based wound dressing, in patients with HNC receiving RT.

This pilot study randomized HNC patients treated with definitive or postoperative RT (≥60 Gy) to KC or standard of care (SOC), applied at least twice daily during and for 1-month after RT. Outcomes of interest included adherence to the assigned regimen (at least 10 applications per week of treatment), clinician- and patient-reported RD, and skin-related quality of life.

24 patients were randomized and completed the study. Most patients had stage III-IV disease and oropharynx cancer. Median RT dose was 68 Gy; the bilateral neck was treated in 19 patients, and 18 patients received concurrent chemotherapy. Complete adherence was observed in 7/12 (SOC) vs. 10/12 (KC, p = 0.65).  Adherence by patient-week was 61/68 versus 64/67, respectively (p = 0.20). No differences in RD were observed between groups.

A randomized trial of KC versus SOC in HNC patients treated with RT is feasible with good adherence to study agent. An adequately powered randomized study is warranted to test the efficacy of KC in reducing RD.

Stereotactic radiotherapy (SRT) for patients with intracranial tumours are delivered using a dedicated platform or a conventional linear accelerator with a flattening filter-free beam.

This study compares treatment plans with intracranial tumours. A total of 29 patients were treated on CyberKnife and planned using the Accuray Precision. The same structure sets ws then exported to Varian Eclipse, and plans were made using a 6 MV FFF beam. Both plans were compared for parameters of target coverage, homogeneity index (HI), new conformity index (nCI), gradient index, selectivity index (SI), volumetric and OAR doses.

The treatment plans made for CyberKnife exhibit better results in terms of nCI (1·168 ± 0·08 versus 1·173 ± 0·077), SI (0·885 ± 0·05 versus 0·877 ± 0·05) and GI (3·64 ± 0·5 versus 4·45 ± 1·25), while HI values are better for TrueBeam. For OAR doses, in 65·5% and 72% of treatment plans, brainstem and optic pathways received lower doses on CyberKnife, respectively. In terms of dose spillage, Truebeam plans are better for very low doses (V5%), while for V10%, V20% and V50% CyberKnife plans are better.

CyberKnife is a better modality for the delivery of SRS/SRT to intracranial tumours except for dose homogeneity where TrueBeam offered better results.