Trans-complementation by the RecB nuclease domain of RecBCD enzyme reveals new insight into RecA loading upon χ recognition.

The loading of RecA onto ssDNA by RecBCD is an essential step of RecBCD-mediated homologous recombination. RecBCD facilitates RecA-loading onto ssDNA in a χ-dependent manner via its RecB nuclease domain (RecBn). Before recognition of χ, RecBn is sequestered through interactions with RecBCD. It was proposed that upon χ-recognition, RecBn undocks, allowing RecBn to swing out via a contiguous 70 amino acid linker to reveal the RecA-loading surface, and then recruit and load RecA onto ssDNA. We tested this hypothesis by examining the interactions between RecBn (RecB928-1180) and truncated RecBCD (RecB1-927CD) lacking the nuclease domain. The reconstituted complex of RecB1-927CD and RecBn is functional in vitro and in vivo. Our results indicate that despite being covalently severed from RecB1-927CD, RecBn can still load RecA onto ssDNA, establishing that RecBn does not function while only remaining tethered to the RecBCD complex via the linker. Instead, RecBCD undergoes a χ-induced intramolecular rearrangement to reveal the RecA-loading surface.

Detecting outliers beyond tolerance limits derived from statistical process control in patient-specific quality assurance.

BACKGROUND: Tolerance limit is defined on pre-treatment patient specific quality assurance results to identify "out of the norm" dose discrepancy in plan. An out-of-tolerance plan during measurement can often cause treatment delays especially if replanning is required. In this study, we aim to develop an outlier detection model to identify out-of-tolerance plan early during treatment planning phase to mitigate the above-mentioned risks. METHODS: Patient-specific quality assurance results with portal dosimetry for stereotactic body radiotherapy measured between January 2020 and December 2021 were used in this study. Data were divided into thorax and pelvis sites and gamma passing rates were recorded using 2%/2 mm, 2%/1 mm, and 1%/1 mm gamma criteria. Statistical process control method was used to determine six different site and criterion-specific tolerance and action limits. Using only the inliers identified with our determined tolerance limits, we trained three different outlier detection models using the plan complexity metrics extracted from each treatment field-robust covariance, isolation forest, and one class support vector machine. The hyperparameters were optimized using the F1-score calculated from both the inliers and validation outliers' data. RESULTS: 308 pelvis and 200 thorax fields were used in this study. The tolerance (action) limits for 2%/2 mm, 2%/1 mm, and 1%/1 mm gamma criteria in the pelvis site are 99.1% (98.1%), 95.8% (91.1%), and 91.7% (86.1%), respectively. The tolerance (action) limits in the thorax site are 99.0% (98.7%), 97.0% (96.2%), and 91.5% (87.2%). One class support vector machine performs the best among all the algorithms. The best performing model in the thorax (pelvis) site achieves a precision of 0.56 (0.54), recall of 1.0 (1.0), and F1-score of 0.72 (0.70) when using the 2%/2 mm (2%/1 mm) criterion. CONCLUSION: The model will help the planner to identify an out-of-tolerance plan early so that they can refine the plan further during the planning stage without risking late discovery during measurement.

Repurposing DailyQA3 for an efficient and spot position sensitive daily quality assurance tool for proton therapy.

INTRODUCTION: Daily quality assurance is an integral part of a radiotherapy workflow to ensure the dose is delivered safely and accurately to the patient. It is performed before the first treatment of the day and needs to be time and cost efficient for a multiple gantries proton center. In this study, we introduced an efficient method to perform QA for output constancy, range verification, spot positioning accuracy and imaging and proton beam isocenter coincidence with DailyQA3. METHODS: A stepped acrylic block of specific dimensions is fabricated and placed on top of the DailyQA3 device. Treatment plans comprising of two different spread-out Bragg peaks and five individual spots of 1.0 MU each are designed to be delivered to the device. A mathematical framework to measure the 2D distance between the detectors and individual spot is introduced and play an important role in realizing the spot positioning and centering QA. Lastly, a 5 months trends of the QA for two gantries are presented. RESULTS: The outputs are monitored by two ion chambers in the DailyQA3 and a tolerance of ± 3 % $ \pm 3\% $ are used. The range of the SOBPs are monitored by the ratio of ion chamber signals and a tolerance of ± 1 mm $ \pm 1\ {\mathrm{mm}}$ is used. Four diodes at ± 10 cm $ \pm 10\ {\mathrm{cm}}$ from the central ion chambers are used for spot positioning QA, while the central ion chamber is used for imaging and proton beam isocenter coincidence QA. Using the framework, we determined the absolute signal threshold corresponding to the offset tolerance between the individual proton spot and the detector. A 1.5 mm $1.5\ {\mathrm{mm}}$ tolerances are used for both the positioning and centering QA. No violation of the tolerances is observed in the 5 months trends for both gantries. CONCLUSION: With the proposed approach, we can perform four QA items in the TG224 within 10 min.

Benefit and harm of anticoagulation in the prevention of thromboembolic stroke for non-valvular atrial fibrillation in haemodialysis patients: a Top End of Northern Australia study.

BACKGROUND: Warfarin for the prevention of non-valvular atrial fibrillation (AF)-related thromboembolic stroke in patients on maintenance haemodialysis is controversial. Despite the exclusion of haemodialysis patients in randomised control trials, the American Heart Association/American College of Cardiology has recommended warfarin in high-risk AF patients. AIMS: To retrospectively examine the utility of warfarin anticoagulation therapy in our prevalent haemodialysis patients over 10 years of follow up. METHODS: Eligible patients were retrospectively identified and stratified to two cohorts based on whether warfarin was prescribed. The outcomes of interest were ischaemic stroke, haemorrhagic stroke and death from any cause. Rate ratio and Cox proportional hazard regression model were used to compare the differences in outcome between the two cohorts. The Kaplan-Meier method was used to analyse survival. RESULTS: Three ischaemic strokes and four haemorrhagic strokes occurred in the unexposed group of 166 patients over 484.44 patient-years of follow up. One ischaemic stroke and no cases of haemorrhagic stroke occurred in the exposed warfarin group of 16 patients over 39.32 patient-years of follow up. Eighty-seven percent of patients in both groups were indigenous. More than 90% of each cohort had a CHA2DS2-VaSc score ≥2. One hundred and one deaths, 90 in the unexposed group and 11 in the warfarin group, occurred in the follow-up period. A non-statistically significant trend towards increasing mortality was observed in the warfarin group (hazard ratio = 1.63; P = 0.13). CONCLUSION: This retrospective study of prevalent haemodialysis patients with co-existing history of non-valvular AF failed to demonstrate sufficient evidence for the routine use of warfarin for prophylaxis of thromboembolic stroke.

Social responsibility perspective in public response to the COVID-19 pandemic: a grounded theory approach.

BACKGROUND: Combating viral outbreaks extends beyond biomedical and clinical approaches; thus, public health prevention measures are equally important. Public engagement in preventive efforts can be viewed as the social responsibility of individuals in controlling an infectious disease and are subjected to change due to human behaviour. Understanding individuals' perception of social responsibility is crucial and is not yet explored extensively in the academic literature. We adopted the grounded theory method to develop an explanatory substantive theory to illustrate the process of how individual responded to the outbreak from a social responsibility perspective. METHODS: In-depth interviews were conducted among 23 Malaysians either through telephone or face-to-face depending on the participant's preference. Both purposive and theoretical sampling were used. Participants were invited to share their understanding, perceptions and activities during the COVID-19 pandemic. They were further probed about their perceptions on complying with the public health interventions imposed by the authorities. The interviews were audio-recorded and transcribed verbatim. Data was analysed via open coding, focus coding and theoretical coding, facilitated by memoing, sketching and modelling. RESULTS: Study findings showed that, social responsibility is perceived within its role, the perceived societal role responsibility. In a particular context, an individual assumed only one of the many expected social roles with their perceived circle of responsibility. Individuals negotiated their actions from this perspective, after considering the perceived risk during the outbreak. The four types of behaviour depicted in the matrix diagram facilitate the understanding of the abstract concept of negotiation in the human decision-making process, and provide the spectrum of different behaviour in relation to public response to the COVID-19 pandemic. CONCLUSIONS: Our study adopted the grounded theory approach to develop a theoretical model that illustrates how individual response to COVID-19 preventive measures is determined by the negotiation between perceived societal role responsibility and perceived infection risk. This substantive theoretical model is abstract, thus has relevance for adoption within similar context of an outbreak.

A head-to-head comparison of the inhibitory activities of 15 peptidomimetic SARS-CoV-2 3CLpro inhibitors.

The COVID-19 pandemic caused by SARS-CoV-2 has created an unprecedented global health emergency. As of July 2021, only three antiviral therapies have been approved by the FDA for treating infected patients, highlighting the urgent need for more antiviral drugs. The SARS-CoV-2 3CL protease (3CLpro) is deemed an attractive drug target due to its essential role in viral polyprotein processing and pathogenesis. Indeed, a number of peptidomimetic 3CLpro inhibitors armed with electrophilic warheads have been reported by various research groups that can potentially be developed for treating COVID-19. However, it is currently impossible to compare their relative potencies due to the different assays employed. To solve this, we conducted a head-to-head comparison of fifteen reported peptidomimetic inhibitors in a standard FRET-based SARS-CoV-2 3CLpro inhibition assay to compare and identify potent inhibitors for development. Inhibitor design and the suitability of various warheads are also discussed.

Socio-economic disparity, access to care and patient-relevant outcomes after kidney allograft failure.

Social disparity is a major impediment to optimal health outcomes after kidney transplantation. In this study, we aimed to define the association between socio-economic status (SES) disparities and patient-relevant outcomes after kidney allograft failure. Using data from the Australia and New Zealand Dialysis and Transplant registry, we included patients with failed first-kidney allografts in Australia between 2005 and 2017. The association between residential postcode-derived SES in quintiles (quintile 1-most disadvantaged areas, quintile 5-most advantaged areas) with uptake of home dialysis (peritoneal or home haemodialysis) within the first 12-months post-allograft failure, repeat transplantation and death on dialysis were examined using competing-risk analysis. Of 2175 patients who had experienced first allograft failure, 417(19%) and 505(23%) patients were of SES quintiles 1 and 5, respectively. Compared to patients of quintile 5, quintile 1 patients were less likely to receive repeat transplants (adjusted subdistributional hazard ratio [SHR] 0.70,95%CI 0.55-0.89) and were more likely to die on dialysis (1.37 [1.04-1.81]), but there was no association with the uptake of home dialysis (1.02 [0.77-1.35]). Low SES may have a negative effect on outcomes post-allograft failure and further research is required into how best to mitigate this. However, small-scale variation within SES cannot be accounted for in this study.

Endovascular treatment of carotid-cavernous sinus fistulas: ophthalmic and visual outcomes.

Purpose: The main objective was to report the epidemiology, clinical manifestations, angiography features, treatment modality and post-treatment outcomes in patients diagnosed with carotid cavernous fistulas (CCF). Methods: A retrospective review of the medical imaging database in conjunction with medical records from 2004 to 2017 at the Royal Brisbane and Women's Hospital (RBWH) was conducted.We identified 39 patients with CCF (16 direct, 23 indirect). A total of 37 diagnoses were confirmed by direct catheter angiography. The remaining two cases were diagnosed using magnetic resonance imaging/magnetic resonance angiography. Results: Coils were deployed in 100% of direct and 83% of treated indirect fistulas that were treated. Other embolic agents were deployed alone or in combination with coils. Successful angiographic closure was achieved in 93% of direct and 92% of indirect fistulas. Multiple treatments were required in 33% of direct and 16% of indirect fistulas. Visual acuity improved in patients with direct fistulae(p = 0.02) and was preserved in those with indirect fistulae. Post-treatment diplopia persisted in six patients with direct fistulas and three patients with indirect fistulas. Four patients with indirect fistulas experienced persistent ocular hypertension post-treatment compared to two patients with direct fistulas. Conclusions: Endovascular coils are the most commonly deployed treatment for CCF. Both indirect and direct fistulas achieved high rates of closure; however, indirect fistulas were less likely to require multiple treatments. Good post-procedural vision was achieved for both groups.

Utilising the Alexis Retractor for lateral orbital access, a case series.

Lateral orbital surgery is challenging and typically involves the use of multiple traction sutures and retractors. This case series describes a novel technique utilising the Alexis retractor to provide access for lateral orbital surgery. Thirteen cases were included and the surgical technique has been described and illustrated. There were no post-operative infections or complications and the Alexis retractor provided excellent exposure whilst reducing the need for further surgical retractors.

A case series of anophthalmic socket cysts excised utilising fibrin sealant.

Anophthalmic socket cysts are challenging to remove and incomplete excision has been shown to increase the risk of recurrence. This case series describes a novel technique utilising the fibrin sealant Tisseel (Baxter AG, Vienna, Austria) to retain the socket cyst integrity during surgical removal to facilitate its complete excision. Five patients were included and followed up for a minimum of 1 year, and there were no signs of recurrence in any of the cases. The surgical technique is described and illustrated. This technique is a safe way of simplifying challenging socket cyst surgery.

Escherichia coli Topoisomerase IV E Subunit and an Inhibitor Binding Mode Revealed by NMR Spectroscopy.

Bacterial topoisomerases are attractive antibacterial drug targets because of their importance in bacterial growth and low homology with other human topoisomerases. Structure-based drug design has been a proven approach of efficiently developing new antibiotics against these targets. Past studies have focused on developing lead compounds against the ATP binding pockets of both DNA gyrase and topoisomerase IV. A detailed understanding of the interactions between ligand and target in a solution state will provide valuable information for further developing drugs against topoisomerase IV targets. Here we describe a detailed characterization of a known potent inhibitor containing a 9H-pyrimido[4,5-b]indole scaffold against the N-terminal domain of the topoisomerase IV E subunit from Escherichia coli (eParE). Using a series of biophysical and biochemical experiments, it has been demonstrated that this inhibitor forms a tight complex with eParE. NMR studies revealed the exact protein residues responsible for inhibitor binding. Through comparative studies of two inhibitors of markedly varied potencies, it is hypothesized that gaining molecular interactions with residues in the α4 and residues close to the loop of ß1-α2 and residues in the loop of ß3-ß4 might improve the inhibitor potency.

Bisphosphonate use and the risk of breast cancer: a meta-analysis of observational studies.

PURPOSE: To summarize current evidence of the association of bisphosphonate use with breast cancer risk, we used a systematic review and meta-analysis of observational studies to explore this issue. METHODS: A comprehensive search was conducted on PubMed, EMBASE, and the Cochrane Library. Pooled relative risk (RR) estimates and 95% confidence intervals (CIs) were calculated using the random effects model. RESULTS: Bisphosphonate use was associated with a 16% lower breast cancer risk (pool RR0.84, 95%CI 0.77-0.90, n = 8). A protective effect of bisphosphonate was found in cohort studies (RR 0.85, 95%CI 0.80-0.90, n = 4) and case-control studies (RR 0.78, 95%CI 0.64-0.96, n = 4).We also found that the use of bisphosphonate resulted in a statistically significant reduction in all breast cancer risk (RR 0.87, 95%CI 0.81-0.93) and greater reduction in invasive breast cancer risk (RR 0.78, 95%CI 0.68-0.91) and contralateral breast cancer risk (RR, 0.41; 95% CI, 0.20-0.84).With respect to the type of bisphosphonate, we found that alendronate and etidronate resulted significant reduction in breast cancer risk. The short-term use of bisphosphonate (<1 y) led to nonsignificant change (RR 0.93, 95%CI 0.86-1.00), but a significant 26% reduction of breast cancer risk was noted with long-term use (>1 y) (RR 0.74, 95%CI 0.66-0.83). CONCLUSIONS: Our results supported bisphosphonate as being effective in preventing breast cancer, including invasive and contralateral breast cancer. Furthermore, the long-term use (>1 y) of bisphosphonate was more significant in lowering breast cancer risk.

Vitreoretinal interface abnormalities in patients treatedwith ranibizumab for diabetic macular oedema.

PURPOSE: Intravitreal anti-vascular endothelial growth factor (VEGF) agents are effective in the treatment of central involving diabetic macular oedema (DMO). Vitreoretinal interface abnormalities (VRIA) are common in patients with DMO, and the effect of these on the response to anti-VEGF treatment is unclear. Furthermore the effect of anti-VEGF agents on the VRIA itself is uncertain. METHOD: Prospective study of consecutive patients treated with ranibizumab (RZB) for DMO as part of routine clinical care in one eye unit over a 1-year period. Visual acuity (Va), central retinal thickness (CRT) and injection frequency data was recorded on an electronic database. Treatment was initiated with four monthly RZB injections and then a monthly PRN regime. All patients underwent high-density spectral-domain optical coherence tomography (SDOCT) at baseline and 12 months. The SDOCTs were graded by two observers masked to the outcome. RESULTS: One hundred and four eyes (77 patients) were included in the analysis. The mean age was 62 years, and 62% were male. The mean presenting vision was 62 letters and CRT 472 µm. Eighty eyes retained stable Va, and 17 had an improvement in Va. At baseline, 39 eyes had associated focal vitreomacular adhesion (VMA) and by 12 months this reduced to 30 (p = 0.04), with 12 releasing VMA and three developing it. Patients with VMA had significantly better final Va than those without VMA. Improvement in CRT was greatest in those where VMA released during the study. Forty-five eyes had some degree of foveal involving epiretinal membrane (ERM) at baseline, and 28 were considered to have clinically significant ERM. There was no clinically relevant change in ERM during the study. Patients with significant ERM at baseline had a lower final vision. Multivariate analysis showed that ERM and more severe retinopathy at baseline were predictive of less visual improvement (p < 0.01). Shorter intraretinal cyst length, ERM and the absence of VMA at baseline were predictive of a worsened anatomical response (p < 0.001). CONCLUSION: VRIA are related to outcome in patients treated with RZB. ERM was associated with a worsened visual and anatomic response, and VMA with an improved anatomical response particularly when spontaneous VMA release occurred during treatment. The presence and severity of ERM was not affected by RZB treatment.

Bisphosphonate use and the risk of endometrial cancer: a meta-analysis of observational studies.

BACKGROUND: The association of bisphosphonate use and the risk of endometrial cancer is still unclear. No meta-analysis was conducted to review the evidence concerning this topic. METHODS: Relevant studies were identified through PubMed and EMBASE and the Cochrane Library databases. The adjusted relative risk (RR) or odds ratios were determined using a fixed effects or random effects model, depending on the overall heterogeneity. RESULTS: Seven studies, including four cohort studies and three case-control studies, met the method criteria and were included. The random effects model showed a significant reduction in the risk association between bisphosphonate use and endometrial cancer incidence (RR 0.75, 95%CI 0.60-0.94, p = 0.064, I2 = 49.6%). A significantly protective effect was observed with the use of bisphosphonate for more than 1 year, and we found a statistically significant risk reduction with the use of bisphosphonate for more than 1 to 3 years (RR 0.58, 95%CI 0.47-0.72) and for more than 3 years (RR 0.44, 95%CI 0.28-0.70). However, with the use of bisphosphonate for less than 1 year (RR 0.92, 95%CI 0.64-1.34), we found no protective effect against endometrial cancer. CONCLUSIONS: We found that the use of bisphosphonate was significantly associated with a 25% risk reduction in the incidence of endometrial cancer in the overall analysis. Furthermore, the use of bisphosphonate for more than 1 year but not less than 1 year may have a more beneficial effect on endometrial cancer risk. Copyright © 2016 John Wiley & Sons, Ltd.

Biophysical Studies of Bacterial Topoisomerases Substantiate Their Binding Modes to an Inhibitor.

Bacterial DNA topoisomerases are essential for bacterial growth and are attractive, important targets for developing antibacterial drugs. Consequently, different potent inhibitors that target bacterial topoisomerases have been developed. However, the development of potent broad-spectrum inhibitors against both Gram-positive (G(+)) and Gram-negative (G(-)) bacteria has proven challenging. In this study, we carried out biophysical studies to better understand the molecular interactions between a potent bis-pyridylurea inhibitor and the active domains of the E-subunits of topoisomerase IV (ParE) from a G(+) strain (Streptococcus pneumoniae (sParE)) and a G(-) strain (Pseudomonas aeruginosa (pParE)). NMR results demonstrated that the inhibitor forms a tight complex with ParEs and the resulting complexes adopt structural conformations similar to those observed for free ParEs in solution. Further chemical-shift perturbation experiments and NOE analyses indicated that there are four regions in ParE that are important for inhibitor binding, namely, α2, the loop between ß2 and α3, and the ß2 and ß6 strands. Surface plasmon resonance showed that this inhibitor binds to sParE with a higher KD than pParE. Point mutations in α2 of ParE, such as A52S (sParE), affected its binding affinity with the inhibitor. Taken together, these results provide a better understanding of the development of broad-spectrum antibacterial agents.

Characterization of the interaction between Escherichia coli topoisomerase IV E subunit and an ATP competitive inhibitor.

Bacterial topoisomerase IV (ParE) is essential for DNA replication and serves as an attractive target for antibacterial drug development. The X-ray structure of the N-terminal 24 kDa ParE, responsible for ATP binding has been solved. Due to the accessibility of structural information of ParE, many potent ParE inhibitors have been discovered. In this study, a pyridylurea lead molecule against ParE of Escherichia coli (eParE) was characterized with a series of biochemical and biophysical techniques. More importantly, solution NMR analysis of compound binding to eParE provides better understanding of the molecular interactions between the inhibitor and eParE.

Effects of modern aesthetic dental fillings on proton therapy.

Background and purpose: High-density dental fillings pose a non-negligible impact on head and neck cancer treatment. For proton therapy, stopping power ratio (SPR) prediction will be significantly impaired by the associated image artifacts. Dose perturbation is also inevitable, compromising the treatment plan quality. While plenty of work has been done on metal or amalgam fillings, none has touched on composite resin (CR) and glass ionomer cement (GIC) which have seen an increasing usage. Hence, this work aims to provide a detailed characterisation of SPR and dose perturbation in proton therapy caused by CR and GIC. Materials and methods: Four types of fillings were used: CR, Fuji Bulk (FB), Fuji II (FII) and Fuji IX (FIX). The latter three belong to GIC category. Measured SPR were compared with SPR predicted using single-energy computed tomography (SECT) and dual-energy computed tomography (DECT). Dose perturbation of proton beams with lower- and higher-energy levels was also quantified using Gafchromic films. Results: The measured SPR for CR, FB, FII and FIX were 1.68, 1.77, 1.77 and 1.76, respectively. Overall, DECT could predict SPR better than SECT. The lowest percentage error achieved by DECT was 19.7 %, demonstrating the challenge in estimating SPR, even for fillings with relatively lower densities. For both proton beam energies and all four fillings of about 4.5 mm thickness, the maximum dose perturbation was 3 %. Conclusion: This study showed that dose perturbation by CR and GIC was comparatively small. We have measured and recommended the SPR values for overriding the fillings in TPS.

Deformable anthropomorphic pelvis phantom for dose accumulation verification.

Objective.The validation of deformable image registration (DIR) for contour propagation is often done using contour-based metrics. Meanwhile, dose accumulation requires evaluation of voxel mapping accuracy, which might not be accurately represented by contour-based metrics. By fabricating a deformable anthropomorphic pelvis phantom, we aim to (1) quantify the voxel mapping accuracy for various deformation scenarios, in high- and low-contrast regions, and (2) identify any correlation between dice similarity coefficient (DSC), a commonly used contour-based metric, and the voxel mapping accuracy for each organ.Approach. Four organs, i.e. pelvic bone, prostate, bladder and rectum (PBR), were 3D printed using PLA and a Polyjet digital material, and assembled. The latter three were implanted with glass bead and CT markers within or on their surfaces. Four deformation scenarios were simulated by varying the bladder and rectum volumes. For each scenario, nine DIRs with different parameters were performed on RayStation v10B. The voxel mapping accuracy was quantified by finding the discrepancy between true and mapped marker positions, termed the target registration error (TRE). Pearson correlation test was done between the DSC and mean TRE for each organ.Main results. For the first time, we fabricated a deformable phantom purely from 3D printing, which successfully reproduced realistic anatomical deformations. Overall, the voxel mapping accuracy dropped with increasing deformation magnitude, but improved when more organs were used to guide the DIR or limit the registration region. DSC was found to be a good indicator of voxel mapping accuracy for prostate and rectum, but a comparatively poorer one for bladder. DSC > 0.85/0.90 was established as the threshold of mean TRE ⩽ 0.3 cm for rectum/prostate. For bladder, extra metrics in addition to DSC should be considered.Significance. This work presented a 3D printed phantom, which enabled quantification of voxel mapping accuracy and evaluation of correlation between DSC and voxel mapping accuracy.

Predicting dice similarity coefficient of deformably registered contours using Siamese neural network.

Objective. Automatic deformable image registration (DIR) is a critical step in adaptive radiotherapy. Manually delineated organs-at-risk (OARs) contours on planning CT (pCT) scans are deformably registered onto daily cone-beam CT (CBCT) scans for delivered dose accumulation. However, evaluation of registered contours requires human assessment, which is time-consuming and subjects to high inter-observer variability. This work proposes a deep learning model that allows accurate prediction of Dice similarity coefficients (DSC) of registered contours in prostate radiotherapy.Approach. Our dataset comprises 20 prostate cancer patients with 37-39 daily CBCT scans each. The pCT scans and planning contours were deformably registered to each corresponding CBCT scan to generate virtual CT (vCT) scans and registered contours. The DSC score, which is a common contour-based validation metric for registration quality, between the registered and manual contours were computed. A Siamese neural network was trained on the vCT-CBCT image pairs to predict DSC. To assess the performance of the model, the root mean squared error (RMSE) between the actual and predicted DSC were computed.Main results. The model showed promising results for predicting DSC, giving RMSE of 0.070, 0.079 and 0.118 for rectum, prostate, and bladder respectively on the holdout test set. Clinically, a low RMSE implies that the predicted DSC can be reliably used to determine if further DIR assessment from physicians is required. Considering the event where a registered contour is classified as poor if its DSC is below 0.6 and good otherwise, the model achieves an accuracy of 92% for the rectum. A sensitivity of 0.97 suggests that the model can correctly identify 97% of poorly registered contours, allowing manual assessment of DIR to be triggered.Significance. We propose a neural network capable of accurately predicting DSC of deformably registered OAR contours, which can be used to evaluate eligibility for plan adaptation.