Target Coverage Research Articles

ANALYSIS OF POLICY IMPLEMENTATION REGARDING THE POSBINDU NCDs PROGRAM IN THE WORKING AREA OF KAPASA PUBLIC HEALTH CENTER, MAKASSAR CITY

Purpose: POSBINDU NCDs is a community forum to carry out early detection, monitoring, and follow-up on NCD risk factors independently and continuously. The research purpose is to analyze the implementation of the POSBINDU NCDs Program policy in the working area of Kapasa Public Health Center. This research uses a qualitative research method with a case study approach. The data were analyzed using content analysis (content analysis). Interviews were conducted with 8 informants including 3 key informants and 5 supporting informants. Research Results: Communication between implementers was carried out through socialization, several cadres were not active, and the budget was not maximized so the facilities were inadequate for places and equipment for medical check-ups. Several SOP activities have not been implemented and only a few implementers support the disposition or attitude of and are less committed to implementing the program. Conclusion: In implementing the Posbindu NCDs program policy, the implementer's socialization activities have not gone well so the target coverage has not been achieved in the program. Human resources are still lacking both in terms of quality and quantity and the budget is inadequate so there are no medical check-up tools and facilities are not yet available. The SOP is a procedure for implementing the program based on the implementing SOP from the Makassar City Health Service. Specific suggestions for the Kapasa Public Health Center to be more highly committed to the program by ensuring appropriate target coverage.

Comparative Dosimetric Analysis of conventional 3DCRT and VMAT for Head and Neck Cancer

Introduction: Advancements in radiation oncology improve the outlook for patients with head and neck cancer which allowed to escalate the dose of radiation to tumours while minimizing the dose to surrounding healthy tissues. This study aims comparison of radiotherapy treatment planning of 3 DCRT and VMAT for head and neck cancer.Methods: Prospective study conducted on fifty patients of head and neck cancer in which 25 patients were treated with 3 DCRT and 25 patients treated with VMAT. Both plans were evaluated to compare the efficiency of VMAT and 3 DCRT dosimetrically in terms of PTV volume, homogeneity index, conformity index and doses to organs at risk. Results: Dose D98% for PTV66 was 59.39 Gy and 51.82 for VMAT and 3DCRT respectively. Conformity index was 1.0816 and 1.4472 for VMAT and 3DCRT plans respectively and the difference was statistically significant. Homogeneity index was 0.1473 for VMAT and 0.2997 for 3DCRT which proves that VMAT was more homogeneous. OARs sparing was also better with VMAT compared to 3DCRT especially the OARs which were very close to target volume especially parotid glands, Brainstem and optic nerve. Conclusion: Compared to 3DCRT plans, VMAT plan produced significantly better target coverage, homogeneous as well as dose conformity. Doses to organs at risk such as spinal cord and parotid glands were also reduced. Besides, the delivery of VMAT treatment was more efficient.

Status of Routine Immunization Coverage in the World Health Organization African Region Three Years into the COVID-19 Pandemic.

Data from the WHO and UNICEF Estimates of National Immunization Coverage (WUENIC) 2022 revision were analyzed to assess the status of routine immunization in the WHO African Region disrupted by the COVID-19 pandemic. In 2022, coverage for the first and third doses of the diphtheria-tetanus-pertussis-containing vaccine (DTP1 and DTP3, respectively) and the first dose of the measles-containing vaccine (MCV1) in the region was estimated at 80%, 72% and 69%, respectively (all below the 2019 level). Only 13 of the 47 countries (28%) achieved the global target coverage of 90% or above with DTP3 in 2022. From 2019 to 2022, 28.7 million zero-dose children were recorded (19.0% of the target population). Ten countries in the region accounted for 80.3% of all zero-dose children, including the four most populated countries. Reported administrative coverage greater than WUENIC-reported coverage was found in 19 countries, highlighting routine immunization data quality issues. The WHO African Region has not yet recovered from COVID-19 disruptions to routine immunization. It is critical for governments to ensure that processes are in place to prioritize investments for restoring immunization services, catching up on the vaccination of zero-dose and under-vaccinated children and improving data quality.

Dosimetric Impact of Voluntary Deep Inspiration Breath Hold (DIBH) in Mediastinal Hodgkin Lymphomas: A Comparative Evaluation of Three Different Intensity Modulated Radiation Therapy (IMRT) Delivery Methods Using Voluntary DIBH and Free Breathing Techniques.

Hodgkin lymphomas are radiosensitive and curable tumors that often involve the mediastinum. However, the application of radiation therapy to the mediastinum is associated with late effects including cardiac and pulmonary toxicities and secondary cancers. The adoption of conformal IMRT and deep inspiration breath- hold (DIBH) can reduce the dose to healthy normal tissues (lungs, heart and breast). We compared the dosimetry of organs at risk (OARs) using different IMRT techniques for two breathing conditions, i.e., deep inspiration breath hold (DIBH) and free breathing. Twenty-three patients with early-stage mediastinal Hodgkin lymphomas were accrued in the prospective study. The patients were given treatment plans which utilized full arc volumetric modulated arc therapy (F-VMAT), Butterfly VMAT (B-VMAT), and fixed field IMRT (FF-IMRT) techniques for both DIBH and free breathing methods, respectively. All the plans were optimized to deliver 95% of the prescription dose which was 25.2 Gy to 95% of the PTV volume. The mean dose and standard error of the mean for each OAR, conformity index (CI), and homogeneity index (HI) for the target using the three planning techniques were calculated and compared using Student's t-test for parametric data and Wilcoxon signed-rank test for non-parametric data. The HI and CI of the target was not compromised using the DIBH technique for mediastinal lymphomas. The mean values of CI and HI for both DIBH and FB were comparable. The mean heart doses were reduced by 2.1 Gy, 2.54 Gy, and 2.38 Gy in DIBH compared to FB for the F-VMAT, B-VMAT, and IMRT techniques, respectively. There was a significant reduction in V5Gy, V10Gy, and V15Gy to the heart (p < 0.005) with DIBH. DIBH reduced the mean dose to the total lung by 1.19 Gy, 1.47 Gy, and 1.3 Gy, respectively. Among the 14 female patients, there was a reduction in the mean right breast dose with DIBH compared to FB (4.47 Gy vs. 3.63 Gy, p = 0.004). DIBH results in lower heart, lung, and breast doses than free breathing in mediastinal Hodgkin Lymphoma. Among the different IMRT techniques, FF-IMRT, B-VMAT, and F-VMAT showed similar PTV coverage, with similar conformity and homogeneity indices. However, the time taken for FF-IMRT was much longer than for the F-VMAT and B-VMAT techniques for both breathing methods. B-VMAT and F-VMAT emerged as the optimal planning techniques able to achieve the best target coverage and lower doses to the OARs, with less time required to deliver the prescribed dose.

ESND-FA: An Energy-Efficient Scheduled Based Node Deployment Approach Using Firefly Algorithm for Target Coverage in Wireless Sensor Networks

ESND-FA: An Energy-Efficient Scheduled Based Node Deployment Approach Using Firefly Algorithm for Target Coverage in Wireless Sensor Networks

Inverse planning of lung radiotherapy with photon and proton beams using a discrete ordinates Boltzmann solver

Objective. A discrete ordinates Boltzmann solver has recently been developed for use as a fast and accurate dose engine for calculation of photon and proton beams. The purpose of this study is to apply the algorithm to the inverse planning process for photons and protons and to evaluate the impact that this has on the quality of the final solution. Approach. The method was implemented into an iterative least-squares inverse planning optimiser, with the Boltzmann solver used every 20 iterations over the total of 100 iterations. Elemental dose distributions for the intensity modulation and the dose changes at the intermediate iterations were calculated by a convolution algorithm for photons and a simple analytical model for protons. The method was evaluated for 12 patients in the heterogeneous tissue environment encountered in radiotherapy of lung tumours. Photon arc and proton arc treatments were considered in this study. The results were compared with those for use of the Boltzmann solver solely at the end of inverse planning or not at all. Main results. Application of the Boltzmann solver at the end of inverse planning shows the dose heterogeneity in the planning target volume to be greater than calculated by convolution and empirical methods, with the median root-mean-square dose deviation increasing from 3.7 to 5.3 for photons and from 1.9 to 3.4 for proton arcs. Use of discrete ordinates throughout inverse planning enables homogeneity of target coverage to be maintained throughout, the median root-mean-square dose deviation being 3.6 for photons and 2.3 for protons. Dose to critical structures is similar with discrete ordinates and conventional methods. Time for inverse planning with discrete ordinates takes around 1–2 h using a contemporary computing environment. Significance. By incorporating the Boltzmann solver into an iterative least squares inverse planning optimiser, accurate dose calculation in a heterogeneous medium is obtained throughout inverse planning, with the result that the final dose distribution is of the highest quality.

Comparison of Doses to Parotid, Temporomandibular Joint, and Pharyngeal Constrictor Muscles Using Different Techniques in Radiotherapy for Oropharyngeal Cancer.

The purpose of this research was to compare two treatment techniques for oropharyngeal cancers: conventional linac-based static intensity-modulated radiotherapy (sIMRT) and helical tomotherapy (HT). The study examined several parameters, including target coverage, organs at risk, integral dose, and beam on time. Additionally, the study evaluated the doses to the parotid, temporomandibular joint, and pharyngeal constrictor muscles, which are important for swallowing. The present study retrospectively analyzed the data of 13 patients with oropharyngeal cancer who underwent radiotherapy between 2019 and 2021. The treatment plans for each patient were regenerated using both sIMRT and HT treatment planning systems with the sequential boost method. The techniques were evaluated and compared based on dose-volume histogram, homogeneity index, and conformity index parameters. The target coverage and organs at risk were statistically compared for two techniques. Additionally, the doses received by the healthy tissue volume were obtained for integral dose evaluation. The beam on time for each technique was assessed. When considering planning target volume evaluation, there was no difference in Dmeans between the two techniques and sIMRT demonstrated higher D2% values compared to the HT. The HT technique had better results for all organs at risk, such as the parotid, temporomandibular joint, and pharyngeal constrictor muscle. As for integral dose, it has been shown that the sIMRT technique provides better protection compared to HT. In addition, the beam on time was also longer with the HT technique. Both techniques may provide optimal target coverage for patients with oropharyngeal cancer. HT conferred notable advantages, especially with regard to critical structures implicated in swallowing, such as the parotid, temporomandibular joint, and pharyngeal constrictor muscle, in comparison to sIMRT.

Iodine deficiency and modern possibilities of its prevention in adolescents

Iodine deficiency is one of the most pressing problems of modern healthcare. Currently, there are 21 countries in the world where iodine deficiency in the diet of the population has been proven, but has not yet been eliminated. Russia is one of them due to the lack of a legislative framework for mass iodine prophylaxis in our country. The strategy for the elimination of iodine deficiency diseases on the scale of the Russian Federation is based on the adoption of a federal law providing for the use of iodized salt as a medium. The strategy for the elimination of iodine deficiency diseases on the scale of the Russian Federation is based on the adoption of a federal law providing for the use of iodized salt as a means of population iodine prophylaxis. Currently, less than 30% of the population in Russia consumes iodized salt in their diet, while the target coverage in iodine-rich regions &gt; 90% of households. In 2022, we conducted a survey of 269 adolescents aged 15–17 living in the Saratov Region and found that the share of families who regularly use YS for food was only 24,2%. Most adolescents rarely eat seafood and do not take iodine-containing drugs, which indicates the ineffectiveness of the «voluntary» model of iodine prevention. In the absence of a federal law, the most important step towards solving the problem of combating iodine deficiency diseases should be the formation of a unified nationwide preventive process based on the appropriate regulatory framework in each constituent entity of Russia – the development and implementation of targeted regional programs for the prevention of diseases caused by iodine deficiency.

Long-term Outcome After Helical Tomotherapy Following Breast Conserving Surgery for Ductal Carcinoma In Situ.

Background: This retrospective study aimed to investigate the outcomes and adverse events (AEs) associated with adjuvant radiotherapy with helical tomotherapy (hT) after breast-conserving surgery (BCS) for ductal carcinoma in situ (DCIS). Methods: Twenty-eight patients with DCIS underwent postoperative hT between 2011 and 2020. hT was chosen since it provided optimal target coverage and tolerable organ-at-risk doses to the lungs and heart when tangential 3-dimensional conformal radiotherapy (3D-CRT) was presumed to provide unfavorable dosimetry. The median total (single) dose was 50.4 Gy (1.8 Gy). The median time between BCS and the start of hT was 5 weeks (range, 4-38 weeks). Statistical analysis included local recurrence-free survival, overall survival (OS), and secondary cancer-free survival. AEs were classified according to the Common Toxicity Criteria for Adverse Events, version 5. Results: The patients' median age was 58 years. The median follow-up period was 61 months (range, 3-123 months). The 1-, 3-, and 5-year OS rates were 100% each. None of the patients developed secondary cancer, local recurrence, or invasive breast cancer during follow-up. The most common acute AEs were dermatitis (n = 27), fatigue (n = 4), hyperpigmentation (n = 3), and thrombocytopenia (n = 4). The late AE primarily included surgical scars (n = 7) and hyperpigmentation (n = 5). None of the patients experienced acute or late AEs > grade 3. The mean conformity and homogeneity indices were 0.9 (range, 0.86-0.96) and 0.056 (range, 0.05-0.06), respectively. Conclusion: hT after BCS for DCIS is a feasible and safe form of adjuvant radiotherapy for patients in whom 3D-CRT is contraindicated due to unfavorable dosimetry. During follow-up, there were no recurrences, invasive breast cancer diagnoses, or secondary cancers, while the adverse effects were mild.

Magnetic Resonance Imaging-Guided Frameless Stereotactic Injections of the Bilateral Cerebellar Dentate Nuclei in Nonhuman Primates: Technical Note.

Nonhuman primates (NHPs) are important preclinical models for evaluating therapeutics because of their anatomophysiological similarities to humans, and can be especially useful for testing new delivery targets. With the growing promise of cell and gene therapies for the treatment of neurological diseases, it is important to ensure the accurate and safe delivery of these agents to target structures in the brain. However, a standard guideline or method has not been developed for stereotactic targeting in NHPs. In this article, we describe the safe use of a magnetic resonance imaging-guided frameless stereotactic system to target bilateral cerebellar dentate nuclei for accurate, real-time delivery of viral vector in NHPs. Seventeen rhesus macaques (Macaca mulatta) underwent stereotactic surgery under real-time MRI guidance using the ClearPoint® system. Bilateral cerebellar dentate nuclei were targeted through a single parietal entry point with a transtentorial approach. Fifty microliters of contrast-impregnated infusate was delivered to each dentate nucleus, and adjustments were made as necessary according to real-time MRI monitoring of delivery. Perioperative clinical outcomes and postoperative volumes of distribution were recorded. All macaques underwent bilateral surgery successfully. Superficial pin site infection occurred in 4/17 (23.5%) subjects, which resolved with antibiotics. Two episodes of transient neurological deficit (anisocoria and unilateral weakness) were recorded, which did not require additional postoperative treatment and resolved over time. Volume of distribution of infusate achieved satisfactory coverage of target dentate nuclei, and only 1 incidence (2.9%) of cerebrospinal fluid penetration was recorded. Mean volume of distribution was 161.22 ± 39.61 mm3 (left, 173.65 ± 48.29; right, 148.80 ± 23.98). MRI-guided frameless stereotactic injection of bilateral cerebellar dentate nuclei in NHPs is safe and feasible. The use of this technique enables real-time modification of the surgical plan to achieve adequate target coverage and can be readily translated to clinical use.

Factors that Influence the Need to Start Adaptive Radiotherapy.

Adaptive radiotherapy (ART) is an essential approach to account for anatomical and biological uncertainties. Adaptive radiotherapy is, however, time-consuming, and it is unclear which patients are eligible or when is the best time to start ART. This prospective study was conducted at Kasr El-Aini Center of Clinical Oncology and Nuclear Medicine, Cairo, Egypt from January 2019 to December 2020. Thirty patients with pathologically proven, limited-stage small cell or stage I-II non-small cell lung cancer who were either not fit for or refused surgery or had stage III disease were recruited and underwent treatment planning to receive 60 Gy on a conventional 3D conformal radiation schedule with platinum-based chemotherapy. All patients underwent computed tomography (CT) planning within 2 and 4 weeks of starting radiation therapy to assess the need for adaptation. Pulmonary function test and echocardiography findings were assessed at the end of treatment and at 3 and 6 months after treatment, and were compared to the baseline. We found a significant reduction in mean value of the planning target volume (PTV) in the CT scans at the second (331 cm3) and fourth (257 cm3) weeks of treatment as compared to baseline (342 cm3) (p-value < 0.0001). Adaptation decreased the dose to the organ at risk with statistical significance and with improvement of the target coverage. At week 2 of radiotherapy, the need for adaptation was correlated to the conformity index (p = 0.0473), esophageal V35 (p = 0.0488), esophageal V50 (p = 0.0295), and its mean dose (p = 0.0087). At week 4 it was correlated to forced expiratory volume in 1 second (FEV1) (p = 0.0303), ratio between the forced expiratory volume in 1 second and the forced vital capacity (FEV1/FVC) (p = 0.0024), and echocardiography (p = 0.0183). Conformity index and esophageal dose constraints can predict the need for adaptation at week 2, whereas baseline pulmonary function parameters and echocardiography can predict the need for adaptation at week 4 of radiotherapy.

A reinforcement learning agent for head and neck intensity-modulated radiation therapy

Head and neck (HN) cancers pose a difficult problem in the planning of intensity-modulated radiation therapy (IMRT) treatment. The primary tumor can be large and asymmetrical, and multiple organs at risk (OARs) with varying dose-sparing goals lie close to the target volume. Currently, there is no systematic way of automating the generation of IMRT plans, and the manual options face planning quality and long planning time challenges. In this article, we present a reinforcement learning (RL) model for the purposes of providing automated treatment planning to reduce clinical workflow time as well as providing a better starting point for human planners to modify and build upon. Several models with progressing complexity are presented, including the relevant plan dosimetry analysis and model interpretations of the resulting strategies learned by the auto-planning agent. Models were trained on a set of 40 patients and validated on a set of 20 patients. The presented models are shown to be consistent with the requirements of an RL model to be underpinned by a Markov decision process (MDP). In-depth interpretability of the models is presented by examination of the decision space using action hyperplanes. The auto-planning agent was able to generate plans with superior reduction in the mean dose of the left and right parotid glands by approximately 7 Gy ± 2.5 Gy (p &amp;lt; 0.01) over a starting, static template plan with only pre-defined general prescription information. RL plans were comparable to a human expert’s clinical plans for the primary (44 Gy), boost (26 Gy) , and the summed plans (70 Gy) with p-values of 0.43, 0.72, and 0.67, respectively, for the dosimetric endpoints and uniform target coverage normalization. The RL planning agent was able to produce the plans used in validation in an average of 13.58 min, with a minimum and a maximum planning time of 2.27 and 44.82 min, respectively.

Comparison of photon energies and field techniques for ovarian dose reduction in volumetric modulated arc therapy

For fertility preservation in young female patients undergoing pelvic radiotherapy for cervical cancer, lateral ovarian transposition (LOT) is a procedure that moves the ovaries away from the radiation field. However, it is still challenging to fully protect the ovaries from radiation damage in volumetric modulated arc therapy (VMAT). In this study, we optimized VMAT techniques and simulated the effect of the LOT position on the ovarian dose. Ten cervical cancer patients who received pelvic radiotherapy after LOT were retrospectively analyzed. A restricted arc plus split field technique, which incorporated beam avoidance sectors, split field, fixed jaw, and orthogonal collimator orientation with 10 MV energy (rasf-10MV-VMAT), was designed to minimize the dose to the ovaries. This technique was compared with dual-arc conventional VMAT (dac-6MV-VMAT) and restricted arc and field VMAT (raf-6MV-VMAT) techniques with 6 MV energy. Ovarian dose, target coverage, and organs at risk (OAR) sparing were compared. The location of the ovaries in the anterior-posterior and superior-inferior directions was changed to simulate the effect of the LOT position on the ovarian dose. Compared to dac-6MV-VMAT and raf-6MV-VMAT, rasf-10MV-VMAT decreased the ovarian dose significantly more, especially for a low-dose volume. Both ovaries, received a 44.0–52.1 % lower volume of >3 Gy dose, and (0.5–1.9 Gy) lower maximum and mean doses with rasf-10MV-VMAT (p < 0.05). Rasf-10MV-VMAT also improved target conformity and coverage more than raf-6MV-VMAT (p < 0.05) and reduced the bladder mean dose more than dac-6MV-VMAT (p < 0.05). The ovarian dose decreased with the distance from the target contour, and placing the ovaries near the mid-frontal plane or as high as possible after the LOT lowered ovarian exposure. This technique, using 10 MV photon energy combined with field technique optimization, reduced the ovarian dose, particularly by decreasing the low-dose exposure of ovarian tissue and improving the target conformity simultaneously. The ovarian dose could be minimized by a proper LOT position. This optimized technique could enhance ovarian protection and fertility preservation for young female survivors of cervical cancer.

Validation of Fully Automated Robust Multicriterial Treatment Planning for Head and Neck Cancer IMPT

Our purpose was to compare robust intensity modulated proton therapy (IMPT) plans, automatically generated with wish-list-based multicriterial optimization as implemented in Erasmus-iCycle, with manually created robust clinical IMPT plans for patients with head and neck cancer. Thirty-three patients with head and neck cancer were retrospectively included. All patients were previously treated with a manually created IMPT plan with 7000 cGy dose prescription to the primary tumor (clinical target volume [CTV]7000) and 5425 cGy dose prescription to the bilateral elective volumes (CTV5425). Plans had a 4-beam field configuration and were generated with scenario-based robust optimization (21 scenarios, 3-mm setup error, and ±3% density uncertainty for the CTVs). Three clinical plans were used to configure the Erasmus-iCycle wish-list for automated generation of robust IMPT plans for the other 30 included patients, in line with clinical planning requirements. Automatically and manually generated IMPT plans were compared for (robust) target coverage, organ-at-risk (OAR) doses, and normal tissue complication probabilities (NTCP). No manual fine-tuning of automatically generated plans was performed. For all automatically generated plans, voxel-wise minimum D98% values for the CTVs were within clinical constraints and similar to manual plans. All investigated OAR parameters were favorable in the automatically generated plans (all P < .001). Median reductions in mean dose to OARs went up to 667 cGy for the inferior pharyngeal constrictor muscle, and median reductions in D0.03cm3 in serial OARs ranged up to 1795 cGy for the spinal cord surface. The observed lower mean dose in parallel OARs resulted in statistically significant lower NTCP for xerostomia (grade ≥2: 34.4% vs 38.0%; grade ≥3: 9.0% vs 10.2%) and dysphagia (grade ≥2: 11.8% vs 15.0%; grade ≥3: 1.8% vs 2.8%). Erasmus-iCycle was able to produce IMPT dose distributions fully automatically with similar (robust) target coverage and improved OAR doses and NTCPs compared with clinical manual planning, with negligible hands-on planning workload.

Stereotactic radiotherapy of intracranial tumor beds on a ring-mounted Halcyon LINAC.

This study sought to evaluate the feasibility and efficacy of the Halcyon Ring Delivery System (RDS) for delivering stereotactic radiotherapy (SRT) treatments for intracranial tumors beds. Ten previously treated brain SRT patients for 30Gy in five fractions with non-coplanar HyperArc plans on TrueBeam (6MV-FFF) were replanned on Halcyon (6MV-FFF) using the same number of arcs and Eclipse's AcurosXB dose engine. Plan quality evaluation metrics per SRT protocol included: PTV coverage, GTV dose (minimum and mean), target conformity indices (CI), heterogeneity index (HI), gradient index (GI), maximum dose 2cm away from the PTV (D2cm), and doses to organs-at-risk (OAR). Additionally, patient-specific quality assurance (QA) results and beam-on-time (BOT) were analyzed. The Halcyon RDS provided highly conformal SRT plans for intracranial tumor beds with similar dose to target. When benchmarked against clinically delivered HyperArc plans, target coverage, CI(s) and HI were statistically similar. The Halcyon plans saw no statistical difference in maximum OAR doses to the brainstem, spinal cord, and cochlea. Due to the machine's coplanar geometry, the Halcyon plans showed a decrease in optic pathway dose (0.75Gy vs. 2.08Gy, p=0.029). Overall, Halcyon's coplanar geometry resulted in a larger GI (3.33vs. 2.72, p=0.008) and a larger D2cm (39.59%vs. 29.07%, p<0.001). In this cohort, multiple cases had the PTV and the optic pathway in the same axial plane. In one such instance, the PTV was<2cm away from the optic pathway but even at this close proximity OAR, Halcyon still adequately spared the optic pathway. Additionally, the Halcyon's geometry provided slightly larger amount of normal brain dose receiving 24.4Gy (8.99 cc vs. 7.36 cc) and 28.8Gy (2.9 cc vs. 2.5 cc), although statistically insignificant. The Halcyon plans achieved similar delivery accuracy, quantified by patient-specific QA results evaluated with a 2%/2mm gamma criteria (99.42%vs. 99.70%). For both plans, independent Monte Carlo second checks calculation agreed within 1%. Average Halcyon BOT was slightly higher by 0.35min (p=0.045), however, due to the one-step patient set-up and verification overall estimated treatment times on Halcyon were lower compared to HyperArc treatments (7.61min vs. 10.26min, p<0.001). When benchmarked against clinically delivered HyperArc treatments, the Halcyon brain SRT plans provided similar plan quality and delivery accuracy but achieved faster overall treatment times. We have started treating select brain SRT patients on the Halcyon RDS for patients having tumor beds greater than 1cm in diameter with the closest OAR distance of greater than 2cm away from the target. We recommend other clinics to consider commissioning SRT treatments on their Halcyon systems-allowing including remote Halcyon-only clinics to provide exceptionally high-quality therapeutic brain SRT treatments to an otherwise underserved patient cohort.

A comparative study of boost dose delivery techniques in breast cancer radiotherapy optimising efficacy and minimising toxicity.

The present study aims to compare three techniques for delivering a boost absorbed dose: conventional reduced tangential (3D), volumetric modulated arc therapy (VMAT) and fields forward-planned technique boost (3DF). The study included 15 postoperative breast cancer patients who received a boost absorbed dose following breast-conserving surgery. The conformity index and homogeneity index were used to evaluate treatment outcomes, along with the average absorbed dose received by organs at risk (OAR). All the calculated dosimetric plans are carried out using Monaco Treatment Planning System (TPS). VMAT offers superior conformity, dose homogeneity and target coverage, it is associated with higher absorbed doses to OAR such as the heart and lung. In contrast, the 3D and 3DF techniques exhibit advantages in reducing absorbed doses to critical structures, potentially minimising the risk of cardiac and pulmonary complications. Each technique has its advantages and disadvantages. The choice of technique should be individualised, taking into account patient-specific factors and treatment goals and involves a multidisciplinary approach.

$\mathbb{T}-$Relative Fuzzy Linear Programming for $\mathbb{T}-$Relative Fuzzy Target Coverage Problems

Optimal set covering problems are commonplace in communication, remote sensing, logistics, image processing, and network fields [3]. Thus, studies on determining optimal covering sets (sensors) of points (targets) in a region have emerged recently. One characteristic of these studies is the consideration of cases where a target is considered fully covered when it falls within a coverage area ("Boolean" coverage). Consequently, optimality solutions/methods/algorithms founded on this coverage scheme are usually too restrictive and (or) precise and so are not suitable for many complex and real life situations, which are most times plagued with ambiguity, vagueness, imprecision and approximate membership of points and (or) covering sets. Fuzzy structures have proven to be suitable for the representation and analysis of such complex systems with many successful applications. Although fuzzy sets generalizes a set, a more recent generalization for both and its related concepts is the Relative fuzzy set [1] which gives a dynamic fuzzy representation to sets. $\mathbb{T}-$Relative Fuzzy fixed points results of $\mathbb{T}-$Relative fuzzy maps were studied in [5] and recently, the concept of $\mathbb{T}-$Relative fuzzy linear programming [6] was introduced as a generalization of fuzzy linear programming. The results were applied to generalize the Boolean set based covering problems in literature to a $\mathbb{T}-$Relative fuzzy Boolean coverage one. Although, Shan et al. in [15] and others [16] - [21] have given a probabilistic coverage consideration but this lacks subjectivity in representing vagueness and imprecision inherent in most systems. In this present article the Linear Programming (LP) formulation of “A Computational Physics-based Algorithm for Target Coverage Problems" by Jordan Barry and Christopher Thron is generalized by considering a fuzzy and relative fuzzy target coverage instead of the crisp set Boolean coverage. Also we introduce the Fuzzy Linear Programming (FLP) and the $\mathbb{T}-$Relative Fuzzy Linear Programming (RFLP) for the set coverage problem which allows for ascertaining dynamic optimality with aspiration levels.

Optimization of collimator angle combined island blocking with parked gap achieves superior normal tissue sparing in SBRT planning of multiple liver lesions.

To propose an efficient collimator angle optimization method by combining island blocking (IB) and parked gap (PG) problem to reduce the radiotherapy dose for normal tissue. The reduction will be done with single-isocenter multi-lesion volumetric modulated arc therapy (VMAT) for the stereotactic body radiation therapy (SBRT) of liver cancer. A novel collimator angle optimization algorithm was developed based on the two-dimensional projection of targets on a beam's eye view (BEV) plane as a function of gantry and collimator angle. This optimization algorithm minimized the sum of the combined IB and PG (IB & PG) areas from all gantry angles for each arc. For comparison, two SBRT plans were respectively generated for each of the 20 retrospective liver cancer cases with multiple lesions. One plan was optimized using the IB & PG algorithm, and the other plan was optimized with a previously reported optimization algorithm that only considered the IB area. Plans were then evaluated and compared using typical dosimetric metrics. With the comparable target coverage, IB & PG plans had significantly lower D500cc, D700cc, mean dose (Dmean), and V15 of normal liver tissues when compared to IB plans. The median percent reductions were 3.32% to 5.36%. The D1cc, D5cc, and Dmean for duodenum and small intestine in IB & PG plans were significantly reduced in a range from 7.60% up to 16.03%. Similarly, the median integral dose was reduced by 3.73%. Furthermore, the percentage of normal liver Dmean sparing when IB & PG plans compared to IB plans, was found to be positively correlated (ρ=0.669, P=0.001) with the inter-target distance. The proposed IB & PG algorithm has been demonstrated to outperform the IB algorithm in almost all normal tissue sparing, and the magnitude of liver sparing was positively correlated with inter-target distance.

A multi-objective approach for optimal target coverage UAV placement: hybrid heuristic formulation

Unmanned Aerial Vehicles (UAV) are utilised in several security operations. However, the major limitation in utilising the UAV for security purpose is its efficiency in monitoring the targets. In real-time applications, the flight range and number of UAVs utilised are insufficient for surveillance of the entire targets. UAVs are operated similarly for the flying base stations to improve the coverage rate. Utilisation of UAVs in target detection offers various benefits owing to their higher chance of ‘line-of-sight’ and monitoring at a higher altitude. The research motive of this paper is to maximise the network coverage by accurately placing UAVs under the condition of maintaining enhanced Quality of Service (QoS). This work intends to implement a Hybridized Colliding Bodies Galactic Swarm Optimization (HCBGSO) for resolving the problem of optimal placement of UAVs. The experimental outcomes demonstrate that the suggested algorithm gives better coverage, ensuring the effectiveness of the new hybrid optimisation.

Approaches for Stereotactic Radiosurgery (SRS)/Stereotactic Radiotherapy (SRT) in brain metastases using different radiotherapy modalities (Feasibility study).

SRS and SRT are precise treatments for brain metastases, delivering high doses while minimizing doses to nearby organs. Modern linear accelerators enable the precise delivery of SRS/SRT using different modalities like three-dimensional conformal radiotherapy (3DCRT), intensity-modulated radiotherapy (IMRT), and Rapid Arc (RA). This study aims to compare dosimetric differences and evaluate the effectiveness of 3DCRT, IMRT, and Rapid Arc techniques in SRS/SRT for brain metastases. 10 patients with brain metastases, 3 patients assigned for SRT, and 7 patients for SRS. For each patient, 3 treatment plans were generated using the Eclipse treatment planning system using different treatment modalities. No statistically significant differences were observed among the three techniques in the homogeneity index (HI), maximum D2%, and minimum D98% doses for the target, with a p > 0.05. The RA demonstrated a better conformity index of 1.14±0.25 than both IMRT 1.21±0.26 and 3DCRT 1.37±0.31. 3DCRT and IMRT had lower Gradient Index values compared to RA, suggesting that they achieved a better dose gradient than RA. The mean treatment time decreased by 26.2% and 10.3% for 3DCRT and RA, respectively, compared to IMRT. In organs at risk, 3DCRT had lower maximum doses than IMRT and RA, but some differences were not statistically significant. However, in the brain stem and brain tissues, RA exhibited lower maximum doses compared to IMRT and 3DCRT. Additionally, RA and IMRT had lower V15Gy, V12Gy, and V9Gy values compared to 3DCRT. While 3D-CRT delivered lower doses to organs at risk, RA and IMRT provided better conformity and target coverage. RA effectively controlled the maximum dose and irradiated volume of normal brain tissue. Overall, these findings indicate that 3DCRT, RA, and IMRT are suitable for treating brain metastases in SRS/SRT due to their improved dose conformity and target coverage while minimizing dose to healthy tissues.