Improved reconstruction methodology of clinical electron energy spectra based on Tikhonov regularization and generalized simulated annealing

Electron beam radiotherapy is the most widespread treatment modality todeal with superficial cancers. In electron radiotherapy, the energy spectrum isimportant for electron beam modelling and accurate dose calculation. Since thepercentage depth-dose (PDD) is a function of the beam’s energy, the reconstruction of the spectrum from the depth-dose curve represents an inverse problem.Thus, the energy spectrum can be related to the depth-dose by means of anappropriate mathematical model as the Fredholm equation of the first kind.Since the Fredholm equation of the first kind is ill-posed, some regularizationmethod has to be used to achieve a useful solution. In this work the Tikhonovregularization function was solved by the generalized simulated annealing optimization method. The accuracy of the reconstruction was verified by thegamma index passing rate criterion applied to the simulated PDD curves forthe reconstructed spectra compared to experimental PDD curves. Results showa good coincidence between the experimental and simulated depth-dose curvesaccording to the gamma passing rate better than 95% for 1% dose difference(DD)/1 mm distance to agreement (DTA) criteria. Moreover, the results showimprovement from previous works not only in accuracy but also in calculationtime. In general, the proposed method can help in the accuracy of dosimetryprocedures, treatment planning and quality control in radiotherapy.

A Review on Mucormycosis Disease & Its Treatment

Mucormycosis is an angio-intrusive disease brought about by the Mucorales organism. Even though it is an uncommon condition, it is turning out to be more normal among immunocompromised patients. Rhino-orbitocerebral, cutaneous, dispersed, gastrointestinal, and pneumonic structures would all be able to be found. Notwithstanding the lively treatment, there is a generally speaking expanded passing rate. The audit's significant objective and objective are as follows: Mucormycosis Overview and Etiopathogenesis, Fatality of Rhino cerebral Mucormycosis Strategies for determination and treatment have as of late progressed. Mucormycosis is more typical in seriously neutropenia patients and people who need phagocytic action. Notwithstanding, this isn’t true on account of Patients with AIDS19. It suggests that T lymphocytes are involved. They are insufficient in forestalling parasitic expansion. Just the neutrophils are impacted. Voriconazole treatment for quite a while, essentially among the People with malignant growths of the blood and bone marrow Transfers of undifferentiated hematopoietic cells are more regular. Besides, Mucormycosis can likewise be found in individuals who don’t have any manifestations Rhino-orbitocerebral, cutaneous, dispersed, gastrointestinal, and pneumonic structures would all be found. Notwithstanding the lively treatment, there is a generally speaking expanded passing rate. Mucormycosis results from various fungi that may be innocuous and primarily affect immunocompromised patients. For this reason, the clinician must have a high index of suspicion to diagnose this disease in any of its forms when it presents in a patient with these risk factors. Starting with the host’s features and the fungus’s tropism once it invades the host, this activity discusses the manifestations of Disease, appropriate evaluation/management of mucormycosis, and highlights the role of the interprofessional team in evaluating and treating patients with this condition.

Dosimetric Verification of Gamma Passing Rate for Head and Neck Cases Treated with Intensity Modulated Radiation Therapy (IMRT) Treatment Planning Technique

Each Intensity Modulated Radiation Therapy (IMRT) plan needs to be tested and verified before any treatment to check its quality. Octavius 4D-1500 phantom detector is a modern and qualified device for quality assurance procedure. This study aims to compare the common dosimetric criteria 3%/3 mm with 2%/2 mm for H&N plans for the IMRT technique. Twenty-five patients with head and neck (H&N) tumor were with 6MV x-ray photon beam using Monaco 5.1 treatment planning software and exported to Elekta synergy linear accelerator then tested for pretreatment verification study using Octavius 4D-1500 phantom detector. The difference between planned and measured dose were assessed by using local and global gamma index (GI) analysis method at threshold 10%. The DD/DTA criteria are performed with 3%/3 mm and 2%/2 mm. A significant difference is shown between the measured and calculated point dose for the treatment plans. A comparison made between the gamma passing rate between the 2%/2 mm and 3%/3 mm shows a significant difference for local and global which shows that the 2%/2 mm are more sensitive to dose variation than 3%/3 mm. The total monitor unit (MU) shows a negative linear relationship with both criteria and %GP types. A significant correlation is shown between the total MU and global %GP at 2%/2 mm criterion. The conclusion of the study indicates that 2%/2 mm criterion is more sensitive to the dose distribution changes than the 3%/3 mm. The total number of monitor units should be taken into consideration during the planning of H&N tumors using the IMRT plans.

Comparison between different Dosimetric Tools based on Intensity-modulated Radiotherapy (IMRT): A Phantom Study

This study examined the gamma passing rate (GPR) consistency during applying different kinds of gamma analyses and dosimeters to IMRT. Methods: Import treatment protocols for QA phantom irradiation have been recalculated. A gamma analysis was used for comparing the measured and calculated dose distribution of IMRT for different gamma criteria (2%/2mm, 3%/3mm, 4%/4mm, 3%/5mm, 3%/5mm). These criteria are evaluated when 5%, 10%, or 15% of the dose distribution is suppressed. Measured and calculated dose distribution was evaluated with gamma analysis to dose difference (DD) with DTA criteria (distance to agreement). IMRT QA plans to 25 patients from various sites were formed with the Varian Eclipse treatment planning system. Results: Results indicate different diverse hardware and software combinations show varied levels of agreement with expected analysis for the same pass-rate criterion. For a dosimetry audit of the IMRT technique, an EPID detector is superior to conventional methods comparable to Gafchromic EPT3 film and 2D array due to cost, time-consuming, and set up error to get result analysis. The gamma passing rate (GPR) average is increased by increasing the low-dose threshold for different dosimetric tools. For EPID, regardless of the gamma criterion employed, the %GP does not appear to be dependent on the low-dose threshold values (5%-15%) because it indicates that fulfilment the low-dose threshold to global normalization has little effect on patient-specific QA outcomes. Conclusions: It is concluded that GPRs differ depending on gamma, dosimetric tools, and the suppressing dose ratio. To get the best results of quality assurance, each institution should thus carefully develop its procedure for gamma analysis by defining the gamma index analysis and gamma criterion using its dosimetric tools.

Deep Multimodal Neural Network Based on Data-Feature Fusion for Patient-Specific Quality Assurance

Patient-specific quality assurance (QA) for Volumetric Modulated Arc Therapy (VMAT) plans is routinely performed in the clinical. However, it is labor-intensive and time-consuming for medical physicists. QA prediction models can address these shortcomings and improve efficiency. Current approaches mainly focus on single cancer and single modality data. They are not applicable to clinical practice. To assess the accuracy of QA results for VMAT plans, this paper presents a new model that learns complementary features from the multi-modal data to predict the gamma passing rate (GPR). According to the characteristics of VMAT plans, a feature-data fusion approach is designed to fuse the features of imaging and non-imaging information in the model. In this study, 690 VMAT plans are collected encompassing more than ten diseases. The model can accurately predict the most VMAT plans at all three gamma criteria: 2%/2 mm, 3%/2 mm and 3%/3 mm. The mean absolute error between the predicted and measured GPR is 2.17%, 1.16% and 0.71%, respectively. The maximum deviation between the predicted and measured GPR is 3.46%, 4.6%, 8.56%, respectively. The proposed model is effective, and the features of the two modalities significantly influence QA results.

Analysis of clinical patient-specific pre-treatment quality assurance with the new helical tomotherapy platform, following the AAPM TG-218 report

Purpose This study presents patient-specific quality assurance (QA) results from the first 395 clinical cases for the new helical TomoTherapy® platform (Radixact) coupled with dedicated Precision TPS. Methods The passing rate of the Gamma Index (GP%) of 395 helical QA of patient-specific tomotherapy, acquired with ArcCHECK, is presented, analysed and correlated to various parameters of the plan. Following TG-218 recommendations, the clinic specific action limit (ALcs) and tolerance limit (TLcs) were calculated for our clinic and monitored during the analysed period. Results The mean values ​​(± 1 standard deviation) of GP% (3%/2 mm) (both global and local normalization) are: 97.6% and 90.9%, respectively. The proposed ALcs and TLcs, after a period of two years’ process monitoring are 89.4% and 91.1% respectively. Conclusions The phantom measurements closely match the planned dose distributions, demonstrating that the calculation accuracy of the new Precision TPS and the delivery accuracy of the Radixact unit are adequate, with respect to international guidelines and reports. Furthermore, a first correlation with the planning parameters was made. Action and tolerance limits have been set for the new Radixact Linac.

Verification of an optimizer algorithm by the beam delivery evaluation of intensity-modulated arc therapy plans

Background In the case of dynamic radiotherapy plans, the fractionation schemes can have dosimetric effects. Our goal was to define the effect of the fraction dose on the plan quality and the beam delivery. Materials and methods Treatment plans were created for 5 early-stage lung cancer patients with different dose schedules. The planned total dose was 60 Gy, fraction dose was 2 Gy, 3 Gy, 5 Gy, 12 Gy and 20 Gy. Additionally renormalized plans were created by changing the prescribed fraction dose after optimization. The dosimetric parameters and the beam delivery parameters were collected to define the plan quality and the complexity of the treatment plans. The accuracy of dose delivery was verified with dose measurements using electronic portal imaging device (EPID). Results The plan quality was independent from the used fractionation scheme. The fraction dose could be changed safely after the optimization, the delivery accuracy of the treatment plans with changed prescribed dose was not lower. According to EPID based measurements, the high fraction dose and dose rate caused the saturation of the detector, which lowered the gamma passing rate. The aperture complexity score, the gantry speed and the dose rate changes were not predicting factors for the gamma passing rate values. Conclusions The plan quality and the delivery accuracy are independent from the fraction dose, moreover the fraction dose can be changed safely after the dose optimization. The saturation effect of the EPID has to be considered when the action limits of the quality assurance system are defined.

Assessment of Delivery Quality Assurance for Stereotactic Radiosurgery With Cyberknife

PurposeThe purpose of this study is to establish and assess a practical delivery quality assurance method for stereotactic radiosurgery with Cyberknife by analyzing the geometric and dosimetric accuracies obtained using a PTW31016 PinPoint ionization chamber and EBT3 films. Moreover, this study also explores the relationship between the parameters of plan complexity, target volume, and deliverability parameters and provides a valuable reference for improving plan optimization and validation.MethodsOne hundred fifty cases of delivery quality assurance plans were performed on Cyberknife to assess point dose and planar dose distribution, respectively, using a PTW31016 PinPoint ionization chamber and Gafchromic EBT3 films. The measured chamber doses were compared with the planned mean doses in the sensitive volume of the chamber, and the measured planar doses were compared with the calculated dose distribution using gamma index analysis. The gamma passing rates were evaluated using the criteria of 3%/1 mm and 2%/2 mm. The statistical significance of the correlations between the complexity metrics, target volume, and the gamma passing rate were analyzed using Spearman’s rank correlation coefficient.ResultsFor point dose comparison, the averaged dose differences (± standard deviations) were 1.6 ± 0.73% for all the cases. For planar dose distribution, the mean gamma passing rate for 3%/1 mm, and 2%/2 mm evaluation criteria were 94.26% ± 1.89%, and 93.86% ± 2.16%, respectively. The gamma passing rates were higher than 90% for all the delivery quality assurance plans with the criteria of 3%/1 mm and 2%/2 mm. The difference in point dose was lowly correlated with volume of PTV, number of beams, and treatment time for 150 DQA plans, and highly correlated with volume of PTV for 18 DQA plans of small target. DQA gamma passing rate (2%/2 mm) was a moderate significant correlation for the number of nodes, number of beams and treatment time, and a low correlation with MU.ConclusionPTW31016 PinPoint ionization chamber and EBT3 film can be used for routine Cyberknife delivery quality assurance. The point dose difference should be within 3%. The gamma passing rate should be higher than 90% for the criteria of 3%/1 mm and 2%/2 mm. In addition, the plan complexity and PTV volume were found to have some influence on the plan deliverability.