Validating knowledge-based volumetric modulated arc therapy plans with a multi-institution model (broad model) using a complete open-loop dataset for prostate cancer.

This study examined the characteristics of the broad model (KBP) through a complete open-loop evaluation of volumetric modulated arc therapy (VMAT) plans for prostate cancer in 30 patients at two institutions. KBP, trained using 561 prostate cancer VMAT plans from five institutions with different treatment protocols, was shared with two institutions. The institutions were not involved in the creation of KBP.

Overcoming Problems Caused by Offset Distance of Multiple Targets in Single-isocenter Volumetric Modulated Arc Therapy Planning for Stereotactic Radiosurgery.

Purpose: The purpose of the study is to investigate the impact of large target offset distances on the dose distribution and gamma passing rate (GPR) in single-isocenter multiple-target stereotactic radiosurgery (SIMT SRS) using volumetric modulated arc therapy (VMAT) with a flattening filter-free (FFF) beam from a linear accelerator.

Methods: Two targets with a diameter of 1 cm were offset by "±2, ±4, and ±6 cm from the isocenter in a verification phantom for head SRS (20 Gy/fr). The VMAT plans were created using collimator angles that ensured the two targets did not share a leaf pair from the multi-leaf collimator.

Comparing Dose Calculation Algorithms for Heterogeneous Media: Analytical Anisotropic Algorithm Versus Acuros XB (Dm/Dw) With Continuous CT Value Variation.

Background: To compare the doses calculated by the analytical anisotropic algorithm (AAA) and two dose reporting modes of Acuros XB (AXB(D) and AXB(D)) with varied CT values on the Eclipse (Varian Medical Systems, Palo Alto, CA).

Materials And Methods: Virtual phantoms with a central layer of heterogeneous material (thickness = 2 or 5 cm) were created with Eclipse. Using single or opposed fields, the field sizes were 5 x 5 cm or 10 x 10 cm.

Dose difference between anisotropic analytical algorithm (AAA) and Acuros XB (AXB) caused by target's air content for volumetric modulated arc therapy of head and neck cancer.

Background: We clarified the dose difference between the anisotropic analytical algorithm (AAA) and Acuros XB (AXB) with increasing target's air content using a virtual phantom and clinical cases.

Materials And Methods: Whole neck volumetric modulated arc therapy (VMAT) plan was transferred into a virtual phantom with a cylindrical air structure at the center. The diameter of the air structure was changed from 0 to 6 cm, and the target's air content defined as the air/planning target volume (PTV) in percent (air/PTV) was varied.

Effectiveness of shielding materials against Lu gamma rays and the corresponding distance relationship.

Objective: The purpose of this study is to determine the dose reduction of different shielding materials at various distances from a Lu photon radiation source.

Methods: Two protective aprons with lead equivalent thicknesses of 0.25 mm and 0.

Standardization of knowledge-based volumetric modulated arc therapy planning with a multi-institution model (broad model) to improve prostate cancer treatment quality.

Purpose: To evaluate whether knowledge-based volumetric modulated arc therapy plans for prostate cancer with a multi-institution model (broad model) are clinically useful and effective as a standardization method.

Methods: A knowledge-based planning (KBP) model was trained with 561 prostate VMAT plans from five institutions with different contouring and planning policies. Five clinical plans at each institution were reoptimized with the broad and single institution model, and the dosimetric parameters and relationship between D and the overlapping volume (rectum or bladder and target) were compared.

Comparison of the Characteristics of Two Types of Parallel-plate Ionization Chamber Under Small-field Electron Irradiation.

Background/aim: This study compared two types of parallel-plate ionization chamber to clarify the pitfalls of dosimetry in electron radiation therapy.

Materials And Methods: The ion recombination correction factor and polarity effect correction factor, sensitivity, and percentage depth doses (PDDs) of PPC05 and PPC40 parallel-plate ionization chambers were compared in a small-field electron beam. The output ratios were measured for 4-20 MeV electron beams with field sizes of 10 cm × 10 cm, 6 cm × 6 cm, and 4 cm × 4 cm.

Volumetric Modulated Arc Therapy Planning for Craniospinal Irradiation With a New O-ring Linac.

This study aims to determine the feasibility of using a new O-ring linear accelerator (Halcyon, Varian Medical Systems, CA, USA) to perform treatment planning using volumetric modulated arc therapy (VMAT) for craniospinal irradiation (CSI). A 20-year-old male patient with leukemia was selected. The planning target volume (PTV) was contoured to include the entire contents of the brain and spinal canal.

The development and characterization of an all-purpose bolus for radiotherapy.

The purpose of this study was to develop a new bolus (HM bolus), with tissue equivalence, transparency, reusability, and free shaping at approximately 40 °C for excellent adhesion, and to evaluate the feasibility of clinically using this bolus as an ideal bolus.We summarized the advantages and disadvantages of existing boluses. To evaluate dose characteristics, a vinyl gel sheet bolus (Gel bolus) and HM bolus placed on a water-equivalent phantom were used to obtain the percentage depth dose (PDD) of electron (6 MeV, 9 MeV) and photon (4 MV, 6 MV) beams.

Development of a Novel Tabletop Device With Suction and Sanitization of Droplets against COVID-19.

Background Coronavirus disease 2019 and other viruses are transmissible by aerosols and droplets from infected persons. This study aimed to develop a portable device that can trap droplets and deactivate viruses, and verify whether the device in an enclosed room can suction droplets and sanitize them using a filter and an ultraviolet-C (UVC) light-emitting diode. Materials and methods The portable device was evaluated by placing it 50 cm away from the droplet initiation point.

Impact of Knowledge-based Plan Model Improvement on Plan Complexity and Deliverability in VMAT For Prostate Cancer: A Multi-institutional Study.

Background/aim: This study evaluated the impact of knowledge-based plan (KBP) model improvement on plan complexity and delivery accuracy in volumetric modulated arc therapy (VMAT) for prostate cancer at multiple institutions.

Materials And Methods: Five institutions created the first KBP model before April 2017 and subsequently devised a new model (second model) based on feedback from the first KBP and the efforts of planners after April 2019. The dose-volume histogram (DVH) parameters were validated for two prostate cancer cases between the first and second KBPs.

Independent monitor unit verification for dynamic flattened beam plans on the Halcyon linac.

Independent monitor unit verification (MUV) methods for the dynamic beam-flattening (DBF) technique have not been established. The purpose of this study was to clarify whether MU values for the DBF technique can be calculated using in-air and in-water output ratios (S and S ). S and S were measured in the DBF mode, and the phantom scatter factor (S ) was calculated.

An updating approach for knowledge-based planning models to improve plan quality and variability in volumetric-modulated arc therapy for prostate cancer.

Purpose: The purpose of this study was to compare the dose-volume parameters and regression scatter plots of the iteratively improved RapidPlan (RP) models, specific knowledge-based planning (KBP) models, in volumetric-modulated arc therapy (VMAT) for prostate cancer over three periods.

Methods: A RP1 model was created from 47 clinical intensity-modulated radiation therapy (IMRT)/VMAT plans. A RP2 model was created to exceed dosimetric goals which set as the mean values +1SD of the dose-volume parameters of RP1 (50 consecutive new clinical VMAT plans).

Plan Complexity and Delivery Accuracy of Knowledge-based Volumetric Modulated Arc Therapy Plans with Single Optimization for Oropharyngeal Cancer.

Background/aim: We investigated the plan complexity of volumetric modulated arc therapy (VMAT) with knowledge-based plan (KBP) for oropharyngeal cancer (OPC) with a single optimization and whether it could be used clinically.

Materials And Methods: KBP model was configured using 55 consecutive OPC and nasopharyngeal cancer plans. Plan complexity as a characteristic of multileaf collimator (MLC) motion and γ pass rate (2%/2 mm criterion) were compared between clinical manual plan (CMP) and KBP for other 10 plans.

Effects of compound-326, a selective delta-5 desaturase inhibitor, in ApoE knockout mice with two different protocols for atherosclerosis development.

Purpose: We previously confirmed its anti-atherosclerotic effects by pre-treatment with compound-326, a selective delta-5 desaturase (D5D) inhibitor, in Western diet-fed ApoE knockout mice. In the present study, we evaluated effects of compound-326 in ApoE knockout mice with two different protocols for atherosclerosis development.

Methods: In a post-treatment protocol, where the compound treatment started after 10 weeks pre-feeding of Western diet, compound-326 (1 and 3 mg/kg/day, p.

Characterization of acoustic streaming in water and aluminum melt during ultrasonic irradiation.

It is well known that ultrasonic cavitation causes a steady flow termed acoustic streaming. In the present study, the velocity of acoustic streaming in water and molten aluminum is measured. The method is based on the measurement of oscillation frequency of Karman vortices around a cylinder immersed into liquid.

[Effect of Gantry Speed on Image Quality of Four-dimensional Cone-beam Computed Tomography Using a Dynamic Phantom of Lung].

Purpose: The purpose of this paper was to determine the optimal imaging conditions for four-dimensional cone-beam computed tomography (4D-CBCT) using an X-ray tube and a flat-panel detector mounted on a radiotherapy device.

Methods: The optimal imaging conditions were examined by changing the gantry speed (GS) parameter that affected the exposure time. Exposed dose during imaging and image quality of moving phantom were compared between examined conditions.

Dosimetric evaluation with knowledge-based planning created at different periods in volumetric-modulated arc therapy for prostate cancer: a multi-institution study.

Dosimetric evaluation and variation assessment were performed with two knowledge-based planning (KBP) models created at different periods for volumetric-modulated arc therapy (VMAT) for prostate cancer at five institutes. The first and second models (F- and S-models) for KBP were created before April 2017 and April 2019, respectively. The S-model was created using feedback plans from the F-model.

Influence of Cleaned-up Commercial Knowledge-Based Treatment Planning on Volumetric-Modulated Arc Therapy of Prostate Cancer.

Purpose: This study aimed to investigate the influence of cleaned-up knowledge-based treatment planning (KBP) models on the plan quality for volumetric-modulated arc therapy (VMAT) of prostate cancer.

Materials And Methods: Thirty prostate cancer VMAT plans were enrolled and evaluated according to four KBP modeling methods as follows: (1) model not cleaned - trained by fifty other clinical plans (KBP); (2) cases cleaned by removing plans that did not meet all clinical goals of the dosimetric parameters, derived from dose-volume histogram (DVH) (KBP); (3) cases cleaned outside the range of ±1 standard deviation through the principal component analysis regression plots (KBP); and (4) cases cleaned using both methods (2) and (3) (KBP). Rectal and bladder structures in the training models numbered 34 and 48 for KBP, 37 and 33 for KBP, and 26 and 33 for KBP, respectively.

Discovery of 1,8-naphthyridin-2-one derivative as a potent and selective sphingomyelin synthase 2 inhibitor.

Sphingomyelin synthase 2 (SMS2) has attracted attention as a drug target for the treatment of various cardiovascular and metabolic diseases. The modification of a high throughput screening hit, 2-quinolone 10, enhanced SMS2 inhibition at nanomolar concentrations with good selectivity against SMS1. To improve the pharmaceutical properties such as passive membrane permeability and aqueous solubility, adjustment of lipophilicity was attempted and 1,8-naphthyridin-2-one 37 was identified as a potent and selective SMS2 inhibitor.

Inter-planner variation in treatment-plan quality of plans created with a knowledge-based treatment planning system.

Purpose: This study aimed to clarify the inter-planner variation of plan quality in knowledge-based plans created by nine planners.

Methods: Five hypofractionated prostate-only (HPO) volumetric modulated arc therapy (VMAT) plans and five whole-pelvis (WP) VMAT plans were created by each planner using a knowledge-based planning (KBP) system. Nine planners were divided into three groups of three planners each: Senior, Junior, and Beginner.

Comparison of patient-specific intensity modulated radiation therapy quality assurance for the prostate across multiple institutions.

Aim: To evaluate the success of a patient-specific intensity modulated radiation therapy (IMRT) quality assurance (QA) practice for prostate cancer patients across multiple institutions using a questionnaire survey.

Background: The IMRT QA practice involves different methods of dose distribution verification and analysis at different institutions.

Materials And Methods: Two full-arc volumetric modulated arc therapy (VMAT) plan and 7 fixed-gantry IMRT plan with DMLC were used for patient specific QA across 22 institutions.