Probabilistic nested model selection in pharmacokinetic analysis of DCE-MRI data in animal model of cerebral tumor.

Best current practice in the analysis of dynamic contrast enhanced (DCE)-MRI is to employ a voxel-by-voxel model selection from a hierarchy of nested models. This nested model selection (NMS) assumes that the observed time-trace of contrast-agent (CA) concentration within a voxel, corresponds to a singular physiologically nested model. However, admixtures of different models may exist within a voxel's CA time-trace.

Institutional experience with implanted cardiac device risk level assessment: Comparing calculation and measurement.

Background: The use of in-vivo dosimetry is a long-standing but also labor-intensive component of risk-level assessment for patients with implanted devices. A calculation-only approach, using treatment planning system (TPS)-calculated doses along with imaging doses estimates when relevant, has the potential to streamline the physics workflow without negatively impacting patient safety.

Purpose: To evaluate the feasibility of using a calculation-only approach for risk level assessment for patients with implanted electronic medical devices.

Development of an EGSnrc multi-leaf collimator component module and treatment head model for a low-field MRI linear accelerator.

Background: Monte Carlo (MC) modeling of MR-guided radiotherapy (MRgRT) treatment machines enables the characterization of photon/electron interactions in the presence of a magnetic field. The EGSnrc MC code system is a well-established system for radiation dose calculations. The multi-leaf collimator (MLC) component modules presently available within the EGSnrc MC code system do not include a model of the double-focused MLC available on a low-field (0.

Probabilistic Nested Model Selection in Pharmacokinetic Analysis of DCE-MRI Data in Animal Model of Cerebral Tumor.

Purpose: Best current practice in the analysis of dynamic contrast enhanced (DCE)-MRI is to employ a voxel-by-voxel model selection from a hierarchy of nested models. This nested model selection (NMS) assumes that the observed time-trace of contrast-agent (CA) concentration within a voxel, corresponds to a singular physiologically nested model. However, admixtures of different models may exist within a voxel's CA time-trace.

Acute toxicity outcomes from salvage high-dose-rate brachytherapy for locally recurrent prostate cancer after prior radiotherapy.

Purpose: Isolated intra-prostatic recurrence of prostate adenocarcinoma after definitive radiotherapy presents a challenging clinical scenario. Salvage options require specialized expertise and pose risks of harm. This study aimed to present the acute toxicity results from using salvage high-dose-rate brachytherapy (sHDR-BT) as treatment in locally recurrent prostate cancer cases.

The impact of advancing the standard of care in radiotherapy on operational treatment resources.

Purpose: To demonstrate the impact of implementing hypofractionated prescription regimens and advanced treatment techniques on institutional operational hours and radiotherapy personnel resources in a multi-institutional setting. The study may be used to describe the impact of advancing the standard of care with modern radiotherapy techniques on patient and staff resources.

Methods: This study uses radiation therapy data extracted from the radiotherapy information system from two tertiary care, university-affiliated cancer centers from 2012 to 2021.

Stereotactic Optimized Automated Radiotherapy (SOAR): a novel automated planning solution for multi-metastatic SRS compared to HyperArc™.

Automated Stereotactic Radiosurgery (SRS) planning solutions improve clinical efficiency and reduce treatment plan variability. Available commercial solutions employ a template-based strategy that may not be optimal for all SRS patients. This study compares a novel beam angle optimized Volumetric Modulated Arc Therapy (VMAT) planning solution for multi-metastatic SRS to the commercial solution HyperArc.

Estimated absolute percentage of biopsied tissue positive for Gleason pattern 4 (eAPP4) in low dose rate prostate brachytherapy: Evaluation of prognostic utility in a large cohort.

Purpose: To determine whether a system to estimate Absolute Percentage of Biopsied Tissue Positive for Gleason Pattern 4 (eAPP4) is useful as a prognostication tool for patients with intermediate risk prostate cancer (IR-PCa) undergoing low dose rate prostate brachytherapy.

Methods: 497 patients with IR-PCa and known grade group 2 or 3 disease treated with low dose rate seed brachytherapy (LDR-BT) at a quaternary cancer centre were retrospectively reviewed. Prostate biopsies for each patient included Gleason grading with synoptic reporting that did not include percentage of pattern 4 disease found within the sample.

Long-term recurrence after endoscopic versus surgical ampullectomy of sporadic ampullary adenomas: a systematic review and meta-analysis.

Background And Aims: Ampullary adenomas are treated both surgically and endoscopically, however, data comparing both techniques are lacking. We aimed to compare long-term recurrence of benign sporadic adenomas after endoscopic (EA) and surgical ampullectomy (SA).

Methods: A comprehensive literature search of multiple databases (until December 29, 2020) was performed to identify studies reporting outcomes of EA or SA of benign sporadic ampullary adenomas.

Fast stereotactic radiosurgery planning using patient-specific beam angle optimization and automation.

Background And Purpose: Linac-based stereotactic radiosurgery (SRS) planning for multi-metastatic cases is a complex and intensive process. A manual planning strategy starts with a template-based set of beam angles and applies modifications though a trial and error process. Beam angle optimization uses patient specific geometric heuristics to determine beam angles that provide optimal target coverage and avoid treating through Organs-at-Risk (OARs).

Competency-Based Medical Education in Radiation Therapy Treatment Planning.

Purpose: To develop a technology-enhanced education methodology with competency-based evaluation for radiation therapy treatment planning. The education program is designed for integration in the existing framework of Commission on Accreditation of Medical Physics Education Programs (CAMPEP) accredited medical physics residency programs.

Methods And Materials: This education program pairs an accessible, multi-institutional infrastructure with established medical education evaluation tools to modernize treatment planning education.

Clinical Outcomes from Dose-Reduced Radiotherapy to the Prostate in Elderly Patients with Localized Prostate Cancer.

Radical treatment of localized prostate cancer in elderly patients may lead to unacceptable treatment-associated toxicities that adversely impact quality of life without improving survival outcomes. This study reports on a cohort of 54 elderly (>70 years) patients that received 4000-5000 cGy of palliative external beam radiotherapy (EBRT) as an alternative to androgen deprivation therapy (ADT). The primary outcome of interest was the period of ADT-free survival, and secondary outcomes included overall survival (OS) and metastases-free survival (MFS).

Modeling Bioinspired Fish Scale Designs via a Geometric and Numerical Approach.

Fish scales serve as a natural dermal armor with remarkable flexibility and puncture resistance. Through studying fish scales, researchers can replicate these properties and tune them by adjusting their design parameters to create biomimetic scales. Overlapping scales, as seen in elasmoid scales, can lead to complex interactions between each scale.

Increasing Demand on Human Capital and Resource Utilization in Radiation Therapy: The Past Decade.

Purpose: To quantify the change resource utilization in radiation therapy in the context of advancing technologies and techniques over the last decade.

Methods And Materials: Prospectively, the time to complete radiation therapy workflow tasks was captured between January 1, 2020, and December 31, 2020. The institutional task workflows are specific to each technique and broadly organized into 4 categories: 3-dimenstional conformal radiation therapy, intensity modulated radiation therapy, volumetric modulated arc therapy simple, and volumetric modulated arc therapy complex.

Emergency Department Visits Increase in Transition-Age Patients Empaneled in a Primary Care Network at a Major Academic Medical Center.

Purpose: The aim of this study is to identify important predictors of emergency department (ED) utilization within a population of transition-aged patients empaneled within a primary care network, particularly with high-risk chronic conditions of childhood (HRC).

Methods: We analyzed cross-sectional data of patients aged 12-29 within a primary care network (n = 19,989). We used negative binomial regression modeling to identify important predictors of ED visits in the last year.

Auto-delineation framework for the focal liver reaction observed in post Stereotactic Body Radiation Therapy (SBRT) Primovist MRI scans.

Development of a novel auto-delineation methodology for observed hypointensity from focal liver reaction in hepatobiliary-specific contrast (Primovist) enhanced MRI acquired post Stereotactic Body Radiation Therapy (SBRT). Additionally, the methodology for the quantification of the threshold dose associated with the observed focal liver reaction was also established. An auto-delineation algorithm was created based on the correlation between intensity and radiation dose information.

MRI-TRUS registration methodology for TRUS-guided HDR prostate brachytherapy.

Purpose: High-dose-rate (HDR) prostate brachytherapy is an established technique for whole-gland treatment. For transrectal ultrasound (TRUS)-guided HDR prostate brachytherapy, image fusion with a magnetic resonance image (MRI) can be performed to make use of its soft-tissue contrast. The MIM treatment planning system has recently introduced image registration specifically for HDR prostate brachytherapy and has incorporated a Predictive Fusion workflow, which allows clinicians to attempt to compensate for differences in patient positioning between imaging modalities.

Excessive waitlists and delays to treatment with low-dose-rate brachytherapy predict an increased risk of recurrence and metastases in intermediate-risk prostatic carcinoma.

Purpose: It has previously been shown that increased wait times for prostatectomy are associated with poorer outcomes in intermediate-risk prostatic carcinoma (PCa). However, the impact of wait times on PCa outcomes following low-dose-rate brachytherapy (LDR-BT) are unknown.

Methods And Materials: We retrospectively reviewed 466 intermediate-risk PCa patients that underwent LDR-BT at a single comprehensive cancer center between 2003 and 2016.

Direct visualization and correlation of liver stereotactic body radiation therapy treatment delivery accuracy with interfractional motion.

This study used the visualization of hypo-intense regions on liver-specific MRI to directly quantify stereotactic body radiation therapy (SBRT) spatial delivery accuracy. Additionally, the interfractional motion of the liver region was determined and compared with the MRI-based evaluation of liver SBRT spatial treatment delivery accuracy. Primovist -enhanced MRI scans were acquired from 17 patients, 8-12 weeks following the completion of liver SBRT treatment.

Early longitudinal experiences increase medical student self-efficacy.

This article was migrated. The article was marked as recommended. The purpose of this study was to investigate the impact of early longitudinal preceptorship experiences on the evolution of general self-efficacy and patient-centeredness self-efficacy through medical school.

Technical Note: A standardized automation framework for monitoring institutional radiotherapy protocol compliance.

Purpose: To establish a framework for the standardization of monitoring radiotherapy protocol compliance.

Methods: An automated protocol compliance tool was developed using best practice in software design and a flexible framework to easily adapt to changing institutional standards. The Eclipse scripting environment was used to develop the application with the scripting application programing interface (API) and direct data extraction from ARIA.

Implementation of high-dose-rate brachytherapy for prostatic carcinoma in an unshielded operating room facility.

Purpose: The purpose of the study was to describe our approach towards safe delivery of single-fraction high-dose-rate (HDR) brachytherapy (BT) boost in patients with prostate cancer in the setting of an unshielded operating room (OR).

Methods And Materials: A total of 95 patients received 15 Gy HDR BT boost. The procedure involved transrectal ultrasound-based catheter insertion and planning in the OR, after which the patient was moved to a shielded treatment room for radiation.

Analysis of outcomes after non-contour-based dose painting of dominant intra-epithelial lesion in intra-operative low-dose rate brachytherapy.

Purpose: To compare the outcomes of patients with intermediate risk prostate cancer (IR-PCa) treated with low-dose rate I-125 seed brachytherapy (LDR-BT) and targeted dose painting of a histologic dominant intra-epithelial lesion (DIL) to those without a DIL.

Methods: 455 patients with IR-PCa were treated at a single center with intra-operatively planned LDR-BT, each following the same in-house dose constraints. Patients with a DIL on pathology had hot spots localized to that region but no specific contouring during the procedure.