Is the Imaging Radiation Oncology Core Head and Neck Credentialing Phantom an Effective Surrogate for Different Anatomic Sites?

Purpose: The Imaging Radiation Oncology Core (IROC) head and neck (H&N) phantom is used to credential institutions for intensity modulated radiation therapy delivery for all anatomic sites where delivery of modulated therapy is a primary challenge. This study evaluated how appropriate the use of this phantom is for varied clinical anatomy by evaluating how closely the IROC H&N phantom described clinical dose errors from beam modeling compared with various anatomic sites.

Methods And Materials: The multileaf collimator (MLC) offset, transmission, percent depth dose, and 7 additional beam modeling parameters for a Varian accelerator were modified in RayStation to match community data at the 2.

A radiotherapy community data-driven approach to determine which complexity metrics best predict the impact of atypical TPS beam modeling on clinical dose calculation accuracy.

Purpose: To quantify the impact of treatment planning system beam model parameters, based on the actual spread in radiotherapy community data, on clinical treatment plans and determine which complexity metrics best describe the impact beam modeling errors have on dose accuracy.

Methods: Ten beam modeling parameters for a Varian accelerator were modified in RayStation to match radiotherapy community data at the 2.5, 25, 50, 75, and 97.

A real-time contouring feedback tool for consensus-based contour training.

Purpose: Variability in contouring structures of interest for radiotherapy continues to be challenging. Although training can reduce such variability, having radiation oncologists provide feedback can be impractical. We developed a contour training tool to provide real-time feedback to trainees, thereby reducing variability in contouring.

Our Experience Leading a Large Medical Physics Practice During the COVID-19 Pandemic.

Purpose: To provide a series of suggestions for other Medical Physics practices to follow in order to provide effective radiation therapy treatments during the COVID-19 pandemic.

Methods And Materials: We reviewed our entire Radiation Oncology infrastructure to identify a series of workflows and policy changes that we implemented during the pandemic that yielded more effective practices during this time.

Results: We identified a structured list of several suggestions that can help other Medical Physics practices overcome the challenges involved in delivering high quality radiotherapy services during this pandemic.

Implementation of a stereotactic body radiotherapy program for unresectable pancreatic cancer in an integrated community academic radiation oncology satellite network.

Unlabelled: With increasing interest in stereotactic body radiotherapy (SBRT) for unresectable pancreatic cancer, quality improvement (QI) initiatives to develop integrated clinical workflows are crucial to ensure quality assurance (QA) when introducing this challenging technique into radiation practices.

Materials/methods: In 2017, we used the Plan, Do, Study, Act (PDSA) QI methodology to implement a new pancreas SBRT program in an integrated community radiation oncology satellite. A unified integrated information technology infrastructure was used to virtually integrate the planned workflow into the community radiation oncology satellite network (P - Plan/D - Do).

Prospective Comparison of Toxicity and Cosmetic Outcome After Accelerated Partial Breast Irradiation With Conformal External Beam Radiotherapy or Single-Entry Multilumen Intracavitary Brachytherapy.

Purpose: This study aimed to prospectively characterize toxicity and cosmesis after accelerated partial breast irradiation (APBI) with 3-dimensional conformal radiation therapy (CRT) or single-entry, multilumen, intracavitary brachytherapy.

Methods And Materials: A total of 281 patients with pTis, pT1N0, or pT2N0 (≤3.0 cm) breast cancer treated with segmental mastectomy were prospectively enrolled from December 2008 through August 2014.

Lower mean heart dose with deep inspiration breath hold-whole breast irradiation compared with brachytherapy-based accelerated partial breast irradiation for women with left-sided tumors.

Purpose: For left-sided breast cancer, radiation to the heart is a concern. We present a comparison of mean heart and coronary artery biologically effective dose (BED) between accelerated partial breast irradiation (APBI) and whole breast irradiation with deep inspiration breath-hold technique (DIBH-WBI).

Methods And Materials: A total of 100 patients with left-sided, early-stage breast cancer were identified.

Contralateral breast dose from partial breast brachytherapy.

The purpose of this study was to determine the dose to the contralateral breast during accelerated partial breast irradiation (APBI) and to compare it to external beam-published values. Thermoluminescent dosimeter (TLD) packets were used to measure the dose to the most medial aspect of the contralateral breast during APBI simulation, daily quality assurance (QA), and treatment. All patients in this study were treated with a single-entry, multicatheter device for 10 fractions to a total dose of 34 Gy.

Commissioning results of an automated treatment planning verification system.

A dose calculation verification system (VS) was acquired and commissioned as a second check on the treatment planning system (TPS). This system reads DICOM CT datasets, RT plans, RT structures, and RT dose from the TPS and automatically, using its own collapsed cone superposition/convolution algorithm, computes dose on the same CT dataset. The system was commissioned by extracting basic beam parameters for simple field geometries and dose verification for complex treatments.

Use of a newly developed delivery device for percutaneous introduction of multiple lead configurations for spinal cord stimulation.

Objective: The Epiducer lead delivery system is a novel lead delivery device that can be used to percutaneously implant S-Series paddle leads (St. Jude Medical, Plano, TX, USA) as well as multiple percutaneous leads obviating the need for laminectomy and/or multiple needle sticks, respectively. This study evaluates the safety and usage of the Epiducer lead delivery system.

Impact of neonatal NOS-1 inhibitor exposure on neurobehavioural measures and prefrontal-temporolimbic integration in the rat nucleus accumbens.

Nitric oxide (NO) is a gaseous neurotransmitter that plays a significant role in the establishment and refinement of functional neural circuits. Genetic and post-mortem studies have suggested that neuronal NO synthase (NOS-1) activity may be compromised in frontal and temporal lobes, and related structures, in schizophrenia. The goal of this study was to determine if there is a link between neonatal disruptions in NO signalling and disturbances in the development and function of prefrontal-temporolimbic circuits.

On the feasibility of treating to a 1.5 cm PTV with a commercial single-entry hybrid applicator in APBI breast brachytherapy.

Purpose: To evaluate and determine whether 30 patients previously treated with the SAVI™ device could have been treated to a PTV_EVAL created with a 1.5 cm expansion. This determination was based upon dosimetric parameters derived from current recommendations and dose-response data.

A new paradigm for calculating skin dose.

Purpose: Most institutions model breast epidermis with a surface contour and record the maximum dose on the external surface of the patient. The objective of this study was to compare the external surface contour (ext) model of the skin with our current volumetric model for skin for radiation treatment planning in accelerated partial breast irradiation brachytherapy.

Methods And Materials: A literature search was conducted to identify studies measuring breast epidermal thickness.

Behavioral sensitization to amphetamine is not accompanied by changes in glutamate receptor surface expression in the rat nucleus accumbens.

We examined whether behavioral sensitization to amphetamine is associated with redistribution of glutamate receptors (GluR) in the rat nucleus accumbens (NAc) or dorsolateral striatum (DLSTR). Following repeated amphetamine treatment and 21 days of withdrawal, surface and intracellular levels of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) or NMDA receptor subunits were determined using a protein cross-linking assay. In contrast to our previous results in cocaine-sensitized rats, we did not observe redistribution of GluR1 or GluR2 to the cell surface in the NAc after amphetamine withdrawal, although a small increase in total GluR1 was found in the shell subregion.

Cortical cholinergic transmission and cortical information processing in schizophrenia.

Models of the neuronal mediation of psychotic symptoms traditionally have focused on aberrations in the regulation of mesolimbic dopaminergic neurons, via their telencephalic afferent connections, and on the impact of abnormal mesolimbic activity for functions of the ventral striatum and its pallidal-thalamic-cortical efferent circuitry. Repeated psychostimulant exposure models major aspects of the sensitized activity of ventral striatal dopaminergic transmission that is observed in patients exhibiting psychotic symptoms. Based on neuroanatomical, neurochemical, and behavioral data, the hypothesis that an abnormally reactive cortical cholinergic input system represents a necessary correlate of a sensitized mesolimbic dopaminergic system is discussed.

Murine lung tumor measurement using respiratory-gated micro-computed tomography.

Objective: The authors explored micro-computed tomography (micro-CT) to quantify lung tumor number and volume in a specific genetic mouse model for lung cancer.

Materials And Methods: The authors used K-ras mice, which develop lung adenomas and adenocarcinomas through somatic activation of the K-ras oncogene. Tumor number measured using micro-CT and were compared at necropsy (n = 38 mice).

Neurochemical correlates of sparing from motor deficits in rats depleted of striatal dopamine as weanlings.

The behavioral and neurochemical effects of striatal DA depletions were investigated in rats lesioned as weanlings (Day 27) or as adults (250-300 g). Administration of 6-OHDA into the medial forebrain bundle resulted in comparably large (> or = 95%) depletions of tissue levels of DA in both age groups. As expected, rats depleted of DA as adults exhibited marked deficits in motoric behavior and body weight regulation that persisted for the 8 days of postsurgical observation.

Sensitization of cortical acetylcholine release by repeated administration of nicotine in rats.

Rationale: The integrity of cortical cholinergic transmission is vital to attentional processing. A growing literature suggests that alterations in attentional processing accompany addictive drug use. This study examined the effects of acute and repeated administration of nicotine on cortical acetylcholine release.

Effects of acute and repeated systemic administration of ketamine on prefrontal acetylcholine release and sustained attention performance in rats.

Rationale: The effects of non-competitive N-methyl- D-aspartate (NMDA) receptor antagonists model aspects of schizophrenic symptomatology. Because effects on both cortical cholinergic transmission and attentional processes have been hypothesized to represent components of the properties of psychotogenic drugs, the present study investigated the effects of ketamine on the activity of cortical cholinergic inputs and attentional performance.

Objective: To determine the effects of acute and repeated ketamine administration on cortical acetylcholine release and performance of rats in an operant task designed to assess sustained attention performance.