Initial Clinical Experience With Novel Directional Low-Dose Rate Brachytherapy for Retroperitoneal Sarcoma.

Background: A novel Palladium-103 low-dose rate (LDR) brachytherapy device was developed to provide dose-escalation to the tumor bed after resection while shielding adjacent tissues. This multicenter report describes the initial experience with this device in patients with retroperitoneal sarcoma (RPS).

Materials And Methods: Patients with recurrent RPS, prior radiotherapy, and/or concern for positive margins were considered.

Characterization of Compton-scatter imaging with an analytical simulation method.

By collimating the photons scattered when a megavoltage therapy beam interacts with the patient, a Compton-scatter image may be formed without the delivery of an extra dose. To characterize and assess the potential of the technique, an analytical model for simulating scatter images was developed and validated against Monte Carlo (MC). For three phantoms, the scatter images collected during irradiation with a 6 MV flattening-filter-free therapy beam were simulated.

Acoustic-based proton range verification in heterogeneous tissue: simulation studies.

Acoustic-based proton range verification (protoacoustics) is a potential in vivo technique for determining the Bragg peak position. Previous measurements and simulations have been restricted to homogeneous water tanks. Here, a CT-based simulation method is proposed and applied to a liver and prostate case to model the effects of tissue heterogeneity on the protoacoustic amplitude and time-of-flight range verification accuracy.

A model for predicting the dose to the parotid glands based on their relative overlapping with planning target volumes during helical radiotherapy.

The sparing of the parotid glands in the treatment of head and neck cancers is of clinical relevance as high doses to the salivary glands may result in xerostomia. Xerostomia is a major cause of decreased quality of life for head and neck patients. This paper explores the relationship between the overlap of the target volumes and their expansions with the parotid glands for helical delivery plans and their ability to be spared.

The sensitivity of ArcCHECK-based gamma analysis to manufactured errors in helical tomotherapy radiation delivery.

Three-dimensional measurement arrays are an efficient means of acquiring a distribution of data for patient plan delivery QA. However, the tie between plan integrity and traditional gamma-based analysis of these data are not clear. This study explores the sensitivity of such analysis by creating errors in Helical Tomotherapy delivery and measuring the passing rates with an ArcCHECK cylindrical diode array.

Patterns of locoregional failure in stage III non-small cell lung cancer treated with definitive chemoradiation therapy.

Purpose: Chemoradiation therapy (CRT) is the core treatment of locally advanced non-small cell lung cancer (LA-NSCLC), but potential toxicities limit radiation therapy dose. These toxicities, plus the advent of increasingly conformal radiation therapy, have prioritized target definition and the use of involved-field radiation therapy (IFRT). Published data largely focus on regional rather than local failure patterns.

Patterns of regional failure in stage III non-small cell lung cancer treated with neoadjuvant chemoradiation therapy and resection.

Purpose: Treatment of locally advanced non-small cell lung cancer (LA-NSCLC) involves definitive chemoradiation therapy (CRT) or neoadjuvant CRT and resection, but radiation treatment volumes remain in question. With CRT, involved-field radiation therapy (IFRT) is replacing elective nodal irradiation, reducing toxicity, and allowing dose escalation. However, prior reports of IFRT describe failures only after radical CRT; with improved local control after resection, IFRT may lead to more regional recurrences.

Optimization for high-dose-rate brachytherapy of cervical cancer with adaptive simulated annealing and gradient descent.

Purpose: To validate an in-house optimization program that uses adaptive simulated annealing (ASA) and gradient descent (GD) algorithms and investigate features of physical dose and generalized equivalent uniform dose (gEUD)-based objective functions in high-dose-rate (HDR) brachytherapy for cervical cancer.

Methods: Eight Syed/Neblett template-based cervical cancer HDR interstitial brachytherapy cases were used for this study. Brachytherapy treatment plans were first generated using inverse planning simulated annealing (IPSA).

Integral dose delivered to normal brain with conventional intensity-modulated radiotherapy (IMRT) and helical tomotherapy IMRT during partial brain radiotherapy for high-grade gliomas with and without selective sparing of the hippocampus, limbic circuit and neural stem cell compartment.

Introduction: We compared integral dose with uninvolved brain (IDbrain ) during partial brain radiotherapy (PBRT) for high-grade glioma patients using helical tomotherapy (HT) and seven field traditional inverse-planned intensity-modulated radiotherapy (IMRT) with and without selective sparing (SPA) of contralateral hippocampus, neural stem cell compartment (NSC) and limbic circuit.

Methods: We prepared four PBRT treatment plans for four patients with high-grade gliomas (60 Gy in 30 fractions delivered to planning treatment volume (PTV60Gy)). For all plans, a structure denoted 'uninvolved brain' was created, which included all brain tissue not part of PTV or standard (STD) organs at risk (OAR).

Sparing of the hippocampus, limbic circuit and neural stem cell compartment during partial brain radiotherapy for glioma: a dosimetric feasibility study.

Introduction: The aim of this study was to assess the feasibility of sparing contralateral or bilateral neural stem cell (NSC) compartment, hippocampus and limbic circuit during partial brain radiotherapy (PBRT).

Methods And Materials: Treatment plans were generated for five hemispheric high-grade gliomas, five hemispheric low-grade gliomas and two brainstem gliomas (12 patients). For each, standard intensity-modulated radiotherapy (IMRT) plans were generated, as well as IMRT plans which spared contralateral (hemispheric cases) or bilateral (brainstem cases) limbic circuit, hippocampus, and NSC.

A dosimetric comparison between the supine and prone positions for three-field intact breast radiotherapy.

Purpose: Supine tangential radiotherapy for the intact breast is a standard component of breast conservation management; a supraclavicular (SCV) field can be added for patients at high risk for nodal failure. Treatment in the prone position has demonstrated improvements in lung sparing, but has been limited to early-stage patients in whom radiation to only the breast was indicated. We sought to investigate the dosimetric feasibility of treating women in the prone position, using a 3-field monoisocentric technique.

Sparing of the neural stem cell compartment during whole-brain radiation therapy: a dosimetric study using helical tomotherapy.

Purpose: To assess the feasibility of dosimetrically sparing the hippocampus and neural stem cell (NSC) compartment during whole-brain radiotherapy (WBRT) and prophylactic cranial irradiation (PCI).

Methods And Materials: We contoured the brain/brainstem on fused magnetic resonance /computed tomography images as the planning target volume (PTV) in 10 patients, excluding the hippocampus and NSC compartment as organs at risk. PCI and WBRT helical tomotherapy plans were prepared for each patient, with 1.

Intracranial metastatic disease rarely involves the pituitary: retrospective analysis of 935 metastases in 155 patients and review of the literature.

We present a case report of a patient recently treated at our institution for an isolated non-small cell lung cancer metastatic lesion to the sella, report the lack of involvement of the pituitary gland in a large single-institution series of treated intracranial parenchymal metastases, and review the pertinent literature. We reviewed cranial imaging studies (CT and MRI) for 935 metastases in 155 patients treated at our institution over the previous 3 years for intracranial metastatic disease. Special attention was paid to the skull base to document the presence of any metastatic disease involving the pituitary gland, infundibular stalk, sella turcica (including anterior and posterior clinoids), or diaphragm sellae.

Estimated risk of perihippocampal disease progression after hippocampal avoidance during whole-brain radiotherapy: safety profile for RTOG 0933.

Background And Purpose: RTOG 0933 is a phase II clinical trial of hippocampal avoidance during whole-brain radiotherapy (HA-WBRT) to prevent radiation-induced neurocognitive decline. By quantifying baseline incidence of perihippocampal or hippocampal metastasis, we sought to estimate the risk of developing metastases in the hippocampal avoidance region (the hippocampus plus 5mm margin).

Materials/methods: Patients with < or = 10 brain metastases treated at two separate institutions were reviewed.

Helical tomotherapy and larynx sparing in advanced oropharyngeal carcinoma: a dosimetric study.

Intensity-modulated radiation therapy (IMRT) is gaining acceptance as a standard treatment technique for advanced squamous cell carcinoma (SCC) of the oropharynx. Dose to the uninvolved larynx and surrounding structures can pose a problem in patients with significant neck disease, potentially compromising laryngeal function and quality of life. Tomotherapy may allow greater laryngeal sparing.

A virtual matching technique for three-field breast irradiation using 3-D planning.

Patients with breast cancer are often treated with radiation to the breast (or chest wall) and draining regional lymph nodes. This is typically performed with a three-field technique in which an anterior supraclavicular field is matched to opposed tangent fields. A single isocenter technique is not always possible.

Case report and dosimetric analysis of an axillary recurrence after partial breast irradiation with mammosite catheter.

Partial breast irradiation (PBI) was designed in part to decrease overall treatment times associated with whole breast radiation therapy (WBRT). WBRT treats the entire breast and usually portions of the axilla. The goal of PBI is to treat a smaller volume of breast tissue in less time, focusing the dose around the lumpectomy cavity.

Monte Carlo calculations of output factors for clinically shaped electron fields.

We report on the use of the EGS4/BEAM Monte Carlo technique to predict the output factors for clinically relevant, irregularly shaped inserts as they intercept a linear accelerator's electron beams. The output factor for a particular combination--energy, cone, insert, and source-to-surface distance (SSD)--is defined in accordance with AAPM TG-25 as the product of cone correction factor and insert correction factor, evaluated at the depth of maximum dose. Since cone correction factors are easily obtained, we focus our investigation on the insert correction factors (ICFs).