Postoperative Radiotherapy ± Cetuximab for Intermediate-Risk Head and Neck Cancer.

Purpose: Radiotherapy (RT)/cetuximab (C) demonstrated superiority over RT alone for locally advanced squamous head and neck cancer. We tested this in completely resected, intermediate-risk cancer.

Methods: Patients had squamous cell carcinoma of the head and neck (SCCHN) of the oral cavity, oropharynx, or larynx, with one or more risk factors warranting postoperative RT.

Stereotactic Radiosurgery for Patients with Brain Metastases from Hepatopancreaticobiliary Cancers.

Background: The role of stereotactic radiosurgery (SRS) for patients with brain metastases from hepatopancreaticobiliary (HPB) cancers has yet to be established. The authors present a single-institution experience of patients with HPB cancers who underwent SRS when their cancer spread to the brain.

Methods: We surveyed our Gamma Knife SRS data base of 18,000 patients for the years 1987-2022.

Recommendations on the practice of calibration, dosimetry, and quality assurance for gamma stereotactic radiosurgery: Report of AAPM Task Group 178.

The American Association of Physicists in Medicine (AAPM) formed Task Group 178 (TG-178) to perform the following tasks: review in-phantom and in-air calibration protocols for gamma stereotactic radiosurgery (GSR), suggest a dose rate calibration protocol that can be successfully utilized with all gamma stereotactic radiosurgery (GSR) devices, and update quality assurance (QA) protocols in TG-42 (AAPM Report 54, 1995) for static GSR devices. The TG-178 report recommends a GSR dose rate calibration formalism and provides tabulated data to implement it for ionization chambers commonly used in GSR dosimetry. The report also describes routine mechanical, dosimetric, and safety checks for GSR devices, and provides treatment process quality assurance recommendations.

Failure modes and effects analysis (FMEA) for Gamma Knife radiosurgery.

Purpose: Gamma Knife radiosurgery is a highly precise and accurate treatment technique for treating brain diseases with low risk of serious error that nevertheless could potentially be reduced. We applied the AAPM Task Group 100 recommended failure modes and effects analysis (FMEA) tool to develop a risk-based quality management program for Gamma Knife radiosurgery.

Methods: A team consisting of medical physicists, radiation oncologists, neurosurgeons, radiation safety officers, nurses, operating room technologists, and schedulers at our institution and an external physicist expert on Gamma Knife was formed for the FMEA study.

Clinical implementation and evaluation of the Acuros dose calculation algorithm.

Purpose: The main aim of this study is to validate the Acuros XB dose calculation algorithm for a Varian Clinac iX linac in our clinics, and subsequently compare it with the wildely used AAA algorithm.

Methods And Materials: The source models for both Acuros XB and AAA were configured by importing the same measured beam data into Eclipse treatment planning system. Both algorithms were validated by comparing calculated dose with measured dose on a homogeneous water phantom for field sizes ranging from 6 cm × 6 cm to 40 cm × 40 cm.

Two-year experience with the commercial Gamma Knife Check software.

The Gamma Knife Check software is an FDA approved second check system for dose calculations in Gamma Knife radiosurgery. The purpose of this study was to evaluate the accuracy and the stability of the commercial software package as a tool for independent dose verification. The Gamma Knife Check software version 8.

Gamma Knife radiosurgery with CT image-based dose calculation.

The Leksell GammaPlan software version 10 introduces a CT image-based segmentation tool for automatic skull definition and a convolution dose calculation algorithm for tissue inhomogeneity correction. The purpose of this work was to evaluate the impact of these new approaches on routine clinical Gamma Knife treatment planning. Sixty-five patients who underwent CT image-guided Gamma Knife radiosurgeries at the University of Pittsburgh Medical Center in recent years were retrospectively investigated.

A round-robin gamma stereotactic radiosurgery dosimetry interinstitution comparison of calibration protocols.

Purpose: Absorbed dose calibration for gamma stereotactic radiosurgery is challenging due to the unique geometric conditions, dosimetry characteristics, and nonstandard field size of these devices. Members of the American Association of Physicists in Medicine (AAPM) Task Group 178 on Gamma Stereotactic Radiosurgery Dosimetry and Quality Assurance have participated in a round-robin exchange of calibrated measurement instrumentation and phantoms exploring two approved and two proposed calibration protocols or formalisms on ten gamma radiosurgery units. The objectives of this study were to benchmark and compare new formalisms to existing calibration methods, while maintaining traceability to U.

A Mobile Alert System for Preparing the Delivery of Radiation Mitigators.

Background/aim: A mobile system allowing hospital medical personnel to prepare for the administration of radiation mitigators prior to receiving casualties is desirable.

Materials And Methods: We evaluated a portable spectroscopic personal radiation detector for use as an ambulance-based unit for early detection and identification of gamma radiation. We tested the sensitivity, time-to-identification, and radionuclide identification accuracy rates, change in detector response to vehicle operation, interference from cardiac equipment, and internal versus external radiation source location.

Dose differences between the three dose calculation algorithms in Leksell GammaPlan.

The purpose of this study was to evaluate the dose differences introduced by the TMR 10 and the convolution dose calculation algorithms in GammaPlan version 10, as compared to the TMR classic algorithm in the previous versions of GammaPlan. Computed axial tomographic images of a polystyrene phantom and a human head were acquired using a GE LightSpeed VCT scanner. A treatment target with a prescription dose of 20 Gy to 50% isodose line was defined in the phantom or the head CT set.

The use of strain tensor to estimate thoracic tumors deformation.

Purpose: Respiration-induced kinematics of thoracic tumors suggests a simple analogy with elasticity, where a strain tensor is used to characterize the volume of interests. The application of the biomechanical framework allows for the objective determination of tumor characteristics.

Methods: Four-dimensional computed tomography provides the snapshots of the patient's anatomy at the end of inspiration and expiration.

Distinguishing borderline personality disorder from adult attention deficit/hyperactivity disorder: a clinical and dimensional perspective.

Adult attention deficit hyperactivity disorder (ADHD) is frequently associated with borderline personality disorder (BPD). As both disorders share some core clinical features they are sometimes difficult to distinguish from one another. The present work aimed to investigate differences in the expression of impulsivity, anger and aggression, quality of life as well as the number and severity of the comorbidities between ADHD, BPD, comorbid BPD-ADHD and control subjects.

Interceptor and Phantom Trials of EDNS at UPMC.

University of Pittsburgh Medical Center (UPMC) installed an Emergency Department Notification System (EDNS) in one of its hospitals. The system, manufactured by Thermo Fisher Scientific (Thermo Fisher Scientific, Inc., 81 Wyman Street, Waltham, MA 02454), consists of four NaI(Tl) scintillation detectors, a 2.

SU-E-J-161: Biomechanical Framework for Thoracic Tumors Characteristics.

Purpose: Respiration-induced kinematics of thoracic tumors suggests a simple analogy with elasticity, where a strain is used to characterize the volume of interests. The application of the biomechanical framework allows for the objective determination of tumor characteristics.

Methods: The deformation of a given tissue element can be determined if its displacement is known.

Implementation of remote 3-dimensional image guided radiation therapy quality assurance for radiation therapy oncology group clinical trials.

Purpose: To report the process and initial experience of remote credentialing of three-dimensional (3D) image guided radiation therapy (IGRT) as part of the quality assurance (QA) of submitted data for Radiation Therapy Oncology Group (RTOG) clinical trials; and to identify major issues resulting from this process and analyze the review results on patient positioning shifts.

Methods And Materials: Image guided radiation therapy datasets including in-room positioning CT scans and daily shifts applied were submitted through the Image Guided Therapy QA Center from institutions for the IGRT credentialing process, as required by various RTOG trials. A centralized virtual environment is established at the RTOG Core Laboratory, containing analysis tools and database infrastructure for remote review by the Physics Principal Investigators of each protocol.

Quality assurance analysis of a large multicenter practice: does increased complexity of intensity-modulated radiotherapy lead to increased error frequency?

Purpose: Error reduction is an important concern in clinical medicine. Intensity-modulated radiotherapy (IMRT) is an important advancement in radiation oncology that increases the complexity of treatment, potentially increasing the error risk. We studied the frequency and severity of errors in a large multicenter practice to ascertain the impact of quality improvement interventions over time, IMRT, and type of practice.

Performance characteristics of a novel radioactive isotope detection and notification system designed for use in hospitals.

Recently, University of Pittsburgh Medical Center (UPMC) Cancer Centers has installed an Emergency Department Notification System (EDNS) in one of its hospitals. This system, manufactured by Thermo Fisher Scientific (Thermo Fisher Scientific, Inc., 81 Wyman Street, Waltham, MA 02454), was designed to discriminate non-medical radioactive isotopes from medical radioactive isotopes routinely used in nuclear medicine and radiation treatments.

A simulation study of irregular respiratory motion and its dosimetric impact on lung tumors.

This study is aimed at providing a dosimetric evaluation of the irregular motion of lung tumors due to variations in patients' respiration. Twenty-three lung cancer patients are retrospectively enrolled in this study. The motion of the patient clinical target volume is simulated and two types of irregularities are defined: characteristic and uncharacteristic motions.

Assessment of variation in Elekta plastic spherical-calibration phantom and its impact on the Leksell Gamma Knife calibration.

Purpose: Traditionally, the dose-rate calibration (output) of the Leksell Gamma Knife (LGK) unit is performed using a 160 mm diameter plastic spherical phantom provided by the vendor of the LGK, Elekta Instrument AB. The purpose of this study was to evaluate variations in the Elekta spherical phantom and to assess its impact and use for the LGK calibration.

Methods: Altogether, 13 phantoms from six different centers were acquired, 10 of these phantoms were manufactured within the past 10 years and the last 3 approximately 15-20 years ago.

Physical characterization and comparison of two commercially available micro-MLCs.

In this study, the physical characteristics (penumbra width variation with the source size and shape, interleaf leakage, transmission through the leaves, and the tongue-and-groove effect) of two linear accelerators (BrainLAB's Novalis and Elekta's Synergy-S Beam Modulator) have been investigated. For similar square fields (about 4.5 cm x 4.

Measurement of relative output factors for the 8 and 4 mm collimators of Leksell Gamma Knife Perfexion by film dosimetry.

Three types of films, Kodak EDR2, Gafchromic EBT, and Gafchromic MD-V2-55, were used to measure relative output factors of 4 and 8 mm collimators of the Leksell Gamma Knife Perfexion. The optical density to dose calibration curve for each of the film types was obtained by exposing the films to a range of known doses. Ten data points were acquired for each of the calibration curves in the dose ranges from 0 to 4 Gy, 0 to 8 Gy, and 0 to 80 Gy for Kodak EDR2, Gafchromic EBT, and Gafchromic MD-V2-55 films, respectively.

Daily image guidance with cone-beam computed tomography for head-and-neck cancer intensity-modulated radiotherapy: a prospective study.

Purpose: To report on a prospective clinical trial of the use of daily kilovoltage cone-beam computed tomography (CBCT) to evaluate the interfraction and residual error motion of patients undergoing intensity-modulated radiotherapy for head-and-neck cancer.

Methods And Materials: Patients were treated with intensity-modulated radiotherapy with an Elekta linear accelerator using a mounted CBCT scanner. CBCT was performed before every treatment, and translational (but not rotational) corrections were performed.

Unintended attenuation in the Leksell Gamma Knife Perfexion calibration-phantom adaptor and its effect on dose calibration.

The calibration of Leksell Gamma Knife Perfexion (LGK PFX) is performed using a spherical polystyrene phantom 160 mm in diameter, which is provided by the manufacturer. This is the same phantom that has been used with LGK models U, B, C, and 4C. The polystyrene phantom is held in irradiation position by an aluminum adaptor, which has stainless steel side-fixation screws.

Report on a randomized trial comparing two forms of immobilization of the head for fractionated stereotactic radiotherapy.

Fractionated stereotactic radiotherapy (SRT) requires accurate and reproducible immobilization of the patient's head. This randomized study compared the efficacy of two commonly used forms of immobilization used for SRT. Two routinely used methods of immobilization, which differ in their approach to reproduce the head position from day to day, are the Gill-Thomas-Cosman (GTC) frame and the BrainLab thermoplastic mask.

Dosimetric comparison of the Leksell Gamma Knife Perfexion and 4C.

Object: The recently introduced Leksell Gamma Knife (LGK) Perfexion is an entirely new system with a different beam geometry compared with the LGK 4C. The new Perfexion system has 192 cobalt-60 sources that are fixed on 8 sectors (each sector has 24 sources). Each sector can be moved independently of the others and can be set to 1 of 5 different positions: 3 positions defining collimator sizes of 4, 8, and 16 mm; an off position (sources are blocked); and a home position.