A Prospective Trial of Single-Fraction Radiation to the Tumor Bed with a Novel Breast-Specific Stereotactic Radiation Therapy Device: The GammaPod.

Purpose: Radiation therapy for early-stage breast cancer is typically delivered in a hypofractionated regimen to the whole breast followed by a tumor bed boost. This results in a treatment course of approximately 4 weeks. In this study, the tumor bed boost was delivered in a single fraction as part of a safety and feasibility study for FDA clearance of the device.

How many brain metastases can be treated with stereotactic radiosurgery before the radiation dose delivered to normal brain tissue rivals that associated with standard whole brain radiotherapy?

Introduction: Clinical trial data comparing outcomes after administration of stereotactic radiosurgery (SRS) or whole-brain radiotherapy (WBRT) to patients with brain metastases (BM) suggest that SRS better preserves cognitive function and quality of life without negatively impacting overall survival. Here, we estimate the maximum number of BM that can be treated using single and multi-session SRS while limiting the dose of radiation delivered to normal brain tissue to that associated with WBRT.

Methods: Multiple-tumor SRS was simulated using a Monte Carlo - type approach and a pre-calculated dose kernel method.

Correlation of treatment time to target volume for GammaPod treatments: A simple second calculation.

Purpose: The GammaPod is a novel device for stereotactic breast treatments that employs 25 rotating Co-60 sources while the patient is continuously translated in three axes to deliver a highly conformal dose to the target. There is no commercial software available for independent second calculations. The purpose of this study is to determine an efficient way to estimate GammaPod treatment times based on target volume and use it as a second calculation for patient-specific quality assurance.

Radiation shielding and safety implications following linac conversion to an electron FLASH-RT unit.

Purpose: Due to their finite range, electrons are typically ignored when calculating shielding requirements in megavoltage energy linear accelerator vaults. However, the assumption that 16 MeV electrons need not be considered does not hold when operated at FLASH-RT dose rates (~200× clinical dose rate), where dose rate from bremsstrahlung photons is an order of magnitude higher than that from an 18 MV beam for which shielding was designed. We investigate the shielding and radiation protection impact of converting a Varian 21EX linac to FLASH-RT dose rates.

Simplified method for determining dose to a non-water phantom through the use of N and IAEA TRS 483 for the GammaPod.

Purpose: GammaPod, a breast stereotactic radiosurgery device, utilizes 25 rotating Co-60 sources to deliver highly conformal dose distributions. The GammaPod system requires that reference dosimetry be performed in a specific vendor-supplied poly-methylmethacrylate (PMMA) phantom. The nonstandard nature of GammaPod dosimetry, in both the phantom material and machine-specific reference (msr), prohibits use of the American Association of Physicists in Medicine Task Group 51 (TG-51) protocol.

Reproducibility of a novel, vacuum-assisted immobilization for breast stereotactic radiotherapy.

A novel, breast-specific stereotactic radiotherapy device has been developed for delivery of highly conformal, accelerated partial breast irradiation. This device employs a unique, vacuum-assisted, breast cup immobilization system that applies a gentle, negative pressure to the target breast with the patient in the prone position. A device-specific patient loader is utilized for simulation scanning and device docking.

Immune checkpoint inhibition in patients treated with stereotactic radiation for brain metastases.

Purpose: Stereotactic radiation therapy (SRT) and immune checkpoint inhibitors (ICI) may act synergistically to improve treatment outcomes but may also increase the risk of symptomatic radiation necrosis (RN). The objective of this study was to compare outcomes for patients undergoing SRT with and without concurrent ICI.

Methods And Materials: Patients treated for BMs with single or multi-fraction SRT were retrospectively reviewed.

The Impact of Radiation Energy on Dose Homogeneity and Organ Dose in the Göttingen Minipig Total-Body Irradiation Model.

Animal models of total-body irradiation (TBI) are used to elucidate normal tissue damage and evaluate the efficacy of medical countermeasures (MCM). The accuracy of these TBI models depends on the reproducibility of the radiation dose-response relationship for lethality, which in turn is highly dependent on robust radiation physics and dosimetry. However, the precise levels of radiation each organ absorbs can change dramatically when different photon beam qualities are used, due to the interplay between their penetration and the natural variation of animal sizes and geometries.

Technical Note: Dosimetric feasibility of lattice radiotherapy for breast cancer using GammaPod.

Purpose: Studies on Lattice radiotherapy (LRT) for breast cancer have been largely lacking. This study investigates the dosimetric feasibility of using Gamma Pod, a stereotactic radiotherapy apparatus originally designed for breast SBRT, to deliver LRT to large, bulky breast tumor as a noninvasive treatment option.

Methods: The GammaPod-based LRT was simulated using Geant4 Gate Monte Carlo software.

Dosimetry evaluation of the GammaPod stereotactic radiosurgery device based on established AAPM and IAEA protocols.

Purpose: The GammaPod is a novel dedicated prone breast stereotactic radiosurgery (SRS) device recently developed at the University of Maryland Medical Center. This device utilizes multiple rotating Co-60 sources to create highly conformal dose distributions for breast treatments, including boosts, partial breast irradiation, or presurgery SRS. However, due to its small field sizes and nonstandard geometry, existing calibration protocols cannot be directly applied.

Development and validation of a comprehensive patient-specific quality assurance program for a novel stereotactic radiation delivery system for breast lesions.

Purpose: The GammaPod is a dedicated prone breast stereotactic radiosurgery (SRS) machine composed of 25 cobalt-60 sources which rotate around the breast to create highly conformal dose distributions for boosts, partial-breast irradiation, or neo-adjuvant SRS. We describe the development and validation of a patient-specific quality assurance (PSQA) system for the GammaPod.

Methods: We present two PSQA methods: measurement based and calculation based PSQA.

Commissioning and acceptance guide for the GammaPod.

The GammaPod breast treatment device has been introduced to provide stereotactic radiation therapy to the breast to patients in the prone position. The GammaPod, using a stereotactic coordinate system, dynamically delivers dose to the target by rotating 25 non-overlapping Co-60 beams while the patient's breast is translated continuously in three axes on the couch during delivery. From simulation to treatment, the patient's breast is immobilized using mild negative pressure (150 mm Hg below atmospheric pressure) through a device-specific dual-cup system with stereotactic fiducials.

A Dose of Reality: How 20 Years of Incomplete Physics and Dosimetry Reporting in Radiobiology Studies May Have Contributed to the Reproducibility Crisis.

Purpose: A large proportion of preclinical or translational studies using radiation have poor replicability. For a study involving radiation exposure to be replicable, interpretable, and comparable, its experimental methodology must be well reported, particularly in terms of irradiation protocol, including the amount, rate, quality, and geometry of radiation delivery. Here we perform the first large-scale literature review of the current state of reporting of essential experimental physics and dosimetry details in the scientific literature.

Dosimetric effects of the kV based image-guided radiation therapy of prone breast external beam radiation: Towards the optimized imaging frequency.

Purpose: For prone breast treatment, daily image-guided radiation therapy (IGRT) allows couch shifting to correct breast position relative to the treatment field. This work investigates the dosimetric effect of reducing kV imaging frequencies and the feasibility of optimizing the frequency using patient anatomy or their first 3-day shifts.

Method: Thirty-seven prone breast patients who had been treated with skin marker alignment followed by daily kV were retrospectively analyzed.

Correlation of radiation dose and activity with clinical outcomes in metastatic colorectal cancer after selective internal radiation therapy using yttrium-90 resin microspheres.

Purpose: Yttrium-90 (Y)-resin microspheres are prescribed using activity. We evaluated overall survival (OS) and radiographic tumor response after selective internal radiation therapy (SIRT) with resin microspheres in patients with liver metastases from colorectal cancer.

Patients And Methods: We retrospectively reviewed 60 metastatic colorectal cancer patients treated at our institution with SIRT using Y-resin microspheres.

Of mice and men: a novel dietary supplement for the treatment of ulcerative colitis.

Background: Curcumin, green tea polyphenols and selenium possess anti-inflammatory and anti-oxidant properties. Individually they have demonstrated some efficacy in animal models and human subjects with inflammatory bowel disease (IBD). To evaluate the efficacy and safety of Coltect [Curcumin (500 mg), green tea (250 mg) and selenium (100 µg)] and in patients with ulcerative colitis (UC).

Collision indicator charts for gantry-couch position combinations for Siemens ONCOR and Elekta Infinity linacs.

Noncoplanar radiation fields from a linear accelerator can be used to deliver radiation dose distributions that are superior to those delivered using coplanar radiation fields. Noncoplanar radiation field arrangements are especially valuable when delivering stereotactic body radiation therapy (SBRT). Noncoplanar radiation fields, however, are geometrically more challenging to deliver than coplanar radiation fields, and are associated with a greater risk of collisions between the gantry, treatment couch, and patient.

Breast radiotherapy in the prone position primarily reduces the maximum out-of-field measured dose to the ipsilateral lung.

Purpose: To quantify the potential advantages of prone position breast radiotherapy in terms of the radiation exposure to out-of-field organs, particularly, the breast or the lung. Several dosimetric studies have been reported, based on commercial treatment planning software (TPS). These TPS approaches are not, however, adequate for characterizing out-of-field doses.

Prone hypofractionated whole-breast radiotherapy without a boost to the tumor bed: comparable toxicity of IMRT versus a 3D conformal technique.

Purpose: We report a comparison of the dosimetry and toxicity of three-dimensional conformal radiotherapy (3D-CRT) vs. intensity-modulated radiotherapy (IMRT) among patients treated in the prone position with the same fractionation and target of the hypofractionation arm of the Canadian/Whelan trial.

Methods And Materials: An institutional review board-approved protocol identified a consecutive series of early-stage breast cancer patients treated according to the Canadian hypofractionation regimen but in the prone position.

Collision indicator charts for gantry-couch position combinations for Varian linacs.

The use of non-coplanar radiation fields can potentially lead to collisions between the gantry and the couch or patient. The collisions are often not realized until the plan is finished and the fields are checked on the machine, or even later when the patient is already on the table. This paper presents an easy method of gauging if a collision is likely between the gantry and couch or patient during treatment planning.

Prospective study of cone-beam computed tomography image-guided radiotherapy for prone accelerated partial breast irradiation.

Purpose: To report setup variations during prone accelerated partial breast irradiation (APBI).

Methods: New York University (NYU) 07-582 is an institutional review board-approved protocol of cone-beam computed tomography (CBCT) to deliver image-guided ABPI in the prone position. Eligible are postmenopausal women with pT1 breast cancer excised with negative margins and no nodal involvement.

Characterization of the transmission of the Elekta Stereotactic Body Frame (ESBF) and accounting for it during treatment planning.

The purpose of this study was to measure the transmission of the Elekta Stereotactic Body Frame (ESBF) and treatment table, to calculate the transmission of the frame in the Eclipse Treatment Planning System (TPS) using analytical anisotropic algorithm (AAA), and to demonstrate a simple method of accounting for this transmission in treatment planning. A solid water body phantom was imaged inside the ESBF and planned with multiple 3D-CRT fields using AAA using both 6-MV and 16-MV energies. In the first set of plans, the frame and table were included in the "Body" contour and, therefore, used in the dose calculations.