Publications by authors named "Edgar Gelover"
Article Synopsis
- Ultra high dose rate (UHDR) radiotherapy, specifically conformal FLASH proton therapy, offers potential benefits by minimizing damage to healthy tissue while effectively targeting tumors.
- Clinical application of conformal FLASH has faced challenges, particularly concerning the quality assurance of measuring dose rate (DR) and linear energy transfer (LET).
- The study successfully validated these parameters, demonstrating strong agreement between experimental data and Monte Carlo simulations, confirming the efficacy of the UHDR treatment approach.
Purpose: The aim of this work is to describe the clinical implementation of respiratory-gated spot-scanning proton therapy (SSPT) for the treatment of thoracic and abdominal moving targets. The experience of our institution is summarized, from initial acceptance and commissioning tests to the development of standard clinical operating procedures for simulation, motion assessment, motion mitigation, treatment planning, and gated SSPT treatment delivery.
Materials And Methods: A custom respiratory gating interface incorporating the Real-Time Position Management System (RPM, Varian Medical Systems, Inc.
The objective of this study was to assess the recommended DVH parameter (e.g., D2 cc) addition method used for combining EBRT and HDR plans, against a reference dataset generated from an EQD2-based DVH addition method.
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- The study compared the effectiveness of a dynamic collimation system (DCS) versus a fixed aperture for proton therapy in treating brain cancer.
- Five patients were re-evaluated using a planning system that assessed both collimated and uncollimated proton beams to measure the advantages of each approach.
- Results showed that DCS significantly reduced the mean dose to surrounding normal tissue by an average of 13.65% and improved treatment conformity by 21.35%, outperforming the fixed aperture method.
Purpose: To quantify improvement in target conformity in brain and head and neck tumor treatments resulting from the use of a dynamic collimation system (DCS) with two spot scanning proton therapy delivery systems (universal nozzle, UN, and dedicated nozzle, DN) with median spot sizes of 5.2 and 3.2 mm over a range of energies from 100 to 230 MeV.
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- Interest in collimation for spot scanning proton therapy aims to enhance the lateral penumbra, particularly for head and neck cancer patients, by comparing uncollimated and collimated treatment plans.
- A study involving 10 head and neck cancer patients demonstrated that collimation improved dose conformity and reduced the mean dose to nearby organs at risk, highlighting benefits like -11.9% for the esophagus and -7.2% for the larynx.
- While collimation generally offers better target conformity and organ sparing, the effectiveness varies based on organ location and target complexity, making individualized assessment crucial for optimal treatment outcomes.
Purpose: To quantify the dosimetric benefit of using a dynamic collimation system (DCS) for penumbra reduction during the treatment of brain tumors by pencil beam scanning proton therapy (PBS PT).
Methods And Materials: Collimated and uncollimated brain treatment plans were created for 5 patients previously treated with PBS PT and retrospectively enrolled in an institutional review board-approved study. The in-house treatment planning system, RDX, was used to generate the plans because it is capable of modeling both collimated and uncollimated beamlets.
The use of collimator or aperture may sharpen the lateral dose gradient for spot scanning proton therapy. However, to date, there has not been a standard method to determine the aperture margin for a single field in collimated spot scanning proton therapy. This study describes a theoretical framework to select the optimal aperture margin for a single field, and also presents the spot spacing limit required such that the optimal aperture margin exists.
View Article and Find Full Text PDFPurpose: To introduce a method to model the 3D dose distribution of laterally asymmetric proton beamlets resulting from collimation. The model enables rapid beamlet calculation for spot scanning (SS) delivery using a novel penumbra-reducing dynamic collimation system (DCS) with two pairs of trimmers oriented perpendicular to each other.
Methods: Trimmed beamlet dose distributions in water were simulated with MCNPX and the collimating effects noted in the simulations were validated by experimental measurement.