Mark Oldham

• PhD
• Professor (Full) at Duke University Medical Center

Background Advanced radiation therapy techniques, including intensity‐modulated radiation therapy (IMRT), stereotactic radiosurgery (SRS), adaptive therapy, and proton therapy, offer high precision in delivering radiation doses to tumors while minimizing exposure to surrounding healthy tissues. These sophisticated methods necessitate stringent qual...

Objective. To develop and benchmark a novel 3D dose verification technique consisting of polymer gel dosimetry (PGD) with cone-beam-CT (CBCT) readout through a two-institution study. The technique has potential for wide and robust applicability through reliance on CBCT readout. Approach. Three treatment plans (3-field, TG119-C-shape spine, 4-target...

A comprehensive 3D dosimetry system consisting of the ClearView ™ 3D dosimeter, VistaScan ™ optical CT scanner, and VistaAce ™ analysis software is commercially available and has the potential to be a strong verification tool with widespread applications. The clinical utility of this system (termed ClearView/Vista) has yet to be determined, and thi...

Background Sophisticated modern radiation therapy treatments require comprehensive validation in 3D. Purpose Investigation and characterization of a novel 3D dosimetry system consisting of ClearView radiochromic gel dosimeters (commercially available from Modus Inc) and an in‐house telecentric optical CT scanner DLOS (the Duke Large Field of View...

Purpose The purpose of this study was to investigate the feasibility of using fused deposition modeling (FDM) three‐dimensional (3D) printer to generate radiation compensators for high‐resolution (~1 mm) intensity‐modulated radiation therapy (IMRT) for small animal radiation treatment. We propose a novel method incorporating 3D‐printed compensator...

Purpose To develop and demonstrate a comprehensive method to directly measure radiation isocenter uncertainty and coincidence with the cone‐beam computed tomography (kV‐CBCT) imaging coordinate system that can be carried out within a typical quality assurance (QA) time slot. Methods An N‐isopropylacrylamide (NIPAM) three‐dimensional (3D) dosimeter...

RECA (Radiotherapy Enhanced with Cherenkov photo-Activation) is a proposed treatment where the anti-cancer drug psoralen is photo-activated in situ by UVA (Ultraviolet A, 320-400nm) Cherenkov light (CL) produced directly by the treatment beam itself. In this study, we develop a UVA-imaging technique to quantify relative UVA CL produced by bulk tiss...

Purpose Radiochromic film remains a useful and versatile clinical dosimetry tool. Current film options are single use. Here, we introduce a novel prototype two‐dimensional (2D) radiochromic sheet, which optically clears naturally at room temperature after irradiation and can be reused. We evaluate the sheets for potential as a 2D dosimeter and as a...

The present study investigates a cost effective and practical non-telecentric optical-CT scanner developed for 3D dosimetry, the Duke Integrated-Lens Optical-CT scanner (DIOS). The DIOS system includes an upgraded light-collimating tank (the LC-tank) made of solid polyurethane with precision curved ends (with lensing functionality) and a precision...

This work investigates a novel reusable radiochromic sheet developed as an economic film substitute or as a radiochromic bolus. The radiation-induced optical density (OD) change of the sheet is read-out with a commercial flat-bed optical scanner. An optimized readout procedure was developed including an optimal scan-time window. Fundamental radioch...

We investigated the feasibility of using N-isopropylacrylamide (NIPAM) dosimeters with x-ray CT to verify radiosurgery dose. Dosimeters were prepared at one facility and shipped to a second facility for irradiation. A simulation CT was acquired and plans prepared for a 4 field box, and a 4 arc VMAT radiosurgery plan to 6 targets with 1cm diameter....

Purpose: To demonstrate proof of principle of visualizing delivered 3-dimensional (3D) dose distribution using kilovoltage (kv) cone beam computed tomography (CBCT) mounted onboard a linear accelerator. We apply this technique as a unique end-to-end verification of multifocal radiosurgery where the coincidence of radiation and imaging systems is q...

The charge of AAPM Task Group 113 is to provide guidance for the physics aspects of clinical trials to minimize variability in planning and dose delivery for external beam trials involving photons and electrons. Several studies have demonstrated the importance of protocol compliance on patient outcome. Minimizing variability for treatments at diffe...

Purpose: Radiotherapy (RT) is commonly used to treat most pelvic malignancies. While treatment is often effective, curative radiation doses to the rectum can result in chronic radiation-induced proctitis, which is characterized by diarrhea, tenesmus, and/or rectal bleeding, recently termed pelvic radiation disease. An animal model of chronic radia...

Purpose: Cherenkov light during MV radiotherapy has recently found imaging and therapeutic applications, but is challenged by relatively low fluence. Our purpose is to investigate the feasibility of increasing Cherenkov light production during MV radiotherapy by increasing photon energy and applying specialized beam hardening filtration. Methods:...

Purpose This work investigates a new approach to enhance radiotherapy through a photo-therapeutic agent activated by Cherenkov light produced from the megavoltage photon beam. The process is termed Radiotherapy Enhanced with Cherenkov photo-Activation (RECA). RECA is compatible with various photo-therapeutics, but here we focus on use with psoralen...

Purpose: To develop a novel remote 3D dosimetry protocol to verify Magnetic Resonance-guided Radiation Therapy (MRgRT) treatments. The protocol was applied to investigate the accuracy of TG-119 IMRT irradiations delivered by the MRIdian(®) system (ViewRay(®) , Oakwood Village, Ohio) allowing for a 48 hour delay between irradiation at a field insti...

Tumor tissue oxygenation significantly affects the outcome of radiotherapy. Real-time monitoring of tumor hypoxia is highly desirable for effective radiotherapy, and is the basis for improved treatment because hypoxic tumor cells are more resistant to radiation damage than fully oxygenated cells. We propose to use Cerenkov imaging to monitor tumor...

Purpose: To develop and validate 3D conformal hippocampal sparing whole-brain radiation therapy (HA-WBRT) for Wistar rats utilizing precision 3D printed immobilization and micro-blocks. This technique paves the way for future pre-clinical studies investigating brain treatments that reduce neurotoxicity. Methods and materials: A novel pre-clinica...

X-ray psoralen activated cancer therapy (X-PACT) is a new therapeutic approach that has been shown to induce tumor cell apoptosis and cytotoxicity in vitro, and slow tumor growth in BALB/c mice with syngeneic 4T1 tumors. X-PACT is accomplished by injection of co-incubated psoralen and phosphors; the phosphors emit UV to activate psoralen, and are a...

Recent years have witnessed a remarkable evolution in the techniques, capabilities and applications of 3D dosimetry. Initially the goal was simple: to innovate new techniques capable of comprehensively measuring and verifying exquisitely intricate dose distributions from a paradigm changing emerging new therapy, IMRT. Basic questions emerged: how w...

This work introduces the Duke Integrated-lens Optical Scanner (DIOS), a prototype optical-CT system designed for convenient and low-cost readout of PRESAGE 3D dosimeters. A key novelty of the DIOS is the incorporation of a multi-purpose light-collimating tank (the LC-tank). The LC-tank collimates light from a point source, maintains parallel ray ge...

This work explores and demonstrates the feasibility of utilizing new 3D printing techniques to implement advanced micro radiation therapy for pre-clinical small animal studies. 3D printed blocks and compensators were designed and printed from a strong x-ray attenuating material at sub-millimeter resolution. These techniques enable a powerful range...

Despite increasing use of stereotactic radiosurgery, whole brain radiotherapy (WBRT) continues to have a therapeutic role in a selected subset of patients. Selectively avoiding the hippocampus during such treatment (HA-WBRT) emerged as a strategy to reduce the cognitive morbidity associated with WBRT and gave rise to a recently published the phase...

To develop and apply a remote dosimetry protocol with PRESAGE® radiochromic plastic and optical-CT readout in the validation of MRI guided radiation therapy (MRgRT) treatments (MRIdian® by ViewRay®). Through multi-institutional collaboration we performed PRESAGE® dosimetry studies in 4ml cuvettes to investigate dose-response linearity, MR-compatibi...

Purpose To validate the dosimetric accuracy of a commercially available magnetic resonance guided intensity modulated radiation therapy (MRgIMRT) system using a hybrid approach: 3-dimensional (3D) measurements and Monte Carlo calculations. Methods and Materials We used PRESAGE radiochromic plastic dosimeters with remote optical computed tomography...

This work investigates X-PACT (X-ray Psoralen Activated Cancer Therapy): a new approach for the treatment of solid cancer. X-PACT utilizes psoralen, a potent anti-cancer therapeutic with current application to proliferative disease and extracorporeal photopheresis (ECP) of cutaneous T Cell Lymphoma. An immunogenic role for light-activated psoralen...

Purpose:The first goal of this work is to develop software that can simulate the physics of linear accelerators (linac). The second goal is to show that this simulation tool is effective in teaching linac physics to medical physicists and linac service engineers. Methods:Linacs were modeled using analytical expressions that can correctly describe t...

Purpose: To validate the dosimetric accuracy of a commercially available MR-IGRT system using a combination of 3D dosimetry measurements (with PRESAGE(R) radiochromic plastic and optical-CT readout) and an in-house developed GPU-accelerated PENELOPE Monte-Carlo dose calculation system. Methods: 60Co IMRT subject to a 0.35T lateral magnetic field ha...

There is substantial current interest in the potential of radiation therapy for synergizing with novel immunotherapies to transform irradiated tumor into an immunogenic hub with capacity to ignite a powerful and adaptive longterm anti-cancer response. Interest stems from new insights into fundamental mechanisms underlying interactions between cance...

There is substantial current interest in the potential of radiation therapy for synergizing with novel immunotherapies to transform irradiated tumor into an immunogenic hub with capacity to ignite a powerful and adaptive longterm anti-cancer response. Interest stems from new insights into fundamental mechanisms underlying interactions between cance...

Despite widespread IMRT treatments at modern radiation therapy clinics, precise dosimetric commissioning of an IMRT system remains a challenge. In the most recent report from the Radiological Physics Center (RPC), nearly 20% of institutions failed an end-to-end test with an anthropomorphic head and neck phantom, a test that has rather lenient dose...

Purpose:This work investigates X-PACT (X-ray Psoralen Activated Cancer Therapy): a new approach for the treatment of cancer. X-PACT utilizes psoralen, a potent anti-cancer therapeutic with immunogenic anti-cancer potential. Psoralen therapies have been limited due to the requirement for psoralen activation by UVA light. X-PACT solves this challenge...

Purpose:Optical transmission and emission computed tomography (optical-CT/ECT) provides high-resolution 3D attenuation and emission maps in unsectioned large (∼1cm3) ex vivo tissue samples at a resolution of 12.9µm3 per voxel. Here we apply optical-CT/ECT to investigate high-resolution structure and auto-fluorescence in a range of optically cleared...

Purpose:To validate the use of a PRESAGE dosimeter as a method to quantitatively measure dose distributions of injectable brachytherapy based on elastin-like polypeptide (ELP) nanoparticles. PRESAGE is a solid, transparent polyurethane-based dosimeter whose dose is proportional to a change in optical density, making it useful for visualizing the do...

Purpose: X-PACT is an experimental cancer therapy where kV x-rays are used to photo-activate anti-cancer therapeutics through phosphor intermediaries (phosphors that absorb x-rays and re-radiate as UV light). Clinical trials in pet dogs are currently underway (NC State College of Veterinary Medicine) and an essential component is the ability to mod...

Purpose:Cerenkov emissions are a natural byproduct of MV radiotherapy but are typically ignored as inconsequential. However, Cerenkov photons may be useful for activation of drugs such as psoralen. Here, we investigate Cerenkov radiation from common radiotherapy beams using Monte Carlo simulations. Methods:GAMOS, a GEANT4-based framework for Monte...

Purpose:Near-IR absorptive up-converting nanoparticles (UCNPs) is a novel contrast for optical-ECT that allows auto-fluorescence-free 3D imaging of labeled cells in a matrix of large (∼1cm3) unsectioned normal tissue. This has the potential to image small metastases or dormant cells that is difficult with down-converting fluorescing dyes due to aut...

Purpose:Comprehensive 3D dosimetry is highly desirable for advanced clinical QA, but costly optical readout techniques have hindered widespread implementation. Here, we present the first results from a cost-effective Integrated-lens Dry-tank Optical Scanner (IDOS), designed for convenient 3D dosimetry readout of radiochromic plastic dosimeters (e.g...

Purpose: To develop, evaluate and apply a novel high-resolution 3D remote dosimetry protocol for validation of MRI guided radiation therapy treatments (MRIdian by ViewRay™). We demonstrate the first application of the protocol (including two small but required new correction terms) utilizing radiochromic 3D plastic PRESAGE™ with optical-CT readout....

Telecentric optical computed tomography (optical-CT) is a state-of-the-art method for visualizing and quantifying 3-dimensional dose distributions in radiochromic dosimeters. In this work a prototype telecentric system (DFOS-Duke Fresnel Optical-CT Scanner) is evaluated which incorporates two substantial design changes: the use of Fresnel lenses (r...

MATLAB data set corresponding to 4-field box treatment 1. (ZIP)

Background: Despite the clinical benefit of whole brain radiotherapy (WBRT), patients and physicians are concerned by the long-term impact on cognitive functioning. Many studies investigating the molecular and cellular impact of WBRT have used rodent models. However, there has not been a rodent protocol comparable to the recently reported Radiatio...

Registration points F1-6 on MRI and CBCT images. (PDF)

Registrations points F1-6 on 3D skull rendering. (AVI)

Purpose: To introduce a pre-clinical treatment technique on a micro-irradiator to treat specific volumes of dorsal mammary tumors in BALB/c mice while sparing lungs and spine. This technique facilitates pre-clinical investigation of tumor response to sub-optimal radiation treatments in which a portion of the tumor is unirradiated, known as a “marg...

Optical-emission computed tomography (optical- ECT) enables high-resolution 3D imaging of emission in optically cleared tissues on the order of 1 cm(3). This work demonstrates capabilities of optical-ECT to quantify the red fluorescent protein (RFP) tdTomato in rat lung, and presents preliminary data on the feasibility of imaging near-IR absorptive...

Purpose 3D‐gel dosimetry provides high‐resolution treatment validation; however, scanners aren't widely available. In remote dosimetry, dosimeters are shipped out from a central base institution to a remote site for irradiation, then shipped back for scanning and analysis, affording a convenient service for treatment validation to institutions lack...

Preliminary studies of a novel, optically-clearing PRESAGE 3D dosimeter formulation (Presage-RU) demonstrated potential reusability. This study investigates the effects of time and temperature on the accuracy and reusability of Presage-RU, and reports on progress toward developing a reusable 3D dosimeter. Presage-RU was cast as small volume samples...

Purpose: Psoralen is a UV-light activated anti-cancer biotherapeutic used for treating skin lesions (PUVA) and advanced cutaneous T-cell lymphoma (ECP). To date psoralen has not been used to treat deep seated tumors due to difficulty in generating UV-light at depth. We recently demonstrated psoralen activation at depth by introducing energy conver...

Purpose: Delta4 dosimetric software can be used to calculate DVH-based metrics for patient-specific quality assurance from measurements made by a Delta4 QA device. This study investigates the effectiveness of a novel transform method that transposes measurements made with a full-density 3D dosimeter onto patient anatomy, enabling the calculation o...

Purpose: To design, construct and commission a prototype in-house three dimensional (3D) dose verification system for stereotatic body radiotherapy (SBRT) verification at an off-site partner institution. To investigate the potential of this system to achieve sufficient performance (1mm resolution, 3% noise, within 3% of true dose reading) for SBRT...

In optical-CT, the use of a refractively matched polyurethane solid-tank in place of a fluid bath has the potential to greatly increase practical convenience, reduce cost, and possibly improve the efficacy of flood corrections. This work investigates the feasibility of solid-tank optical-CT imaging for 3D dosimetry through computer simulation. A ma...

The application of a biomechanical deformable image registration algorithm has been demonstrated to overcome the potential limitations in the use of intensity-based algorithms on low-contrast images that lack prominent features. Because validation of deformable registration is particularly challenging on such images, the dose distribution predicted...

The purpose of this work was to characterize three formulations of PRESAGE® dosimeters (DEA-1, DEA-2, and DX) and to identify optimal readout timing and procedures for accurate in-house 3D dosimetry. The optimal formulation and procedure was then applied for the verification of an intensity modulated radiation therapy (IMRT) and a volumetric modula...

Purpose: Sophisticated small animal irradiators, incorporating cone-beam-CT image-guidance, have recently been developed which enable exploration of the efficacy of advanced radiation treatments in the preclinical setting. Microstereotactic-body-radiation-therapy (microSBRT) is one technique of interest, utilizing field sizes in the range of 1–15...

This study investigates a reusable PRESAGE® 3D dosimeter (Presage-RU), which would improve cost-effectiveness and facilitate wider implementation of comprehensive, high resolution 3D dosimetry. Small (1x1x4.5 cm) and large (8 cm diameter, 4.5 cm length) sample dosimeters were irradiated multiple times to characterize dose response (i.e. radiation-i...

Optical computed tomography (optical-CT) is a method for visualizing 3dimensional dose distributions in radiochromic dosimeters. Projection images are acquired by collimating a visible light point source into parallel-beam geometry and imaging differential absorption through the sample dosimeter. Practical challenges involved in optical-CT imaging...

Micro-beam Radiation Therapy (MRT) is an experimental radiation therapy with provocative experimental data indicating potential for improved efficacy in some diseases. Here we demonstrated a comprehensive micro-beam verification method utilizing high resolution (50pm) PRESAGE/Micro-Optical-CT 3D Dosimetry. A small PRESAGE cylindrical dosimeter was...

Radiochromic materials exhibit a colour change when exposed to ionising radiation. Radiochromic film has been used for clinical dosimetry for many years and increasingly so recently, as films of higher sensitivities have become available. The two principle advantages of radiochromic dosimetry include greater tissue equivalence (radiologically) and...

Purpose: To investigate the feasibility of and challenges yet to be addressed to measure dose from low energy (effective energy <50 keV) brachytherapy sources (Pd-103, Cs-131, and I-125) using polyurethane based 3D dosimeters with optical CT. Methods: The authors' evaluation used the following sources: models 200 (Pd-103), CS-1 Rev2 (Cs-131), an...

Purpose: This study investigates the feasibility of remote high-resolution 3D dosimetry with the PRESAGE®/Optical-CT system. In remote dosimetry, dosimeters are shipped out from a central base institution to a remote institution for irradiation, then shipped back to the base institution for subsequent readout and analysis. Methods: Two nominally...

Determining accurate in vivo dosimetry in brachytherapy treatment with high dose gradients is challenging. Here we introduce, investigate, and characterize a novel in vivo dosimeter and readout technique with the potential to address this problem. A cylindrical (4 mm × 20 mm) tissue equivalent radiochromic dosimeter PRESAGE® in vivo (PRESAGE®-IV) i...

Purpose To perform simulations investigating the feasibility of “dry” optical‐CT, and determine optimal design and scanning parameters for a novel dry tank telecentric optical‐CT 3D dosimetry system. Such a system would have important advantages in terms of practical convenience and reduced cost. Methods A Matlab based ray‐tracing simulation platf...

Purpose To test the ability of the TG‐119 commissioning process and RPC credentialing to detect errors in the commissioning process for a commercial Treatment Planning System (TPS). Methods We introduced commissioning errors into the commissioning process for the Anisotropic Analytical Algorithm (AAA) within the Eclipse TPS. We included errors in...

Purpose: Presage-Def, a deformable radiochromic 3D dosimeter, has been previously shown to have potential for validating deformable image registration algorithms. This work extends this effort to investigate the feasibility of using Presage-Def to validate dose-accumulation algorithms in deforming structures. Methods: Two cylindrical Presage-Def do...

Purpose To quantitatively evaluate a 3D patient specific QA tool using 2D film and 3D Presage dosimetry. Methods A brain IMRT case was delivered to Delta4, EBT2 film and Presage plastic dosimeter. The film was inserted in the solid water slabs at 7.5cm depth for measurement. The Presage dosimeter was inserted into a head phantom for 3D dose measur...

Purpose: PRESAGE is a radiochromic plastic which has demonstrated strong potential for high resolution single-use 3D dosimetry. This study evaluates a new PRESAGE formulation (Presage-RU) in which the radiochromic response is reversible (the dosimeter optically clears after irradiation), enabling the potential for reusability.

Online education is rapidly becoming an important means of communicating content in educational activities across a broad spectrum of fields, including medical physics. We are currently at a point of broad change in educational strategies and methodologies, and the use of online content is likely to play an increasingly important role in medical ph...

Purpose: Pre-clinical micro-radiation therapy studies often utilize very small beams (∼0.5-5mm), and require accurate dose delivery in order to effectively investigate treatment efficacy. Here we present a novel high-resolution absolute 3D dosimetry procedure, capable of ∼100-micron isotopic dosimetry in anatomically accurate rodent-morphic phantom...

Purpose To characterize and explore the efficacy of a novel low‐cost, lowfluid, broad‐beam optical‐CT system for 3D‐dosimetry in radiochromic Presage dosimeters. Leading current optical‐CT systems incorporate expensive glass‐based telecentric lens technology, and a fluid bath with substantial amounts of fluid (which introduces an inconvenience fact...

Accurate and robust deformable image registration (DIR) is a key enabling technique in the clinical realization of two approaches for advancing radiation therapy treatment efficacy: adaptive radiation therapy and treatment response assessment. Currently there are a wide variety of DIR methods including the categories of splines, optical/diffusion,...

Purpose: The feasibility of MRT has recently been demonstrated utilizing a new technology of Carbon-Nano-Tube(CNT) field emission x-ray sources.This approach can deliver very high dose(10's of Gy) in narrow stripes(sub-mm) of radiation which enables the study of novel radiation treatment approaches. Here we investigate the application of highresolu...

Purpose: To demonstrate an embedded tissue equivalent presage dosimeter for measuring 3D doses in moving tumors and to study the interplay effect between the tumor motion and intensity modulation in hypofractioned Volumetric Modulated Arc Therapy(VMAT) lung treatment. Methods: Motion experiments were performed using cylindrical Presage dosimeters (...

Purpose: Recent trends in stereotactic radiosurgery use multifocal volumetric modulated arc therapy (VMAT) plans to simultaneously treat several distinct targets. Conventional verification often involves low resolution measurements in a single plane, a cylinder, or intersecting planes of diodes or ion chambers. This work presents an investigation...

There is significant interest in delivering precisely targeted small-volume radiation treatments, in the pre-clinical setting, to study dose-volume relationships with tumour control and normal tissue damage. For these studies it is vital that image guidance systems and target positioning are accurately aligned (IGRT), in order to deliver dose preci...

To introduce and evaluate a novel deformable 3-dimensional (3D) dosimetry system (Presage-Def/Optical-CT) and its application toward investigating the accuracy of dose deformation in a commercial deformable image registration (DIR) package. Presage-Def is a new dosimetry material consisting of an elastic polyurethane matrix doped with radiochromic...

There is a pressing need for clinically intuitive quality assurance methods that report metrics of relevance to the likely impact on tumor control of normal tissue injury. This paper presents a preliminary investigation into the accuracy of a novel "transform method" which enables a clinically relevant analysis through dose-volume-histograms (DVHs)...

Achieving accurate optical CT 3D dosimetry without the use of viscous refractive index (RI) matching fluids would greatly increase convenience. Software has been developed to simulate optical CT 3D dosimetry for a range of scanning configurations including parallel-beam, point and converging light sources. For each configuration the efficacy of 3 r...

There is significant interest in delivering precisely targeted small-volume radiation treatments, in the pre-clinical setting, to study dose-volume relationships with tumor control and normal tissue damage. In this work we investigate the IGRT targeting accuracy of the XRad225Cx system from Precision x-Ray using high resolution 3D dosimetry techniq...

Deformable 3D dosimeters have potential applications in validating deformable dose mapping algorithms. This study evaluates a novel deformable PRESAGE(®) dosimeter and its application toward validating the deformable algorithm employed by VelocityAI. The deformable PRESAGE(®) dosimeter exhibited a linear dose response with a sensitivity of 0.0032 Δ...

We describe a method to directly measure the radial dose and anisotropy functions of brachytherapy sources using polyurethane based dosimeters read out with optical CT. We measured the radial dose and anisotropy functions for a Cs-137 source using a PRESAGE® dosimeter (9.5cm diameter, 9.2cm height) with a 0.35cm channel drilled for source placement...

PRESAGE(®) is a solid radiochromic dosimeter consisting of a polyurethane matrix, a triarylmethane leuco dye, and a trihalomethane initiator. Varying the composition and/or relative amounts of these constituents can affect the dose sensitivity, post-irradiation stability, and physical properties of the dosimeter. This allows customisation of PRESAG...

Six base of skull IMRT treatment plans were delivered to Presage dosimeters within the RPC Head and Neck Phantom for quality assurance (QA) verification. Isotropic 2mm 3D data were acquired by optical-CT scanning with the DLOS system (Duke Large Optical-CT Scanner) and compared to the Eclipse (Varian) treatment plan. Normalized Dose Distribution (N...

Stereotactic radiosurgery has become a widely used technique to treat solid tumors and secondary metastases of the brain. Multiple targets can be simultaneously treated with a single isocenter in order to reduce the set-up time to improve patient comfort and workflow. In this study, a 5-arc multifocal RapidArc treatment was delivered to multiple PR...

Six base of skull IMRT treatment plans were delivered to 3D dosimeters within the RPC Head and Neck Phantom for QA verification. Isotropic 2mm 3D data was obtained using the DLOS-PRESAGE system and compared to an Eclipse (Varian) treatment plan. Normalized Dose Distribution pass rates were obtained for a number of criteria. High quality 3D dosimetr...

Purpose: Achieving accurate optical-CT 3D dosimetry without the use of viscous refractive index (RI) matching fluids would greatly increase convenience. This work evaluates various potential 'dry-scan' optical-CT configurations (including parallel, point, and converging light-ray geometries) through computer simulations. Methods: Three surroundi...

Purpose: To evaluate the feasibility of novel rodentmorphic 3D dosimeters for comprehensive high-resolution verification of the treatment accuracy of a state-of-the-art micro-irradiator equipped with on-line cone-beam-CT guidance. Methods: Anatomically accurate 3D dosimeter molds were created in a two step procedure. First, rodents were CT scann...

Purpose: Compact microbeam radiation therapy (MRT) recently became feasible through the development of carbon-nanotube based distributed x-ray array technology. This work investigates the feasibility of novel highresolution 3D dosimetry techniques (50μm isotropic) for the challenging task of characterizing microbeam irradiations of nominal width 3...

Purpose: Recent innovations in 3D dosimetry include deformable polyurethane dosimeters (PRESAGE) and high resolution optical CT (∼50 microns). These developments enable 3D dosimetry in deformation conditions present during prostate LDR brachytherapy. However, water equivalence for the deformable dosimeter formulations has not been quantified. The...

Purpose: Previous work has demonstrated that Presage-Def, a deformable, polyurethane-based radiochromic 3D dosimeter, has strong potential for validating deformable image registration algorithms by tracking optically measured radiation patterns from the deformed shape to the non-deformed shape. Here we present recent investigations into the effica...