Toward a pre-clinical irradiator using clinical infrastructure.

Published on Feb 1, 2019in Physica Medica2.485
· DOI :10.1016/J.EJMP.2019.01.006
David Parsons6
Estimated H-index: 6
(UTSW: University of Texas Southwestern Medical Center),
Cody Church2
Estimated H-index: 2
(Dal: Dalhousie University),
Alasdair Syme8
Estimated H-index: 8
(Dal: Dalhousie University)
Sources
Abstract
Abstract Purpose Pre-clinical irradiation systems use kilovoltage x-ray systems to deliver small fields of radiation in static beam arrangements or arcs. The systems are costly and the radiobiological effectiveness of kilovoltage beams is known to differ from the megavoltage photon beams used clinically. This work used Developer mode on the Varian TrueBeam STx linear accelerator to create a pre-clinical irradiator capable of treating millimeter-sized targets. Materials and methods A treatment field defined by a single opposed leaf pair was used to deliver arc-based treatments. Dynamic couch trajectories were used to create a shortened virtual isocentre. Initially, a pre-treatment imaging procedure was used to quantify target misalignment at control points along the arcs and determine appropriate couch positional corrections. This was followed by the treatment arcs in which the positional corrections were implemented. Monte Carlo simulations and radiochromic film were used to calculate and measure dose distributions. Results A 1 mm leaf separation produced the optimal dose distributions. Couch position corrections up to 2.1 mm were required to maintain a target at virtual isocentre. Application of couch corrections reduced non-coplanar arc treatments dose profile by 1.2 mm at 30% of the maximum dose. Treatment of a 1 mm diameter target would result in falloff distances to the 80%, 50% and 25% of the 90% prescription line of 0.3 mm, 0.5 mm and 1.3 mm from the target edge respectively. Conclusions This work has demonstrated that it is possible to deliver highly compact dose distributions using megavoltage photon beams from existing clinical infrastructure.
📖 Papers frequently viewed together
5 Authors (C Ma, ..., Lili Chen)
3 Citations
15 Citations
References33
Newest
#1M. Tynan R. Stevens (Dal: Dalhousie University)H-Index: 6
#2D Parsons (Dal: Dalhousie University)H-Index: 3
Last. James Robar (Dal: Dalhousie University)H-Index: 9
view all 3 authors...
Purpose To investigate the improvement of combined monoscopic/stereoscopic prostate motion monitoring with room-mounted dual x-ray systems by adopting patient specific methods. Methods The linac couch was used as a motion stage to simulate 40 highly dynamic real patient prostate trajectories. For each trajectory, 40 s pretreatment and 120 s treatment periods were extracted to represent a typical treatment fraction. Motion was monitored via continuous stereoscopic x-ray imaging of a single gold f...
6 CitationsSource
#1David Parsons (Dal: Dalhousie University)H-Index: 6
#2M. Tynan R. Stevens (Dal: Dalhousie University)H-Index: 6
Last. James Robar (Dal: Dalhousie University)H-Index: 9
view all 3 authors...
PURPOSE: The focus of this work was to improve the available kV image quality for continuous intrafraction monitoring of the prostate during volumetric modulated arc therapy. This is investigated using a novel blade collimation system enabling tube current modulated (TCM) volume-of-interest (VOI) imaging of prostate fiducial markers during radiotherapy, and Monte Carlo simulation of MV scatter. MATERIALS AND METHODS: A four-blade dynamic kV collimator was used to track a VOI containing gold fidu...
1 CitationsSource
#1M. Tynan R. Stevens (Dal: Dalhousie University)H-Index: 6
#2D Parsons (Dal: Dalhousie University)H-Index: 3
Last. James L. Robar (Dal: Dalhousie University)H-Index: 8
view all 3 authors...
Purpose: To demonstrate continuous kV x-ray monitoring of prostate motion using both stereoscopic and monoscopic localizations, assess the spatial accuracy of these techniques, and evaluate the dose delivered from the added image guidance. Methods: The authors implemented both stereoscopic and monoscopic fiducial localizations using a room-mounted dual oblique x-ray system. Recently developed monoscopic 3D position estimation techniques potentially overcome the issue of treatment head interferen...
12 CitationsSource
#1B. R. B. WaltersH-Index: 5
#2Iwan KawrakowH-Index: 39
DOSXYZnrc is an EGSnrc-based Monte Carlo simulation code for calculating dose distributions in a rectilinear voxel phantom and is based directly on the DOSXYZ code developed for the EGS4 code system (see NRC Report PIRS-509B). DOSXYZnrc is part of the OMEGABEAM system of codes developed at NRC. Density and material in every voxel may vary. A variety of beams may be incident on the phantom, including full phase-space files from BEAMnrc and beams characterized using Beam Characterization models. T...
80 Citations
#1J. Stewart (U of T: University of Toronto)H-Index: 11
#2Steve Ansell (Princess Margaret Cancer Centre)H-Index: 7
Last. David A. JaffrayH-Index: 96
view all 4 authors...
Advances in precision microirradiators for small animal radiation oncology studies have provided the framework for novel translational radiobiological studies. Such systems target radiation fields at the scale required for small animal investigations, typically through a combination of on-board computed tomography image guidance and fixed, interchangeable collimators. Robust targeting accuracy of these radiation fields remains challenging, particularly at the millimetre scale field sizes achieva...
8 CitationsSource
#1M. Jermoumi (UMass: University of Massachusetts Amherst)H-Index: 1
#2Houari Korideck (Brigham and Women's Hospital)H-Index: 10
Last. Wilfred Ngwa (UMass: University of Massachusetts Amherst)H-Index: 19
view all 8 authors...
Purpose To develop and test the suitability and performance of a comprehensive quality assurance (QA) phantom for the Small Animal Radiation Research Platform (SARRP).
18 CitationsSource
#1C. Noblet (French Institute of Health and Medical Research)H-Index: 6
#2Sophie Chiavassa (French Institute of Health and Medical Research)H-Index: 13
Last. Gregory Delpon (French Institute of Health and Medical Research)H-Index: 15
view all 6 authors...
Abstract The aim of this study was to evaluate, by comparing simulation results with measurement results, the impact of the lack of scattering volume in experimental conditions of preclinical irradiation. First, a Monte Carlo model of a small animal irradiator, the Faxitron CP-160, was developed with GATE (Geant4 Application for Tomography Emission). To validate the model, simulated data were compared to depth dose and off-axis ratio profiles measured with a plane-parallel ionization chamber and...
15 CitationsSource
#1J. Stewart (Princess Margaret Cancer Centre)H-Index: 11
#2Patricia Lindsay (Princess Margaret Cancer Centre)H-Index: 19
Last. David A. Jaffray (Princess Margaret Cancer Centre)H-Index: 96
view all 3 authors...
Purpose: Recent advances in preclinical radiotherapy systems have provided the foundation for scaling many of the elements of clinical radiation therapy practice to the dimensions and energy demanded in small animal studies. Such systems support the technical capabilities to accurately deliver highly complex dose distributions, but methods to optimize and deliver such distributions remain in their infancy. This study developed an optimization method based on empirically measured two-dimensional ...
23 CitationsSource
#1Rulon Mayer (Henry M. Jackson Foundation for the Advancement of Military Medicine)H-Index: 15
#2Fuhwa Ma (Walter Reed National Military Medical Center)H-Index: 1
Last. John O'Connell (Walter Reed National Military Medical Center)H-Index: 6
view all 7 authors...
Purpose: Quantitatively determine an optimum image analysis procedure to mitigate inhomogeneities within the EBT2 film and from scanning for accurate absolute dose measurement deposited by an external radiation therapy beam. Multichannel dosimetry procedures were conceived, described, and quantitatively tested against single and dual channel dosimetry. Methods: A solid waterTM block was placed on CTimaging and treatment tables in a configuration that avoids bulky compressive devices. CT markers ...
74 CitationsSource
#1Hiroshi OnishiH-Index: 32
#2Hiroki Shirato (Hokkaido University)H-Index: 82
Last. Tsutomu ArakiH-Index: 34
view all 20 authors...
Purpose To review treatment outcomes for stereotactic body radiotherapy (SBRT) in medically operable patients with Stage I non–small-cell lung cancer (NSCLC), using a Japanese multi-institutional database. Patients and Methods Between 1995 and 2004, a total of 87 patients with Stage I NSCLC (median age, 74 years; T1N0M0, n = 65; T2N0M0, n = 22) who were medically operable but refused surgery were treated using SBRT alone in 14 institutions. Stereotactic three-dimensional treatment was performed ...
453 CitationsSource
Cited By2
Newest
#1Cody Church (Dal: Dalhousie University)H-Index: 2
#2David Parsons (UTSW: University of Texas Southwestern Medical Center)H-Index: 6
Last. Alasdair Syme (Dal: Dalhousie University)H-Index: 8
view all 3 authors...
PURPOSE Intrafraction patient motion is a well-documented phenomenon in radiation therapy. In stereotactic radiosurgery applications in which target sizes can be very small and dose gradients very steep, patient motion can significantly impact the magnitude and positional accuracy of the delivered dose. This work investigates the impact of intrafraction motion on dose metrics for small targets when treated with a virtual cone. MATERIALS AND METHODS Monte Carlo simulations were performed to calcu...
Source
#1Gage RedlerH-Index: 10
#2E Pearson (U of C: University of Chicago)H-Index: 6
Last. Rodney D. Wiersma (UPenn: University of Pennsylvania)H-Index: 1
view all 10 authors...
PURPOSE Preclinical radiation replicating clinical IMRT techniques can provide data translatable to clinical practice. For this work, treatment plans are created for oxygen-guided dose-painting in small animals utilizing inverse-planned IMRT. Spatially varying beam intensities were achieved using 3D-printed compensators. METHODS AND MATERIALS Optimized beam fluence from arbitrary gantry angles was determined using a verified model of the XRAD225Cx treatment beam. Compensators were 3D-printed wit...
2 CitationsSource