Abstract:
PURPOSE:To achieve more translatable preclinical research results, small animal irradiation needs to more closely simulate human radiotherapy. Although the clinical gold standard is intensity-modulated radiation therapy (IMRT), the direct translation of this method for small animals is impractical. In this study we describe the treatment planning system for a novel dose modulation device to address this challenge. METHODS:Using delineated target and avoidance structures, a rectangular aperture optimization (RAO) problem was formulated to penalize deviations from a desired dose distribution and limit the number of selected rectangular apertures. RAO was used to create IMRT plans with highly concave targets in the mouse brain, and the plan quality was compared to that using a hypothetical miniaturized multileaf collimator (MLC). RAO plans were also created for a realistic application of mouse whole liver irradiation and for a highly complex two-dimensional (2D) dose distribution as a proof-of-principle. Beam commissioning data, including output and off-axis factors and percent depth dose (PDD) curves, were acquired for our small animal irradiation system and incorporated into the treatment planning system. A plan post-processing step was implemented for aperture size-specific dose recalculation and aperture weighting reoptimization. RESULTS:The first RAO test case achieved highly conformal doses to concave targets in the brain, with substantially better dose gradient, conformity, and target dose homogeneity than the hypothetical miniaturized MLC plans. In the second test case, a highly conformal dose to the liver was achieved with significant sparing of the kidneys. RAO also successfully replicated a complex 2D dose distribution with three prescription dose levels. Energy spectra for field sizes 1 to 20 mm were calculated to match the measured PDD curves, with maximum and mean dose deviations of 4.47 ± 0.30% and 1.71 ± 0.18%. The final reoptimization of aperture weightings for the complex RAO test plan was able to reduce the maximum and mean dose deviations between the optimized and recalculated dose distributions from 10.3% to 6.6% and 4.0% to 2.8%, respectively. CONCLUSIONS:Using the advanced optimization techniques, complex IMRT plans were achieved using a simple dose modulation device. Beam commissioning data were incorporated into the treatment planning process to more accurately predict the resulting dose distribution. This platform substantially reduces the gap in treatment plan quality between clinical and preclinical radiotherapy, potentially increasing the value and flexibility of small animal studies.
journal_name
Med Physjournal_title
Medical physicsauthors
Woods K,Nguyen D,Neph R,Ruan D,O'Connor D,Sheng Kdoi
10.1002/mp.13872subject
Has Abstractpub_date
2019-12-01 00:00:00pages
5703-5713issue
12eissn
0094-2405issn
2473-4209journal_volume
46pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract::The intensity modulated arc has been proposed as an alternative to tomotherapy. Treatment planing systems more typically model the conventional step and shoot or sliding window dynamic multileaf collimator (DMLC) deliveries, and may not support intensity modulated arc therapy (IMAT). As well, another potential drawbac...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1508110
更新日期:2002-10-01 00:00:00
abstract:PURPOSE:The appearance of parenchymal∕stromal patterns in mammography have been characterized as having a Wiener power spectrum with an inverse power-law shape described by the exponential parameter, β. The amount of fibroglandular tissue, which can be quantified in terms of volumetric breast density (VBD), influences ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4736422
更新日期:2012-08-01 00:00:00
abstract:PURPOSE:Most radiation therapy optimization problems can be formulated as an unconstrained problem and solved efficiently by quasi-Newton methods such as the Limited-memory Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) algorithm. However, several next generation planning techniques such as total variation regularization- b...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12165
更新日期:2017-04-01 00:00:00
abstract::An analytic expression is derived for the transmission of isotropic scattered radiation incident upon an ideal parallel grid. It is found that the expression for the transmission usually found in the literature overestimates the transmission by approximately a factor of two. ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.594877
更新日期:1981-11-01 00:00:00
abstract::In many of brachytherapy procedures, a large amount of radioactive sources are used to deliver desired doses to the target volume. It is both the federal regulation recommendation (U.S. Nuclear Regulatory Commission, 10 CFR 35.432) and recommendations of the American Association of Physicists in Medicine (AAPM) [Kutch...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2734723
更新日期:2007-06-01 00:00:00
abstract:PURPOSE:There are growing expectations that imaging biomarkers for tumor therapeutic drug response assessment will speed up preclinical testing of anticancer drugs in rodent models. The only imaging biomarker presently approved by the U.S. Food and Drug Administration is tumor size measurement based on either World Hea...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3464491
更新日期:2010-09-01 00:00:00
abstract::When parallel-plate chambers are used for dosimetry in electron fields, the AAPM dosimetry protocol recommends a value of 1.0 for the replacement correction factor, P(repl),pp,E, until further data become available. Here, P(repl),pp,E for five commercially available parallel-plate chambers was measured as a function o...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596740
更新日期:1991-11-01 00:00:00
abstract:PURPOSE:To provide specific experience-based guidance and recommendations for centers wishing to develop, validate, and implement an accurate and efficient process for directly using positron emission tomography-computed tomography (PET-CT) for the radiotherapy planning of head and neck cancer patients. METHODS:A PET-...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4867856
更新日期:2014-04-01 00:00:00
abstract:PURPOSE:A series of examples are presented in which potential errors in the delivery of radiation therapy were prevented through use of incident learning. These examples underscore the value of reporting near miss incidents. METHODS:Using a departmental incident learning system, eight incidents were noted over a two-y...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4760774
更新日期:2012-11-01 00:00:00
abstract:PURPOSE:For almost four decades bead and wire ramps have been used in the evaluation of slice width as part of QA testing for CT scanners. While each of these approaches have been recognized and accepted as reliable, in this paper we investigate the differences, advantages and limitations of these tools. Moreover, we s...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4734753
更新日期:2012-06-01 00:00:00
abstract::Intravascular brachytherapy requires that the dose be specified within millimeters of the source. High dose gradients near brachytherapy sources require that the source-detector distance be accurately known for dosimetry purposes. Solid phantoms can be designed to accommodate these stringent requirements. This study r...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1376176
更新日期:2001-06-01 00:00:00
abstract::Estimated photon energy spectra are derived from transmission measurements using aluminium, copper, and sodium iodide absorbers. Two spectral models are proposed. One is based on a previously published model that analyzes the electron's penetration into the anode, and the production and attenuation of bremsstrahlung p...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598159
更新日期:1997-05-01 00:00:00
abstract:PURPOSE:Many biological objects, including neuronal dendrites, blood vasculature, airways, phylogenetic trees, produce tree structured data. Current methods of analysis either ignore the complex structure of trees or use distance-based methods which limit the scope of multivariate modeling. METHODS:We propose a branch...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12751
更新日期:2018-03-01 00:00:00
abstract:PURPOSE:A radiophotoluminescent glass rod dosimeter (RGD) has recently become commercially available. It is being increasingly used for dosimetry in radiotherapy to measure the absorbed dose including scattered low-energy photons on the body surface of a patient and for postal dosimetry audit. In this article, the dosi...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4747261
更新日期:2012-10-01 00:00:00
abstract::Digital tomosynthesis (DTS) is a fast, low-dose three-dimensional (3D) imaging approach which yields slice images with excellent in-plane resolution, though low plane-to-plane resolution. A stack of DTS slices can be reconstructed from a single limited-angle scan, with typical scan angles ranging from 10 degrees to 40...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2756941
更新日期:2007-08-01 00:00:00
abstract:PURPOSE:The possible clinical applications which can be performed using a newly developed detector depend on the detector's characteristic performance in a number of metrics including the dynamic range, resolution, uniformity, and stability. The authors have evaluated a prototype energy resolved fast photon counting x-...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4892174
更新日期:2014-09-01 00:00:00
abstract::A commercially available open MRI unit is under routine use for radiation therapy simulation. The effects of a gradient distortion correction (GDC) program used to post process the images were assessed by comparison with the known geometry of a phantom. The GDC reduced the magnitude of the distortions at the periphery...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1513991
更新日期:2002-11-01 00:00:00
abstract:PURPOSE:To formulate convex planning objectives of treatment plan multicriteria optimization with explicit relationships to the dose-volume histogram (DVH) statistics used in plan quality evaluation. METHODS:Conventional planning objectives are designed to minimize the violation of DVH statistics thresholds using pena...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12146
更新日期:2017-06-01 00:00:00
abstract::A computer dose model for a low energy gamma-emitting stent in a heterogeneous medium is described. The method is based on the Sievert model which is adapted to the dose-point-kernel (DPK) model to compute the dose distribution about filtered gamma sources (Sievert-DPK model). The new gamma stent model can take into a...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1380214
更新日期:2001-07-01 00:00:00
abstract:PURPOSE:To find an upper bound on the maximum dose reduction possible for any reconstruction algorithm, analytic or iterative, that result from the inclusion of the data statistics. The authors do not analyze noise reduction possible from prior knowledge or assumptions about the object. METHODS:The authors examined th...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4941954
更新日期:2016-03-01 00:00:00
abstract:PURPOSE:Two-dimensional ultrasound (2D US) imaging is commonly used for diagnostic and intraoperative guidance of interventional liver procedures; however, 2D US lacks volumetric information that may benefit interventional procedures. Over the past decade, three-dimensional ultrasound (3D US) has been developed to prov...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4824326
更新日期:2013-11-01 00:00:00
abstract::Positron emission tomography (PET) is increasingly considered as an effective imaging method to support several stages of radiation therapy. The combined usage of functional and morphological imaging in state-of-the-art PET/CT scanners is rapidly emerging to support the treatment planning process in terms of improved ...
journal_title:Medical physics
pub_type: 杂志文章,评审
doi:10.1118/1.4935869
更新日期:2015-12-01 00:00:00
abstract::A fast method of seed matching and reconstruction in prostate brachytherapy is proposed. Previous approaches have required all seeds to be matched with all other seeds in other projections. The fast cross-projection algorithm for the reconstruction of seeds (Fast-CARS) allows for matching of a given seed with a subset...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1489044
更新日期:2002-07-01 00:00:00
abstract:PURPOSE:Stereotactic body radiation therapy (SBRT) is a radiotherapy technique which uses high dose fractions with multiple coplanar and noncoplanar beams. Due to the large fractional doses, treatments are typically protracted and there are more fields than in conventional radiation treatment schemes. The effect of tem...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4709605
更新日期:2012-06-01 00:00:00
abstract:PURPOSE:Small animal immobilization devices facilitate positioning of animals for reproducible imaging and accurate focal radiation therapy. In this study, the authors demonstrate the use of three-dimensional (3D) printing technology to fabricate a custom-designed mouse head restraint. The authors evaluate the accuracy...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4933200
更新日期:2015-11-01 00:00:00
abstract:PURPOSE:To accurately and efficiently implement charged particle transport in a magnetic field in EGSnrc and validate the code for the use in phantom and ion chamber simulations. METHODS:The effect of the magnetic field on the particle motion and position is determined using one- and three-point numerical integrations...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4954318
更新日期:2016-07-01 00:00:00
abstract:PURPOSE:Respiratory gating in PET is an approach used to minimize the negative effects of respiratory motion on spatial resolution. It is based on an initial determination of a patient's respiratory movements during a scan, typically using hardware based systems. In recent years, several fully automated databased algor...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3483784
更新日期:2010-10-01 00:00:00
abstract::Single kernel scatter correction algorithms are based on the model that the scatter field can be predicted by convolution of the primary intensity (Iprim) with a spatially invariant scatter point-spread function (PSF). Practical limitations (Iprim unknown) suggest the substitution of the total detected intensity (Idet...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.597297
更新日期:1994-02-01 00:00:00
abstract:PURPOSE:To report on significant dose enhancement effects caused by magnetic fields aligned parallel to 6 MV photon beam radiotherapy of small lung tumors. Findings are applicable to future inline MRI-guided radiotherapy systems. METHODS:A total of eight clinical lung tumor cases were recalculated using Monte Carlo me...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4938580
更新日期:2016-01-01 00:00:00
abstract::The physical characteristics of a clinical charge coupled device (CCD)-based imager (Senovision, GE Medical Systems, Milwaukee, WI) for small-field digital mammography have been investigated. The imager employs a MinR 2000 (Eastman Kodak Company, Rochester, NY) scintillator coupled by a 1:1 optical fiber to a front-il...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1286720
更新日期:2000-08-01 00:00:00