Resampling: an optimization method for inverse planning in robotic radiosurgery.


:By design, the range of beam directions in conventional radiosurgery are constrained to an isocentric array. However, the recent introduction of robotic radiosurgery dramatically increases the flexibility of targeting, and as a consequence, beams need be neither coplanar nor isocentric. Such a nonisocentric design permits a large number of distinct beam directions to be used in one single treatment. These major technical differences provide an opportunity to improve upon the well-established principles for treatment planning used with GammaKnife or LINAC radiosurgery. With this objective in mind, our group has developed over the past decade an inverse planning tool for robotic radiosurgery. This system first computes a set of beam directions, and then during an optimization step, weights each individual beam. Optimization begins with a feasibility query, the answer to which is derived through linear programming. This approach offers the advantage of completeness and avoids local optima. Final beam selection is based on heuristics. In this report we present and evaluate a new strategy for utilizing the advantages of linear programming to improve beam selection. Starting from an initial solution, a heuristically determined set of beams is added to the optimization problem, while beams with zero weight are removed. This process is repeated to sample a set of beams much larger compared with typical optimization. Experimental results indicate that the planning approach efficiently finds acceptable plans and that resampling can further improve its efficiency.


Med Phys


Medical physics


Schweikard A,Schlaefer A,Adler JR Jr




Has Abstract


2006-11-01 00:00:00












  • Tomographic-based 3D scintillation dosimetry using a three-view plenoptic imaging system.

    abstract:PURPOSE:To demonstrate the feasibility of a three-plenoptic camera projection, scintillation-based dosimetry system for measuring three-dimensional (3D) dose distributions of static photon radiation fields. METHODS:Static x-ray photon beams were delivered to a cubic plastic scintillator volume embedded within acrylic ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Rilling M,Allain G,Thibault S,Archambault L

    更新日期:2020-08-01 00:00:00

  • Response of tissue-equivalent ionization chamber to 15-MeV neutrons.

    abstract::The calibration (in rad/nC) of an air-filled tissue-equivalent ionization chamber for neutrons of 15-MeV average energy was determined by measuring absolute fluences and calculating the kerma per unit fluence. The neutron calibration determined from the gamma-ray calibration and application of the Bragg-Gray relation ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Barschall HH,Goldberg E

    更新日期:1977-03-01 00:00:00

  • Multipinhole collimator with 20 apertures for a brain SPECT application.

    abstract:PURPOSE:Several new technologies for single photon emission computed tomography (SPECT) instrumentation with parallel-hole collimation have been proposed to improve detector sensitivity and signal collection efficiency. Benefits from improved signal efficiency include shorter acquisition times and lower dose requiremen...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Lee TC,Ellin JR,Huang Q,Shrestha U,Gullberg GT,Seo Y

    更新日期:2014-11-01 00:00:00

  • Image resolution of a microchannel plate x-ray image intensifier.

    abstract::The resolution has been evaluated for an experimental x-ray image intensifier employing three microchannel plates (MCPs) as the photon absorber and electron multipliers. The line spread function (LSF) was measured and used for determination of the modulation transfer function (MTF). The MTF was found to be independent...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Gould RG

    更新日期:1978-01-01 00:00:00

  • A dosimetry review system for cooperative group research.

    abstract::The validity of conclusions drawn from multi-institutional radiotherapy studies is dependent upon the degree to which participating hospitals adhere to study requirements. A major effort undertaken by the Quality Assurance Review Center (QARC) assesses whether or not patient data which are deemed evaluable actually co...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Reinstein LE,McShan D,Glicksman AS

    更新日期:1982-03-01 00:00:00

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

    abstract: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 irradi...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Becker SJ,Culberson WS,Poirier Y,Mutaf Y,Niu Y,Nichols EM,Yi B

    更新日期:2020-08-01 00:00:00

  • Noninvasive cardiac arrhythmia ablation with particle beams.

    abstract::Cardiac arrhythmias are a major health burden, associated with reduced quality of life and substantial morbidity and mortality. Current therapy includes moderately effective medication and catheter-based ablation of arrhythmogenic substrates in the heart. Catheter interventions frequently have to be repeated due to re...

    journal_title:Medical physics

    pub_type: 杂志文章,评审


    authors: Graeff C,Bert C

    更新日期:2018-11-01 00:00:00

  • MR acoustic radiation force imaging: in vivo comparison to ultrasound motion tracking.

    abstract::MR acoustic radiation force (ARF) imaging was developed for measuring tiSsue elastic properties using focused ultrasound to deliver a localized tissue motion. In this study, an imaging ultrasound transducer was mounted on the focused ultrasound transducer and ultrasound motion tracking was performed simultaneously to ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Huang Y,Curiel L,Kukic A,Plewes DB,Chopra R,Hynynen K

    更新日期:2009-06-01 00:00:00

  • Application of high field magnetic resonance microimaging in polymer gel dosimetry.

    abstract:PURPOSE:The purpose of this work was to examine the suitability of VIPARnd polymer gel-9.4 T magnetic resonance microimaging system for high spatial resolution dose distribution measurements. METHODS:The VIPARnd samples (3 cm in outside diameter and 12 cm in height) were exposed to ionizing radiation by using a linear...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Skorupa A,Woźnica A,Ciszek M,Staniszewski M,Kijonka M,Kozicki M,Woźniak B,Orlef A,Polański A,Boguszewicz Ł,Sokół M

    更新日期:2020-08-01 00:00:00

  • Anatomical pulmonary magnetic resonance imaging segmentation for regional structure-function measurements of asthma.

    abstract:PURPOSE:Pulmonary magnetic-resonance-imaging (MRI) and x-ray computed-tomography have provided strong evidence of spatially and temporally persistent lung structure-function abnormalities in asthmatics. This has generated a shift in their understanding of lung disease and supports the use of imaging biomarkers as inter...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Guo F,Svenningsen S,Eddy RL,Capaldi DPI,Sheikh K,Fenster A,Parraga G

    更新日期:2016-06-01 00:00:00

  • Cascaded-systems analyses and the detective quantum efficiency of single-Z x-ray detectors including photoelectric, coherent and incoherent interactions.

    abstract:PURPOSE:Theoretical models of the detective quantum efficiency (DQE) of x-ray detectors are an important step in new detector development by providing an understanding of performance limitations and benchmarks. Previous cascaded-systems analysis (CSA) models accounted for photoelectric interactions only. This paper des...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Yun S,Tanguay J,Kim HK,Cunningham IA

    更新日期:2013-04-01 00:00:00

  • Gamma dose measurement in a d(80) + Be neutron beam.

    abstract::The gamma-ray dose component of a d(80) + Be neutron beam was measured with a 6Li-shielded Geiger-Mueller counter in a tissue-equivalent liquid phantom. The proportion of gamma-ray dose to total dose increased from 0.07 near the surface to 0.09 at 25 cm depth. Due to thermal neutron sensitivity, the G-M count rate inc...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Harrison GH,Cox CR

    更新日期:1979-05-01 00:00:00

  • Comparison of CBCT-based dose calculation methods in head and neck cancer radiotherapy: from Hounsfield unit to density calibration curve to deep learning.

    abstract:PURPOSE:Anatomical variations occur during head and neck (H&N) radiotherapy treatment. kV cone-beam computed tomography (CBCT) images can be used for daily dose monitoring to assess dose variations owing to anatomic changes. Deep learning methods (DLMs) have recently been proposed to generate pseudo-CT (pCT) from CBCT ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Barateau A,De Crevoisier R,Largent A,Mylona E,Perichon N,Castelli J,Chajon E,Acosta O,Simon A,Nunes JC,Lafond C

    更新日期:2020-10-01 00:00:00

  • Clinical evaluation of a commercial orthopedic metal artifact reduction tool for CT simulations in radiation therapy.

    abstract:PURPOSE:Severe artifacts in kilovoltage-CT simulation images caused by large metallic implants can significantly degrade the conspicuity and apparent CT Hounsfield number of targets and anatomic structures, jeopardize the confidence of anatomical segmentation, and introduce inaccuracies into the radiation therapy treat...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Li H,Noel C,Chen H,Harold Li H,Low D,Moore K,Klahr P,Michalski J,Gay HA,Thorstad W,Mutic S

    更新日期:2012-12-01 00:00:00

  • Elements of microdosimetry.

    abstract::This is an introductory tutorial to the field of microdosimetry. Following a brief historical outline, we review the physics of experimental and theoretical microdosimetry and the application of microdosimetry to radiation biology within the so-called "site" approximation. Modern interpretations of microdosimetry that...

    journal_title:Medical physics

    pub_type: 杂志文章,评审


    authors: Rossi HH,Zaider M

    更新日期:1991-11-01 00:00:00

  • The role of water desorption on optical clearing of biotissue: studied with near infrared reflectance spectroscopy.

    abstract::In order to understand the role of water desorption, i.e., the opposite of water adsorption, in optical clearing of biological tissue created by the application of hyperosmotic agents, dynamics of water loss in fresh porcine muscle tissue administrated with glycerol or ethylene glycol was investigated with the near-in...

    journal_title:Medical physics



    authors: Xu X,Wang RK

    更新日期:2003-06-01 00:00:00

  • Variations in energy spectra and water-to-material stopping-power ratios in three-dimensional conformal and intensity-modulated photon fields.

    abstract::Because of complex dose distributions and dose gradients that are created in three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiation therapy (IMRT), photon- and electron-energy spectra might change significantly with spatial locations and doses. This study examined variations in photon- and...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Jang SY,Liu HH,Mohan R,Siebers JV

    更新日期:2007-04-01 00:00:00

  • Real-time distortionless high-factor compression scheme.

    abstract::Nowadays, digital subtraction angiography systems must be able to sustain real-time acquisition (30 frames per second) of 512 x 512 x 8 bit images and store several sequences of such images on low cost and general-purpose mass memories. Concretely, that means a 7.8 Mbytes per second rate and about 780 Mbytes disk spac...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Liénard J

    更新日期:1989-11-01 00:00:00

  • Poster - Thur Eve - 77: Coordinate transformation from DICOM to DOSXYZnrc.

    abstract::DICOM format is the de facto standard for communications between therapeutic and diagnostic modalities. A plan generated by a treatment planning system (TPS) is often exported to DICOM format. BEAMnrc/DOSXYZnrc is a widely used Monte Carlo (MC) package for beam and dose simulations in radiotherapy. It has its own defi...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Zhan L,Jiang R,Osei EK

    更新日期:2012-07-01 00:00:00

  • A chamber and electrometer calibration factor as determined by each of the five AAPM accredited dosimetry calibration laboratories.

    abstract::The same calibration grade ionization chamber and electrometer were sequentially sent to all five currently AAPM Accredited Dosimetry Calibration Laboratories (ADCL). A Cesium-137 based check device was utilized to ensure chamber and electrometer factor constancy and showed a maximum deviation of 0.32% (typically less...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Blackwell CR,McCullough EC

    更新日期:1992-01-01 00:00:00

  • SPECT imaging of high energy isotopes and isotopes with high energy contaminants with rotating slat collimators.

    abstract:PURPOSE:Quantitative SPECT imaging is limited by many factors, including penetration of high energy photons through the collimator. Even small peaks of high energy yield extensive contamination in the photopeak energy window. Rotating slat collimators typically offer a 40- to 50-fold increase in geometric detection eff...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Van Holen R,Staelens S,Vandenberghe S

    更新日期:2009-09-01 00:00:00

  • Correlation between physical measurements and observer evaluations of image quality in digital chest radiography.

    abstract:PURPOSE:The aim of this paper was to investigate the relationship between the physical and subjective (observer) image quality metrics in digital chest radiography. METHODS:Five digital radiography systems, four with indirect flat panel detector and one with storage phosphor-based computed radiography system, were use...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Yalcin A,Olgar T,Sancak T,Atac GK,Akyar S

    更新日期:2020-09-01 00:00:00

  • Anniversary paper: Role of medical physicists and the AAPM in improving geometric aspects of treatment accuracy and precision.

    abstract::The last 50 years have seen great advances in the accuracy of external beam radiation therapy. Geometrical uncertainties have been reduced from a centimeter or more in presimulation, skin-mark guided days to 1-2 mm in today's image-guided radiation therapy treatments. Medical physicists, with the support and guidance ...

    journal_title:Medical physics

    pub_type: 杂志文章,评审


    authors: Yorke ED,Keall P,Verhaegen F

    更新日期:2008-03-01 00:00:00

  • Focal spot motion of linear accelerators and its effect on portal image analysis.

    abstract::The focal spot of a linear accelerator is often considered to have a fully stable position. In practice, however, the beam control loop of a linear accelerator needs to stabilize after the beam is turned on. As a result, some motion of the focal spot might occur during the start-up phase of irradiation. When acquiring...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Sonke JJ,Brand B,van Herk M

    更新日期:2003-06-01 00:00:00

  • A computer simulation of wavelet noise reduction in computed tomography.

    abstract::We describe the use of a graphical mathematical spreadsheet programming environment which can be used to simulate the acquisition and reconstruction processes of an x-ray computed tomography (CT) machine. The simulation is used to study the effect of photon counting statistics on the noise in the reconstructed image. ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Harpen MD

    更新日期:1999-08-01 00:00:00

  • Effects of x-ray beam equalization on mammographic imaging.

    abstract::We employed an elastic reservoir filled with tissue-equivalent fluid as an x-ray beam filter for exposure equalization. The filter is designed to be placed between the upper compression plate and the breast. During compression, it will conform to the shape of the peripheral region of the breast and fill the space betw...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Lam KL,Chan HP

    更新日期:1990-03-01 00:00:00

  • Sheet beam x-ray fluorescence computed tomography (XFCT) imaging of gold nanoparticles.

    abstract:PURPOSE:X-ray fluorescence computed tomography (XFCT) experiments have typically used pencil beams for data acquisition, which yielded good quality images of gold nanoparticles (AuNP) but prolonged the imaging time. Here we propose three novel collimator geometries for use with faster sheet beam XFCT data acquisition. ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Dunning CAS,Bazalova-Carter M

    更新日期:2018-06-01 00:00:00

  • Skeletal dosimetry in cone beam computed tomography.

    abstract::Cone beam computed tomography (CBCT) is a relatively new patient imaging technique that has proved invaluable for treatment target verification and patient positioning during image-guided radiotherapy (IGRT). It has been shown that CBCT results in additional dose to bone that may amount to 10% of the prescribed dose. ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Walters BR,Ding GX,Kramer R,Kawrakow I

    更新日期:2009-07-01 00:00:00

  • Transrectal electrical impedance tomography of the prostate: spatially coregistered pathological findings for prostate cancer detection.

    abstract:PURPOSE:Prostate cancer ranks as one of the most common malignancies and currently represents the second leading cancer-specific cause of death in men. The current use of single modality transrectal ultrasound (TRUS) for biopsy guidance has a limited sensitivity and specificity for accurately identifying cancerous lesi...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Wan Y,Borsic A,Heaney J,Seigne J,Schned A,Baker M,Wason S,Hartov A,Halter R

    更新日期:2013-06-01 00:00:00

  • Characterization of distensibility, plaque burden, and composition of the atherosclerotic carotid artery using magnetic resonance imaging.

    abstract:PURPOSE:Arterial distensibility is a marker that can measure vessel wall functional and structural changes resulting from atherosclerosis with applications including estimation of mechanical properties of the wall. We sought to assess the feasibility of using magnetic resonance imaging (MRI) to include wall distensibil...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Canton G,Hippe DS,Sun J,Underhill HR,Kerwin WS,Tang D,Yuan C

    更新日期:2012-10-01 00:00:00