A quality assurance program for monitor unit calculators.

abstract：PURPOSE:To estimate and correct for the volume averaging effect which results from the intra-chamber dose gradients when a Farmer ionization chamber (IC) is used for reference dosimetry in flattening-filter-free (FFF) MV photon beams. METHODS:An intra-chamber dose gradients correction factor (kicdg) to the charge read...

journal_title：Medical physics

authors： Ruggieri R,Naccarato S,Stavrev P,Stavreva N,Pasetto S,Salamone I,Alongi F

更新日期：2016-08-01 00:00:00

abstract：PURPOSE:Fusion of intraprocedure ultrasound and preprocedure CT data is proposed for guidance in percutaneous spinal injections, a common procedure for pain management. CT scan of the lumbar spine is usually collected in a supine position, whereas spinal injections are performed in prone or sitting positions. This lead...

journal_title：Medical physics

authors： Rasoulian A,Abolmaesumi P,Mousavi P

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:Spirometry exhibits baseline drift and frequent measurement errors so it cannot be used by itself to provide tidal volume-based image sorting or breathing motion modeling. Other breathing surrogates, in this study an abdominal bellows system, are drift free but do not measure tidal volume. Simultaneously using ...

journal_title：Medical physics

authors： Werner R,White B,Handels H,Lu W,Low DA

更新日期：2010-02-01 00:00:00

abstract：PURPOSE:To evaluate plan quality of a novel MRI-compatible direction modulated brachytherapy (DMBT) tandem applicator using 192 Ir, 60 Co, and 169 Yb HDR brachytherapy sources, for various cervical cancer high-risk clinical target volumes (CTVHR ). MATERIALS AND METHODS:The novel DMBT tandem applicator has six periphe...

journal_title：Medical physics

authors： Safigholi H,Han DY,Mashouf S,Soliman A,Meigooni AS,Owrangi A,Song WY

更新日期：2017-12-01 00:00:00

abstract：PURPOSE:Computational models of microwave tissue ablation are widely used to guide the development of ablation devices, and are increasingly being used for the development of treatment planning and monitoring platforms. Knowledge of temperature-dependent dielectric properties of lung tissue is essential for accurate mo...

journal_title：Medical physics

authors： Sebek J,Bortel R,Prakash P

更新日期：2019-10-01 00:00:00

abstract：PURPOSE:To evaluate a commercial volumetric modulated arc therapy (VMAT), using multiple noncoplanar arcs, for linac-based cranial radiosurgery, as well as evaluate the combined accuracy of the VMAT dose calculations and delivery. METHODS:Twelve patients with cranial lesions of variable size (0.1-29 cc) and two multip...

journal_title：Medical physics

authors： Audet C,Poffenbarger BA,Chang P,Jackson PS,Lundahl RE,Ryu SI,Ray GR

更新日期：2011-11-01 00:00:00

abstract：PURPOSE:The ability to monitor intrafractional tumor motion is essential for radiation therapy of thoracic and abdominal tumors. This study aims to develop a method to track lung tumor motion using intrafractional continuous ultrasound (US) and periodic cone-beam projection images (CBPI). METHODS:Time-sequenced b-mode...

journal_title：Medical physics

authors： Mostafaei F,Tai A,Gore E,Johnstone C,Haase W,Ehlers C,Cooper DT,Lachaine M,Li XA

更新日期：2018-10-01 00:00:00

abstract：PURPOSE:The purpose of the work is to describe a new algorithm for the automatic detection of implanted radioactive seeds within the prostate. The algorithm is based on the traditional Hough transform. A method of quality assurance is described as well as a quantitative phantom study to determine the accuracy of the al...

journal_title：Medical physics

authors： Holupka EJ,Meskell PM,Burdette EC,Kaplan ID

更新日期：2004-09-01 00:00:00

abstract：:AAPM Magnetic Resonance Task Group #9 on proton magnetic resonance spectroscopy (MRS) in the brain was formed to provide a reference document for acquiring and processing proton (1H) MRS acquired from brain tissue. MRS is becoming a common adjunct to magnetic resonance imaging (MRI), especially for the differential di...

journal_title：Medical physics

authors： Drost DJ,Riddle WR,Clarke GD,AAPM MR Task Group #9.

更新日期：2002-09-01 00:00:00

abstract：PURPOSE:To investigate how the setting of optimization parameters, fractional dose and tuning structure in tomotherapy treatment planning affects plan dosimetric quality and treatment efficiency. METHODS:A digital phantom to simulate head and neck radiotherapy was constructed for this study. Tumor was 10cm long C-shap...

journal_title：Medical physics

authors： Lian J,Burkhardt K,Chera B,Chang S

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:Photon counting arrays (PCAs), capable of measuring the spectral information of individual x-ray photons and recording that information digitally, provide a number of advantages compared to conventional, energy-integrating active matrix flat-panel imagers - such as reducing the undesirable effects of electronic...

journal_title：Medical physics

authors： Liang AK,Koniczek M,Antonuk LE,El-Mohri Y,Zhao Q

更新日期：2018-10-01 00:00:00

abstract：PURPOSE:The purpose of this study was to quantitatively characterize the fundamental aspects of image quality (IQ) associated with different computed tomography (CT) reconstruction algorithms, the resolution, noise texture, noise magnitude per dose, and use those data to devise a methodology to match IQ between differe...

journal_title：Medical physics

authors： Winslow J,Zhang Y,Samei E

更新日期：2017-11-01 00:00:00

abstract：PURPOSE:The aim of this study was to evaluate a surrogate-driven motion model based on four-dimensional computed tomography that is able to predict CT volumes corresponding to arbitrary respiratory phases. Furthermore, the comparison of three different driving surrogates is examined and the feasibility of using the mod...

journal_title：Medical physics

authors： Wölfelschneider J,Seregni M,Fassi A,Ziegler M,Baroni G,Fietkau R,Riboldi M,Bert C

更新日期：2017-06-01 00:00:00

abstract：:Spectrally resolved bioluminescence optical tomography is an approach to recover images of, for example, Luciferase activity within a volume using multiwavelength emission data from internal bioluminescence sources. The underlying problem of uniqueness associated with nonspectrally resolved intensity-based bioluminesc...

journal_title：Medical physics

authors： Dehghani H,Davis SC,Pogue BW

更新日期：2008-11-01 00:00:00

abstract：:Intensity modulated radiation therapy (IMRT) is used to deliver highly conformal radiation doses to tumors while sparing nearby sensitive tissues. Discrepancies between calculated and measured dose distributions have been reported for regions of high dose gradients corresponding to complex radiation fluence patterns. ...

journal_title：Medical physics

authors： Bergman AM,Otto K,Duzenli C

更新日期：2004-12-01 00:00:00

abstract：PURPOSE:Intensity-Modulated Radiation Therapy (IMRT), including its variations (including IMRT, Volumetric Arc Therapy (VMAT), and Tomotherapy), is a widely used and critically important technology for cancer treatment. It is a knowledge-intensive technology due not only to its own technical complexity, but also to the...

journal_title：Medical physics

authors： Ge Y,Wu QJ

更新日期：2019-06-01 00:00:00

abstract：PURPOSE:The implementation of an accurate beam model is an integral part of the commissioning of any planning system. This process is especially challenging in the case of IMRT beam models owing to the complexity of small field sizes and MLC leaf-end and tongue-and-groove effects. The question of how to judge the quali...

journal_title：Medical physics

authors： Veltchev I,Fourkal E,Price R,Ma C

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:To investigate dosimetry for ocular brachytherapy for a range of eye plaque models containing(103)Pd, (125)I, or (131)Cs seeds with model-based dose calculations. METHODS:Five representative plaque models are developed based on a literature review and are compared to the standardized COMS plaque, including pla...

journal_title：Medical physics

authors： Lesperance M,Martinov M,Thomson RM

更新日期：2014-03-01 00:00:00

abstract：:A detailed derivation is presented of the formulas required to determine Ngas and Dmed in the AAPM TG-21 dosimetry protocol. This protocol specifies how to determine the absorbed dose in an electron or photon beam when using exposure or absorbed dose calibrated ion chambers. It is shown that the expression given in TG...

journal_title：Medical physics

authors： Rogers DW,Ross CK

更新日期：1988-01-01 00:00:00

abstract：PURPOSE:To evaluate the feasibility of using an objective computer-aided system to assess bladder cancer stage in CT Urography (CTU). MATERIALS AND METHODS:A dataset consisting of 84 bladder cancer lesions from 76 CTU cases was used to develop the computerized system for bladder cancer staging based on machine learnin...

journal_title：Medical physics

authors： Garapati SS,Hadjiiski L,Cha KH,Chan HP,Caoili EM,Cohan RH,Weizer A,Alva A,Paramagul C,Wei J,Zhou C

更新日期：2017-11-01 00:00:00

abstract：PURPOSE:The research is to develop a novel CNN-based adversarial deep learning method to improve and expedite the multi-organ semantic segmentation of CT images and to generate accurate contours on pelvic CT images. METHODS:Planning CT and structure datasets for 120 patients with intact prostate cancer were retrospect...

journal_title：Medical physics

authors： Zhang Z,Zhao T,Gay H,Zhang W,Sun B

更新日期：2020-11-05 00:00:00

abstract：PURPOSE:IAEA TRS-398 notes that cylindrical ionization chambers are preferred for reference proton dosimetry. If a cylindrical ionization chamber is used in a phantom to measure the dose as a function of depth, the effective point of measurement (EPOM) must be taken into account. IAEA TRS-398 recommends a displacement ...

journal_title：Medical physics

authors： Sugama Y,Nishio T,Onishi H

更新日期：2015-07-01 00:00:00

abstract：:We applied Monte Carlo methods for the simulation of x-ray scattering in water phantoms. The phantom thickness was varied from 5 to 20 cm, and the monoenergetic incident x rays were varied from 15 to 100 keV. Eight screen pairs and a total absorption system were used as x-ray receptors. We determined the angular, spec...

journal_title：Medical physics

authors： Chan HP,Doi K

更新日期：1985-03-01 00:00:00

abstract：PURPOSE:Linac-magnetic resonance (MR) systems have been proposed in order to achieve realtime image guided radiotherapy. The design of a new linac-MR system with the in-line 6 MV linac generating x-rays along the symmetry axis of an open MR imager is outlined. This new design allows for a greater MR field strength to a...

journal_title：Medical physics

authors： St Aubin J,Santos DM,Steciw S,Fallone BG

更新日期：2010-09-01 00:00:00

abstract：PURPOSE:To implement the DMAIC (Define-Measure-Analyze-Improve-Control) can be used for customizing the patient-specific QA by designing site-specific range tolerances. METHODS:The DMAIC framework (process flow diagram, cause and effect, Pareto chart, control chart, and capability analysis) were utilized to determine ...

journal_title：Medical physics

authors： Rah JE,Shin D,Manger RP,Kim TH,Oh DH,Kim DY,Kim GY

更新日期：2018-02-01 00:00:00

abstract：:Skeletal dosimetry based on microCT images of trabecular bone has recently been introduced to calculate the red bone marrow (RBM) and the bone surface cell (BSC) equivalent doses in human phantoms for external exposure to photons. In order to use the microCT images for skeletal dosimetry, spongiosa voxels in the skele...

journal_title：Medical physics

authors： Kramer R,Khoury HJ,Vieira JW,Robson Brown KA

更新日期：2009-11-01 00:00:00

abstract：:Current generation electronic portal imaging devices (EPID) contain a 1.0 mm copper conversion plate to increase detection efficiency of a therapeutic megavoltage spectrum. When using these EPIDs for low-Z target imaging, the conversion plate largely attenuates the large populations of diagnostic energy photons, there...

journal_title：Medical physics

authors： Parsons D,Robar JL

更新日期：2012-07-01 00:00:00

abstract：PURPOSE:In fluoroscopy-guided clinical procedures that involve tracking objects over long treatment times, there is a need for reducing the amount of imaging dose delivered to the patient and the operating staff. In this study, we introduce a feedback metric to minimize tube current while maintaining a targeting precis...

journal_title：Medical physics

authors： Siddique S,Fiume E,Jaffray D

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:Consistency verification between the data from treatment planning system (TPS), record and verification system (R&V), and delivered recorder with visual inspection is time consuming and subject to human error. The purpose of this work is to develop a software tool to automatically perform such verifications. M...

journal_title：Medical physics

authors： Chen G,Li X

更新日期：2012-06-01 00:00:00

abstract：:Depth dose distributions for a d(14)Be neutron beam, measured separately for total and gamma absorbed dose, are presented for nine tissue substitutes and for two field sizes. These data are used to examine methods to transform depth dose curves from one material to another. Best results are found when the local depths...

journal_title：Medical physics

authors： Hensley FW,Rassow J,Temme A

更新日期：1985-05-01 00:00:00