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MV and KV dose

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https://www.readbyqxmd.com/read/28211070/use-of-proximal-operator-graph-solver-for-radiation-therapy-inverse-treatment-planning
#1
Xinmin Liu, Charles Pelizzari, Andrew H Belcher, Zachary Grelewicz, Rodney D Wiersma
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 based optimization and MV+kV optimization, involve constrained or mixed-norm optimization, and cannot be solved by quasi-Newton methods. Using standard optimization algorithms on such problems often leads to prohibitively long optimization times and large memory requirements...
February 17, 2017: Medical Physics
https://www.readbyqxmd.com/read/28133751/feasibility-of-external-beam-radiation-therapy-to-deep-seated-targets-with-kilovoltage-x-rays
#2
Magdalena Bazalova-Carter, Michael D Weil, Dylan Yamabe Breitkreutz, Brian P Wilfley, Edward E Graves
PURPOSE: Radiation therapy to deep-seated targets is typically delivered with megavoltage x-ray beams generated by medical linear accelerators or (60) Co sources. Here, we used computer simulations to design and optimize a lower energy kilovoltage x-ray source generating acceptable dose distributions to a deep-seated target. METHODS: The kilovoltage arc therapy (KVAT) x-ray source was designed to treat a 4-cm diameter target located at a 10-cm depth in a 40-cm diameter homogeneous cylindrical phantom...
December 9, 2016: Medical Physics
https://www.readbyqxmd.com/read/28133744/current-modulated-volume-of-interest-imaging-for-kilovoltage-intrafaction-monitoring-of-the-prostate
#3
David Parsons, Tynan Stevens, James L Robar
PURPOSE: The focus of this work is 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 fiducial markers embedded in a dynamic pelvis phantom during gantry rotation...
January 30, 2017: Medical Physics
https://www.readbyqxmd.com/read/28069053/influence-of-daily-imaging-on-plan-quality-and-normal-tissue-toxicity-for-prostate-cancer-radiotherapy
#4
Katharina Bell, Marina Heitfeld, Norbert Licht, Christian Rübe, Yvonne Dzierma
BACKGROUND: Modern radiotherapy offers various possibilities for image guided verification of patient positioning. Different clinically relevant IGRT (image guided radiotherapy) scenarios were considered with regard to their influence on dosimetric plan quality and normal tissue complication probability (NTCP). METHODS: This study is based on treatment plans of 50 prostate patients. We evaluate the clinically performed IGRT and simulate the influence of different daily IGRT scenarios on plan quality...
January 10, 2017: Radiation Oncology
https://www.readbyqxmd.com/read/28048828/su-g-bra-09-estimation-of-motion-tracking-uncertainty-for-real-time-adaptive-imaging
#5
H Yan, Z Chen, R Nath, W Liu
PURPOSE: kV fluoroscopic imaging combined with MV treatment beam imaging has been investigated for intrafractional motion monitoring and correction. It is, however, subject to additional kV imaging dose to normal tissue. To balance tracking accuracy and imaging dose, we previously proposed an adaptive imaging strategy to dynamically decide future imaging type and moments based on motion tracking uncertainty. kV imaging may be used continuously for maximal accuracy or only when the position uncertainty (probability of out of threshold) is high if a preset imaging dose limit is considered...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048750/su-f-j-26-performance-of-2-5mv-portal-imaging-in-comparison-with-kv-x-ray-and-6mv-and-flattening-filter-free-6mv-portal-imaging
#6
J Duan, Y Yang, A Faught, E Subashi, Q Wu, F Yin
PURPOSE: To assess image quality and imaging dose of 2.5MV electronic portal imaging in comparison to kV imaging and 6MV and Flattening-Filter-Free 6MV (6MVFFF) portal imaging using a DMI imager. METHODS: Quantitative assessment of image quality was performed with Leeds and Las Vegas test phantoms in conjunction with qualitative evaluation of clinical patient images for kV imaging and 2.5MV, 6MV and 6MVFFF portal imaging. High and low contrast resolutions were evaluated and imaging doses were measured using these x-rays...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048732/su-f-j-15-the-use-of-cbct-for-dose-calculations-in-h-n-patients-impact-of-limited-fov
#7
B Rosen, C Lee, K Brock
PURPOSE: To investigate the impact of limited superior and inferior (SI) field-of-view (FOV) associated with on-board kV CBCT images for dose calculation. METHODS: First, a (10×10) cm(2) continuous arc 6 MV treatment plan was calculated for fourteen virtual water phantoms of varying SI thicknesses (5 to 15 cm) to replicate the FOV effect. In addition, 70 Gy VMAT plans from two H/N patients were calculated on their corresponding planning CT (pCT) and first fraction CBCT image volumes...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048660/tu-b-201-01-an-overview-of-tg-180
#8
G Ding
: Radiotherapy is in the era of image guided radiation therapy (IGRT) in which imaging procedures are routinely performed for patient positioning, and target localization. The additional imaging dose delivered may increase risk to the patient and therefore needs to be managed. This lecture provides an overview of the AAPM TG-180 which is charged with: providing an overview on imaging dose including megavoltage electronic portal imaging (MV EPI), kilovoltage digital radiography (kV DR), Tomotherapy MV-CT, megavoltage cone-beam CT (MV-CBCT) and kilovoltage cone-beam CT (kV-CBCT) as well as providing general guidelines for commissioning and managing imaging dose calculations...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048549/th-a-204-01-part-i-key-data-for-ionizing-radiation-dosimetry
#9
S Seltzer
: The ICRU is currently finalizing a report on key data for radiation dosimetry. This multi-year review has resulted in a number of recommendations regarding "fundamental" data that are used in dosimetry related to radiation therapy. This educational session will explain the background for the ICRU committee's work, the content and conclusions of the report and the impact on outputs, including NIST primary standards, ADCL calibration coefficients and clinical reference dosimetry. Parameters and beam modalities potentially affected by this report include: The mean excitation energy, I, for graphite, air, and water, The average energy required to create an ion pair in dry air (commonly referred to as W/e), The uncertainty in the determination of air kerma in kV x-rays The absolute value of Co-60 and Cs-137 primary standards and the dissemination of calibration coefficients, The determination of air kerma strength for Ir-192 HDR brachytherapy sources Ion chamber kQ factors for linac MV beams Ion chamber kQ factors for proton beams...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048393/su-f-t-529-dosimetric-investigation-of-a-rotating-gamma-ray-system-for-imagedguided-modulated-arc-radiotherapy
#10
C Ma, O Chibani, A Eldib, J Li, L Chen
PURPOSE: Because of their effectiveness and efficiency, rotational arc radiotherapy (MAT) techniques have been developed on both specialty machines such as Tomotherapy and conventional linear accelerators. This work investigates a new rotating Gamma therapy system for image guided MAT and SBRT of intra/extracranial tumors. METHODS: The CyberMAT system (Cyber Medical Corp., China) consists of a ring gantry with a gamma source (effective source size 1cm and 1.7cm respectively), a 120-leaf MLC, a kV CBCT and an EPID...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048308/we-de-bra-01-science-council-junior-investigator-competition-winner-acceleration-of-a-limited-angle-intrafraction-verification-live-system-using-adaptive-prior-knowledge-based-image-estimation
#11
Y Zhang, F Yin, Y Zhang, L Ren
PURPOSE: To develop an adaptive prior knowledge based image estimation method to reduce the scan angle needed in the LIVE system to reconstruct 4D-CBCT for intrafraction verification. METHODS: The LIVE system has been previously proposed to reconstructs 4D volumetric images on-the-fly during arc treatment for intrafraction target verification and dose calculation. This system uses limited-angle beam's eye view (BEV) MV cine images acquired from the treatment beam together with the orthogonally acquired limited-angle kV projections to reconstruct 4D-CBCT images for target verification during treatment...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048270/su-g-jep3-06-lower-kv-image-dose-are-expected-from-a-limited-angle-intra-fractional-verification-live-system-for-sbrt-treatments
#12
G Ding, F Yin, L Ren
PURPOSE: In order to track the tumor movement for patient positioning verification during arc treatment delivery or in between 3D/IMRT beams for stereotactic body radiation therapy (SBRT), the limited-angle kV projections acquisition simultaneously during arc treatment delivery or in-between static treatment beams as the gantry moves to the next beam angle was proposed. The purpose of this study is to estimate additional imaging dose resulting from multiple tomosynthesis acquisitions in-between static treatment beams and to compare with that of a conventional kV-CBCT acquisition...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048256/su-f-t-667-development-and-validation-of-dose-calculation-for-an-open-source-kv-treatment-planning-system-for-small-animal-radiotherapy
#13
S Prajapati, X Mo, B Bednarz, M Lawless, C Hammer, R Flynn, D Westerly, R Jeraj, T Mackie
PURPOSE: An open-source, convolution/superposition based kV-treatment planning system(TPS) was developed for small animal radiotherapy from previously existed in-house MV-TPS. It is flexible and applicable to both step and shoot and helical tomotherapy treatment delivery. For initial commissioning process, the dose calculation from kV-TPS was compared with measurements and Monte Carlo(MC) simulations. METHODS: High resolution, low energy kernels were simulated using EGSnrc user code EDKnrc, which was used as an input in kV-TPS together with MC-simulated x-ray beam spectrum...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048208/su-g-jep4-13-continuous-intra-fractional-monitoring-of-the-prostate-using-dynamic-kv-collimation-and-tube-current-modulation
#14
D Parsons, J Robar
PURPOSE: The focus of this work is to improve the available kV image quality for continuous intra-fraction monitoring of the prostate. This is investigated using a novel blade collimation system enabling modulated volume-of-interest (VOI) imaging of prostate fiducial markers. METHODS: A four-blade dynamic kV collimator was used to track a VOI during gantry rotation. Planar image quality was investigated as a function of collimator dimension, while maintaining the same dose to isocenter, for a 22...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048073/su-f-j-16-planar-kv-imaging-dose-reduction-study
#15
E Gershkevitsh, D Zolotuhhin
PURPOSE: IGRT has become an indispensable tool in modern radiotherapy with kV imaging used in many departments due to superior image quality and lower dose when compared to MV imaging. Many departments use manufacturer supplied protocols for imaging which are not always optimised between image quality and radiation dose (ALARA). METHODS: Whole body phantom PBU-50 (Kyoto Kagaku ltd., Japan) for imaging in radiology has been imaged on Varian iX accelerator (Varian Medical Systems, USA) with OBI 1...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047993/tu-b-201-02-accounting-for-kv-imaging-dose
#16
P Alaei
: Radiotherapy is in the era of image guided radiation therapy (IGRT) in which imaging procedures are routinely performed for patient positioning, and target localization. The additional imaging dose delivered may increase risk to the patient and therefore needs to be managed. This lecture provides an overview of the AAPM TG-180 which is charged with: providing an overview on imaging dose including megavoltage electronic portal imaging (MV EPI), kilovoltage digital radiography (kV DR), Tomotherapy MV-CT, megavoltage cone-beam CT (MV-CBCT) and kilovoltage cone-beam CT (kV-CBCT) as well as providing general guidelines for commissioning and managing imaging dose calculations...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047887/th-a-204-02-part-ii-worldwide-radiation-metrology
#17
M McEwen
: The ICRU is currently finalizing a report on key data for radiation dosimetry. This multi-year review has resulted in a number of recommendations regarding "fundamental" data that are used in dosimetry related to radiation therapy. This educational session will explain the background for the ICRU committee's work, the content and conclusions of the report and the impact on outputs, including NIST primary standards, ADCL calibration coefficients and clinical reference dosimetry. Parameters and beam modalities potentially affected by this report include: The mean excitation energy, I, for graphite, air, and water, The average energy required to create an ion pair in dry air (commonly referred to as W/e), The uncertainty in the determination of air kerma in kV x-rays The absolute value of Co-60 and Cs-137 primary standards and the dissemination of calibration coefficients, The determination of air kerma strength for Ir-192 HDR brachytherapy sources Ion chamber kQ factors for linac MV beams Ion chamber kQ factors for proton beams...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047326/tu-b-201-03-accounting-for-mv-imaging-dose-and-the-future-of-mv-imaging
#18
R Flynn
: Radiotherapy is in the era of image guided radiation therapy (IGRT) in which imaging procedures are routinely performed for patient positioning, and target localization. The additional imaging dose delivered may increase risk to the patient and therefore needs to be managed. This lecture provides an overview of the AAPM TG-180 which is charged with: providing an overview on imaging dose including megavoltage electronic portal imaging (MV EPI), kilovoltage digital radiography (kV DR), Tomotherapy MV-CT, megavoltage cone-beam CT (MV-CBCT) and kilovoltage cone-beam CT (kV-CBCT) as well as providing general guidelines for commissioning and managing imaging dose calculations...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047071/su-f-t-634-feasibility-study-of-respiratory-gated-rapidarc-sbrt-using-a-6mv-fff-photon-beam
#19
K Dou, M Jacobs, B Laser, M Safaraz, J Rodgers
PURPOSE: To conduct a feasibility study on retrospective respiratory gating and marker tracking for lung stereotactic body radiotherapy (SBRT) with a gated RapidArc delivery using a 6MV flattened filter free photon mode. METHODS: A CIRS dynamic thorax phantom Model 008A with different inserts was used for treatment planning and respiratory gating. 4D CT had a free breathing simulation followed by a respiration gated, ten phased CT using a Philips Brilliance CT with a Varian RPM respiratory gating system...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047035/su-g-tep3-15-radiation-dose-enhancement-by-anatase-tio2nps
#20
E Youkhana, M Geso, B Feltis
PURPOSE: This work investigates radiation dose enhancement caused by TiO2 nanoparticles covering entire X-ray energy ranges used in radiation therapy. METHODS: Anatase TiO2NPs crystal were synthesised and modified as hydrophilic and hydrophobic to disperse in culture-medium and halocarbons (PRESAGE chemical composition) respectively. TiO2NPs were characterised using TEM, XPS, XRD, TGA and FTIR. Various Concentrations have been utilised for determination of radiation-dose enhancement...
June 2016: Medical Physics
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