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Concetta Laliscia, Maria Grazia Fabrini, Durim Delishaj, Riccardo Morganti, Carlo Greco, Martina Cantarella, Roberta Tana, Fabiola Paiar, Angiolo Gadducci
OBJECTIVE: The objective of this study was to assess the role of stereotactic body radiotherapy (SBRT) in the treatment of distantly recurrent, oligometastatic gynecological cancer. METHODS: The hospital records of 45 patients with F-fluorodeoxyglucose (F-FDG) positron emission tomography positive, distantly recurrent, oligometastatic gynecological cancer were reviewed. All these patients had a number of target lesions less than 5, with largest diameter less than 6 cm...
February 2017: International Journal of Gynecological Cancer
G Sandhu, F Cao, S Szpala, K Kohli
PURPOSE: The aim of the current study is to investigate the effect of machine output variation on the delivery of the RapidArc verification plans. METHODS: Three verification plans were generated using Eclipse™ treatment planning system (V11.031) with plan normalization value 100.0%. These plans were delivered on the linear accelerators using ArcCHECK- device, with machine output 1.000 cGy/MU at calibration point. These planned and delivered dose distributions were used as reference plans...
June 2016: Medical Physics
C Knill, M Snyder, J Rakowski, L Zhuang, M Matuszak, Burmeister J
PURPOSE: PTW's Octavius 1000 SRS array performs IMRT QA measurements with liquid filled ionization chambers (LICs). Collection efficiencies of LICs have been shown to change during IMRT delivery as a function of LINAC pulse frequency and pulse dose, which affects QA results. In this study, two methods were developed to correct changes in collection efficiencies during IMRT QA measurements, and the effects of these corrections on QA pass rates were compared. METHODS: For the first correction, Matlab software was developed that calculates pulse frequency and pulse dose for each detector, using measurement and DICOM RT Plan files...
June 2016: Medical Physics
P Atkinson, Q Chen
PURPOSE: To assess the clinical efficacy of auto beam hold during prostate RapidArc delivery, triggered by fiducial localization on kV imaging with a Varian True Beam. METHODS: Prostate patients with four gold fiducials were candidates in this study. Daily setup was accomplished by aligning to fiducials using orthogonal kV imaging. During RapidArc delivery, a kV image was automatically acquired with a momentary beam hold every 60 degrees of gantry rotation. The position of each fiducial was identified by a search algorithm and compared to a predetermined 1...
June 2016: Medical Physics
F Salinas Aranda, V Suarez, S Arbiser, R Sansogne
PURPOSE: To implement an end-to-end QA test of the radiation therapy imaging, planning and delivery process, aimed to assess the dosimetric agreement accuracy between planned and delivered treatment, in order to identify and correct possible sources of deviation. To establish an internal standard for machine commissioning acceptance. METHODS: A test involving all steps of the radiation therapy: imaging, planning and delivery process was designed. The test includes analysis of point dose and planar dose distributions agreement between TPS calculated and measured dose...
June 2016: Medical Physics
B Liu, J Kim
PURPOSE: To compare the dosimetry of coplanar and non-coplanar RapidArc whole brain plans for hippocampal sparing METHODS: We studied the RapidArc plans of patient with brain metastases, with the prescription of 3750 cGy in 15 fractions. The coplanar approach used a full clockwise (CW) arc and a full counterclockwise (CCW) arc, with the couch angle to be 0°. The non-coplanar approach used a full arc with a couch angle of 0°, and a partial arc with a couch angle of 90°. Treatment planning system is Eclipse Ver...
June 2016: Medical Physics
U Mwidu, S Devic, M Shehadeh, M AlKafi, R Mahmood, B Moftah
PURPOSE: A retrospective comparison of dose distributions achievable by High dose rate brachytherapy (HDRBT), Helical TomoTherapy (TOMO), CyberKnife (CK) and RapidArc (RA) in locally advanced inoperable cervical cancer patients is presented. METHODS: Five patients with advanced stage cervical carcinoma were selected for this study after a full course of external beam radiotherapy (EBRT), chemotherapy and HDR Brachytherapy. To highlight any significant similarities/differences in dose distributions, high-risk clinical target volume (HRCTV) coverage, organs at risk (OAR) sparing, and machine specific delivery limitations, we used D90 (dose received by 90% of the volume) as the parameter for HRCTV coverage as recommended by the GEC-ESTRO Working Group...
June 2016: Medical Physics
J Pursley, G Gueorguiev, H Prichard, D Gierga
PURPOSE: To demonstrate the commissioning of constant dose rate volumetric modulated arc therapy (VMAT) in the Raystation treatment planning system for a Varian Clinac iX with Exact couch. METHODS: Constant dose rate (CDR) VMAT is an option in the Raystation treatment planning system, enabling VMAT delivery on Varian linacs without a RapidArc upgrade. Raystation 4.7 was used to commission CDR-VMAT for a Varian Clinac iX. Raystation arc model parameters were selected to match machine deliverability characteristics...
June 2016: Medical Physics
C Tien, M Brewer, M Studenski
PURPOSE: Dynamic-jaw tracking maximizes the area blocked by both jaw and MLC in RapidArc. We developed a method to quantify jaw tracking. METHODS: An Eclipse Scripting API (ESAPI) was used to export beam parameters for each arc's control points. The specific beam parameters extracted were: gantry angle, control point number, meterset, x-jaw positions, y-jaw positions, MLC bank-number, MLC leaf-number, and MLC leaf-position. Each arc contained 178 control points with 120 MLC positions...
June 2016: Medical Physics
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
D Desai, G Narayanasamy, S Senthamizhchelvan, H Elasmar, R Zwicker, E Johnson
PURPOSE: SBRT of lung tumor results in steep dose fall-off outside the PTV to limit the normal tissue dose. RTOG report 0915 recommended metrics for plan quality measure, CI, D2cm, R50% and HDloc were evaluated. This study was aimed at ascertaining moderate to low dose spillage using 5 mm ring structures outside the PTV. METHODS: In this retrospective study, 41 clinical RapidArc lung SBRT plans (Eclipse TPS ver 8.9) previously treated at our institution in a TrueBeam STx linac were analyzed...
June 2016: Medical Physics
M Ferreyra, F Salinas Aranda, D Dodat, R Sansogne, S Arbiser
PURPOSE: To use end-to-end testing to validate a 6 MV high dose rate photon beam, configured for Eclipse AAA algorithm using Golden Beam Data (GBD), for SBRT treatments using RapidArc. METHODS: Beam data was configured for Varian Eclipse AAA algorithm using the GBD provided by the vendor. Transverse and diagonals dose profiles, PDDs and output factors down to a field size of 2×2 cm2 were measured on a Varian Trilogy Linac and compared with GBD library using 2% 2mm 1D gamma analysis...
June 2016: Medical Physics
J Ho, R Chin
PURPOSE: Linac-based single isocenter SRS treatments for multiple brain lesions have been developed in recent years. However, it is a challenge to perform patient specific plan QA in cases where a large number of small and widely spread-out lesions are involved. We have developed a method to measure all target dose distributions in a single planar measurement. METHODS: Varian Eclipse TPS was used to create dynamic conformal arc or RapidArc© plans. Verification plans are created with a fixed gantry angle, and planar projections of 3D dose distributions are created which show high dose regions correlated to each individual lesion...
June 2016: Medical Physics
B Weethee, J Cheung, A Perez-Andujar, A Sudhyadhom, J Chen
PURPOSE: To investigate the sensitivity of traditional gamma-index-based analysis using diode arrays to detect significant dosimetric errors in patientspecific measurements for VMAT brain SRT plans. METHODS: Quality assurance measurements were performed using an ion chamber and two different diode array devices for four brain SRT treatment plans. All cases were planned with Eclipse AAA RapidArc using 6MV VMAT for a TrueBeam STx. Ion chambers measurements were performed with a PinPoint 3D micro-ion chamber in both the Standard Imaging Stereotactic Dose Verification (SI) Phantom and in the ArcCheck (AC) cavity plug...
June 2016: Medical Physics
A Perez-Andujar, J Cheung, C Chuang
PURPOSE: To investigate the effect of dynamic and static jaw tracking on patient peripheral doses. MATERIALS AND METHODS: A patient plan with a large sacral metastasis (volume 800cm3, prescription 600cGyx5) was selected for this study. The plan was created using 2-field RapidArc with jaw tracking enabled (Eclipse, V11.0.31). These fields were then exported and edited in MATLAB with static jaw positions using the control point with the largest field size for each respective arc, but preserving the optimized leaf sequences for delivery...
June 2016: Medical Physics
E Kendall, S Ahmad, O Algan, C Higby, S Hossain
PURPOSE: To compare biophysical indices of Volumetric Modulated Arc Therapy (VMAT) and Intensity Modulated Radiation Therapy (IMRT) treatment plans for whole brain radiation therapy following the NRG-CC001 protocol. METHODS: In this retrospective study, a total of fifteen patients were planned with Varian Eclipse Treatment Planning System using VMAT (RapidArc) and IMRT techniques. The planning target volume (PTV) was defined as the whole brain volume excluding a uniform three-dimensional 5mm expansion of the hippocampus volume...
June 2016: Medical Physics
E Kendall, C Higby, O Algan, S Ahmad, S Hossain
PURPOSE: To compare the treatment plan quality and dose gradient near the hippocampus between VMAT (RapidArc) and IMRT delivery techniques for whole brain radiation therapy. METHODS: Fifteen patients were evaluated in this retrospective study. All treatments were planned on Varian Eclipse TPS, using 3-Arc VMAT and 9-Field IMRT, following NRG Oncology protocol NRG-CC001 guidelines evaluated by a single radiation oncologist. Prescribed doses in all plans were 30 Gy delivered over 10 fractions normalized to a minimum of 100% of the dose covering 95% of the target volume...
June 2016: Medical Physics
F Chen
PURPOSE: For a give PTV dose, beam-on time is shorter in the FFF than the non-FFF mode because of higher MU/min. Larger tumors usually require more complex intensity modulation, which might affect plan quality and total MU. We investigated the relationship between PTV size and plan quality using FFF and non-FFF modes. METHODS: Two different PTV volumes (PTV and PTV+1 cm margin) were drawn in brain, lung and liver. 3-full to 7-partial arc (Rapidarc) of 6 MV, 1400 MU/min were studied...
June 2016: Medical Physics
Johan P Cuijpers, Max Dahele, Marianne Jonker, Bianca Kraan, Suresh Senan, Ben Slotman, Wilko Far Verbakel
PURPOSE: Online tumor matching for SABR lung setup requires margins for inaccuracies due to intra-fraction variability of breathing-averaged tumor position (BATP) and CBCT image guidance. We studied intra-fraction variability during SABR delivery using VMAT, corrected these for measurement inaccuracies, and quantified the CBCT image-guidance uncertainties. MATERIALS AND METHODS: For 193 fractions in 38 patients positioned without immobilization devices, CBCT scans were acquired before and after 2 arcs of a RapidArc treatment...
December 29, 2016: Medical Physics
Jennifer Pursley, Antonio L Damato, Maria A Czerminska, Danielle N Margalit, David J Sher, Roy B Tishler
The purpose of this study was to investigate class solutions using RapidArc volumetric-modulated arc therapy (VMAT) planning for ipsilateral and bilateral head and neck (H&N) irradiation, and to compare dosimetric results with intensity-modulated radiotherapy (IMRT) plans. A total of 14 patients who received ipsilateral and 10 patients who received bilateral head and neck irradiation were retrospectively replanned with several volumetric-modulated arc therapy techniques. For ipsilateral neck irradiation, the volumetric-modulated arc therapy techniques included two 360° arcs, two 360° arcs with avoidance sectors around the contralateral parotid, two 260° or 270° arcs, and two 210° arcs...
December 2, 2016: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
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