This report from the Stereotactic Radiotherapy Working Group of German Society Radiation Oncology (Deutschen Gesellschaft für Radioonkologie, DEGRO) provides a definition stereotactic body radiotherapy (SBRT) that agrees with other international societies. SBRT is defined as method external beam (EBRT) accurately delivers high irradiation dose to an extracranial target in one or few treatment fractions. Detailed recommendations concerning principles and practice for early stage non-small...

A variety of detectors and procedures for the measurement small field output factors are discussed in current literature. Different with or without corrections recommended. Correction often derived by Monte Carlo methods, where bias due to approximations model is difficult judge. Over that, results appear be contradictory some cases. In this work, were measured sizes from 4 mm up 180 side length different detectors. simple linear correction energy response solid state proposed. This led...

The aim of this work was to evaluate the accuracy dose predicted in heterogeneous media by a pencil beam (PB), collapsed cone (CC) and Monte Carlo (MC) algorithm. For purpose, simple multi-layer phantom composed Styrofoam white polystyrene irradiated with 10 x cm2 as well 20 open 6 MV photon fields. axis aligned parallel layers various field offsets were applied. Thereby, amount lateral scatter controlled. Dose measurements performed an ionization chamber positioned both central layer...

Small-field dosimetry used in advance treatment technologies poses challenges due to loss of lateral charged particle equilibrium (LCPE), occlusion the primary photon source, and limited choice suitable radiation detectors. These greatly influence dosimetric accuracy. Many high-profile incidents have demonstrated a poor understanding appropriate methodology for small-field dosimetry. are cause concern because use small fields various specialized techniques continues grow rapidly. Reference...

Abstract Motivation Online adaptive radiotherapy with Ethos is based on the anatomy determined from daily cone beam computed tomography (CBCT) images. Dose optimization and computation are performed density map of a synthetic CT (sCT), deformable registration initial planning (pCT) onto current CBCT. Large changes as present in lung region challenging system. Methods Treatment plans for were created delivered 1, 2, 3 cm diameter lesions an anthropomorphic phantom, combining different insets...

Purpose: A commonly used beam quality index for high‐energy photon beams is the tissue phantom ratio a square field of and SDD . On some specialized radiotherapy treatment equipment such reference collimator setting not achievable. Likewise flat profile, explicitly required in dosimetry protocols, but certainly influences measurement , always produced. In this work, method was developed order to determine at any size, especially small nonflattened beams. Methods: An analytical relationship...

To introduce a novel method of patient positioning for high precision intracranial radiotherapy.An infrared(IR)-array, reproducibly attached to the via vacuum-mouthpiece(vMP) and connected table 6 degree-of-freedom(DoF) mechanical arm serves as fixation system. After IR-based manual prepositioning rough treatment position arm, cone-beam CT(CBCT) is performed. A robotic DoF couch (HexaPOD) then automatically corrects all remaining translations rotations. This absolute infrared markers at...

Convolution/superposition software has been used to produce a library of photon pencil beam dose matrices. This beams is designed serve as tool for both education and investigation in the field radiotherapy optimization. The elegance this model stems from its cylindrical symmetry. Because symmetry, distribution any arbitrary angle can be determined through simple rotation pre-computed matrix. Rapid calculations thus performed while maintaining accuracy convolution/superposition based...

The purpose of this work is the development a robust and reliable three-dimensional (3D) Cartesian imaging technique for fast flexible retrospective 4D abdominal MRI during free breathing. To end, non-uniform quasi random (NU-QR) reordering phase encoding (k y -k z ) lines was incorporated into 3D acquisition. proposed sampling scheme allocates more points near k-space origin while reducing density in outer part k-space. Respiratory self-gating combination with SPIRiT-reconstruction used...

In stereotactic radiosurgery, sharp beam edges have clear advantages to spare normal tissues. general, the dose gradient is a limiting factor in minimizing nearby critical structures for clinical cases. Therefore penumbral width should be diminished.A Varian Clinac 2100 linear accelerator equipped with in-house designed radiosurgical collimator was modeled using EGSnrc/BEAMnrc Monte Carlo code and compared measurements. The 0.015 cm(3) PinPoint chamber used measure 6 MV photon...

Essential for the calculation of photon fluence distributions intensity modulated radiotherapy (IMRT) is use a suitable objective function. The function should reflect clinical aims tumor control and low side effect probability. Individual radiobiological parameters patient organs are not yet available with sufficient accuracy. Some major drawbacks some current optimization methods include an inability to converge solution arbitrary input parameters, and/or need intensive user in order guide...

In the vicinity of interfaces between materials different atomic number Z, extremes in absorbed dose occur for high-energy photon irradiations. The spatial extension effects is within range 1 cm, which may not be ignorable from radiobiological point view. At front side a high-Z slab maximum observed, whereas at exit small buildup zone occurs, e.g., 5 MV beam, water/iron interface, enhancement about 30% that to homogeneous medium. reduction back iron 16% this energy, but vanishes with...

Evaluation of set up error detection by a transperineal ultrasound in comparison with cone beam CT (CBCT) based system external radiation therapy (EBRT) prostate cancer.Setup verification was performed (TPUS) and CBCT for 10 patients treated EBRT cancer. In total, 150 scans were acquired rapid succession analyzed setup errors. The deviation between errors the two modalities evaluated separately each dimension.A moderate correlation lateral, vertical longitudinal direction observed comparing...

Purpose To investigate the energy dependence/spectral sensitivity of silicon diodes designed for small-field dosimetry and obtain response factors (RFs) arbitrary photon spectra using Monte Carlo (MC) simulations. Methods The EGSnrc user-code DOSRZnrc was used to calculate dose deposition in water active volume a stereotactic diode field detector (SFD). Then, RFs SFD were calculated several circular sizes energies at 5 cm depth water. Several low-energy (mean 55 200 keV), as well Co-60...

Purpose The integral quality monitor (IQM) transmission detector is a wedge‐shaped large area ionization chamber that reports position‐weighted dose product for each control point of an IMRT or VMAT plan. In this study, the accuracy signal prediction verified Synergy Agility MLC. Tolerance criteria plan verification with IQM were obtained from observed sensitivity detection incorrectly delivered plans. Methods predicted was compared to measured recorded set 30 plans beam 6 and 10 MV....

Purpose: The tissue phantom ratio (TPR) is a common dosimetric quantity used in photon dose calculations. For small fields with side lengths less than , TPR data hardly exist literature. In this work, self‐contained functional representation of proposed, valid for the whole range clinically relevant depth and field sizes. This especially useful shaped by multileaf collimators. Methods: TPRs were measured quadratic between 0.4 . fitted to physically meaningful function taking electron...

Abstract Purpose To assess the impact of isocenter shifts due to linac gantry and table rotation during cranial stereotactic radiosurgery on D 98 , target volume coverage (TVC), conformity (CI), gradient index (GI). Methods Winston‐Lutz (WL) checks were performed two Elekta Synergy linacs. A quality assurance (QA) plan was applied ArcCHECK phantom shift corrections Gamma pass rates. These included sag, distance collimator couch axes axis, between cone‐beam computed tomography (CBCT)...

Purpose To demonstrate that desynchronization between Cartesian k‐space sampling and periodic motion in free‐breathing lung MRI improves the robustness efficiency of retrospective respiratory self‐gating. Methods Desynchronization was accomplished by reordering phase (k y ) partition z encoding a three‐dimensional FLASH sequence according to two‐dimensional, quasi‐random (QR) numbers. For self‐gating, center signal (DC signal) acquired separately after each encoded line. QR results uniform...