Search Results

You are looking at 1 - 10 of 52 items for :

  • "organs at risk" x
Clear All
Free access

Mayur Sharma, Elizabeth E. Bennett, Gazanfar Rahmathulla, Samuel T. Chao, Hilary K. Koech, Stephanie N. Gregory, Todd Emch, Anthony Magnelli, Antonio Meola, John H. Suh and Lilyana Angelov

predicting the relative safety of treatment plans in regard to surrounding organs at risk (OAR). 35 Although efforts have been focused on evaluating spinal cord tolerance when treating spinal column metastases, no recommendations exist for partial-volume tolerance of the nearby OAR, such as the brachial plexus and oropharyngeal structures (larynx, trachea, and esophagus), during SRS in the cervicothoracic region. The aim of our study was to evaluate the radiation dosimetry and acute and delayed effects (toxicity) of SRS on the spinal cord, larynx, trachea, esophagus, and

Full access

Sung Kwon Kim, Dong Gyu Kim, Young-Bem Se, Jin Wook Kim, Yong Hwy Kim, Hyun-Tai Chung and Sun Ha Paek

Analysis Quantitative analyses were performed to evaluate the effect of radiation dose on organs at risk (OARs), including the brainstem and the CN VII–VIII complex. Various parameters, including the radiation dose received by 2% or 50% of the tissue (D 2% and D 50% , respectively), and tissue volume covered by a dose of 12 Gy (V 12Gy ), were evaluated in the OAR analysis. Tumor coverage was defined as a dose that covered 95% of the tumor. Dosimetry evaluations were conducted by a medical physicist who was blinded to the clinical information of each patient. All

Full access

Jason P. Sheehan and Jay Jagannathan

radiosurgical centers currently utilize doses of 12–24 Gy to the margin of the treatment volume and deliver spinal radiosurgery in 1–5 fractions. 15 , 20 , 23 The prescription dose depends in part upon the tumor location, histological characteristics, and volume as well as the fractionation scheme, surrounding organs at risk, and prior radiation therapy. Numerous studies have demonstrated the safety and effectiveness of intracranial stereotactic radiosurgery for treating metastatic disease to the brain. Local tumor control rates following radiosurgery range from

Restricted access

Carys Thomas, Salvatore Di Maio, Roy Ma, Emily Vollans, Christina Chu, M.Math., Brenda Clark, Richard Lee, Michael McKenzie, Montgomery Martin and Brian Toyota

defined as an organ at risk. The plans were analyzed for cochlear V90%, V80%, and V50% of the prescription dose. Additionally, for each plan the Radiation Therapy Oncology Group conformity index was calculated 43 (this is the ratio of the prescription isodose volume divided by the target volume). The lower the value the more conformal the plan is, with a value of 1 representing perfect conformation. Radiation Therapy Oncology Group guidelines recommend that this value should fall between 1.0 and 2.0, with values between 2.0 and 2.5 classified as a minor deviation. The

Free access

Cormac G. Gavin and H. Ian Sabin

tractography data set was imported into GammaPlan (version 10.1; Elekta Instruments AB) using the native DICOM CD import function. The DICOM data sets were imported into the treatment planning session and coregistered with the main T1-weighted stereotactic treatment volume. The imported tract images appeared in gray scale in the DICOM format and were color coded with GammaPlan to facilitate clear identification. The GammaPlan software allowed critical tracts to be segmented as a structural volume and integrated into GammaPlan as an “organ at risk” during shot planning ( Fig

Free access

Michael Torrens, Caroline Chung, Hyun-Tai Chung, Patrick Hanssens, David Jaffray, Andras Kemeny, David Larson, Marc Levivier, Christer Lindquist, Bodo Lippitz, Josef Novotny Jr., Ian Paddick, Dheerendra Prasad and Chung Ping Yu

in contouring of arteriovenous malformations (AVMs) has been described. 8 A contouring consensus, both for the target and organs at risk (OARs), should be the subject for a separate standardization report. Any contouring or delineation recommendations in the current report should be considered provisional until such a consensus statement is prepared. 4.1 Terminology and Definitions Currently In Use The terminology in current use for defining volume in the various disciplines and comments on its applicability follow. 4.1.1 ICRU Reports Gross Tumor Volume The Gross

Free access

Marc Levivier, Rafael E. Carrillo, Rémi Charrier, André Martin and Jean-Philippe Thiran

Gamma Knife workflow. Images of the LGK treatment console ( upper right ) and of the LGK ICON ( middle right ) are courtesy of Elekta AB. Fig. 2. Screen shots of the GUI of IntuitivePlan. A vestibular schwannoma from one of the United Kingdom benchmark cases (courtesy of Ian Paddick), for which the target volume ( red line ) and the organs at risk ( orange line , brainstem; purple line , cochlea) were preexisting, is tested in our inverse planning system. Upper: Only the prescription dose for target volume (13 Gy, yellow line ) is used as a constraint. In the

Free access

Güliz Acker, Anne Kluge, Mathias Lukas, Alfredo Conti, Diana Pasemann, Franziska Meinert, Phuong Thuy Anh Nguyen, Claudius Jelgersma, Franziska Loebel, Volker Budach, Peter Vajkoczy, Christian Furth, Alexander D. J. Baur and Carolin Senger

recurrent intracranial meningiomas and for high-risk patients and those who refuse surgery. The most critical step of SRS treatment planning is the precise definition of tumor boundaries together with boundaries of the organs at risk (OARs). It is a matter of fact, also from a revised Leksell concept, that accuracy of targeting depends strongly on the quality of cross-sectional imaging. 13 In selected cases, especially for skull base tumors or tumors that have recurred after previous skull base surgeries, the standard diagnostic tools, namely contrast-enhanced CT and MRI

Free access

Alexis Dimitriadis and Ian Paddick

S tereotactic radiosurgery (SRS) is defined as a high dose of radiation, most commonly prescribed to an intracranial target. In intracranial treatments, the target is often surrounded by healthy brain, which is usually the primary organ at risk (OAR). In these treatments, it is essential to achieve a steep dose falloff from the periphery of the target to normal tissue in order to minimize normal tissue toxicity and resulting complications. Several studies have demonstrated the necessity for reducing volumes of high doses outside the target volume (TV; achieved

Restricted access

Hongbin Cao, Zhiyan Xiao, Yin Zhang, Tiffany Kwong, Shabbar F. Danish, Joseph Weiner, Xiao Wang, Ning Yue, Zhitao Dai, Yu Kuang, Yongrui Bai and Ke Nie

the target volume; and 4) the mean and maximum point dose and the integral dose (defined as the volume integral to the dose deposited, which is also equal to the mean dose times the volume) to the organs at risk and the total dose volume (V) in Gy to the normal brain for 2 Gy (V2), 5 Gy (V5), and 12 Gy (V12) were compared across all platforms. The group differences of all of the above indices were examined using paired nonparametric ANOVA tests, with p < 0.05 considered statistically significant. Results Case Example Figure 1 demonstrates a single case example