PO-0924: PTV margin calculation using an IGRT system for prostate treatments. Pelvic nodes margin assessment

IGRT versus non-IGRT for postoperative head-and-neck IMRT patients: dosimetric consequences arising from a PTV margin reduction

BACKGROUND To evaluate the impact of image-guided radiation therapy (IGRT) versus non-image-guided radiation therapy (non-IGRT) on the dose to the clinical target volume (CTV) and the cervical spinal cord during fractionated intensity-modulated radiation therapy (IMRT) for head-and-neck cancer (HNC) patients. MATERIAL AND METHODS For detailed investigation, 4 exemplary patients with daily con...

PTV margin definition in hypofractionated IGRT of localized prostate cancer using cone beam CT and orthogonal image pairs with fiducial markers

PURPOSE To evaluate PTV margins for hypofractionated IGRT of prostate comparing kV/kV imaging or CBCT. PATIENTS AND METHODS Between 2009 and 2012, 20 patients with low- (LR), intermediate- (IR) and high-risk (HR) prostate cancer were treated with VMAT in supine position with fiducial markers (FM), endorectal balloon (ERB) and full bladder. CBCT's and kV/kV imaging were performed before and ad...

PTV margin determination in conformal SRT of intracranial lesions

The planning target volume (PTV) includes the clinical target volume (CTV) to be irradiated and a margin to account for uncertainties in the treatment process. Uncertainties in miniature multileaf collimator (mMLC) leaf positioning, CT scanner spatial localization, CT-MRI image fusion spatial localization, and Gill-Thomas-Cosman (GTC) relocatable head frame repositioning were quantified for the...

A Margin Calculation Method For Illiquid Products

The role of the central counterparties (CCPs) on the market is to take over the counterparty risk during the trading on stock exchanges. CCPs use a multilevel guarantee system to manage this risk. The margin has a key role in this guarantee system, and the paper will focus only on this level. The main motivation of this paper is to introduce a potential margin calculation method which is compli...

Voltage Security Margin Assessment