background: accurate small radiation field dosimetry is essential in modern radiotherapy techniques such as stereotactic radiosurgery (srs) and intensity modulated radiotherapy (imrt). precise measurement of dosimetric parameters such as beam profile, percentage depth doses and output factor of these beams are complicated due to the electron disequilibrium and the steep dose gradients. in the p...

In a stroke lesion, there is a core of necrotic cell death surrounded by a zone of tissue at risk, termed the penumbra. In the penumbra, there is usually less severe tissue damage. Programmed cell death (PCD) pathways have been documented to be present in the penumbra. While many studies have used the term apoptosis as equivalent to PCD, the absence of complete biochemical and morphological cha...

In this paper, we present an image based method for computing contact hardening soft shadows by utilizing an erosion operator. Our method is based on shadow mapping and operates in screen space. By using object silhouettes in hard shadows, we estimate the penumbra size and scale an erosion operator to generate the penumbra areas. Furthermore, we present two solutions to generate the shadow fact...

Corporate law has done a very poor job on executive pay: executives have been rewarded for stellar "performance" that turned out to be anything but stellar, and shareholders have had no meaningful recourse. Indeed, there are many other such cases where there is no breach of the fiduciary duties of care and loyalty, but the board's behavior nevertheless smacks of a classic agency problem known a...

A robust whole brain magnetic resonance (MR) bolus tracking technique based on indicator dilution theory, which could quantitatively calculate cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) on a regional basis, was developed and tested. T2*-weighted gradient-echo echoplanar imaging (EPI) volumes were acquired on 40 hyperacute stroke patients after gadolinium...

This report presents the "penumbra sign" of a Brodie's abscess in a 69-year-old male patient. The lesion was located in the proximal metaphysis of the left tibia. Histopathology confirmed the diagnosis of subacute osteomyelitis. The penumbra sign on magnetic resonance (MR) images is a helpful sign for the diagnosis of Brodie's abscess.

Hemodynamic Changes in Subacute and Acute Poststroke Stages It is important to consider issues related to hemodynamic changes in the hours and days after stroke or brain injury. Acute stroke is an evolving event in which there may be opportunities to intervene over several days following the insult. Dysfunctional regions within the ischemic penumbra may include viable tissue, but how long it wi...