Digging in the penumbra of master categories.

Study the effect of source to diaphragm distance (SDD) on beam penumbra width of Gamma Knife machine model 4C using Monte Carlo simulation

Introduction: Stereotactic radiosurgery (SRS) is one of the conformal radiotherapy methods and Gamma Knife is a non-invasive SRS technique to treat intracranial lesions with 201 Co- 60 sources without need to surgery and bleeding. Beam penumbra phenomenon leads to irradiation outside the field and normal tissues. Therefore, considering it is momentous to attain the acceptable t...

Investigation of physical penumbra definition in treatment planning

Background: Due to the small size of the beamlets in IMRT (intensity modulated radiotherapy), physical penumbra is one of the important dosimetric parameters and small changes in the penumbra have a notable impact on the results. The physical penumbra width is defined as the lateral distance between two specified isodose curves at a specified depth of phantom. In this study, after demonstrating...

Investigation of physical penumbra definition in IMRT applications

Introduction: Because of small size of the beamlets in IMRT, physical penumbra is one of the important dosimetric parameters and small changes in the penumbra will have a great impact on the results. The physical penumbra width is defined as the lateral distance between two specified isodose curves at a specified depth of phantom. In this study, after demonstrating the inconsi...

Penumbra Measurements and Comparison of In-House and Standard Circular Cones by the Gafchoromic Film, Pinpoint Ion Chamber, and MCNPX Monte Carlo Simulation

Introduction: Penumbra is an important property of the radiation beam to obtain a suitable margin surrounding the target volume. Therefore, the precise penumbra width determination in stereotactic radiotherapy is necessary for treatment planning. This study aimed to compare the obtained results of penumbra width by in-house and standard circul...

Structure of proper motions in a sunspot penumbra