Statistical properties of counting distributions for intensity- modulated sources
نویسندگان
چکیده
Furthermore, we can see that the outline in Fig. 6 does not have a second plane of symmetry at right angles to that shown. This means that, even if we were to determine the lines of flow for the truncated cone, the condition of detailed balance of the rays (Sec. III) at a mirror along the flow lines could not be fulfilled. Thus, the flow at other regions would be perturbed, and the concentrators would not be ideal.
منابع مشابه
Influence of Compensator Thickness and Field Size on Buildup factor of a Brass Compensator for Intensity- Modulated Radiation Therapy
Introduction: Radiotherapy is one of the effective methods in the treatment of cancer. In the recent methods of radiotherapy, intensity modulated radiotherapy (IMRT) technique by compensators is used. when photon beam passes the compensator, scattered photons can be generated within the compensator. The presence of scattered photons may complicate the design of compensators as...
متن کاملPhotoelectron - Counting Distributions for Irradiance - Modulated Radiation
Photoelectron-counting distributions are obtained for modulated radiation sources, with arbitrary modulation waveforms and depths. Cases treated in detail include chaotic, amplitude-stabilized, and Risken sources, with square-wave, triangular, and sinusoidal modulation. Modulation is shown to broaden the counting distributions, an effect interpretable as accentuated photon bunching. The broaden...
متن کاملThe Dosimetric Effects of Different Multileaf Collimator Widths on Physical Dose Distributions
Introduction: Geometric changes in the multileaf collimator (MLC) led to dosimetric considerations in intensity-modulated radiation therapy (IMRT) due to the number and size of the pixels in the intensity map, which are determined by the MLC leaf width. In this study, we evaluated the dosimetric effects of different MLC widths on physical dose distributions for IMRT plans. Materials and Method...
متن کاملGrid: A location dependent intensity modulated radiotherapy for bulky tumors
Background: An effective method for management of large and bulky malignant tumors. This treatment modality is also known as Specially Fractionated Radiation Therapy (SFRT). In this treatment technique a grid block converted the open radiation field into a series of pencil beams. Dosimetric characteristics of an external beam grid radiation field have been investigated using experimental and Mo...
متن کاملAnalysis of Resting-State fMRI Topological Graph Theory Properties in Methamphetamine Drug Users Applying Box-Counting Fractal Dimension
Introduction: Graph theoretical analysis of functional Magnetic Resonance Imaging (fMRI) data has provided new measures of mapping human brain in vivo. Of all methods to measure the functional connectivity between regions, Linear Correlation (LC) calculation of activity time series of the brain regions as a linear measure is considered the most ubiquitous one. The strength of the dependence obl...
متن کامل