Radiation dose to organs outside the radiotherapy treatment field can be significant and clinical interest. Therefore, in order to estimate peripheral doses (PD) during the stereotactic radiosurgery treatment with Leksell Gamma Knife for single isocenter treatment technique in particular as a part of the method can be described the all plan treatment in general. Knowledge of PD can be used effe...

The concept of in-air output ratio (Sc) was introduced to characterize how the incident photon fluence per monitor unit (or unit time for a Co-60 unit) varies with collimator settings. 2 This quantity is also called inair output factor, collimator-scatter factor, and headscatter factor. 6 The latter two names were somewhat misleading since they emphasized a single component of the output ratio....

We developed SPECT imaging capability on an animal PET scanner to provide a cost effective option for animal SPECT imaging. The SPECT add-on sub-system was enabled by mechanically integrating a multiple-pinhole collimator in the PET detector ring. This study introduces a method to calibrate the geometrical parameters of the SPECT add-on using the PET imaging capability of the scanner. The propo...

The goal of quality assurance (QA) for a radiation oncology medical LINAC is to maintain an acceptable level of equipment performance and reliability. The increasing complexity of Radiation Oncology equipment and treatment techniques have led to increased demands on the work load of the medical physicist. Regular testing needs to be as efficient as possible. Generally, the QA tests, as recommen...

The concept of in-air output ratio (Sc) was introduced to characterize how the incident photon fluence per monitor unit (or unit time for a Co-60 unit) varies with collimator settings. However, there has been much confusion regarding the measurement technique to be used that has prevented the accurate and consistent determination of Sc. The main thrust of the report is to devise a theoretical a...

Inverting the exponential Radon transform has a potential use for SPECT (single photon emission computed tomography) imaging in cases where a uniform attenuation can be approximated, such as in brain and abdominal imaging. Tretiak and Metz derived in the frequency domain an explicit inversion formula for the exponential Radon transform in two dimensions for parallel-beam collimator geometry. Pr...

The purpose of this paper is to present the dosimetry and mechanical accuracy of the first rotating gamma system (RGS) installed in North America for stereotactic radiosurgery. The data were obtained during the installation, acceptance test procedure, and commissioning of the unit. The RGS unit installed at UC Davis Cancer Center (RGSu) has modifications on the source and collimator bodies from...