Bremsstrahlung imaging from the liver using the Monte Carlo simulation

Most beta and gamma radiation radioisotopes used for treatment are not suitable for imaging. The bremsstrahlung images on a conventional gamma camera helped to localize the radionuclide within and outside of the lesion. Secondary scattering of gamma rays of higher energy and bremsstrahlung causes contamination in the energy window and reducing the contrast and resolution of the images and the quantization validation of the images cannot be performed. Therefore, the accuracy of scatter correction methods is of great importance. The method involves the use of energy window, empirically selected broad bremsstrahlung energy to enhance the signal to noise ratio and a wiener restoration filter to compensate for system blur.

To simulate and validate the system, a water bottle containing Phosphorus-32 (P32) radio was taken. GATE package was used to determine the spectrum of bremsstrahlung radiation from P32 inside the liver and Zubal phantom was used to model a liver. Importantly, simulations were performed in the presence of a collimator without collimator and the collimator function was calculated. Zubal Phantom was also used to model liver imaging. The Wiener filter was used as a resolution adjuster.

Despite the small number of electrons reaching the collimator, a considerable spectrum is produced. Collimator function and simulated liver image were calculated. No significant change in resolution was observed after using the Weiner filter.

The energy spectrum of the beams was altered after collimation to the collimator. Also, the shape of the energy spectrum was influenced by the type of tissue and size of the patient. The results had shown that planar gamma camera imaging and quantitation of P32 can be done. There is no compelling reason to suggest that the Wiener filter is useful in planning a Plane.