Collimator and energy window optimization for YTTRIUM-90 bremsstrahlung SPECT imaging

Developing a protocol for 90Y bremsstrahlung imaging after Transarterial Radioembolization

“…A small and large region of interest (ROI) were drawn around the tumor and over the image's background, respectively. Contrast, SBR, CNR, %FOV, and sensitivity were calculated using the following formulas [3,20,21]:…”

“…As mentioned above, one of the limitations of 90 Y bremsstrahlung imaging is the low bremsstrahlung photon yield [26]. To address this limitation, several studies have documented the use of high-sensitivity collimators such as ME (Medium Energy), as higher sensitivities reduce the imaging time and the possibility of motion artifact and variance of activity estimation [21,27]. As shown in figure 3(a), the sensitivity value of the image taken with HEMR collimator and energy window of 50-200 keV is approximately 14% higher than the images acquired by the MEMR collimator and energy window of 50-100 keV.…”

Energy window optimization in bremsstrahlung imaging after Yttrium-90 microsphere therapy

“…The figure 4 shows an example of Y-90 Bremsstrahlung energy spectrum acquired with MEGP collimator and energy window with of 90-110 keV. As expected, 90 Y bremsstrahlung photons have a continuous and broad energy distribution in the energy range from 0 to 500 keV [11]. The characteristic lead x-ray peak, shown in the 70-90 keV energy range is results of the interaction between bremsstrahlung photons and the lead collimator.…”

“…Many experimental and simulation imaging studies have been conducted on the energy window selection in planar/SPECT bremsstrahlung imaging and detailed information was given in our previous study [11]. In a Y-90 bremsstrahlung imaging optimization study using a Monte Carlo code, the appropriate imaging condition was obtained with a High-Energy Medium-Resolution (HEMR) collimator in the energy range of 50-200 keV [4].…”

“…In our previous study based on a Y-90 vial imaging with very high-count rates, optimum imaging parameters were obtained using HEGP collimator in the 90-110 keV energy range [11]. However, in the case of 90 Y bremsstrahlung imaging during patients' treatments, it is well known that the count rates are low.…”