• The Korean Journal of Nuclear Medicine Technology
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• v.27 no.1
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• pp.36-41
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• 2023

Purpose The long-term trend of extrinsic uniformity by type of gamma camera was analyzed, and the factors affecting uniformity were investigated. Based on this, the purpose was to predict the life of the gamma camera, pay attention to factors that affect uniformity, and obtain better quality images. Materials and methods Four of the gamma cameras in operation at a senior general hospital in Seoul were selected and the trend of extrinsic uniformity from the first operation date to the present was analyzed. In order to minimize various factors affecting uniformity, a detailed analysis was conducted by calculating the monthly and annual average of the uniformity values. Results Two Symbia E gamma cameras from SIEMENS, one Symbia Evo Excel gamma camera, and one Symbia Intevo16 gamma camera were selected and analyzed. The uniformity of Symbia E₁ (2012 warehousing) changed unevenly, and the uniformity of Symbia E₂ (2014 warehousing) changed according to the replacement cycle of ⁵⁷Co sheet sources. The uniformity of Symbia Evo Excel (received in 2017) and Symbia Intevo 16 (received in 2017) was constant compared to Symbia E. Conclusion The extrinsic uniformity of the gamma camera gradually increased over time. However, there was a difference in uniformity for each type of gamma camera, and there was a change in uniformity in which the cause could not be accurately identified. In order to improve the quality of the image, it is necessary to periodically check changes in uniformity and minimize factors that affect uniformity.

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.1
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• pp.29-33
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• 2011

Background and Purpose: Uniformity is the one of the important quality control features with respect to gamma cameras. To maintain adequate uniformity, we must acquire suitable flood table (=flood map) data because the flood table effects energy, and the type or dose of input radiation. Therefore, in this study we evaluated the difference in uniformity when uniformity does not match between the type of input radiation and the flood table data or collimator type. Subjects and Methods: For input radiation, we prepared 370 MBq of $^{57}Co$, $^{99m}Tc$, and $^{201}Tl$. Using SKYLight (Philips) and Infinia gamma cameras (GE), we acquired nine uniformity data that were corrected by technetium, cobalt flood table and did not corrected image for the three sources. Additionally, we acquired two uniformity images with a collimator that were corrected by intrinsic and extrinsic flood tables. Using this data, we evaluated and compared the uniformity values. Results: In the case of the SKYLight gamma camera, the uniformities of the images that matched between the input radiation and flood table with respect to $^{99m}Tc$ and $^{57}Co$ were better than the unmatched uniformity (3.96% vs. 5.69% ; 4.9% vs. 5.91%). However, because there was no thallium flood table, the uniformities of images at Tl were significantly incorrect (7.49%, 7.03%). The uniformities of the Infinia gamma camera had the same pattern as the SKYLight gamma camera (3.7% vs. 4.5%). Moreover, the uniformity of the $^{99m}Tc$ image acquired with a collimator and corrected by an extrinsic flood table was better than the intrinsic flood table (3.96% vs. 6.28%). Conclusion: Correcting an image by a suitable flood table can help achieve better uniformity for a gamma camera. Therefore, we have to acquire images with suitable uniformity correction, and update the flood table periodically. Whenever we acquire a nuclear medicine image, we always have to check the appropriate flood table according to the acquired condition.

• Nuclear Engineering and Technology
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• v.55 no.8
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• pp.2873-2878
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• 2023

The purpose of this study is to perform radiation monitoring by acquiring gamma images and real-time optical images for ^99mTc vial source using charge couple device (CCD) cameras equipped with the proposed compact gamma camera. The compact gamma camera measures 86×65×78.5 mm³ and weighs 934 g. It is equipped with a metal 3D printed diverging collimator manufactured in a 45 field of view (FOV) to detect the location of the source. The circuit's system uses system-on-chip (SoC) and field-programmable-gate-array (FPGA) to establish a good connection between hardware and software. In detection modules, the photodetector (multi-pixel photon counters) is tiled at 8×8 to expand the activation area and improve sensitivity. The gadolinium aluminium gallium garnet (GAGG) measuring 0.5×0.5×3.5 mm³ was arranged in 38×38 arrays. Intrinsic and extrinsic performance tests such as energy spectrum, uniformity, and system sensitivity for other radioisotopes, and sensitivity evaluation at edges within FOV were conducted. The compact gamma camera can be mounted on unmanned equipment such as drones and robots that require miniaturization and light weight, so a wide range of applications in various fields are possible.