Investigation of Multiple Head Registration / Center of Rotation for SPECT Gamma Cameras
Abstract
Introduction:
One of the important quality control checks for SPECT Gamma Camera is the centre of rotation (COR). Multiple Head Registration / Center of Rotation (MHR/COR) is also important not only to observe the mechanical errors in the state-of-art Gamma Camera, but also to correct, quantitatively, the errors from the movement of patients and detectors on the SPECT images.
Material and Method:
Three gamma cameras (two Siemens and one Philips), were studied using Low Energy High Resolution (LEHR) collimators with protocols provided by the manufacturers based on the international regulations and committees.
In Siemens cameras (Ecam and Duet), MHR/COR was studied using five point sources of Tc99m (1 mCi) each in a special phantom. In Philips camera (Forte), COR was measured using an assembly consisting three point sources of Tc99m (0.5 – 1 mCi) with the Jet stream Quality Assurance (QA) software.
Results:
The MHR/COR was studied in Siemens cameras (Ecam and Duet) including the error of X- max., X-min., Y shift and back projection angle with 180 and 90 degrees configurations for 30 months. Ecam results showed high stability through this period but Duet values are slightly varied. The results of COR in Forte camera including the error of X- max., X-min and Y error range with 180 and 90 degree configurations indicated marked changes within 26 months. However these changes were observed within the acceptable limits.
Conclusion:
The MHR/COR quality control checks are crucial indication about the mechanical performance of a SPECT camera. It is important to update the correction map of the software to correct the camera heads registration errors and the patients movements. It is recommended for Forte to measure the COR on weekly basis in order to maximize the benefit from the COR calibration correction software.
One of the important quality control checks for SPECT Gamma Camera is the centre of rotation (COR). Multiple Head Registration / Center of Rotation (MHR/COR) is also important not only to observe the mechanical errors in the state-of-art Gamma Camera, but also to correct, quantitatively, the errors from the movement of patients and detectors on the SPECT images.
Material and Method:
Three gamma cameras (two Siemens and one Philips), were studied using Low Energy High Resolution (LEHR) collimators with protocols provided by the manufacturers based on the international regulations and committees.
In Siemens cameras (Ecam and Duet), MHR/COR was studied using five point sources of Tc99m (1 mCi) each in a special phantom. In Philips camera (Forte), COR was measured using an assembly consisting three point sources of Tc99m (0.5 – 1 mCi) with the Jet stream Quality Assurance (QA) software.
Results:
The MHR/COR was studied in Siemens cameras (Ecam and Duet) including the error of X- max., X-min., Y shift and back projection angle with 180 and 90 degrees configurations for 30 months. Ecam results showed high stability through this period but Duet values are slightly varied. The results of COR in Forte camera including the error of X- max., X-min and Y error range with 180 and 90 degree configurations indicated marked changes within 26 months. However these changes were observed within the acceptable limits.
Conclusion:
The MHR/COR quality control checks are crucial indication about the mechanical performance of a SPECT camera. It is important to update the correction map of the software to correct the camera heads registration errors and the patients movements. It is recommended for Forte to measure the COR on weekly basis in order to maximize the benefit from the COR calibration correction software.