Important Safety Notice 

Limitations Related to Dynamic Scans 

To: Nuclear Medicine Department Manager 

This notice is to draw your attention to certain limitations regarding the usage of dynamic 
scans on the Infinia and Infinia II nuclear medicine cameras. These limitations must be 
considered when setting up and performing such scans. 

This notice contains important information concerning the safe use of the medical device 
mentioned above. Communicate this to all users in your facility and retain this document with 
the system user instructions. 

Background 

Dynamic scans are commonly used to image time-dependent processes in nuclear medicine 
practice. A dynamic scan is a sequence of “frames”collected at given time intervals, without 
any camera motion. The result is a series of static images (“frames”) that may be viewed 
consecutively or processed using dedicated protocols. 

In many cases, the dynamic protocol utilizes several phases, each containing its own 
definitions regarding the number and duration of frames, in order to sample different parts of 
the process at different rates. 

With the evolution of nuclear camera software, some operators use dynamic scans to acquire a 
set of consecutive static images, sampling a slower changing process. In order to allow this 
functionality, the Infinia acquisition software enables incorporating pre-defined "delays" 
within a dynamic scan. The "delay" may appear between phases or between consecutive 
frames within a phase. 

In addition, as in any scan, the user may initiate a pause in the scan at any point in time, by 
clicking the [Pause] button on the Acquisition Console or the <Go/Pause> on the handheld 
controller (RCU). 

While a "delay" is being "counted down" or a pause in a scan is in effect, data is not saved into 
frames until the flow of the scan is resumed. 


Customers using the “delay” or [Pause] operations are likely aware of the implications on data 
processing. The following should be noted: 

• Because the frames stored in such a dynamic study do not display the evolution 
of a continuous process but rather "discrete" points in time, it is necessary to use 
a dedicated processing application that accounts for this delay. Building standard 
"time-activity" curves is not appropriate for such studies. 
• Factory-provided processing protocols only support processing of dynamic data 
that was acquired continuously, without any "delays" or pauses that alter the time 
axis. 
The Issue 

This letter is to draw your attention to a limitation related to the combined simultaneous use of 
"delays" and the [Pause] option. 

In a recent incident, a customer defined a short "delay" between the two pre-defined phases in 
a hepato-billiary (HIDA) study. During the pre-defined "delay" between the phases, the 
operator also used the [Pause] option and then resumed the scan. This action corrupted the 
structure of the data acquired after this point in time. The second phase of the scan was 
acquired into a single static image, rather than into separate frames. 

A similar issue will occur if the user clicks [Pause] during a "delay" between frames. 

Recommended Solution 

To avoid data corruption, avoid defining "delays" within dynamic scans. This applies to both 
delays between phases and delays between frames. In such a setup, the [Pause] option may be 
used without generating technical problems with the acquisition. 

If pre-defined "delays" must be included within a dynamic scan, avoid using the pause option 
throughout the duration of the scan. 

As stated above, "interruptions" that occur in sampling the dynamic process are not accounted 
for during standard processing. When interpreting the results of dynamic scans in which 
“delays” or Pauses occurred, the user must be aware of the implications. 

Should you have questions concerning this notice, please contact your local GE Nuclear 
Service Representative. 

Thank you for your attention and continued support of GE Healthcare products and services. 

Sincerely