Computers in Nuclear Medicine :Computers in Nuclear Medicine Jessica Castillo Rotha Mam Jessenia Ramirez


Objectives :Objectives Describe the 2 basic formats in which the data from a scintillation camera is stored in Describe what a histogram mode is Discuss the difference between frame mode and list mode Determine the difference between statics and dynamics Determine matrix size


Acquisition :Acquisition The data from a scintillation camera may be stored in 2 basic format It may be framed in memory Or recorded in list or serial mode Do to low speed use of the disk some systms can only record data in frame mode


Frame mode :Frame mode Is sometimes referred to as histogram mode Because the data is blocked in time A matrix of memory location is established to correspond to the positions at which the scintillations take place in the detectors The matrix size is limited in order for the infinite number of positions that the scintillation could take place is reduced to those limited dimensions


Frame mode :Frame mode


List mode :List mode In contrast to frame mode, list mode does not create a digital image The memory contains a list of x and y locations List mode is created in chronological order and to allow play back of dynamic data, timing marks are also placed into this list at regular intervals


List mode :List mode As a result anyone location in memory will contain only the x and y information about 1 count This data is then converted to the disk as a continuous list of event Unlike frame mode, in list mode the amount of disk storage depends on how many counts are recorded


List mode :List mode


Matrix size :Matrix size After acquiring the data in frame mode and framing list mode data, one must make a choice pertaining to the size of matrix How much memory is used or how much disk space is utilize must be taken into consideration The matrix is usually adjusted to accept the full field of view of the camera


Matrix size :Matrix size Studies that are collected in byte mode occupy half of the space required for the equivalent word mode matrix


Matrix size :Matrix size Matrix size takes on the values of 32x32 64x64 128x128 256x256 A 32x32 matrix will occupy less memory and disk space then one of 256x256


Matrix size :Matrix size


Statics :Statics The most significant difference between static and dynamic studies is the way in which each frame is closed A static study maybe completed on the basis of a preset time or present count


Dynamic :Dynamic Each frame of dynamic study is closed on the basis of preset time and is controlled by a clock internal to the computer When an acquisition is set up the time fro each frame is entered


Disk space requirement :Disk space requirement The max. framing rate possible depends on the disk access and the transferred speed


Gated :Gated Is normally associated with cardiac studies The first frame represents end diastole and subsequent frame proceed to systole to end systole and back to the filing phase The computer is programmed to respond to the ecg which is an electrical signal that is not necessarily representative of the true mechanical state of the heart


Gated :Gated Some gated synchronized acquisition programs have the option of some form of arrhythmia detection and rejection built into them If the computer sense that the duration of R R interval is outside of the established tolerance, data acquisition is interrupted until the length of the R R interval is within tolerance once again


Gated :Gated The disadvantage of this program is that it can only detect that the RR interval is out of tolerance only after the data of one bad beat has been collected The data from the next “good” beat will be ignored since the computer cannot determine that it was a “good” beat until after the RR interval is completed, then it will resume data acquisition based on the assumption that the next interval will also be within tolerance


Gated :Gated


Gated List Collections :Gated List Collections Used when other methods of data collection are unsatisfactory such as in cases of severe arrhythmia Differs from a list mode study only in the sense that the chronological position of each R-wave is also recorded. Because only R-R intervals of a chosen length are being selected, such data are not a measure of the function of the heart.


Real Time List Mode :Real Time List Mode Usually a hybrid system using two list mode buffers to store data as they are initially inputted and then framed in real time. Arrhythmic beats and optionally, the following compensatory beats may be entirely eliminated. This program provides true arrhythmia rejection and ensures that the data for the later filling phase of the cardiac cycle are valid without the usual count drop off resulting from minor R-R variations.


Predefinition :Predefinition These are predefined established acquisition protocols used for convenience and efficiency. The name of the study, the matrix size, the framing rate and all other parameters of data collection will remain constant.


Predefinition :Predefinition Generally, the user enters the appropriate responses for the collection parameters, and these responses are stored under that protocol. When one wishes to use that protocol, it’s just a matter of “filling in the blanks”. This assists in quality control of the acquisition protocols by ensuring consistency.


Predefinition :Predefinition Predefined parameters should also be able to be edited since it may be necessary to tailor the collection parameters to a particular patient. Other useful features are the ability to have the predefined study collection protocols call a predefined processing protocol or to call itself again in order to invoke an automatic repeat of the same study.


Reference :Reference Alpert ML, McKuicik KA, Pohost GM, et al. Noninvasive nuclear kinecardiograhy. J Nucl Med 1974; 15:1182. Adam WE, Tarkowski Abutter F et al. Equilibrium (gated) radionuclide ventriculoggraphy. Cardiocasc radiol 1979;2:161


Question 1 :Question 1 What are the 2 basic formats in which a scintillation camera data is stored in?


Answer 1 :Answer 1 It may be framed in memory Or recorded in list or serial mode


Question 2 :Question 2 Why is frame mode referred to has a histogram mode?


Answer 2 :Answer 2 Because the data is blocked in time


Question 3 :Question 3 What is the difference between frame mode and list mode?


Answer 3 :Answer 3 List mode does not create a digital image like frame mode


Question 4 :Question 4 What is to be taken into consideration when dealing with matrix size?


Answer 4 :Answer 4 How much memory is used or how much disk space is utilize


Question 5 :Question 5 What is the difference between static and dynamic mode?


Answer 5 :Answer 5 The most significant difference between static and dynamic studies is the way in which each frame is closed


Question 6 :Question 6 What is a disadvantage of the ECG program?


Answer 6 :Answer 6 The disadvantage of this program is that it can only detect that the RR interval is out of tolerance only after the data of one bad beat has been collected


Question 7 :Question 7 How does a gated list collection differ from a general list mode study?


Answer 7 :Answer 7 Chronological position of each R-wave is recorded.


Question 8 :Question 8 What mode uses two list mode buffers to store data as they are inputted and then framed in real time?


Answer 8 :Answer 8 Real Time List Mode


Question 9 :Question 9 What are predefined sequences?


Answer 9 :Answer 9 Sequences which certain parameters are constant leaving only pertinent patient data to be filled in.


Question 10 :Question 10 Predefined acquisition parameters assist in quality control of the acquisition protocols by ensuring consistency. True or False.


Answer 10 :Answer 10 True