imagen instrumentation of nuclear medicine quality control phantom, including some device used for control of spect ct gamma cammera for diagnostic in nm

1. Master in Medical Physics 2015 to 2016
Imaging Instrumentation (SPECT) QC
Francisco J. Hernandez Flores
International Centre for Theoretical Physics
franciscohernandez_f2010@hotmail.com
December 25, 2015
Abstract
This task is relation to visit the Cattinara Hospital nuclear medicine area,
the mean part of this practice was to now the layout of the nuclear medicine the
structure of the all room and your respective equipment used in cuality control of
image. and discuses about which parameter affect the quality of image such as:
differential and integral uniformity, spatial resolution, energy resolution, pixel
dimension, intrinsic spatial resolution, intrinsic spatial linearity, intrinsic count
rate, system sensitivity, system spatial resolution etc. are all calculated with
reproducible methodology that allows the user reliable technique for creation of
these standards to avoid any lack of clinical service that may violate the ethics of
patient care. Because Tc-99m is the most frequently used radionuclide in nuclear
medicine, many clinics perform the daily uniformity and weekly resolution checks
using this radionuclide.
I. Introduction
The objective of this practice based in nuclear medicine layout and instrumenta-
tion is to give basic knowledge at student based in nuclear medicine detailed
quality control test procedures for the camera and computer system. During
the practice were described in detail: acceptance, reference and routine tests
for the camera, both in single and multiple head configurations, for obtaining
images and quantitative data in planar imaging mode; whole body imaging
mode; and single-photon emission computed tomography (SPECT).
II. Theory
I. PLANAR INTRINSIC UNIFORMITY
Uniformity is a measure of a camera’s response to uniform irradiation of detec-
tor surface; the ideal response is a perfectly uniform image (all pixels have the
same counts). [2]
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2. Master in Medical Physics 2015 to 2016
II. PIXEL DIMENSION.
Definition: The actual physical dimension of pixels.
Evaluation of pixel dimension. draw on the image two profiles (along X and
Y directions) and evaluate the central position of the point sources. Evaluate
the distance (in pixel) along the x and y direction. [2]
Pixeldimension =
200mm
Numbero f pixel
(1)
Figure 1: Three sources (drops) of about 25 MBq. for evaluate pixel dimension
III. INTRINSIC SPATIAL RESOLUTION
Definition. The ability to accurately distinguish as separate two close radioac-
tive (point or linear) sources. The pixel dimension is the physical size of the
smallest element in the image obtained by a specific sampling frequency (ma-
trix). The spatial resolution is never < pixel dimension. [2]
Evaluation. the calculated average values of FWHM and FWTM for both axes,
lying within UFOV and CFOV.
IV. INTRINSIC SPATIAL LINEARITY
Definition. The ability to portray the shape of objects accurately, i.e. the amount
of positional distortion or displacement of the measured position of a source
relative to the actual position. [2]
Evaluation.
• Differential linearity: Standard deviation of the distance of peaks of the
fitted LSF (Line Spread Function) from the straight line fitting the slit
image.
• Integral Linearity: maximum distance of peaks of the fitted LSF (Line
Spread Function) from the straight line fitting the slit image.
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3. Master in Medical Physics 2015 to 2016
III. Materials and Methods
During this practice were discuses two point patient management and quality
assurance of gamma cameras.
1. Patient management.
The layout of the department of Nuclear medicine.
• Different rooms, patient path, staff path, radiation protection criteria.
Radio pharmaceutical preparation room.
• The manipulation cell, the activity calibrator.
• Calibration quality control.
2. Quality assurance of gamma cameras.
Scintigraphic examination room
• Acquisition console, gamma camera, collimator.
• Test objects and phantom.
Practice gamma camera quality control.
• Intrinsic and system test.
• Intrinsic uniformity and sensitivity according to NEMA protocol
(a) Gamma camera (b) Phantom
(c) ionization camera (d) Phantom pixel dimension
Figure 2: Instrument used for quality control in Gamma Camera
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4. Master in Medical Physics 2015 to 2016
Figure 3: layout nuclear medicine of the Catinara Hospital [1]
IV. discussion and results
This practice was qualitative not quantitative. The discussion during this prac-
tice was about how to use adequate instrumentation, and different equipment
that to use for quality control of gamma camera.
And during the practice talked about each test for quality control of image
how we can measure or obtaine each parameter in quality control of image such
as: Pixel dimension, Uniformity, intrinsic spatial resolution, intrinsic spatial
linearity and intrinsic counter rate.
The count density (counts per pixel) has a significant impact on image qual-
ity. Spatial resolution and lesion detectability are reduced in low-count density
images.
In the case of Pixel dimension they use a sheet of plexiglass with three holes
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5. Master in Medical Physics 2015 to 2016
in the edges of a square of 200 mm they obtain pixel dimension see fig.1 and
this image obtained is processed with software osiris or imagej the pixcel size
can calculate using the equation 1
V. Conclusion
• This report has briefly commentary the the practical in Cattinara Hospital
in nuclear medicine department about routine QC procedures of current
nuclear medicine instrumentation, including dose calibrator, well counter,
SPECT and SPECT/CT scanner, this training practice is very useful for
our knowledge like medical physicist.
References
[1] Dedenaro, Lecture Radiation protection Italian law , Mageore Hospital Trieste
Italy, 3rd trimester 2015.
[2] Formasier M.R, Lecture Nuclear Medicine , ICTP, Trieste Italy, 3rd trimester
2015.
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