Design, Development and Implementation of µSPC Phantom for

Quality Control in Micro-SPECT / CT and Micro-PET / CT Systems

Qualitative Study

Hatem Besbes

, Nejla Majoul

, Fatma Ben Hamida

and Philippe Choquet

Laboratory of Biophysics and Medical Technology, El Manar University, Tunis, Tunisia

Biophysics and Nuclear Medicine Service, Hautepierre Hospital, Strasbourg, France

Keywords: µSPC Phantom, Quality Control, Micro-SPECT/CT.

Abstract: The μSPC phantom is designed for the quality control of micro-SPECT/CT and micro-PET/CT systems.

However, it is an assembly of six patterns stored in a cylindrical box and enabling to control both micro-

SPECT unit in terms of uniformity, linearity and spatial resolution than micro-CT unit in terms of

uniformity , linearity, spatial resolution, diffusion rate, low contrast detectability, linearity of Hounsfield

coefficients and slice thickness. The construction material is plexiglass. As for the implementation, it was

made on a micro-SPECT/CT machine of the type "speCZT eXplore CT 120".

1 INTRODUCTION

Preclinical imaging has recently evolved

considerably, but it has only been concerned with

small animals (mice, rats...). The results obtained in

preclinical tests are extremely useful in the fields of

clinical imaging (Glover, 2010; Dillenseger, 2013;

Lina, 2009; Peremans, 2011) and pharmacology

((Matthews, 2013; Slavine, 2008). However, given

the size of these animals, the instruments used have

better imaging performance than those used for

humans.

The expected results of the images obtained are

so important that we must be quite demanding in

considering their qualities. The continuous

production of better qualities of these images is

ensured by the development of adequate quality

control protocols (Glover, 2010; Moran, 2011; Jan,

2006). These protocols are developed with

reference to quality control protocols already

adopted in clinical imaging.

The preclinical imaging techniques targeted by

this work are micro-SPECT / CT and micro-PET /

CT.

2 METHODS AND MATERIALS

For the design of our phantom we chose to work

with solid works software (Fig.1) because it’s easy

to use and to adapt.

When designing the μSPC phantom (Fig. 1), we

have tried to make sure that it allows checking the

majority of quality parameters acquisition micro-

SPECT / CT and micro-PET / CT systems while

respecting the dimensions of acquisition areas

offered by each machine. For this, we have referred

to the NEMA accreditation for micro-SPECT and

micro-PET (Seret, 2011) and ACR accreditation for

micro-CT (Panetta, 2012) and we have fixed seven

quality control parameters that are uniformity

(micro-SPECT, micro-PET, micro-CT), linearity

(micro-SPECT, micro-PET, micro-CT), spatial

resolution (micro-SPECT, micro-PET, micro-CT),

diffusion profile (micro-CT), linearity coefficients

Hunsfield (micro-CT), low contrast detectability

(micro-CT) and thicknesses of slices (micro-CT).

As for the uniformity that can be measured

following an acquisition done on the homogeneous

solution, for each of the selected parameters we

designed a pattern enabling to evaluate it (Tab.1).

The patterns will be stored in a cylinder (part 1)

with sealing cover (parts 8, 9, 10, 11 and 12), which

are the body of the phantom (Fig. 1).

For the implementation of the μSPC phantom,

we made acquisitions on micro-SPECT/CT machine

of the type "speCZT eXplore CT 120" (GE

Healthcare) of the in vivo preclinical imaging

283

Besbes H., Majoul N., Ben Hamida F. and Choquet P..

Design, Development and Implementation of µSPC Phantom for Quality Control in Micro-SPECT / CT and Micro-PET / CT Systems - Qualitative Study.

DOI: 10.5220/0004915702830288

In Proceedings of the International Conference on Biomedical Electronics and Devices (BIODEVICES-2014), pages 283-288

ISBN: 978-989-758-013-0

 2014 SCITEPRESS (Science and Technology Publications, Lda.)



Figure 1: Conception of the μSPC phantom with SOLIDWORKS.

service in the Hospital Hautepierre of Strasbourg.

This camera is constituted by a micro-SPECT unit

and micro-CT unit. The detection head of the

micro-SPECT unit "eXplore speCZT" consists of

ten sensors plan CZT semiconductor having a

surface of 64 cm2 and 5 mm thick. The detectors

are stationary and located in form of decagon

around a rotating and interchangeable cylindrical

collimator (Fig. 4) ((Glover, 2010; Dillenseger,

2013; Hohui, 2010). As for the CT unit "Explore

CT 120", it is constituted by an X-ray high

efficiency tube of 5 kW whose voltage can vary

between 70 and 120 kV and is attached to a planar

array of CCD detectors 3500x2300. The X-ray

beam used for the micro-CT unit is conical

(Dillenseger, 2013).

For the realization of the phantom we used

essentially the Plexiglas which is cheaper than and

as efficient as plastic acrylate. When for machining

the various parts, we carefully performed on

conventional lathe and milling despite their small

size.

3 RESULTS

3.1 Realization of the µSPC Phantom

Figure 2: µSPC phantom.

According to the design, we realized the body of

the phantom that is a cylindrical enclosure with

sealed cover and with two holes for the introduction

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Table 1: Conception of patterns contained in the μSPC

phantom with SOLIDWORKS.

Parameter N° (fig.1) Pattern

Linearity (µPET,

µSPECT, µCT)

Spatial resolution

(µPET, µSPECT)

Spatial resolution and

diffusion profil (µCT)

Linearity of Hounsfield

coefficients (µCT).



Low contrast

detectability (µCT)



Slice thickness (µCT) 7

Figure 3: µSPC phantom body.

of solutions with contrast agents (Fig.3) and all the

patterns for control of various performances like

linearity, spatial resolution, diffusion profile,

Hounsfield coefficients linearity, low contrast

detectability and slice thickness measurements

(Fig.2, Tab.2).

Table 2: Patterns contained in the µSPC phantom.

Quality parameter Pattern

Linearity (µPET, µSPECT,

µCT)

Spatial resolution (µPET,

µSPECT)

Spatial resolution and

diffusion profil (µCT)

Linearity of Hounsfield

coefficients (µCT).

Low contrast detectability

(µCT)

Slice thickness (µCT)

3.2 Acquisitions

For the realization of the acquisitions on µSPC

phantom, we first filled it with a radioactive

solution (V = 11.5 cm

) made of demineralized and

degasified water (for 48 hours) + 1 drop of aqueous

eosin 2% + 0.1 ml of pertechnetate-99m solution

(activity = 4.10 mCi) + 1 drop of Iomeron 400.

After filling the phantom, we placed it in the tunnel

of the machine.

The micro-CT acquisitions concerned the

linearity, the diffusion profile, the linearity of

Hounsfield coefficients, the slice thickness, the low

contrast detectability and the uniformity (Tab.3).

Design,DevelopmentandImplementationofµSPCPhantomforQualityControlinMicro-SPECT/CTandMicro-PET/

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Table 3: Micro-CT Acquisitions.

Quality parameter Acquisition

Linearity

Linearity of Hounsfield

coefficients



Low contraste detectability

Diffusion profile



Slice thickness

Uniformity

The micro-SPECT and micro-SPECT/CT

acquisitions concerned linearity, uniformity and

spatial resolution (Tab.4).

Micro-SPECT/CT acquisitions are made

following the micro-CT acquisitions. Indeed, it

comes to be positioned on the micro-CT

acquisitions for achieving the micro-SPECT

acquisitions, and then we proceed with image

fusions. Thus, we were able to test micro-

SPECT/CT images for uniformity, linearity and

spatial resolution (Tab.5).

Table 4: Micro-SPECT Acquisitions.

Quality parameter Acquisition

Linearity

Spatial resolution



Uniformity

Table 5: Micro-SPECT/CT Acquisitions.

Quality parameter Acquisition

Linearity

Spatial resolution



Uniformity

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4 DISCUSSION

Knowing that we have worked on a new machine,

we found that it presents qualitatively very good

quality in terms of acquisition micro-SPECT.

Our μSPC phantom allowed, simultaneously,

the quality control of the micro-SPECT unit and the

micro-CT unit and consequently the whole of

micro-SPECT/CT system. Indeed, for the micro-

SPECT unit, we found that the spatial resolution is

close to 1mm as we distinguished a boundary

separation between the images of the two holes of

1mm diameter and separated by a distance also

1mm (Tab.4). In addition we have seen qualitatively

the presence of geometric distortions (Tab.4). As

for uniformity, we observed an artifact caused by

the presence of air bubbles (Tab.4).

At the micro-CT acquisitions, we have tested the

linearity of this unit (Tab.3), where the diffusion

profile, it is very easy to measure on the image of

Table 3 and in terms of the uniformity it is still easy

to calculate on the image of the same table. While

the study of the linearity coefficients of Hounsfield

(Tab.3) is clearly measurable for air, Teflon and

polyethylene, it is not the same for water because of

the presence of contrast agent (Iomeron 400). The

same thing for the low contrast detectability

(Tab.3), the Iomeron 400 increased shift of X-ray

attenuation rate between the Plexiglas and the

solution what makes the condition of low water-

Plexiglas contrast (Fig.4) is no longer there where it

is convenient to work without contrast agent. On the

other hand, to measure the slice thickness, low

contrast with water gives results with more

uncertainty (Fig.4) so that the results of this side are

better with the contrast agents (Tab.3).

Figure 4: Image test for slice thickness in micro CT

without Iomeron 400.

For micro-SPECT/CT acquisitions, we have noticed

that uniformity parameter is rather imposed by

micro-SPECT unit (Tab.4) which present

morphologically weaker qualities compared to

micro-CT. The same applies to geometric

distortions, they are more pronounced in the figure

in Table 5. Regarding the spatial resolution of the

whole system, it is better than 1mm because the

fusion with micro-CT can improve this quality.

If you do not see the test results of the spatial

resolution micro-CT, it is because the needle of the

test was broken when filling the phantom at

Hautepierre hospital.

5 CONCLUSIONS

This work has allowed us to offer to the practitioner

a new tool to better validate their results. Indeed,

μSPC the phantom we realized present very

interesting qualities because it allows to measure

the fundamental parameters of quality whatever for

micro-SPECT / CT or micro-PET / CT as the spatial

resolution and linearity.

The dimensions of the field of view that differ

from one device to another may or may not allow us

to add a test pattern contrast especially for devices

with a micro-PET unit. Moreover, we can achieve

as an accessory that can mount or dismount

depending on types of machines.

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