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Dosimetry concepts for scanner quality assurance and tissue dose assessment in micro-CT
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10.1118/1.3675400
/content/aapm/journal/medphys/39/2/10.1118/1.3675400
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/39/2/10.1118/1.3675400

Figures

Image of FIG. 1.
FIG. 1.

(a) Cylindrical PMMA phantoms of 20 and 32 mm diameter and (b) dosimetric equipment (phantom, ionization chamber, TLD holder, and TLD rods) used for dose measurements.

Image of FIG. 2.
FIG. 2.

Example for the TLD placement in the 2 mice cadavers (maximum intensity projections of mouse two, first scan). Three sets of two TLDs each were placed at different positions in the mouse cadaver: One in the abdomen and two in the thorax [anatomical right (r) and left (l)].

Image of FIG. 3.
FIG. 3.

Calibration results: ionization chamber response over the voltage range typical for (a) the TomoScope micro-CT scanner (40, 50, and 60 kV) and (b) clinical CT (beam qualities RQR 9, RQA 9, RQT 8–10, see Table IV).

Image of FIG. 4.
FIG. 4.

CTDI100 measured free in air and in the central cavity of the 20 and 32 mm cylindrical PMMA phantoms in a six month interval between June and December 2010.

Image of FIG. 5.
FIG. 5.

Spectra calculated according to Tucker et al. as well as measured spectra (40 and 60 kV).

Image of FIG. 6.
FIG. 6.

CTDI100,c as a function of voltage for both cylindrical PMMA phantoms using (a) spectra calculated according to Tucker et al. and (b) spectra measured at our institute.

Image of FIG. 7.
FIG. 7.

Dose profiles along the z-axis measured with TLD rods (points) and calculated using MC calculations (lines) for three different voltages and the 32 mm PMMA phantom.

Image of FIG. 8.
FIG. 8.

(a) Measured versus calculated CT values at 40 kV for all materials listen in Table III. (b) Density vs CT value for different human tissues at 40 kV.

Image of FIG. 9.
FIG. 9.

(a) Slice through an acquired CT dataset of a mouse and (b) corresponding dose distribution.

Image of FIG. 10.
FIG. 10.

Approach of CTDI L to the equilibrium dose for the 32 mm phantom and a tube voltage of 60 kV.

Tables

Generic image for table
TABLE I.

Technical parameters of the TomoScope micro-CT scanner.

Generic image for table
TABLE II.

Tube voltage, total tube output, and air kerma for all scan protocols used.

Generic image for table
TABLE III.

Materials used for stoichiometric calibration of the MC tool.

Generic image for table
TABLE IV.

Beam qualities for clinical CT [according to IEC 51267:2005 (Ref. 28)].

Generic image for table
TABLE V.

Materials and corresponding CT value thresholds used for material decomposition at 40 kV.

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TABLE VI.

Measured and calculated TLD readings, calibrated in air kerma at different positions (r = anatomical right, l = anatomical left) in two mice cadavers.

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/content/aapm/journal/medphys/39/2/10.1118/1.3675400
2012-01-12
2014-04-19
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Dosimetry concepts for scanner quality assurance and tissue dose assessment in micro-CT
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/39/2/10.1118/1.3675400
10.1118/1.3675400
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