Photon Factory Activity Report 2014 #32 (2015) B

BL-4A/2013G722,2015G081

Detector Setting of X-ray Fluorescence Analysis for Histological Specimens
Akihiro Matsuura, Miyuki Kinebuchi
Fujita Health University School of Medicine Department of Pathology
Kutsukake, Toyoake 470-1192, Japan

1 Introduction	  The measurement condition of X-ray fluorescenceanalysis is very important to analyze biological
specimens. Because there are very little amount ofelements on thin tissue sections, the condition setting
is much more difficult than the measurement ofelemental standards, such as metal foil andgeological stone samples[1]. Therefore, various
conditions need to be improved to increasesignals/noise ratio and to maximize secondary X-ray
energyresolution.

We

previously

testedFigure 1 SDD detector and its positioning

anddetermined the conditions of X-ray energy and

3 Results and Discussion

thickness of backing films [2][3]. In this experiment,

The copper accumulated tissue section was used to

we determine the distance of photon detector fromassess relationship of copper signals and counting

sample to acquire high signals and to reduce

loss. The same area of the sample was exposed tocounting

X-ray beam (11keV) with the different distance fromloss(%deadtime)

duringdefinedmeasurement time.

a tip of probe to sample. At 30 mm, the counting loss
was very high; approximately 32.5%. Therefore, we

2 Methods and Experiments

tested the distance at 40, 45, and 50 mm. As shown

The silicon drift X-ray detector (SDD, Vortex-EX,in Figure 2, whereas the elastic scattering peak

Hitachi, Japan), a type of energy dispersive X-ray(Thomson scattering) as well as copper and otherdetector (XEDS), connected to the current amplifier

elemental peaks were gradually decreased as the(Model 428, Keithley, U.S.A.) was placed on thedistance increased, the element-specific X-ray peaks

mobile rack that could be readily moved to adjust thewere clearly distinguishable. The resolution wasdistance between a tip of probe and sample (Figuresufficiently high in all settings.

1). The thermoelectrically cooled SDD does not
require liquid nitrogen. Formalin fixed paraffin
embedded (FFPE) tissue sections were prepared andplaced on backing films. The samples were irradiatedby a 11 keV X-ray beam focused by thepoly-capillary system. The resultant fluorescence
X-ray emission was detected, amplified, analyzed

Figure 2 Fluorescence yields and probe distanceand depicted as histogram. Basic settings of BL-4A
were selected as follows: scan mode, spot analysis

Furthermore, the counting loss of each point was(MCA); acquire mode, MCA; MCA preset type, live;

gradually decreased as shown in Table 1, about 20%

Preset time, 100; counter channel number, 2.

dead time at 40 mm, 15% dead time at 45 mm, and30Photon Factory Activity Report 2014 #32 (2015) B

about 10% dead time at 50 mm. Although thecounting loss can be corrected by calculation, it ispreferable to use the raw count to on-site settings.

Table 1 Probe distance, incident beam intensity,copper signals and counting loss (% dead time)
We used the probe distance of 50 mm in a series ofexperiments using poly-capillary focusing [4].
Whether the setup is appropriate for samples
contains much less amount of copper and otherelements, need to be reappraised.
4 References[1] T Paunesku et al. J Cell Biochem 99, 1489-1502(2006).
[3] A Matsuura A and M Kinebuchi. PFACR 31, 309(2014)[3] A Matsuura A and M Kinebuchi. PFACR 31, 315(2014)[4] M Kinebuchi and A Matsuura. Acute Med Surg 2,
in press DOI: 10.1002/ams2.100* amatsuu@fujita-hu.ac.jp

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