Columnar-structured cesium iodide (CsI) scintillators doped with thallium (Tl) are frequently used as x-ray converters in medical and industrial imaging. In this study we investigated the imaging characteristics of CsI:Tl films with various reflective layers-aluminum (Al), chromium (Cr), and titaniu...
Columnar-structured cesium iodide (CsI) scintillators doped with thallium (Tl) are frequently used as x-ray converters in medical and industrial imaging. In this study we investigated the imaging characteristics of CsI:Tl films with various reflective layers-aluminum (Al), chromium (Cr), and titanium dioxide ($TiO_2$) powder-coated on glass substrates. We used two effusion-cell sources in a thermal evaporator system to fabricate CsI:Tl films on substrates. The scintillators were observed via scanning electron microscopy (SEM), and scintillation characteristics were evaluated on the basis of the emission spectrum, light output, light response to x-ray dose, modulation transfer function (MTF), and x-ray images. Compared to control films without a reflective layer, CsI:Tl films with reflective layers showed better sensitivity and light collection efficiency, and the film with a $TiO_2$ reflective layer showed the best properties.
Columnar-structured cesium iodide (CsI) scintillators doped with thallium (Tl) are frequently used as x-ray converters in medical and industrial imaging. In this study we investigated the imaging characteristics of CsI:Tl films with various reflective layers-aluminum (Al), chromium (Cr), and titanium dioxide ($TiO_2$) powder-coated on glass substrates. We used two effusion-cell sources in a thermal evaporator system to fabricate CsI:Tl films on substrates. The scintillators were observed via scanning electron microscopy (SEM), and scintillation characteristics were evaluated on the basis of the emission spectrum, light output, light response to x-ray dose, modulation transfer function (MTF), and x-ray images. Compared to control films without a reflective layer, CsI:Tl films with reflective layers showed better sensitivity and light collection efficiency, and the film with a $TiO_2$ reflective layer showed the best properties.
* AI 자동 식별 결과로 적합하지 않은 문장이 있을 수 있으니, 이용에 유의하시기 바랍니다.
제안 방법
We used two effusion-cell sources in a thermal evaporator system to fabricate CsI:Tl films on the different substrates and evaluated their scintillation properties and x-ray imaging characteristics. Fabricated CsI:Tl scintillators were observed by means of scanning electron microscopy (SEM), and scintillation characteristics such as emission spectrum, light output, light response to x-ray dose, and modulation transfer function (MTF) were evaluated. Furthermore, x-ray images of a CsI:Tl scintillator memory chip were obtained using an x-ray measurement system.
In this study we investigated the imaging characteristics of CsI:Tl films with various reflective layers of aluminum (Al), chromium (Cr), and titanium dioxide (TiO2) powder, coated on glass substrates. Compared to glass without a reflective layer, CsI:Tl films with a TiO2 reflective layer showed the best properties.
In this study, we investigated the imaging characteristics of a CsI:Tl film with various reflective layers of aluminum (Al), chromium (Cr), and titanium dioxide (TiO2) powder, coated on glass substrates 150 μm thick.
light output, intensity of x-ray induced luminescence (XL) spectra, and emission spectrum, were measured using a UV-visible spectrometer (Spectra Academy, K-MAC, Korea) with an optical cable in a dark chamber equipped with a lens-coupled CCD imaging device (1024 × 1024 active pixels with 13-μm pixel pitch and an effective field of 13.2 mm × 13.2 mm; Andor DV-434, UK) connected to a PCI controller card.
이론/모형
Although CsI:Tl films with columnar structure deposited via vacuum evaporation are commercially available, there is demand for scintillators with higher sensitivity and spatial resolution for x-ray detectors used in medical imaging to minimize the radiation dose [9]. In this study, we fabricated CsI:Tl scintillators using a thermal evaporation method. CsI:Tl scintillator films were deposited on bare glass and glass with Al, Cr, and TiO2 reflective layers to increase the light collection efficiency by reducing light loss in the vertical direction.
The modulation transfer function (MTF) curves of CsI:Tl films were measured quantitatively by a slant edge phantom method for evaluating spatial resolution. The modulation transfer function (MTF) of each CsI:Tl film was measured using the obtained edge images.
성능/효과
Compared to glass without a reflective layer, CsI:Tl films with a TiO2 reflective layer showed the best properties. In conclusion, CsI:Tl films with high sensitivity and spatial resolution can be fabricated on a glass substrate coated with a TiO2 reflective layer.
참고문헌 (16)
H. Wieczorek, "Physical aspects of detector design," Rad. Meas. 33, 541-545 (2001).
C. W. Bates, "Scintillation processes in thin films of CsI (Na) and CsI(Tl) due to low energy X-rays, electrons and protons," Adv. Eletron. E1. Phys. A 28, 451-459 (1969).
V. Ryzhikov, D. Kozin, B. Grinyov, E. Lysetskaya, J. Katrunov, V. Kvyatnitskaya, and V. Chernikov, "Scintillationphotodiode detector for scanning introscopy with high spatial resolution," Nucl. Instrum. Meth A 505, 58-62 (2003).
V. V. Nagarkar, J. S. Gordon, S. Vasile, P. Gothoskar, and F. Hopkins, "High resolution X-ray sensor for non destructive evaluation," IEEE. Trans. Nucl. Sci. 43, 1559-1563 (1996).
R. Gwin and R. B. Murray, "Scintillaton process in CsI(Tl). II. Emission spectra and the possible role of self-trapped hole," Phys. Rev. Lett. 131, 508-512 (1963).
A. Fedorov, A. Lebedinsky, and O. Zelenskaya, "Scintillation efficiency, structure and spatial resolution of CsI(Tl) layers," Nucl. Instrum. Meth A 564, 328-331 (2006).
B. K. Cha, J. Y Kim, T. J. Kim, C. Sim, and G. Cho, "Fabrication and imaging characterization of high sensitive CsI(Tl) and $Gd_2O_2S(Tb)$ scintillator screens for X-ray imaging detector," Rad. Meas. 45, 742-745 (2010).
B. K. Cha, J. H. Bae, C. Lee, H. Jeon, H. Kim, S. Chang, B. S. Kang, and G. Cho, "Improvement of the sensitivity and spatial resolution of pixelated CsI:Tl scintillator with reflective coating," Nucl. Instrum., Meth A 607, 145-149 (2009).
B. Schmitt, M. Fuchs, E. Hell, W. Knupfer, P. Hackenschmied, and A. Winnake, "Structured alkali halides for medical applications," Nucl. Instrum. Meth B 191, 800-804 (2002).
B. K. Cha, J. H. Shin, J. H. Bae, C. Lee, S. Chang, H. K. Kim, C. K. Kim, and G. Cho, "Scintillation characteristics and imaging performance of CsI:Tl thin films for X-ray imaging applications," Nucl. Instrum. Meth A 604, 224-228 (2009).
B. Wang, K. Barner, D. Lee, B. Rodricks, and C. Liu, "A simple edge device method for determining the presampling modulation transfer function (MTF) of flat field digital detectors," Proc. SPIE 5745, 1191-1198 (2005).
E. Samei, M. J. Flynn, and D. A. Reimann, "A method for Measuring the pre-sampled MTF of digital radiographic system using an edge test device," Med. Phys. 25, 102-113 (1998).
E. Samei and M. J. Flynn, "An experimental comparison of detector performance for direct and indirect digital radiography systems," Med. Phys. 30, 608-622 (2003).
※ AI-Helper는 부적절한 답변을 할 수 있습니다.