Ahmadi, Nematollah, Karimian, Alireza, Nasri Nasrabadi, Mehdi, Rahmim, Arman. (1397). stimate bowtie filter shape in PET/CT scan with TLD. , 15(Special Issue-12th. Iranian Congress of Medical Physics), 118-118. doi: 10.22038/ijmp.2018.12607
Nematollah Ahmadi; Alireza Karimian; Mehdi Nasri Nasrabadi; Arman Rahmim. "stimate bowtie filter shape in PET/CT scan with TLD". , 15, Special Issue-12th. Iranian Congress of Medical Physics, 1397, 118-118. doi: 10.22038/ijmp.2018.12607
Ahmadi, Nematollah, Karimian, Alireza, Nasri Nasrabadi, Mehdi, Rahmim, Arman. (1397). 'stimate bowtie filter shape in PET/CT scan with TLD', , 15(Special Issue-12th. Iranian Congress of Medical Physics), pp. 118-118. doi: 10.22038/ijmp.2018.12607
Ahmadi, Nematollah, Karimian, Alireza, Nasri Nasrabadi, Mehdi, Rahmim, Arman. stimate bowtie filter shape in PET/CT scan with TLD. , 1397; 15(Special Issue-12th. Iranian Congress of Medical Physics): 118-118. doi: 10.22038/ijmp.2018.12607

stimate bowtie filter shape in PET/CT scan with TLD

Iranian Journal of Medical Physics
مقاله 118، دوره 15، Special Issue-12th. Iranian Congress of Medical Physics، بهمن و اسفند 2018، صفحه 118-118
نوع مقاله: Conference Proceedings
شناسه دیجیتال (DOI): 10.22038/ijmp.2018.12607
نویسندگان
Nematollah Ahmadi1؛ Alireza Karimian2؛ Mehdi Nasri Nasrabadi3؛ Arman Rahmim4
1PhD candidate, Department of Nuclear Engineering, Faculty of Advanced Sciences & Technologies, University of Isfahan, Isfahan, Iran
2Associate Professor, Department of Biomedical Engineering, University of Isfahan, Isfahan, Iran
3Department of Nuclear Engineering, Faculty of Advanced Sciences & Technologies, University of Isfahan, HezarJerib Street, 8174673441, Isfahan, Iran
4Associate Professor, Department of Radiology, Johns Hopkins University, Baltimore, Maryland, USA
چکیده
Introduction: The CT machine utilizes a bowtie filter to shape the X-ray beam and remove lower energy photons. Configuration of this bowtie filter is complex and its geometry is often not available in detail. It causes the CT dose index (CTDI) be with the different values in measurement versus Monte Carlo simulation studies and other analytical calculations. It is important especially in dosimetry of internal organs. In this study, the bowtie filter shape is extracted by using Thermolumenecence dosimeters (TLDs).
Materials and Methods: In this work, the shape of the bowtie filter of the Biograph 6 PET/CT was derived by using 31 Thermolumenecence chips dosimeters (GR-200 series) made of LiF: Mg, Cu, and P were utilized. These chips calibrated by Cs-137 in SSDL organization and ECC (Element Correction Coefficient) of them by using TLD reader Harshaw-4000. Eventually, to evaluate the accuracy of the body bowtie filter shape as generated by TLDs, Monte Carlo simulation of CT was performed. 16 X-ray sources in various angles were used within the Monte Carlo code (MCNP-4C) to simulate the CT section of the PET-CT Biograph 6 system and to calculate dose. In the simulation code, absorbed dose was determined for CT scan with MeV/gram/source particle units and converted into absorbed dose with mGy/100 mAs units by conversion factor (CF).
Results: The relative difference (RD) between simulated and measured CTDI value for the PET/CT Siemens Biograph 6 at 80, 110 and 130kVp were 4.2, 2.9 and 2.3%, respectively.
Conclusion: The results showed that it is possible to determine the shape of the bowtie filter in PET/CT using an inexpensive TLDs with acceptable accuracy.
کلیدواژه‌ها
PET/CT؛ bowtie filter؛ TLD dosimeter؛ dosimetry
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