Publications by authors named "Neslihan Sarigul"

6 Publications

  • Page 1 of 1

Urine analysis using FTIR spectroscopy: A study on healthy adults and children.

J Biophotonics 2021 Mar 26:e202100009. Epub 2021 Mar 26.

Biophysics Laboratory, Faculty of Engineering, Atilim University, Ankara, Turkey.

Urine spectra from 108 healthy volunteers are studied by attenuated total refraction-Fourier transform infrared (ATR-FTIR) spectroscopy. The spectral features are correlated with observable urine components. The variation of spectra within a healthy population is quantified and a library of reference spectra is constructed. Using the band assignments, these spectra are compared with both age-wise and gender-wise. Children show the least intensity variations compared to both adult groups. Young adults show the highest variation, particularly in the 1650 to 1400 cm and 1200 to 900 cm regions. These results indicate the importance of the size of the control group in comparative studies utilizing FTIR. Age-wise comparisons reveal that phosphate and sulfate excretion decreases with age, and that the variance of phosphate among individuals is higher with adults. As for gender-wise comparisons, females show a slightly higher citrate content at 1390 cm regardless of the age and they show a higher variance in the 1200 to 1000 cm region when compared to men.
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http://dx.doi.org/10.1002/jbio.202100009DOI Listing
March 2021

Determination of inflection points of CyberKnife dose profiles within acceptability criteria of deviations in measurements.

Rep Pract Oncol Radiother 2020 Jan-Feb;25(1):6-12. Epub 2019 Nov 12.

Institute of Nuclear Sciences, Hacettepe University, Ankara, Turkey.

Aim: The aim of this study was to determine the Inflection Points (IPs) of flattening filter free (FFF) CyberKnife dose profiles for cone-based streotactic radiotherapy. In addition, dosimetric field sizes were determined.

Background: The increased need for treatment in the early stages of cancer necessitated the treatment of smaller tumors. However, efforts in that direction required the modeling accuracy of the beam. Removal of the flattening filter (FF) from the path of x-ray beam has provided the solution to those efforts, but required a different normalization approach for the beam to ensure the delivery of the dose accurately. As a solution, researchers proposed a normalization factor based on IPs.

Materials And Methods: Measurements using microDiamond (PTW 60019), Diode SRS (PTW 60018) and Monte Carlo (MC) calculations of dose profiles were completed at SAD 80 cm and 5 cm depth for 15-60 mm cones. Performance analysis of detectors with respect to MC calculation was carried out. Gamma evaluation method was used to determine achievable acceptability criteria for FFF CyberKnife beams.

Results: Acceptability within (3%-0.5 mm) was found to be anachievable criterion for all dose profile measurements of the cone beams used in this study. To determine the IP, the first and second derivatives of the dose profile were determined via the cubic spline interpolation technique.

Conclusion: Derivatives of the interpolated profiles showed that locations of IPs and 50% isodose points coincide.
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http://dx.doi.org/10.1016/j.rpor.2019.10.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7002887PMC
November 2019

A practical method for quantifying dose in bone and lung using TLDs when using 6 and 15 MV photon beams.

Phys Med Biol 2020 03 6;65(5):05NT01. Epub 2020 Mar 6.

Institute of Nuclear Science, Hacettepe University, 06532 Ankara, Turkey. Both authors contributed equally to this manuscript.

This paper presents a practical method for converting dose measured with thermoluminescent dosimeters (TLD) to dose in lung and bone for 6 MV and 15 MV photon beams. Monte Carlo (MC) simulations and Burlin cavity theory calculations were performed to calculate [Formula: see text], the dose-to-TLD to dose-to-medium conversion factor. A practical method was proposed for converting TLD-measured-dose to dose-in-medium using the TLD dose calibration in water and [Formula: see text] dose-to-medium to dose-to-water conversion factor. Theoretical calculations for [Formula: see text] were performed using photon spectrum weighted parameters and were compared with MC simulations. Verification of the proposed method was done using phantoms having either bone or lung equivalent slabs stacked in between solid water slabs. Percent depth dose (PDD) curves were measured using 0.089 cm thick LiF:Mg,Ti (TLD-100) dosemeters placed at various depths within these phantoms. They were then corrected with [Formula: see text] factors using the proposed dose conversion method, and were compared with the MC simulations. For 6 MV beam, the MC calculated [Formula: see text] factors were 0.942 and 1.002 for bone and lung, and for 15 MV it was 0.927 and 1.005 for bone and lung, respectively. The difference between the MC simulated and spectrum weighted theoretical [Formula: see text] factors were within 3% for both lung and bone. The PDD curves measured with TLD-100 chips that were corrected using the proposed method agreed well within 1.5% of the MC simulated PDD curves for both the water/lung/water and water/bone/water (WBW) phantoms. The dose-to-medium correction using MC simulated [Formula: see text] is convenient, easy, and accurate. Therefore, it can be used instead of Burlin cavity theory, especially in media with high atomic numbers such as bone for accurate dose quantification.
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http://dx.doi.org/10.1088/1361-6560/ab735dDOI Listing
March 2020

A New Artificial Urine Protocol to Better Imitate Human Urine.

Sci Rep 2019 12 27;9(1):20159. Epub 2019 Dec 27.

Trakya University, Faculty of Medicine, Department of Nephrology, 22000, Edirne, Turkey.

Artificial urine has many advantages over human urine for research and educational purposes. By closely mimicking healthy individuals' urine, it may also be important in discovering novel biomarkers. However, up until now, there has not been any specific protocol to prove the similarity in terms of the chemical composition at the molecular level. In this study, a new artificial urine protocol is established to mimics the urine of healthy individuals. The multi-purpose artificial urine (MP-AU) presented here is compared with two other protocols most cited in literature. Furthermore, these three protocols are also compared with samples from 28 healthy young individuals. To do so, attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) is used, according to which MP-AU shows a significantly close similarity with human urine. In formulating MP-AU, the infrared spectra of nine compounds is provided, making possible the band assignment of some absorption bands to certain compounds. Given its properties, the MP-AU protocol introduced here is both economical and practical, making it useful when designing comparative-controlled experiments.
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http://dx.doi.org/10.1038/s41598-019-56693-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6934465PMC
December 2019

Evaluation of NanoDot Optically Stimulated Luminescence Dosimeter for Cone-shaped Small-field Dosimetry of Cyberknife Stereotactic Radiosurgery Unit: A Monte Carlo Simulation and Dosimetric Verification Study.

J Med Phys 2019 Jan-Mar;44(1):27-34

Institute of Nuclear Science, Hacettepe University, Ankara, Turkey.

Aim: The aim of this study was to investigate the adequacy of nanoDot optically stimulated luminescence (OSL) dosimeter for small field dosimetry before its applications in CyberKnife SRS unit.

Materials And Methods: A PTW 60018 SRS Diode, 60019 microDiamond, and Gafchromic EBT3 films were used along with a nanoDot carbon-doped aluminum oxide OSL dosimeter to collect and compare beam data. In addition, the EGSnrc/BEAMnrc code was employed to simulate 6-MV photon beams of CyberKnife SRS system.

Results: All detectors showed good consistency with each other in output factor measurements for cone sizes of 15 mm or more. The differences were maintained within 3% for these cones. However, OSL output factors showed higher discrepancies compared to those of other detectors for smaller cones wherein the difference reached nearly 40% for cone size of 5 mm. Depending on the performance of OSL dosimeter in terms of output factors, percentage depth doses (PDDs) were only measured for cones equal to or larger than 15 mm. The differences in PDD measurements were within 5% for depths in the range of 5-200 mm.

Conclusion: Its low reliable readings for cones smaller than 15 mm should be considered before its applications of Cyberknife system.
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http://dx.doi.org/10.4103/jmp.JMP_96_18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6438048PMC
April 2019

ENERGY RESPONSE FACTOR of BeO DOSEMETER CHIPS: A MONTE CARLO SIMULATION AND GENERAL CAVITY THEORY STUDY.

Radiat Prot Dosimetry 2019 Dec;185(3):303-309

Department of Radiation and Cellular Oncology, University of Chicago Pritzker School of Medicine, Chicago, IL, USA.

The objective of this study is to determine the energy response factors for BeO optically simulated dosemeter (OSLD) using general cavity theory and Monte Carlo (MC) simulations. A virtual phantom is constructed in EGSnrc MC program and energy response of BeO OSLDs were simulated at 5 cm depth for x-ray beams ranging from 1.25 to 25 MV and at 2 cm for beams with <250 kV including ISO 4037 narrow beam energies in a virtual water phantom. The energy response factor for a given radiation quality relative to 60Co was determined for BeO and compared to the Al2O3:C and LiF:Mg,Ti dosemeters. Burlin cavity theory calculations were done using mean photon energy (MPE) of the beam spectra, while EGSnrc software package was used to carry out MC simulation of full spectra. The cavity theory and MC methods agreed well within the 0.7%. Energy response of x-ray beams at MV range showed a maximum of 1.5% under-response. At energies higher than 150 kV (105 keV MPE) showed no significant difference while a significant under-response were observed at 100 kV (53 keV MPE) and 50 kV (29 keV MPE), ~8 and ~12%, respectively. BeO, Al2O3:C and LiF:Mg,Ti dosemeters exhibited very similar energy response at higher energies mainly in the MeV range. At 50 kV (29 keV MPE), however, BeO dosemeter under responded by a factor of 0.878, while Al2O3:C and LiF:Mg,Ti dosemeters over responded by a factor of 3.2 and 1.44, respectively. Furthermore, at low energies, BeO energy response showed dependence on photon spectra. For instance, at 100 kV, the difference was ~8, ~6 and 2% for 53, 60 and 83 keV MPE (ISO 4037N-100), respectively. Furthermore, calibration with 137Cs instead of 60Co resulted up to 1.8% differences in energy response. Both energy spectrum and calibration methods make considerable differences in energy response of OSLDs. This study concludes that BeO chips are nearly energy independent at energies higher than 100 keV MPE, while Al2O3:C dosemeters show an extremely enhanced energy-response ranging between 1.44 and 3.2 at energies between 170 and 29 keV MPE mainly due to dominance of photoelectric effect.
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http://dx.doi.org/10.1093/rpd/ncz010DOI Listing
December 2019