A treatment planning comparison of 3 dimensional conformal radiotherapy and intensity modulated radiotherapy for treatment of head and neck tumours.

TEZ9760Tez (Yüksek Lisans) -- Çukurova Üniversitesi, Adana, 2012.Kaynakça (s. 83-87) var.xi, 89 s. : res. (bzs. rnk.), tablo ; 29 cm.Radyoterapi, baş-boyun kanserli hastaların tedavisinde büyük öneme sahip bir tedavi yöntemidir. Baş-boyun kanserlerinde radyoterapi, uygun tekniklerin kullanımı ile komşu dokulara olan zararın en aza indirilmesi açısından tercih edilmektedir. Uygulanmakta olan farklı tedavi planlama teknikleri ve yöntemlerinin birbirleriyle olan farklılıkları, avantaj ve dezavantajlarının incelenmesi oldukça önemlidir. Bu çalışmada Çukurova Üniversitesi Radyasyon Onkolojisi A.B.D.’da 01.01.2011-01.01.2012 tarihleri arasında tedavi edilmiş 20 baş-boyun kanserli hastanın tedavi planları 3-Boyutlu Konformal Radyoterapi (3B KRT) ve yoğunluk ayarlı radyoterapi (IMRT) teknikleri kullanılarak hazırlanmış ve karşılaştırılmıştır. Bu hastalar 5’i nazofarenks, 5’i supraglottik larenks, 5’i oral kavite, 2’si parotis, 1’i hipofarenks, 1’i orofarenks ve 1’i de nazal kavite hastası olarak seçilmiştir. Radyasyon onkologları tarafından tanımlanan hedef hacimler aldıkları dozlara göre sınıflandırılmış ve herbölge için kritik organ tanımlamaları yapılmıştır. Hedef hacimlerin minimum, maksimum, V%95 doz değerleri yüzdelik olarak incelenirken, kritik organların maruz kaldıkları doz değerleri Gray (Gy) olarak incelenerek değerlendirilmiş ve her iki teknikle elde edilen sonuçlar Tedavi Planlama Sistemi (TPS)’de karşılaştırılmıştır. Özellikle baş-boyun kanserli hastalarda IMRT tekniği kullanıldığında daha iyi hedef kapsamı ile daha iyi kritik organ korumasının yapıldığı gösterilmiştir.Radiotherapy is a treatment method having an important value in the treatment of patients presenting with head and neck tumours. Radiotherapy is preferred using with suitable techniques in head and neck tumours in terms of being reduced at least the damage to vicinity tissues. It is significant to be investigated the differences, advantages and disadvantages of the different methods and treatment planning techniques which are in progress. In this work, the treatment plans of 20 head and neck patients treated between 01.01.2011-01.01.2012 in Radiation Oncology Department in Cukurova University were prepared and comprised with using 3-dimensional conformal radiotherapy (3D CRT) and intensity modulated radiotherapy (IMRT). Thesepatients were choosen as 5 nasopharynx, 5 supraglottic larynx, 5 oral cavity, 2 parotid, 1 hipopharynx, 1 oropharynx and 1 nasal cavity. Target volumes described by radiation oncologists were classified according to the taken doses and organs at risk had defined for each area. Minimum, maximum and V95% of target volumes’ dose values were investigated as percentage, the dose values of organs at risk were investigated as Gray (Gy) and each results for these two techniques were comprised in Treatment Planning System (TPS). Especially, it is showed that better target coverage and beter organs at risk protection are obtained with using IMRT technique to head and neck patients.Bu çalışma Ç.Ü. Bilimsel Araştırma Projeleri Birimi tarafından desteklenmiştir. Proje No: FEF2011YL26

İleri görüntüleme teknikleri kullanarak HDR ve/veya LDR brakiterapide hedef hacim optimizasyonu için jel fantom çalışması.

TEZ11266Tez (Doktora) -- Çukurova Üniversitesi, Adana, 2018.Kaynakça (s. 105-115) var.xxii, 117 s. : res. (bzs. rnk.), tablo ; 29 cm.Bu tez çalışmasında, Yüksek Doz Hızlı (HDR) ve/veya Düşük Doz Hızlı (LDR) brakiterapide hedef hacim optimizasyonunu sağlamada uygun sekanslar geliştirmek amacıyla Difüzyon Kurtosis Görüntülemeye (DKI) uygun doku benzeri jel fantomları oluşturmak için konsantrasyonları sırasıyla %1,0 ile %3,5; %0,5 ile %3,0 ve %10 ile %20 arasında değişen agar, agaroz ve polivinil alkol kriyojel fantomlar hazırlanmıştır. Jellerin kurtosis değerleri konsantrasyonla artsa da saf olarak hazırlandıklarında çeşitli doku değerlerini yansıtmada oldukça düşük kalmıştır. Bu nedenle, daha gerçekçi kurtosis değerleri ile dokuyu yansıtan fantomlar oluşturmak için farklı konsantrasyonlardaki jellere cam mikroküreler eklenmiştir. Difüzyon katsayıları (ADC ya da D(1) ve D(2)), ilave kurtosis (K) değerleri ve relaksasyon parametreleri deneysel olarak belirlenmiş ve katkısız jeller için kurtosis değerleri %95 güven aralığıyla 0,05 (0,029; 0,071) ile 0,216 (0,185; 0,246) aralığında çıkmıştır. Cam mikrokürelerin eklenmesi kurtosis değerini, en yüksek mikroküreler içeren jeller için gözlenen 0,523 (0,465; 0,581) değerine kadar arttırmıştır. Cam mikrokürelerin varlığı ADC değerlerini azaltmış, boylamsal ve enine relaksasyon hızlarını arttırmıştır. Fantomlar ayrıca X-ışını Bilgisayarlı Tomografi ve Ultrason elastografi kullanılarak fiziksel parametreleri açısından değerlendirilmiştir. Çalışma, cam mikrokürelere sahip agar jellerinin, ayarlanabilir difüzyon ve relaksasyon özelliklerine sahip Difüzyon Ağırlıklı Manyetik Rezonans Görüntüleme (DW-MRI) ve DKI için ucuz ve dayanıklı fantomlar olarak ümit verici materyaller olduğunu göstermektedir.In this thesis, agar, agarose, and polyvinyl alcohol cryogel phantoms with concentrations ranging from 1.0% to 3.5%, 0.5% to 3.0%, and 10% to 20%, respectively, were prepared to create tissue-mimicking gel phantoms convenient for Diffusion Kurtosis Imaging (DKI) in order to develop proper sequences for target volume optimization in High Dose Rate (HDR) and/or Low Dose Rate (LDR) brachytherapy. The kurtosis values of the gels increased with the concentration but they were too low to mimic values for various tissues when created purely. Therefore, glass microspheres were added into the gels at different concentrations to create tissue-mimicking phantoms with more realistic kurtosis values. Diffusion coefficients (ADC or D(1) and D(2)), excess kurtosis (K) values, and relaxation parameters were experimentally determined and the kurtosis values for the plain gels ranged from 0.05 (0.029, 0.071) to 0.216 (0.185, 0.246) with 95% confidence interval (CI). Inclusion of glass microspheres increased the kurtosis with values up to 0.523 (0.465, 0.581) observed for gels with the highest concentration of microspheres. The presence of glass microspheres reduced ADCs and increased the transverse and longitudinal relaxation rates. Phantoms were also evaluated for the further physical parameters using X-ray Computed Tomography (CT) and Ultrasound (US) elastography. The study shows that agar gels including glass microspheres in particular are encouraging materials as low-cost and durable phantoms for Diffusion Weighted-Magnetic Resonance Imaging (DW-MRI) and DKI with tuneable diffusion and relaxation properties.Bu çalışma Ç.Ü. Bilimsel Araştırma Projeleri Birimi tarafından desteklenmiştir. Proje No: FDK-2014-2709

A Study on the Correction of the Trap Depth Value for Low Temperature TL Peak of Quartz

One of the significant factors that should be examined when performing a thermoluminescence (TL) study related to a natural material is the detection of the trap depth. The various heating rate (VHR) method is one of the practical methods used in the calculation of the trap depth. Even though the HRs used in TL measurements do not affect the trap depth of the thermoluminescent materials, the corrected TL peak data should be used in the calculation of the trap depth. In this paper, low temperature TL glow peak of natural quartz (NQ) was recorded by using different linear HRs between 0.5 and 10 K/s from room temperature (RT) to 425 K by applying the same irradiation with the beta dose of 0.5 Gy. The trap depth of NQ sample was calculated using VHR method for both experimental and corrected TL glow peaks of NQ. The trap depth values were found to be 0.57 ± 0.03 and 0.79 ± 0.04  eV with VHR and Mott-Seitz correction methods, respectively.Çukurova Üniversitesi Rektörlüğü Bilimsel Araştırma Projeleri Koordinasyon Birimi, Proje No: FAY-2015-473

THERMOLUMINESCENCE GLOW CURVE PROPERTIES OF TLD-500 DOSIMETER

In this paper, TL characteristics and glow curves of alpha-Al2O3:C dosimeter, known as TLD-500, were analyzed using different methods and softwares. The effect of heating rate (HR) and low dose (from to cGy up to 5o cGy) on TL glow curves of alpha-Al2O3:C chips have been investigated after beta-irradiation. TL kinetic parameters were also calculated by using computerized glow curve deconvolution (CGCD), peak shape (PS), various heating rate (VHR) and three points (TP) methods. Furthermore, using Mathematica software, all TL glow curves of TLD-500 were decomposed in order to compare with the results of other methods and simulated after exposed different beta doses

Natural Radioactivity Study of Soil Samples from Some Villages in Mersin

The aim of this study is to determine the level of natural radioactivity occured by radionuclides, 226Ra, 232Th and 40K, in soil samples collected from some villages in Mersin, Turkey. The mean activity concentrations of 226Ra, 232Th and 40K are measured over all collected soil samples as 19.96 ± 2.34 Bq/kg, 42.8 ± 3.28 Bq/kg and 388.68 ± 5.26 Bq/kg, respectively using gamma ray spectroscopy by HPGe dedector. It was observed that these activity concentrations are mostly in agreement with the world activity averages of 35, 30 and 400 Bq/kg for 238U, 232Th and 40K, respectively, indicated in UNSCEAR 2008 report. Mean 232Th activity was achieved a bit higher than the avarage. However, the average annual effective dose equivalent was calculated as 0.062 mSv/y and found to be lower than the worldwide avarage value of 0.063 mSv/y.Çukurova University (FBA-2015-4478 / FBA-2017-9055

Thermoluminescence properties of Tb doped Mg2SiO4 after beta irradiation

In this study, we performed Thermoluminescence (TL) experiments to extract the trapping parameters and dosimetric properties of Tb-doped Mg2SiO4 phosphors. Glow peaks located at 193, 270, and 350 degrees C were observed in the glow curve but the peak at 193 degrees C was especially investigated as a dosimetric peak in this study. We also observed an anomalous heating rate effect in which the maximum TL intensity of the glow curve augmented with an increasing heating rate. The computerized glow curve deconvolution (CGCD) method, initial rise (IR) and Hoogenstraaten's method were used to determine the activation energies of associated trapping centers for both BSL-TL 365 nm and IRSL-TL wideband blue filters. The TL characteristics of this phosphor indicate that Mg2SiO4:Tb3+ could be a promising material for dosimetric applications. Efforts should be made to improve the fading behaviour by adding other activators as co-dopants.Cukurova University (FAY-2015-4735

Normal and anomalous heating rate effects on thermoluminescence of Ce-doped ZnB2O4

The effect of heating rate (HR) on thermoluminescence (TL) glow curves of 1%, 4%, and 10% Ce-3 (+) doped ZnB2O4 phosphors was investigated in detail. The glow peaks are examined and, activation energy (E) and frequency factor (s) are determined by using various heating rate (VHR) method. In the obtained glow curves with nine different HRs between 2 and 10 degrees C/s, it was observed that the TL intensities of the first peaks of all three samples and the second peak of 10% Ce-3 (+) doped sample decrease with increasing HR. The decrease in TL intensity was investigated whether it may be due to the presence of thermal quenching or not. On the other hand, the second glow peaks of 1, 4% Ce-3 (+) doped ZnB2O4 phosphors show an anomalous TL behavior, which the probability of the radiative processes increases due to recombination of free electrons, so the TL intensity increases with the HR. The graphs of full width at the half maximum (FWHM) versus HR were also plotted to evaluate the influence of HR on TL intensity. In this paper, we suggest that the non-localized Schon - Klasens model may give an explanation for the second peaks of 1, 4% Ce-3 (+) doped ZnB2O4 phosphors showing an unexpected increase with the increasing HR. In addition, the calculated E values of all doped phosphors were found similar in the range of 0.47-0.53 eV for peak 1 and 0.61-0.66 eV for peak 2. However, s values of Ce-3 (+) doped ZnB2O4 phosphors were found slightly different according to the dopant amount and the equation used. Furthermore, different amount of Ce-3 (+) doped samples indicate the similar properties for the repeated cycles of 5 Gy in the same irradiation conditions

A Preliminary Study of TL and OSL Traps for the Aragonite Mineral

Luminescence (thermoluminescence (TL) and optically stimulated luminescence (OSL)) methods are important for dosimetric studies. Understanding the TL and OSL traps of dosimetric materials is critical to explain their different and similar properties. In this study, TL and OSL signals of natural aragonite mineral were recorded using lexsyg smart TL/OSL reader after different beta irradiations. TL and OSL trap properties were compared with each other using the obtained TL glow curves and OSL signals. In sequential measurements, while the TL signals were observed after the OSL measurements, the OSL signals were not observed after the TL measurements. In conclusion, TL and OSL traps are located close to each other within the band gap of aragonite mineral and the OSL traps affect the TL signals if the TL measurements are done firstly.Cukurova University, FED-2017-804

Thermoluminescence properties of annealed natural quartz after beta irradiation

Here we investigated the effects of annealing, heating rate and fading (after annealing at 800 degrees C) on the thermoluminescence (TL) glow curves of natural quartz (NQ). All of the samples were annealed at different temperatures between 100 degrees C and 800 degrees C and then irradiated with a beta dose of about 34 Gray (Gy), in order to determine the effects of annealing treatments on TL peaks of natural quartz. TL glow curves of the samples were recorded. It was observed that the intensities of TL peaks were strongly sensitive to annealing temperatures at 800 degrees C. The heating rate and fading effect of TL peaks of natural quartz were examined for the annealed samples at 800 degrees C for 30 min. It was observed that the intensities of the TL peaks were differently affected from heating rate and fading. Additionally, TL kinetic parameters (activation energy, frequency factor and order of kinetics) of all peaks were determined for annealed samples using a computerized glow curve deconvolution (CGCD) method and Mathematica software. Copyright (C) 2016 John Wiley & Sons, Ltd