Darbeli mod fototerapi ile bilirubin konsantrasyonunun değişiminin incelenmesi
The investigation of bilirubin concentration using pulse  
mode phototherapy
Yazar: NAZİRE ASLAN
Danışman: PROF. DR. CENAP ŞAHABETTİN ÖZBEN
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Fizik Mühendisliği Ana Bilim Dalı
Derece: Yüksek Lisans, 2015
Konu: Fizik ve Fizik Mühendisliği = Physics and Physics Engineering

Özet:
Yeni doğan sarılığı, bebekler arasında en sık rastlanan klinik  vakalardandır.  Bebeklerin yaklaşık üçte ikisi, yaşamlarının ilk haftasında klinik anlamda sarılık  olur. Sarılık, gözetim altına alınmazsa genellikle ciddi nörogelişimsel durumlar  oluşabilir. Neonatal hiperbilirubenimia, yenidoğan sarılığında çok sık karşıl aşılan  bir durumdur. Bu tip sarılık, cildin ve skleranın sarılaşması demektir ve bunun  nedeni de bilirubin seviyesinin yükselmesidir. Bilirubin, alyuvar hücrelerinin  bozulmasının bir sonucudur, genellikle vücut yaşlı kırmızı kan hücrelerini  parçaladığı zam an oluşur. Normal durumlarda karaciğer bu oluşan bilirubini  görevinin bir parçası olarak doğal yollarla kandan uzaklaştırır. Bebeklerde sarılık  ise kırmızı kan hücrelerinin parçalanması sonucu oluşan bilirubinin karaciğer  tarafından kandan uzaklaştırılamam ası sonucu görülür. Bazı durumlarda, Rh  uyuşmazlığı gibi hemolitik hastalıklar, hiperbilirubinemia'ya yol açabilir.  Hyperbilirubinemia klinik olarak, 5mg/dL üzerindeki bilirubin seviyesi ile  tanımlanır. Bilirubin sirkülasyonu iki şekilde ölçülebilir. Bunl ar, kan sayımı ile  deri içinden geçen bilirubin, transkütan bilirubin (TcB) ve toplam serum bilirubini  (TSB) veren spektrofotometri metodları ile ölçülmektedir. Yenidoğan sarılığının tedavisinde kullanılan yaygın metotlardan biri fototerapi'dir.  Fototerapi, derinin hemen altında biriken ve derinin sarımsı renk almasına neden  olan fazla biluribinin vücuda uygulanan ışık ile kırılıp, doğal yollar ile vücüttan  atılması yöntemidir. Fototerapi'de genelde mavi ışık kullanılmakta ve kullanılan  ışığın d alga boyu ve şiddetine bağlı çalışmalara literatürde  rastlanmaktadır. Tedavide kullanılan ışığın şiddeti ve uygulama süresi, hasta  rahatını etkileyen unsurların başında gelmektedir. Hasta kanındaki biluribin  konsantrasyonuna göre fototerapi süresi geneld e 6 - 24 saat aralığında  uygulanmaktadır Bu süreyi kısaltacak her türlü çabanın, sadece tedavi maliyetlerini değil, aynı  zamanda yenidoğan için oldukça sıkıntılı bir süreç olan tedavi sürecini kısaltacağı  bilinmektedir. Bu çalışmada, diğer az sayıdaki b enzeri gibi kullanılan ışığın dalga boyundan  ziyade, mavi ışığın sürülme modları üzerine çalışılmıştır. Çalışmanın orjinalliği de  bu noktadan kaynaklanmaktadır.

Abstract:
Neo natal jaundice is among the most common clinical cases for newborns. Almost  two thirds of the newborns becomes jaundice within their first week. If jaundice  does not taken under control, many  neurodevelopmental stages may occur.  Neonatal  hyperbilirubine mia is one of the common cases in newborn  jaundice. This kind of  jaundice shows itself by becoming yellowish of the skin and  sclera as a result of  increase of bilirubin concentration in the blood. Bilirubin is the result of breakdown  of red - cells and thi s happens mostly when the body breaks down the aged blood  cells. In the regular circumstances, liver gets rid of this high bilirubin in the blood  with conventional ways. However, n eonatal jaundice seen if liver can't handle this  procedure among the babie s.  Hemo l ytic  cases such as Rh conflict may also results  hyperbilirubinemia. Hyperbilirubinemia is defined as the bilirubin concentrations  above 5mg/dL in the blood. There are two types of methods to measure the bilirubin  concentration. These methods ar e TcB and TSB methods. Both of them are  spectrophotometric methods. Phototherapy is a preferred method of treatment for neonatal hyperbilirubinemia by  virtue of its noninvasive nature and its safety. Neonatal jaundice is a common  condition and phototherapy is an accepted modality for its management.  Phototherapy convers  unconjugated bilirubin to its oxidation products as well as to  photo and structured isomers which are easily eliminated through the gastro - intestinal tract or lost in urine. Recently, phototherapy has been shown to be related  to oxidative stress, lipid pe roxidation or DNA damage.  Neonates have limited anti - oxidant protective capacity and oxidative damage place  an important role in pathogenesis of many diseases in the newborn period. Bilirubin  absorbs light most strongly in the blue region of the spectrum near 460 nm  xx wavelength. Se veral devices using light source with different wavelengths and  intensities are available for phototherapy. Phototherapy is one of the common methods used for the treatment of  neonatal  jaundice. Phototherapy is a method to break down the bilirubin accumu lated under  the skin by exposing the large portion of body to preferably blue light and getting rid  of the excess bilirubin from the body. In phototherapy, mostly a blue light is used.  However, there are few studies about the effect of frequency or wavel ength of the  light used. Exposure time and intensity of the light used are the parameters directly  influence the comfort of the patient. Depending on the concentration level of  bilirubin, treatment of phototherapy may take between 6 to 24 hours. Any e ffort to  decrease the treatment time is very welcome for both reducing the costs of treatment  and decrease the time of the treatment which is mostly very uncomfortable for the  newborns. In this thesis, we concentrate on the methods for driving the light ( LED) rather than  the frequency of the light. In this sense, this work is original.  There are very few number of publications about the physics of phototherapy in the  literature. As mentioned before, these works are based on the influence of the  wavele ngth of the light used in phototherapy. Dose rate of the light provided by  LED's or other light sources is proportional to the current and the voltage (briefly  power) of the power supply. Instead of applying a constant power to LED, we  propose power the L ED in pulsed mode.  Since physics of breakdown of bilirubin molecule by light has not been investigated  in detail (there is almost no literature about it), we have decided to make this study  with trial and error method. Samples of bilirubin were prepared using powder by  Sigma - Aldrich (with B4126 product code). Bilirubin samples were prepared in  blood stimulating serum with the concentration of 5 mg/dL.  These solutions were irradiated in the experimental setup with the LED light. Extra  care is taken to  make the light intensity stable during the irradiations. The humidity  and the temperature are monitored during the experiments. The light intensity  measurements were performed with TES 1336 unit in terms of Lux.  xxi We used Yonton brand blue LED light wit h 50W peak power and an audio amplifier  with 120 W power (at 8 ohm impedance) and wide bandwidth of 150 kHz was used  for driving the LED in pulse mode. The pulses were generated from a frequency  generator. The spectrum of the LED is taken by a spectromet er and given in this work  since no  technical information about the exact wavelength  was  available for this LED. The first measurements took place in this study were about the intensity of the LED  at the irradiation position of the samples. The intensity v ersus frequency graphs wer e  produced between 50 Hz and 1 k Hz. Intensity variation was measured to be between  66.8 and 72.2 Lux for the given frequency interval