Lecture 1

 for more than 100 years, the use of x-ray has developed along two separate paths. In diagnostic medicine their use has been restricted to the imaging of transmitted X-ray. In contrast X-ray diffraction, based on the scattering of x-ray, is the method of choice for stud...

 for more than 100 years, the use of x-ray has developed along two separate paths. In diagnostic medicine their use has been restricted to the imaging of transmitted X-ray. In contrast X-ray diffraction, based on the scattering of x-ray, is the method of choice for studying atomic and molecular structure. ‫ن‬.‫منفصلي‬ ‫ر‬ ‫ تطور استخدام األشعة السينية عىل طول مسارين‬،‫ عام‬100 ‫ألكث من‬.‫ اقترص استخدامها عىل تصوير األشعة السينية‬،‫نف الطب التشخيص‬ ‫يتم دراسة ر‬.‫الثكيب الذري والجزيئ عن طريق دراسة حيود األشعة السينية‬ What are X-Rays? X-rays are electromagnetic radiation (EM): 1. Ionize: photon of X-ray and gamma ray radiation can ionize matter. 2. non-ionizing: radio, infrared, visible, ultraviolet can’t ionize matter. ‫راح تعرف ر‬ ‫أكث عن التأين والغث تأين‬.‫بالصفحات القادمة‬ ‫ن‬ :‫نوعي‬ ‫( ر‬EM( ‫تعد األشعة السينية مثاال عىل األشعة الكهرومغناطيسية‬ ‫الئ تقسم اىل‬.‫غث مؤين‬.2.‫ مؤين‬.1 X-rays are a valuable tool in research, but there are associated health risks.  These risks can be minimized by adhering to the safety practices explained in this module.  X-rays are capable of traversing great distances and have the ability to penetrate material.  However, they can be blocked or attenuated by shielding made from dense materials such as lead and concrete..‫ ولكن هناك مخاطر صحية مرتبطة بها‬،‫األشعة السينية ه أداة قيمة نف البحث‬ ‫يمكن تقليل هذه المخاطر عن طريق ر ن‬.‫االلثام بإجراءات السالمة‬ ‫ر‬ ‫ ويمكن تخفيف هذه األشعة عن‬،‫واخثاق المواد‬ ‫األشعة السينية لديها القدرة عىل اجتياز مسافات كبثة‬.)‫طريق التدري ع المصنوع من مواد كثيفة مثل (الرصاص والخرسانة‬ Medical x-rays come from a machine that is designed to emit radiation on command. The history of how x-rays were discovered is interesting. In the late 1800’s there were many scientists experimenting of that era hat were with electricity which at that time was a new phenomena. One particular experiment involved the behavior of electricity in a vacuum. Roentgen experiments ‫ر‬ ‫تأت األشعة السينية الطبية من جهاز مصمم إلصدار‬ ‫ تاري خ كيفية اكتشاف األشعة‬.‫اإلشعاع عند الطلب‬ ‫ن‬ ‫ كان هناك‬، 1800 ‫ ف أواخر عام‬.‫السينية مثث لالهتمام‬ ‫ن‬ ‫العديد من العلماء ف تلك الحقبة كانوا يجربون‬.‫الئ كانت نف ذلك الوقت ظاهرة جديدة‬ ‫الكهرباء ر‬ ‫ن‬ ‫تضمنت إحدى التجارب الخاصة سلوك الكهرباء ف‬.‫الفراغ‬ Crookes tube There were many famous people that were conducting the electrical experiments at the time. Besides Roentgen, there were other scientists that were involved in the early experiments. Later even individuals like Thomas Edison were credited with producing the first fluoroscopic device which uses x-rays and can provide “moving x- ray images” Fluoroscopy is used to do examinations of many parts of the body, but perhaps it is most well-known for conducting x-ray examinations of the digestive organs such as the esophagus, stomach, small intestine, and colon. ‫ر‬ ‫بتدور عىل التحمة؟‬ ‫صح‬.‫كان هناك العديد من المشاهث الذين كانوا يجرون التجارب الكهربائية نف ذلك الوقت إىل جانب رونتجن‬ ‫ يستخدم ر‬..... "‫ صنع اول جهاز بالمنظار الفلوري ويوفر “صور اشعه سينيه متحركة‬:‫توماس اديسون‬ ‫أكث‬.)‫ القولون‬،‫ األمعاء الدقيقة‬،‫ المعدة‬،‫شء نف تصوير االعضاء الهضمية مثل (المريء‬ The experiments that scientists were conducting involved a bulb like device called a Crooks tube which is illustrated here. You will notice that the tube has two electrodes; an anode (+) which is electrically positive and a cathode (-) which is negative. The idea here was to pass electricity from the cathode to the anode. Because electricity is comprised of electrons flowing ina conductor, what they did in this case they made the electrons stream across the space between the cathode to the anode. If there is air in the tube, this means that any electrons that are streaming across the space between the cathode and anode will most likely collide with the atoms whatever gas is in the tube. These collisions will reduce the efficiency of transmitting the electricity (current) and thisis why they tried to remove as much of the air as they could in the Crookes tube. ‫تضمنت التجارب ر‬.‫الئ أجراها العلماء جهازا يشبه المصباح يسىم أنبوب كروكس الموضح هنا‬ ‫ن‬.‫) سالب‬-( ‫) وهو موجب كهربائيا وكاثود‬+( ‫ أنود‬.‫قطبي‬ ‫ستالحظ أن األنبوب يحتوي عىل‬.‫كانت الفكرة هنا ه تمرير الكهرباء من المهبط إىل المصعد‬ ‫ن‬ ‫ن‬ ‫نظرا ألن الكهرباء تتكون من ر‬ ‫ فإن ما فعلوه ف هذه الحالة جعل‬،‫إلكثونات تتدفق ف موصل‬.‫بي المهبط إىل المصعد‬‫عث الفراغ ن‬ ‫ر‬ ‫اإللكثونات تتدفق ر‬ ‫بي المهبط والمصعد‬‫عث الفراغ ن‬ ‫ر‬ ‫يعئ أن أي إلكثونات تتدفق ر‬ ‫ فهذا ن‬،‫إذا كان هناك هواء نف األنبوب‬ ‫ن‬ ‫ ستقلل هذه االصطدامات من كفاءة‬.‫ستصطدم عىل األرجح بالذرات أيا كان الغاز الموجود ف األنبوب‬.‫أكث قدر ممكن من الهواء نف أنبوب كروكس‬‫نقل الكهرباء (التيار) ولهذا السبب حاولوا إزالة ر‬  History of radiography Anna Bertha Röntgen Wilhelm Röntgen Radiography started in 1895 with the discovery of X-ray, also called Roentgen (Wilhelm Conrad Roentgen) rays after the manwho first discovered them. 1901: The First Nobel Prize in Physics Wilhelm Conrad Röntgen. Prize motivation: "in recognition of the extraordinary services he has rendered by the discovery of the remarkable rays subsequently named after him. 1901 ‫ ونتيجة هذا االكتشاف حصل عىل جائزة نوبل عام‬, 1895 ‫تم اكتشاف األشعة السينية بواسطة رونتجن عام‬ During Roentgen’s experiments, the small screen that was mentioned in the previous slide was situated similar to what is seen in this diagram. He did not understand how theglowing could occur since he could not see,hear, or feel anything that could be causing the “glowing effect”. And to make this phenomena more fascinating to Roentgen, the Crookes tube was covered with black cardboardso he knew that there no sort of light leaking out of the tube. ‫بالبداية رونتجن ما فهم كيف صار التوهج ليش؟ النه ما كان يقدر يشوف او يسمع او يحس باي شء يسبب‬.‫التوهج عشان هيك غىط أنبوب كروكس بالورق األسود المقوى عشان ما يترسب أي ضوء لألنبوب‬  He understood then that this probably represented some sort of “ray” or “particles” that were able to penetrate the thickness of the books and make the screen glow anyway.It was with this discovery that he began a series of experiments where he would position his hand and other objects between the Crookes tube and the painted screen andhe could actually see a type of shadow of the bones in his hand. ‫هون فهم رونتجن انه فيه " اشعه " وبلش بمجموعة من التجارب منها بوضع يده ن‬ ‫بي انبوب كروكس والشاشة ونتيجة‬.‫هذه التجربة كان بإمكانه يشاهد ضل العظام بيده‬ One thing that they did not know at the time, whenever the electrons streamed across the distance between the cathode and anode, the electrons would accelerateto a very high velocity. The electrons that were streaming across the space between the cathode and anode were called “cathode rays”. This velocity was controlledby the voltage applied to the Crookes tube. ‫ر‬ ‫االلكثونات ن‬ ‫ بس بنقدر‬،‫بي المصعد والمهبط بتتسارع بشكل كبث‬ ‫ بس تتدفق‬.... ‫رونتجن ما فهم شء واحد فقط‬.‫نتحكم بهذا التسارع عن طريق الجهد المطبق عىل االنبوب‬ The higher the voltage ↑ , the greater the velocity ↑ of the electron stream. Little did the scientists know that when the electrons arrived at the anode as well as the surrounding glass tube, collisions between thehigh speed electrons and the atomic structureof the anode metal and glass would take place. It is these interactions that that are responsible for the production of x-rays as well as a “glowing effect” in the glass tube thatwas often observed when the tube was energized. ‫ر‬.‫االلكثونات المتدفقة (المنتقلة) من الكاثود (المصعد) اىل االنود (المهبط) وزادت سعة‬ ‫كلما زاد الجهد زاد عدد‬ ‫ر‬ ‫ر‬ ‫االلكثونات ن‬ ‫االلكثونات تتسارع وتصطدم بالمهبط ونتيجة هذا االصطدام‬ ‫بي المصعد والمهبط فان‬ ‫عندما تتدفق‬.‫تنتج األشعة السينية‬ Max von Laue W. H. Bragg and his son W. L. Bragg 1914: The Nobel prize for and the diffraction of x-rays by crystals physics Prize motivation: 1915: The Nobel prize for physics “for his discovery of the Prize motivation: "for their services in the analysis of crystal structure by diffraction of X-rays by crystals” means of X-rays Director at the FHI (1951-1959 Bragg: In sodium chloride there appear to be no molecules represented by NaCl. The equality in number of sodium and chloride atoms is arrived at by a chess-board pattern of these atoms; it is a result of geometry and no of a pairing off of the atoms. This statement is…absurd to the nth degree; not chemical cricket. Chemistry is neither chess nor geometry, whatever X-ray physics may be.It is time that chemists took charge of chemistry once more and protected neophytes against the worship of false gods. - 1912 NaCl(2 atoms)Iron Pyrite FeS2(3 atoms)Calcite CaCO3(5 atoms). - 1945 Penicillin, Dorothy Hodgkin’s (41 atoms). - 1953 DNA, James Watson and Francis Crick (77 atoms, diameter~20Å). - 1954 Vitamin B12, Dorothy Hodgkin’s (181 atoms). - 1962 Hemoglobin structure (diameter 50 Å). - 2011 Yeast Ribosome structure (diameter ~250-300 Å) 404714 atoms.  ‘The Electromagnetic Spectrum’ Radiation Wavelength Frequency description are a typeof ray emitted by -12 21 radioactive materials. They are Gamma Rays 1x10 m 1x10 Hz extremely hazardous to living things,but when used correctly they can kill cancer cells Used a lot in medicine to help -9 18 doctors see broken bones, x-rays x- Ray 1 x 10 m 1 x 10 Hz can pass through tissue but not bone. 1 x 1016 Hz This is responsible for Ultra Violet 1 x 10-7m people getting a tan or sunburn! This is the light Humans can see, it Visible light -6 1x 10 m 1 x 1014 Hertz makes up the colours of the rainbow, Red, Orange, Yellow, Green, Blue, Indigo, Violet. we can’t see it , but we feel its effects…it’s called HEAT. Infra-red 1x 105m 1 x 1011Hz commonly used in cooking and mobile phones. Microwaves 1m 1 x 109 Hz.‫ ال تمتلك عدد ذري وال عدد كتىل‬:(EM) You know more about this than you may think! The Electromagnetic spectrum or EMS is the name given to all of the types of “waves” which exist in the universe. They all have some things in common  They all travel at 300,000,000 metres per second (3 x 108 ms-1) also they do not have any mass, i.e. they have no weight or atomic structure.  The types of waves that people are most familiar with are visible light (light we can see), infra-red light, ultra violet light, x rays, micro-waves and radio waves Radiation ‫اشعة‬ Diagnostic ‫تشخيص‬ Diffraction ‫حيود‬/‫انحراف‬ Ionize ‫تأين‬ Phenomena ‫فرضية‬ Vacuum ‫فراغ‬ Electrodes ‫اقطاب‬ Collisions ‫تصادم‬ Current ‫تيار‬ Experiment ‫تجربة‬ Penetrate ‫ر‬ ‫اخثاق‬ Thickness ‫سماكة‬ Cathode ) ‫(القطب السالب‬ Anode ) ‫(القطب الموجب‬