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كلية الزرقاء الجامعية

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medical physics laser tissue interactions electromagnetic radiation

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This document provides a detailed overview of medical physics, focusing on lasers, their basic principles, interactions with tissue, and associated hazards. It also covers different types of lasers and important parameter like pulse duration, giving a general understanding of the subject.

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Medical Physics (3 , 4 ,5) Laser is an electromagnetic radiation The ward LASER is acronym, stand for Light Amplification by Stimulated Emission of Radiation ‫ هٍ اختظبس ٌـ اٌزٍّخ اٌّظٍخ ثبالطفش‬LASER ‫ ووٍّخ‬،ٍ‫...

Medical Physics (3 , 4 ,5) Laser is an electromagnetic radiation The ward LASER is acronym, stand for Light Amplification by Stimulated Emission of Radiation ‫ هٍ اختظبس ٌـ اٌزٍّخ اٌّظٍخ ثبالطفش‬LASER ‫ ووٍّخ‬،ٍ‫اٌٍُضس هى إشؼبع وهشوِغٕبؽُغ‬ Basic Principle The basic principle of lasing action is the stimulated transition of an electron in a high energy level to a lower one, emitting a photon with the same properties as the incident photon that initiated the transition ٍ‫اٌّجذأ األعبع‬ ،ً‫اٌّجذأ األعبعٍ ٌؼًّ اٌٍُضس هى تحفُض أتمبي اإلٌىتشوْ ِٓ ِغتىي ؽبلخ ِشتفغ إًٌ ِغتىي ؽبلخ أل‬ ‫ِّب َٕجؼج ِٕه فىتىْ ٌه ٔفظ خظبئض اٌفىتىْ اٌغبلؾ اٌزٌ ثذأ اٌتحىي‬ Atoms of any substance are made up of electrons, protons, and neutrons. Electron usually in a resting stage, when they absorb a photon the rising to an excited state A laser beam is generated by amplification, which is simulated emission repeated innumerable times. ‫رساد أٌ ِبدح تتىىْ ِٓ إٌىتشؤبد وثشوتىٔبد ؤُىتشؤبد‬.1 ‫ حُج َّتض اٌفىتىْ وَظؼذ إًٌ حبٌخ ِخبسح‬،‫ َىىْ اإلٌىتشوْ ػبدحً فٍ ِشحٍخ اٌشاحخ‬.‫ وهى ِحبوبح االٔجؼبث اٌّتىشس ِشاد ال حظش ٌهب‬،ُُ‫ َتُ تىٌُذ شؼبع اٌٍُضس ػٓ ؽشَك اٌتؼخ‬ ُ‫ِه‬/There are four basic components to every laser? Lasting medium ‫ ِتىعطخ دائّخ‬Power source‫ِظذس اٌطبلخ‬ Optical cavity ٌ‫اٌتزىَف اٌجظش‬ Delivery systemًُ‫ٔظبَ اٌتىط‬ 1 ‫اٌّىىٔبد األعبعُخ ٌٍُضس‬ Basic components of laser The lasting medium (located inside the optical cavity) is the substance that produces the laser beam, which is determines the wavelength of the Laser. )ٌ‫(تمغ داخً اٌتزىَف اٌجظش‬: ‫اٌىعٍُخ اٌذائّخ‬ ‫ وهٍ اٌتٍ تحذد اٌطىي اٌّىرٍ ٌٍُضس‬،‫هٍ اٌّبدح اٌتٍ تٕتذ شؼبع اٌٍُضس‬ The delivery system modifies the Laser beam and brings it from the optical cavity of the patient..‫ َؼذي شؼبع اٌٍُضس وَخشره ِٓ اٌتزىَف اٌجظشٌ ٌٍّشَغ‬:ٍُُ‫ٔظبَ اٌتغ‬ The Power source is used to simulate the lasing medium to produce the Laser beam ‫ َغتخذَ ٌّحبوبح وعؾ اٌٍُضس إلٔتبد شؼبع اٌٍُضس‬:‫ِظذس اٌطبلخ‬ ُ‫ِه‬The Laser light has three unique properties: monoclinic coherent‫ِتّبعه‬ collimated‫ِىاصَخ‬ ُ‫ِه‬There are two types of Lasers Continuous wave Laser (pulse duration is not relevant) )‫ٌُضس اٌّىرخ اٌّغتّشح (ِذح إٌجؼخ غُش راد طٍخ‬ Pulsed wave Laser (pulse duration is variable) )‫ٌُضس اٌّىرخ إٌجؼُخ (ِذح إٌجؼخ ِتغُشح‬ 2 How dose LASER interact with Tissue Wavelength chosen partly based on absorption curve Of the tissue target chromosphores ‫تُ اختُبس اٌطىي اٌّىرٍ رضئًُب ثٕب ًء ػًٍ ِٕحًٕ االِتظبص ٌٍىشوِىعفىساد اٌّغتهذفخ فٍ األٔغزخ‬ Chromophores in dermatology are Haemoglobin, Water, Melanin. ُٓٔ‫ اٌُّال‬،‫ اٌّبء‬،ُٓ‫اٌىشوِىفىساد فٍ األِشاع اٌزٍذَخ هٍ اٌهُّىرٍىث‬ Reflection Scaltering Transmission Absorption Important Parameters Pulse duration: refers to the duration of each Laser pulse ‫ تشُش إًٌ ِذح وً ٔجؼخ ٌُضس‬:‫ِذح إٌجؼخ‬ In order to get sensitive effect on the target only, the pulse duration should be matched to the thermal relaxation time of the target..‫ َزت أْ تتىافك ِذح إٌجؼخ ِغ صِٓ االعتشخبء اٌحشاسٌ ٌٍهذف‬،‫ِٓ أرً اٌحظىي ػًٍ تأحُش حغبط ػًٍ اٌهذف فمؾ‬ Smaller targets require smaller pulse duration‫تتطٍت األهذاف األطغش ِذح ٔجؼخ أطغش‬ Spot size refers to the diameter of beam emitted, larger spot size induced deeper penetration..‫ وحزُ اٌجمؼخ األوجش َغجت اختشالًب أػّك‬،‫َشُش حزُ اٌجمؼخ إًٌ لطش اٌشؼبع إٌّجؼج‬ Hazards Laser sign:Laser classified into four groups: 3 1. Class one No biological Hazard 2. Class two Chronic viewing hazard only 3. Class three Direct viewing Hazard 4. Class four Direct and reflected hazard ٍ‫اٌفئخ األوًٌ ال َىرذ خطش ثُىٌىر‬.1 ‫اٌفئخ اٌخبُٔخ خطش اٌّشبهذح اٌّضِٕخ فمؾ‬.2 ‫خطش اٌّشبهذح اٌّجبششح ِٓ اٌذسرخ اٌخبٌخخ‬.3 ‫اٌفئخ اٌشاثؼخ اٌخطش اٌّجبشش وإٌّؼىظ‬.4 Therefore there should no mirror in the treatment room ‫وٌزٌه ال َٕجغٍ أْ َىىْ هٕبن ِشآح فٍ غشفخ اٌؼالد‬ Eyes of patients and health care workers should be protected from laser beam‫َزت حّبَخ ػُىْ اٌّشػً واٌؼبٍُِٓ فٍ ِزبي اٌشػبَخ اٌظحُخ ِٓ شؼبع اٌٍُضس‬ ُ‫ِه‬/General Hazards i. Laser sign‫ػالِخ اٌٍُضس‬ ii. Doors closed‫األثىاة ِغٍمخ‬ iii. Windows covered‫إٌىافز ِغطبح‬ iv. Eye protectionُٓ‫حّبَخ اٌؼ‬ v. Standby mode‫وػؼُه اإلعتؼذاد‬ vi. Fire ‫حشَك او ٔبس‬ vii. Smoke evacuators should have high efficiency in airborne particle reduction ‫َزت أْ تتّتغ أرهضح إخالء اٌذخبْ ثىفبءح ػبٌُخ فٍ تمًٍُ اٌزغُّبد‬ ً‫اٌّحّىٌخ رىا‬ viii. Electrical safety‫اٌغالِخ اٌىهشثبئُخ‬ The negative potential difference is caused by the unequal distribution of ions on either side of the cell membrane..‫َٕزُ فشق اٌزهذ اٌغٍجٍ ػٓ اٌتىصَغ غُش اٌّتغبوٌ ٌألَىٔبد ػًٍ ربٔجٍ غشبء اٌخٍُخ‬ Cells control the flow of specific charged elements across the membrane with proteins that sit on the cell surface and create an opening for certain ions to pass through. ‫تتحكم الخالٌا فً تدفق عناصر مشحونة محددة عبر الغشاء من خالل البروتٌنات‬.‫الموجودة على سطح الخلٌة وتخلق فتحة لتمرٌر أٌونات معٌنة‬ 4 These proteins are called ion channels. Movements of ions across the cell membrane generates an electrical pulse known as an action potential..‫تسمى هذه البروتٌنات القنوات األٌونٌة‬.‫ضا كهربائ ًٌا ٌعرف باسم جهد الفعل‬ ً ‫تولد حركات األٌونات عبر غشاء الخلٌة نب‬ Our nervous system uses these action potentials to send signals around our body, to initiate the correct movements, thoughts and behaviours..‫ٌستخدم نظامنا العصبً إمكانات الفعل هذه إلرسال إشارات حول الجسم لبدء الحركات واألفكار والسلوكٌات الصحٌحة‬ Calcium contains two positive charges, sodium and potassium contain one positive charge, and chloride contains a negative charge. ،‫ وٌحتوي الصودٌوم والبوتاسٌوم على شحنة موجبة واحدة‬،‫ٌحتوي الكالسٌوم على شحنتٌن موجبتٌن‬.‫وٌحتوي الكلورٌد على شحنة سالبة‬ The nervous system can be divided into two parts The central nervous system (consists of the brain, the spinal cord neurons). The autonomic nervous system. Neurons: are the fundamental units of the brain and nervous system the cells responsible for receiving sensory input from the external world, for sending motor commands to our muscles, and for transforming and relaying the electrical signals at every step in between. ً‫ وهً الخالٌا المسؤولة عن تلق‬،ً‫الوحدات األساسٌة فً الدماغ والجهاز العصب‬: ‫الخالٌا العصبٌة‬ ،ً‫المدخالت الحسٌة من العالم الخارج‬.‫ وتحوٌل ونقل اإلشارات الكهربائٌة فً كل خطوة بٌنهما‬،‫وإرسال األوامر الحركٌة إلى عضالتنا‬ Action potential:- also called a nerve impulse, is an electrical charge that travels along the membrane of a neuron. It can be generated when a neuron's membrane potential is changed by electrical signals from a nearby cell. 5 ً ‫وتسمى‬-:‫إمكانات العمل‬ ‫ وهً عبارة عن شحنة كهربائٌة تنتقل عبر غشاء‬،‫أٌضا النبضة العصبٌة‬ ‫ وٌمكن تولٌده عندما تتغٌر إمكانات غشاء الخلٌة العصبٌة عن طرٌق اإلشارات‬.‫الخلٌة العصبٌة‬.‫الكهربائٌة من خلٌة مجاورة‬ ‫مهم‬/Electrical signals ‫االشارات الكهربائٌة‬ 1. Electrical signals from muscles 2. Electrical signals from the heart 3. Electrical signals from the brain 4. Electrical signals from the eye Electrical shock Hazards  ‫مهم‬/At a minimum, electric shock can cause: 1) Headache‫الصداع‬ 2) Muscle fatigue or spasms ‫التعب العضلً أو التشنجات‬ 3) Temporary unconsciousness‫فقدان الوعً المؤقت‬ 4) Temporary breathing difficulty‫صعوبة مؤقتة فً التنفس‬ ُ‫ِه‬/Some of the more serious and possibly fatal side effects of electrical shock are: :ٍ‫ثؼغ اِحبس اٌزبٔجُخ األوخش خطىسح وسثّب اٌُّّتخ ٌٍظذِخ اٌىهشثبئُخ ه‬ 1- Severe burns at point of contact and along the electricity's course through the body‫الحروق الشدٌدة عند نقطة التالمس وعلى طول مسار الكهرباء فً الجسم‬ 2- Vision loss‫فقدان الرؤٌة‬ 3- Hearing loss‫فقدان السمع‬ 4- Brain damage‫تلف الدماغ‬ 5- Respiratory arrest or failure‫توقف أو فشل التنفس‬ 6- Cardiac arrest (heart attack))‫) السكتة القلبٌة‬ 7- Death ‫الموت‬ A. heat therapy: the heating effects of (HFE) is done by using: :‫( باستخدام‬HFE) ‫ تتم التأثٌرات الحرارٌة لـ‬:‫ العالج الحراري‬-‫أ‬ 1) Short wave & diathermy.‫الموجة القصٌرة واإلنفاذ الحراري‬ 2) Long wave & diathermy.‫ الموجة الطوٌلة واإلنفاذ الحراري‬. 3) Microwave & diathermy.‫المٌكرووٌف واإلنفاذ الحراري‬ 6 B. Electro surgery: uses of (HFE) to: :‫) من أجل‬HFE( ‫ استخدامات‬:‫ الجراحة الكهربائٌة‬.‫ب‬ 1. Control haemorrhage during During surgery.‫السٌطرة على النزٌف أثناء الجراحة‬ 2. Sear the wounds. ‫حرق الجروح‬ 3. Electro surgery = cut through tissues.‫الجراحة الكهربائٌة = قطع األنسجة‬ 4. Electro cauterizing = coagulate small or moderate- size blood vessels that are too tie..‫الكتٌرازٌنك الكهربائً = تخثر األوعٌة الدموٌة الصغٌرة أو المتوسطة الحجم والتً تكون مربوطة للغاٌة‬ *Micro shock: it is the shock, which occurs when the current is applied inside the body. It does not move to pass through the high resistance of the skin..‫ هً الصدمة التً تحدث عند تطبٌق التٌار داخل الجسم‬:‫الصدمة الدقٌقة‬.‫ال ٌتحرك لٌمر عبر المقاومة العالٌة للجلد‬ *ventricular fibrillation can be induced with very much smaller than the current level of macro shock. It has been estimated 30 μΑ through human heart would cause ventricular fibrillation..‫* ٌمكن تحفٌز الرجفان البطٌنً بمستوى أقل بكثٌر من المستوى الحالً للصدمة الكلٌة‬.ً‫ مٌكرومتر من خالل قلب اإلنسان من شأنه أن ٌسبب الرجفان البطٌن‬30 ‫تشٌر التقدٌرات إلى أن‬ Low frequency electricity (LFE) & magnetism in medicine:It used for:- A.measure the blood flow by electromagnetic methods B. Measure the skin resistance by LFE to monitor psychological change ‫ قٌاس تدفق الدم بالطرق الكهرومغناطٌسٌة‬.i ً‫ لرصد التغٌر النفس‬LFE ‫ قٌاس مقاومة الجلد بجهاز‬.ii ‫ أمٌر احمد مناف‬/‫اعداد الطالب‬ 7

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