Medical Physics - Lecture Notes 2022-2023 - Pharmacy Students - PDF

Medical Physics Department of Pharmacy 1.Temperature: is a thermal state of a body which distinguishes a hot body from a cold body. Matter is composed of molecules that are in motion, the fact that the molecules move means that they have kinetic energ...

Medical Physics Department of Pharmacy 1.Temperature: is a thermal state of a body which distinguishes a hot body from a cold body. Matter is composed of molecules that are in motion, the fact that the molecules move means that they have kinetic energy ‫ طاقة حركية‬is related to temperature. In order is increasing the temperature of molecules (e.g., gas). This can be done by putting the gas in contact with a flame ‫اللهب‬. The energy transferred from the flame to the gas causing the temperature rise is called heat. The reverse, heat can be removed ‫ إزالة الحرارة‬from substance to lower the temperature are referred to as the cryogenic region. ‫المنطقة المبردة‬ Temperature Scales The most common ‫ األكثر شيوعًا‬scales to measure temperature are: 1-Celsius (°C): or Centigrade scale using ice point of (0 °C) as the lower fixed point and steam point of (100 ºC) as upper fixed point for developing the scale. It is denoted by the letter (C). Ice point refers to the temperature at which freezing of water takes place at standard atmospheric pressure. Steam point refers to the temperature of water at which its vaporization takes place at standard atmospheric pressure. The interval between the two fixed points was equally divided into 100 equal parts and each part represented (1ºC). 2-Fahrenheit scale (°F): in this scale the freezing temperature ‫ درجة حرارة التجمد‬is 32°F and boiling point ‫ نقطة الغليان‬is 212°F, and normal body temperature ‫درجة حرارة الجسم‬ ‫ الطبيعية‬is about 98.6°F, and each part represented (1ºC). 3- Kelvin scale (°K): or the absolute scale this scale has the same divisions as the Celsius but takes the 0° K at the absolute zero which is: - 273.15°C. It is related to Celsius scale as given below: 4- Rankin scale: it was developed by William John Macquorn Rankine, a Scottish engineer. It is denoted by the letter R. It is related to Fahrenheit scale as given below: 8 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy Example: The temperature of the human body is normally about 98.6°F.calculate the temperature of the body in °C and °K? Solution: 37.44 oC = 310.15 oK Thermometry and Temperature Scales Temperature is difficult to measure directly, so usually measure it indirectly by measuring one of many physical properties that change with temperature. In the thermometer, a temperature increase causes the mercury to expand ‫تمدد الزئبق‬, as Fig.(2-1). Figure (2-1): Mercury thermometers. 9 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy 2.Pressure: It is the effect of normal force acting on an area. If a force acts at an angle on an area, the fundamental SI unit of pressure is (N/m2), which is called a Pascal (Pa) or bar. 1 bar = 105 N/m2 = 105 Pa. 1bar = 105 N/m2 = 105 Pa. Pressure: It is the force per unit area in a gas or liquid. (For solid ‫ الصلب‬the term pressure is replaced by "stress" ‫)اإلجهاد‬, i.e., the pressure has the same units as stress, and indeed that a pressure is just a constant normal stress applied around all surfaces bounding a body. ‫الضغط إجهاد طبيعي ثابت يتسلط حول كل السطوح المحيط بالجسم‬ The pressure unit Pascal is too small for pressures encountered in practice. Therefore, its multiples kilo Pascal (1 kPa = 103 Pa) and mega Pascal (1 MPa = 106 Pa) are commonly used. Three other pressure units commonly used in practice which are: bar, standard atmosphere (atm) and pound-force per square inch (psi). The relationships between these units are: 1 atm = 101325 Pa = 14.696 psi43 Pressure in the Body We all know many people who have problems with high blood pressure ‫ضغط الدم‬ ‫العالي‬, and will be aware that blood pressure is taken routinely in the course of a general medical examination. There are many other pressure measurements made by physician's ‫ األطباء‬and sometimes by medical physicist's ‫الفيزياويين الطبيين‬. These include respiratory pressures ‫ضغوط تنفسية‬, bladder pressure ‫ضغط مثانة‬, foot pressure ‫ضغط قدم‬, ocular pressure and middle-ear pressure. ‫ضغط بصري وأذن وسطى‬ Measurement of Pressure in the Body The physicists naturally use SI units: a. Dynes per square centimeters. b. Newton per square meter N , (Pascal) or (Pa). But, the clinical colleague, the used unit is the height of a column of mercury (Hg) ‫عمود الزئبق‬, as in Figure (2-2). - The peak systolic pressure ‫ = الضغط اإلنقباضي‬120 mmHg = a pressure of a liquid mercury of this height on its base. - While the atmospheric pressure ‫ = الضغط الجوي‬760 mm Hg or sometimes in millimeters (or centimeters) of sea surface. When we measure pressures using devices such as manometers, and the pressure that is lower than atmospheric pressure ‫ الضغط الذي هو أوطأ من الضغط الجوي‬is usually quoted as a negative pressure. ‫الضغط السلبي‬ 10 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy Figure (2-2): The column of mercury. Typical levels of pressure in and around the body are presented in Table (2-1), and the pressure conversion factors can be shown in Table (2-2). Table (2-1): The pressure in the body. Table (2-2): Pressure conversion factors. For Example: 1 atm =101325 Pa= 1.01325 bar = 0.76 m (or 760 mm) Hg. 11 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy 1- Manometer: this is a U-shaped tube containing a fluid that is connected to the pressure to be measured (see Figure: 4-2). The levels in the arms change until the different in the levels (h) is equal to the pressure. - This type of manometer can measure both (positive) and (negative) pressure. ‫يقيس كال‬ ‫من اإليجابي والسلبي‬ - The fluid used can be: a. Mercury for high pressure measurements. b. Water or other low density fluid for low pressures. Figure (2-3): Manometer: U-shaped tube. 2- Sphygmomanometer: is the most common clinical instrument used for measuring the blood pressure, as shown Figure (2-4). Mercury gauge‫ مقياس زئبقي‬: the pressure is indicated by the height of mercury inside a glass tube. Figure (2-4): Sphygmomanometer 12 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy Standard procedure for use of this device is outlined below. Place cuff around upper arm. Rest armor flat surface just below heart level. Place stethoscope ‫ السماعة‬on hollow of elbow ‫ جوف المرفق‬over brachial artery. ‫الشريان‬ ‫العضدي‬ Inflate ‫ ينفخ‬cuff to a pressure at which the blood does not flow ‫الدم ال يتدفق‬, usually about 180 mmHg is sufficient. Release pressure slowly until sounds of blood squirting through restricted artery are heard. These sounds are called Korotk off or ‘K’ sounds. This is systolic pressure. ‫هذا‬ ‫ضغط إنقباضي‬ Continue to release pressure until no further sound is heard. This is diastolic pressure. ‫هذا ضغط إنبساطي‬ Thus, the pressure (P) under a column of liquid can be calculated from the following low: P = g h ………… (1) where: : is the density of liquid for: Mercury ρ =13.6 g/ Water ρ =1 g/ g: is the acceleration due to the gravity. h: is height of the column. Example 1: Calculate the atmospheric pressure in N/. Solution: 1 atm =760 mmHg =76 cmHg. The atmospheric pressure in N/ is equal: P= gh P = 13600 kg/ x 9.8 m/ x 0.76 m = 1.01x N/ Home work Example 2: Calculate the length of water column that can produce the same pressure of a column of mercury of (1mm) length. (Answer =13.6 mm). Example 3: What height of water will produce the same pressure as 120 mm Hg? (Answer 163 cm O). 13 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy Eye Pressures The eyeball ‫ مقلة العين‬contains aqueous humour ‫ماء قرنية‬, a fluid comprised mostly of water. This fluid is produced continuously, and should drain to maintain normal pressure ‫يصرف إلبقاء الضغط طبيعي‬. A blockage ‫ عائق‬in the drain causes an increase in pressure (glaucoma).‫ وهو مرض ينشأ نتيجة ارتفاع ضغط العين فينتج عنه تلف في أنسجة العصب البصري‬:‫ الماء األزرق أو األسود‬,glaucoma and can lead to a restricted blood supply to the retina ‫ يحدد تجهيز الدم إلى الشبكية‬then affect the vision. This is condition called glaucoma: 1- Moderate ‫ معتدل‬---------- tunnel vision ‫رؤية نفقية‬ 2- Severe ‫ حاد‬-------------- blindness ‫عمى‬ The pressure in normal eyes ranges from (12 – 23) mmHg. Methods for Measuring Intraocular Pressure 1- Sticking the tips of both index fingers on the closed upper eyelid to monitor pressure ‫لصق أطراف كال إصبعي السبابة على الجفن العلوي المغلق لمراقبة الضغط‬ 2- Can be measure the pressure within eye by relating the deformation of the globe to an externally applied force..‫يمكن قياس الضغط الداخلي من خالل ربط تشوه الكرة بالقوة الخارحية المسلطة‬ Other highly sophisticated methods of measuring intraocular pressure have also been developed. 14 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy 3.Heat Heat is the energy transferred without transfer of mass across the boundary of the system due to the difference in temperature between the system and its surroundings. It is denoted ( ). If there is no temperature difference there is no heat transfer. The unit of heat is Joule (J = N.m)..‫الحرارة هي الطاقة المنقولة دون نقل الكتلة عبر حدود النظام بسبب االختالف في درجة الحرارة بين النظام ومحيطه‬ Specific Heat Capacity The specific heat capacity of a substance is defined as the amount of heat which transfers into or out of a unit mass of the substance, while the temperature of the substance changes by one degree. ‫ بينما تتغير درجة‬، ‫يتم تعريف السعة الحرارية النوعية لمادة ما على أنها كمية الحرارة التي تنتقل إلى أو خارج وحدة كتلة المادة‬.‫حرارة المادة بدرجة واحدة‬ Thus if: : Specific heat capacity of the substance. : Mass of the substance. : Heat transfer. 1: Initial temperature. 2: Final temperature. Then: Specific heat capacity may vary with temperature. It should also be noted that when heat is transferred to the system, it will have a positive sign, and when it is transferred from the system, it will have a negative sign, (i.e. gained is positive and rejected is negative). ‫ سيكون لها عالمة‬، ‫ وتجدر اإلشارة أيضً ا إلى أنه عند نقل الحرارة إلى النظام‬.‫قد تختلف السعة الحرارية المحددة مع درجة الحرارة‬.)‫ (أي أن المكتسبة موجبة و مرفوضة سلبية‬، ‫ سيكون لها عالمة سلبية‬، ‫ وعندما يتم نقلها من النظام‬، ‫موجبة‬ Example (1): An unknown metal weighing (0.9 kg) at an initial temperature of (140 °C) is placed into an insulated container holding (3 kg) of water at an initial temperature of (60 °C). After thermal equilibrium the water rose to (65 °C). Knowing that (Cwater = 4186 J/kg.°C), what is the specific heat capacity of the metal? Solution: The amount of heat lost by the metal equals the amount of heat gained by the water, thus: 15 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy Example (2): A (10 g) iron bar at (80 °C) is dropped into (70 g) of water at (25 °C). Knowing that (Cwater = 4.186 J/g.°C) and (Ciron = 0.47 J/g.°C), what is the final temperature after thermal equilibrium? Solution: The amount of heat lost by the iron bar equals the amount of heat gained by the water, thus: Enthalpy Enthalpy (H): is a thermodynamic quantity equivalent to the total heat content of a system. It is equal to the internal energy of the system plus the product of pressure and volume. Enthalpy is a dependent property. Enthalpy is a property of a substance and a form of energy. It is equal to the combined internal energy and flow energy: where U: is the internal energy. PV: is the flow energy. Like internal energy, enthalpy is an extensive property and can have a specific value: Enthalpy is equivalent to the total heat content of a system and it is a dependent property. 16 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy Ideal - Gas Equation of State A gas is made of molecules that move around with random motion. In a perfect gas, the molecules may collide but they have no tendency to stick ‫ لاللتصاق‬together or repel ‫ تنافر‬each other, as in Table (2-3). Table (2-3): Ideal-gas specific heats of various common gases at (300 K). - In reality, there is a slight force of attraction between gas molecules ‫قوة جذب طفيفة‬ ‫ بين جزيئات الغاز‬but this is so small that gas laws formulated for an ideal gas work quite well for a real gas. ‫أن قوانين الغاز المصاغة للغاز المثالي تعمل جيدًا بالنسبة للغاز الحقيقي‬ - Any equation that relates the pressure, temperature, and specific volume of a substance is called an equation of state. ‫معادلة الحالة‬ - Property relations that involve other properties of a substance at equilibrium states ‫ لمادة في حاالت التوازن‬are also referred to as equations of state. - The simplest and best-known equation of state for substances in the gas phase is the ideal-gas equation of state ‫معادلة حالة الغاز المثالي‬. This equation predicts the (P-υ- T) behavior of a gas quite accurately within some properly selected region. - Gas and vapor are often used as synonymous words. The vapor phase ‫المرحلة‬ ‫ البخارية‬of a substance is customarily called a gas when it is above the critical temperature. ‫عندما تكون أعلى من درجة الحرارة الحرجة‬ - In 1662, Robert Boyle, an Englishman, observed during his experiments with a vacuum chamber that the pressure of gases is inversely proportional to their volume. ‫أن ضغط الغازات يتناسب عكسياً مع حجمها‬ 17 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy - In 1802, J. Charles and J. Gay-Lussac, Frenchmen, experimentally determined that at low pressures the volume of a gas is proportional to its temperature..‫تجريبيا ً أن حجم الغاز يتناسب مع درجة حرارته عند الضغط المنخفض‬ That is, where, R: is called the gas constant and it is different for each gas. Table (1) shows the values of the gas constant for different gases. P: is the absolute pressure. T: is the absolute temperature (K). V: is the volume (m3) υ: is the specific volume (m3/kg). Equations (1 and 2) is called the ideal-gas equation of state, or simply the ideal- gas relation, and a gas that obeys this relation is called an ideal gas. where : is the universal gas constant. , the same for all substances. M: is the molar mass (also called molecular weight) of the gas. N: number of mols. Boyle’s law states that the pressure of a given mass of an ideal gas is inversely proportional to its volume at a constant temperature. It is expressed as: Charles’s law states that the volume of an ideal gas at constant pressure is directly proportional to the absolute temperature. It is expressed as: Gay-Lussac’s law states that, for a given mass and constant volume of an ideal gas, the pressure exerted on the sides of its container is directly proportional to its absolute temperature. It is expressed as: 18 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy Example (3): Determine the mass of the air in a room whose dimensions are (4 m ×5 m × 6 m) at (100 kPa) and (25 °C). Solution: From Table (1), the gas constant of air is: Example (4): An amount of gas has a pressure of (350 kPa), a volume of (0.03 m3) and a temperature of (35 °C). If (R = 0.29 kJ/kg.K), calculate the mass of the gas and the final temperature if the final pressure is (1.05 MPa) and the volume remains constant. Solution: The absolute temperature: Applying the equation of state between two conditions at constant volume: 19 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy Example (5): A tank has a volume of (0.5 m3) and contains (10 kg) of an ideal gas having a molecular weight of (24). The temperature is (25 °C). What is the pressure of the gas? Solution: The absolute temperature: Home Work: 1- A container of (0.2 m3) contains nitrogen at a pressure of (1.013 bar) and at a temperature of (15 °C). (2 kg) of nitrogen was pumped by a special pump to the tank. Calculate the new gas pressure when the tank returns to its initial temperature. Nitrogen was considered an ideal gas, take R = 296.9 J / kg. K. Ans. (1.87 bar) 2- Air in an internal combustion engine has (227°C), (1000 kPa) with a volume of (0.1 m3). Now combustion heats it to (1500 K) in a constant volume process. What is the mass of air and how high does the pressure become? Ans. (0.697 kg, 3000 kPa) 3- A rigid tank of 1 m3 contains nitrogen gas (molecular weight 28) at 600 kPa, 400 K. By mistake someone lets 0.5 kg flow out. If the final temperature is 375 K what is the final pressure? Ans. (506.9 kPa) 3 4- A (1 m ) rigid tank contains propane (molecular weight 44) at (100 kPa), (300 K) and connected by a valve to another tank of (0.5 m3) with propane at (250 kPa), (400 K). The valve is opened and the two tanks come to a uniform state at (325 K). What is the final pressure? Ans. (139.9 kPa) 3 5- (0.1) kg of ideal gas occupies a volume of (0.003 m ) at a pressure of (7 bar) and a temperature (131 °C) when the gas was expand to a pressure of (1 bar), its final volume became (0.02 m3). Calculate the final temperature. 20 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy Ans. (384.6 K) 6- Air is at (25 º C) and (101.325 kPa). If the gas constant (R = 287 J / kg. k), find the specific volume and the molar mass of this gas, assuming it behaves as an ideal gas. Ans. (0.8445 m3/kg, 28.97 kg/kmol) Energy, Work, and Power Energy is the ability to do work. ‫هي القدرة على القيام بعمل‬ - Energy is a scalar quantity with SI units of joules (J). Joules are derived units equivalent to Newton meters (N. m). - The concept of work is similar to that of energy. ‫مفهوم العمل مشابه لمفهوم الطاقة‬ The work done by constant force acting on a body is equal to the force multiplied by the distance moved in the direction of the force. ‫الشغل المبذول بواسطة القوة الثابتة المؤثرة على الجسم يساوي القوة مضروبة في المسافة المقطوعة في اتجاه القوة‬ - If the force and the distance moved are taken to be vectors ‫متجهات‬, then the work done is their dot product. By definition, therefore, a force that produces no displacement does not work. ‫القوة التي ال تنتج أي إزاحة ال تعمل‬ All activities of the body, including thinking ‫ التفكير‬involve energy changes. The conversion of energy into work ‫ تحويل الطاقة إلى عمل‬such as lifting a weight or riding a bicycle represents only a small fraction of total energy conversions of the body. For example under resting conditions: ‫في ظل ظروف الراحة‬  Skeletal muscles and the heart are using 25% of the body's energy.  19%is being used by the brain. ‫الدماغ‬  10%is being used by the kidneys. ‫الكلى‬  27% is being used by the liver and the spleen. ‫الكبد والطحال‬ The body uses the food energy ‫ الطاقة الغذائية‬to: 1. Operate its various organs. ‫لعمل األجهزة المختلفة‬ 2. Maintain a constant body temperature. ‫للحفاظ على درجة حرارة الجسم‬ 3. Do external work e.g. lifting. ‫للقيام بعمل خارجي‬ Note: - A small percentage (~5%) of the food is excreted ‫ الطعام يفرز‬in the feces and urine. - Any energy that is left over is stored as body fat. ‫دهون في الجسم‬ - The energy used to operate the organs appears as body heat. ‫تظهر كحرارة في الجسم‬ 21 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy Work and Power Chemical energy stored in the body is converted into external mechanical work as well as into life preserving functions. ‫يتم تحويل الطاقة الكيميائية المخزنة في الجسم إلى عمل ميكانيكي خارجي وكذلك إلى وظائف الحفاظ على الحياة‬ The internal work: is the force (F) moved through a distance Δx. ΔW = F Δx The force and the motion Δx must be in the same direction. ‫نفس األتجاه‬ Power: is the rate of work done. ‫معدل العمل المنجز‬ P = ΔW / Δt = F Δx / Δt = F v (v =velocity) External work is done when a person ‫ يتم العمل الخارجي عندما يتسلق الشخص‬is climbing hill or walking up stairs. We can calculate the work by: multiplying the person weight (mg) by the vertical distance (h) moved. W = mg × h We can also measure the oxygen consumed during any activity: - The total food consumed can be calculated since 4.8 kcal are produced for each 1 liter of oxygen consumed. - The efficiency of the human body as machine can be obtained from the following: € = work done / energy consumed - Efficiency is usually lowest at low power ‫الكفاءة في أدنى مستوياتها عند الطاقة المنخفضة‬ but can increase to 20% for trained individual's ‫ لألفراد المدربين‬in activities such as cycling and rowing. Example 1: A man of mass 84 kg runs up of 100 steps in 30 seconds. Calculate the power output of his leg muscles, if the vertical height of each step = 20 cm. Solution: Work done (w) = Pt w = mg × h w= 84 × 9.8 × 20 × w= 164.64 J (the one step) w for 100 steps = 164.64 × 100 = 16464 J P= = = 548.8 J/s or watt 22 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy Home work Example 2: Suppose that the elevator is broken in the building in which you work and you have to climb 9 stories – a height of 45 m above ground level.How many extra calories will this external work cost you if your mass is 70 kg and your body at 15% efficiency ? Example 3: A 70 kg hiker climbed a mountain 1000 m high. He reached the peak in 3 hr. A. Calculate the external work done by the climber. B. Assuming the work was done at a steady rate during the 3 hr period. Calculate the power generated during the climb. C. Assuming the average consumption during he climb was 2 liters/min (corresponding to 9.6 kcal/min). Find the efficiency of the hiker's body. D. How much energy appeared as heat in the body? First Law of Thermodynamic 1st Law of Thermodynamics is a statement about conservation of energy and it categorizes the method of energy transfer into two basic forms: work (W) and heat (Q), as in Figure (2-5). )Q( ‫) والحرارة‬W( ‫ العمل‬:‫هو بيان حول الحفاظ على الطاقة ويصنف طريقة نقل الطاقة إلى شكلين أساسيين‬ The “internal” energy of a system (U) (for a container of ideal gas, U =kinetic energy ‫ الطاقة الحركية‬of the molecules) can be changed by transferring heat to and from the environment ‫ البيئة‬and/or performing work on or by the environment. Figure (2-5): 1st Law of Thermodynamics about work (W) and heat (Q). ΔQ = ΔU + ΔW where: ΔQ: is the change of quantity of heat of the system. ΔU: is the change in the internal or stored energy. 23 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy ΔW: is the work done. This can be written as: ΔU= ΔQ – ΔW Note: Positive Q → heat input to the system from the environment. Negative Q → heat output from the system to the environment. Positive W → work done by the system on the environment. Negative W → work done on the system by the environment. A body doing no work (ΔW = 0) at constant temperature. It continues to lose heat to its surroundings, ΔQ is negative. Therefore, ΔU is negative; indicating a decrease in stored energy and the rate of change of their variables is just taken per unit time where by dividing on Δt: ΔU/Δt = ΔQ/Δt - ΔW/Δt where: ΔU/Δt: Rate of change of stored energy. ‫معدل تغير الطاقة المخزنة‬ ΔQ/Δt: Rate of heat loss or gain. ‫معدل فقدان الحرارة أو اكتسابها‬ ΔW/Δt: Rate of doing work. ‫معدل العمل‬ This is the equation tells us that energy is conserved ‫ الطاقة محفوظة‬in all processes, but it does not tell us whether or not a process can occur. ‫ال تخبرنا المعادلة العملية يمكن أن تحدث أم ال‬  Internal energy (U): is a property consisting of the combined molecular kinetic and potential energies. This property is derived from the first law of thermodynamics. Internal energy is a dependent property.  Volume (V): is the quantity of three-dimensional space enclosed by a closed surface, for example: the space that a substance (solid, liquid, gas or plasma) occupies or contains. Volume is an independent property. Second Law of Thermodynamics The second law of thermodynamics states that the heat energy cannot transfer from a body at a lower temperature to a body at a higher temperature without the addition of energy. This is why running an air conditioner for a long period of time, costs you money. ‫ينص القانون الثاني للديناميكا الحرارية على أن الطاقة الحرارية ال يمكن أن تنتقل من جسم عند درجة حرارة منخفضة إلى جسم عند‬.‫درجة حرارة أعلى دون إضافة طاقة‬ Or, the second law of thermodynamics asserts that processes occur in a certain direction and that the energy has quality as well as quantity, as in Figure (2-6). 24 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy Figure (2-6): Heat transfer from a hot container to the cold surroundings is possible; however, the reveres process (although satisfying the first law) is impossible. The second law of thermodynamics also says that the entropy of any isolated system always increases ‫أن إنتروبيا أي نظام معزول تزداد دائ ًما‬. Isolated systems spontaneously evolve towards thermal equilibrium ‫ نحو التوازن الحراري‬the state of maximum entropy of the system. More simply put: the entropy of the universe (the ultimate isolated system ‫النظام‬ ‫ )المعزول المطلق‬only increases and never decreases. A simple way to think of the second law of thermodynamics is that a room ‫هناك طريقة‬ ‫بسيطة للتفكير في القانون الثاني للديناميكا الحرارية وهي أن الغرفة‬, if not cleaned and tidied, will invariably become more messy and disorderly with time – regardless of how careful one is to keep it clean. When the room is cleaned, its entropy decreases ‫تتناقص إنتروبياها‬, but the effort to clean it has resulted in an increase in entropy ‫لكن الجهد المبذول لتنظيفها أدى إلى زيادة في‬ ‫االنتروبيا‬outside the room that exceeds the entropy lost. Entropy Entropy (S): is a thermodynamic quantity representing the unavailability of a system's thermal energy for conversion into mechanical work, often interpreted as the degree of disorder or randomness in the system. This property is derived from the second law of thermodynamics. Entropy is a dependent property. The entropy of the system is measured in terms of the changes the system has undergone from the previous state to the final state..‫تم قياس إنتروبيا النظام من حيث التغييرات التي خضع لها النظام من الحالة السابقة إلى الحالة النهائية‬ Thus the entropy is always measured as the change in entropy of the system denoted by ∆S. 25 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy Increase in Entropy In a closed system, the mass of the system remains constant but it can exchange the heat with surroundings. ‫ تظل كتلة النظام ثابتة ولكن يمكنها تبادل الحرارة مع البيئة المحيطة‬، ‫في النظام المغلق‬ - Any change in the heat content of the system leads to disturbance in the system ‫اضطراب في النظام‬, which tends to increase the entropy of the system. - Due to internal changes in the movements of the molecules of the system, there is a disturbance inside the system. This causes irreversibility inside the system and an increase in its entropy. ‫ هذا يسبب عدم رجعة داخل النظام‬.‫هناك اضطراب داخل النظام‬ - The reversible isentropic process never really occurs ‫;ال تحدث العملية المتوازنة العكسية أبدًا‬ it is only an ideal process. In actual practice whenever there is a change in the state of the system the entropy of the system increases. Efficiency Heat Loses from the Body 40–45 percent of the heat lost from the body is lost through the head and neck ‫الرأس‬ ‫ والرقبة‬due to increased blood flow in comparison with the rest of the body. Combined with the wrists and ankles ‫الرسغين والكاحلين‬, this can approach 60 percent. These areas need to be covered. The normal human temperature is 37°C. The temperature of the body depends on the: 1-Time of the day (lower in the morning) ‫توقيت اليوم‬ 2- Environment temperature. ‫البيئة‬ 3-The amount of clothing 4-Health of the person 5- On his recent physical activity. The body losses heat mainly by radiation, convection, and evaporation, all these processes can take place in the skin. Evaporation occurs during breathing as well, resulting in a cooling effect. ‫يحدث التبخير أيضا في التنفس‬ The production of heat in the body ‫ إنتاج الحرارة في الجسم‬for 2400 Kcal/day (assuming no change in body weight ‫=)وزن الجسم‬1.7Kcal/min=120J/sec =120W. So the body must lose the same amount of heat ‫ يفقد نفس كمية الحرارة‬to stay at constant temperature. The heat loses depends on many factors: 1- The temperature of the surroundings ‫البيئة المحيطة‬ 2-Humidity ‫الرطوبة‬ 3-Motion of the air 4-The physical activity of the body ‫نشاط الجسم الطبيعي‬ 5-The amount of the body exposed ‫كمية الجسم المكشوفة‬ 6- The amount of insulation of the body (like clothes and fat). ‫كمية عزل الجسم‬ 26 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy Transfer of Heat by Radiation ‫انتقال الحرارة باإلشعاع‬ All objects regardless on their temperature emit electromagnetic radiation ‫تبعث إشعاعا‬ ‫ ;كهرومغناطيسيا‬the amount of energy emitted by the body is proportional to the absolute temperature ‫ درجة الحرارة المطلقة‬raised to the fourth power. The amount of heat difference between the energy radiated ‫ شعت‬by the body and the energy absorbed ‫ إمتصت‬from the surrounding ‫ المحيط‬can be calculated from the equation: where: Hr: is the rate of heat energy loss or gain. ‫نسبة خسارة أو أكتساب الطاقة الحرارية‬ Kr: is a constant depends upon various physical parameters ‫ثابت يعتمد على البارامترات الفيزيائية‬ and it's about =5Kcal/ hr C° for man. : is effective body surface area emitting radiation. ‫منطقة سطح الجسم الفعال التي تبعث إشعاعا‬ e: is the emissivity of the surface ‫ قوة إشعاع السطح‬which is nearly=1,independent ‫ مستقل‬on the color of the skin indicating that the skin at this wavelength is almost a perfect emitter and absorber ‫ باعثًا وامتصاصً ا‬of radiation. : is the skin temperature in C°. ‫درجة حرارة الجلد‬ : is the temperature of the surrounding walls. ‫درجة حرارة الجدران المحيطة‬ Hint: Heat losses by radiation occur even the temperature differences is not high. ‫درجة‬ ‫الحرارة ليست عالية‬ Home work Example : for a nude person have a skin temp. 34°C in a room of walls temperature 25°C and his body area 1.2 will lose 54 Kcal/hr which is 54% of the total losses. Most of the remaining heat will be by convection. Transfer of Heat by Convection ‫نقل الحرارة بالحمل الحراري‬ Heat losses by convection (Hc): where: : is the amount of heat gained or lost is convection. ‫كمية الحرارة المكتسبة أو المفقودة‬ : is the effective surface area. ‫المنطقة السطحية الفعالة‬ : is the skin temperature. : is the environment ‫ البيئة‬temperature or air temperature. : is a constant that depends on the movement of the air ‫ثابت الذي يعتمد على حركة الهواء‬, for a resting body and no apparent wind ‫ ريح‬is about 2.3 kcal/ hr °C. 27 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy Note: when the air is moving increases according to the equation: where: v: is the wind speed in m/sec. ‫سرعة الريح‬ This equation is valid for speeds ‫ هذه المعادلة صالحة للسرعات‬between 2.23 m/sec (5mph ‫ميل في‬ ‫ )الساعة‬and 20m/sec (45mph) (1 mile = 1.6 km). Example1: 1- Calculate the convection heat loss per hour for a nude standing in a(5m/sec) wind. Assume =33°C, =10°C and =1.2 ? where: = 27.8 at 5m/sec. Solution: =27.8×1.2× (33-10) = 767Kcal/hr 2- If the wind speed were (2.23m/sec). Find the still air temperature that would produce the same heat loss (the wind chill equivalent temperature)? Solution: 767=23.2×1.2× (33-Ta) =5°C Home work Example 2: Consider a man on a beach in Florida.It is a sunny day so he is receiving radiation from the sun at the rate of 30 Kcal/hr.He has an effective body surface of 0.9 m² , = 32 °C , and the temperature of his surrounding is 30 °C. a. Find the net energy gained by radiation per hour. b. If there is a breeze at 4m/sec, find the energy lost by convection per hour. c. If he loses 10 Kcal/hr and his metabolic rate is 80 kcal/hr, how much heat is lost by evaporation? Transfer of Heat by Evaporation ‫انتقال الحرارة عن طريق التبخير‬ - Under normal ‫ الطبيعية‬temperature conditions and in the absence of hard work or exercise ‫وفي غياب العمل الشاق أو التمرين‬, heat loss mainly by radiation and convection. ‫باإلشعاع والحمل الحراري‬ 28 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy - Since each gram of water that evaporate carries with it the heat of vaporization of 580 calories ‫الماء يتبخر يحمل معه حرارة تبخير‬, the evaporation of I liter carries with it 580 kcal. - There is some heat losses by perspiration ‫ بالعرق‬even if the body does not feel sweaty ‫متعرق‬, it amount to about 7 Kcal/hr, equivalent to 7% of the body losses. A similar loss of heat is due to the evaporation of moisture ‫ الرطوبة‬in the lungs. ‫الرئتين‬ - Under typical ‫ المثالية‬conditions the total respiratory heat losses ‫فإن إجمالي فقدان الحرارة‬ ‫ من الجهاز التنفسي‬is about 14% of the body's heat loss. - Under extreme ‫ قاسي جدا‬condition of heat and exercise the sweat ‫ العرق‬evaporation is very important, a man may sweat more than 1 lit/hr, this is if all sweat is evaporated. ‫هذا إذا كل العرق مبخر‬ Energy Changes in the Body - The rate at which the body uses food energy to sustain life and to do different activities is called the metabolic rate (MR). ‫المعدل الذي يستخدم به الجسم الطاقة الغذائية للحفاظ على الحياة وللقيام بأنشطة مختلفة يسمى معدل األيض‬ - The total energy conversion rate of a person at rest is called the basal metabolic rate (BMR) ‫ في حالة الراحة معدل األيض األساسي‬and is divided among various systems in the body. - The BMR is a function of age, gender, total body weight, and amount of muscle mass ‫( هو وظيفة العمر والجنس ووزن الجسم الكلي وكمية الكتلة العضلية‬which burns more calories than body fat). - Athletes ‫ الرياضيون‬have a greater BMR due to this last factor. - Children have high values ‫ بقيم عالية‬of BMR because of the energy required for growing. ‫للنمو‬ - Men have slightly higher ً‫ أعلى قليال‬values than women, because men have less body fat ‫ دهون أقل‬and therefore use more energy ‫ المزيد من الطاقة‬in maintaining ‫ المحافظة‬body temperature, shown on Figure (2-7). - The largest fraction goes to the liver and spleen ‫الكبد والطحال‬, with the brain ‫الدماغ‬ coming next. - Of course, during vigorous exercise, the energy consumption of the skeletal muscles and heart increase markedly ‫يزداد استهالك الطاقة للعضالت الهيكلية والقلب‬, about 75% of the calories burned in a day go into these basic functions (see pp: 33). 29 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy Figure (2-7): Losses normalized to body surface area. where: the released internal energy. Example average daily internal energy consumption of a middle aged faculty member, as in Table (2-4). ‫مثال متوسط استهالك الطاقة الداخلي اليومي لعضو هيئة تدريس في منتصف العمر‬ Table (2-4): Daily internal energy of a middle aged. Note: - The energy value of food referred to by nutritionists as a Calorie: is actually a kilocalorie; thus a diet ‫ الحمية‬of 2500 C/day is the same as 2500 Kcal/day. 30 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy A kilocalorie is the amount of heat required to raise the temperature of one kilogram of water one degree Celsius ‫ التي نشير إليها في الطعام هي في الواقع كيلو كالوري‬Calorie "‫"السعرات الحرارية‬ ‫كيلو كالوري هو مقدار الحرارة المطلوب لرفع درجة حرارة كيلوغرام واحد من الماء درجة مئوية واحدة‬ - Energy unit is joule or erg. (erg) ‫ وعلي األخـص الطاقة الحرارية‬،‫هو وحدة من وحدات الطاقة‬ 1 Kcal =4184j 1J= ergs - Power is given in joule per second or watts (W). - The metabolic rate ‫معدل األيض‬, or human body heat or power production, is often measured in the unit "Met". The metabolic rate of a relaxed seated person ‫معدل‬ ‫ التمثيل الغذائي لشخص جالس مسترخي‬is one (1) Met, where: 1 Met = 58 W/m2 or, 1 met =50 Kcal/m² hr A typical man has about 1.85m² of surface area ‫مساحة سطح الرجل النموذجي‬ In woman has about 1.4m². Thus, for a typical man is: 1 met ≈ 92 Kcal/hr or 107 W and, In woman is: 1 met ≈ 70 Kcal/hr. - The rate at which the body produces energy ‫ إنتاج الجسم للطاقة‬depends largely on tissue volume. ‫حجم األنسجة‬ - Whereas the rate at which energy ‫ معدل فقدان الطاقة‬is lost depends on body surface area. - The body of smaller is the greater as a ratio of surface area to volume S/V. - So babies ‫ األطفال‬are more at risk for the hypothermia than adults. ‫البالغين‬ - The small people need to eat more per kilogram of body mass than large people. Harris-Benedict Formula 1. Calculate your BMR (basal metabolic rate):  Women: BMR = 655.1 + (9.563 × weight in kg) + (1.850 × height in cm) – (4.676 × age in years). or: BMR = 655 + (4.35 x weight in pounds) + (4.7 x height in inches) - (4.7 x age in years).  Men: BMR = 66.5 + (13.75 × weight in kg) + (5.003 × height in cm) – (6.755 × age in years). or: BMR = 66 + (6.23 x weight in pounds) + (12.7 x height in inches) - (6.8 x age in years). 2. Multiply you're BMR by the appropriate activity factor, as follows: ‫اضرب معدل األيض األساسي الخاص بك في عامل النشاط المناسب‬ 31 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy  Sedentary ‫( قلة الحركة‬little or no exercise): BMR x 1.2  Lightly active ‫( النشاط الخفيف‬light exercise/sports 1-3 days/week): BMR x 1.375  Moderately active ‫( معتدل النشاط‬moderate exercise/sports 3-5 days/week): BMR x 1.55  Very active ‫( نشط جدا‬hard exercise/sports 6-7 days a week): BMR x 1.725  Extra active ‫( نشاط إضافي‬very hard exercise/sports & physical job or 2x training): BMR x 1.9 3. Your final number is the approximate number of calories you need each day to maintain your weight. ‫للحفاظ على وزنك‬ Electromagnetic radiation (EMR) Energy propagating through space at the speed of light in the form of sine-shaped electromagnetic waves ‫ موجات كهرومغناطيسية جيبية‬composed of perpendicularly arranged electric and magnetic fields, as in the Figure (2-8). EMR ranges from gamma rays ‫ أشعة جاما‬with very short wavelength to long radio waves ‫موجات الراديو‬. The shortest wavelengths can also be modeled as particles (photons). The interaction of EMR with matter forms the basis for remote sensing. ‫االستشعار عن بعد‬ Figure (2-8): Electromagnetic wave. The amount of energy carried by each photon depends on the frequency of radiation: E=hυ=hc/λ where: h = Plan's constant = 6.6 (joule. sec). c = velocity of light = 3 (m/sec). υ = frequency of radiation. 32 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy Figure (2-9): electromagnetic radiation. X – Rays: electromagnetic radiation (EMR) of very short wave length range → ° or (0.01 – 10 nm) and very high penetrating power. It is very useful in diagnosis and radio therapy; see Figure (2-9). Production of X-Ray beam A high-speed electron can convert some or all of its energy into an X-ray photon when it strikes an atom, to us we need to speed up electrons to produce X-rays ‫تسريع‬ ‫ اإللكترونات إلنتاج األشعة السينية‬trying to speed up on electron in air is difficult since there are to many electrons on the atoms- about 4 x in 1. Before an electron gets going it bumps into another one it in thus necessary to eliminate most of electrons, and this is done by using a glass blub (X-ray tube), as in Figure (2-10). The main components of a modern X-ray unit are: 1- A source of electrons- a filament ‫خيوط‬, or cathode. 2- An evacuated space (with low pressure tor): This is accelerating ‫ تعجيل‬the electrons from the cathode to the anode. 3- A high positive potential to accelerate the negative electrons, usually within the range (40 to 120 Kev). 4- A target or anode, which the electrons strike to produce X-rays. 5- The space between the tubes insert (the enveloped and electrode) and the shield is filled with oil, the oil converts heat from the insert to the tube shield (oil used to cool the target). ‫الزيت المستخدم لتبريد الهدف‬ 33 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy Figure (2-10): Rotating anode X-ray tube. Note: The energy of most electrons striking the target (99.8%) is dissipated in the form of heat ‫تتبدد على شكل حرارة‬. This is remaining few energy (0.2%) produce useful X- rays. The intensity of X–ray beam produced when the electron strike the anode is highly dependent on the anode material: 1- The higher the atomic number (Z) of the target, the more efficiency X-ray are produced. ‫زادت كفاءة إنتاج األشعة السينية‬ 2- The target material used should also have a high melting point ‫ نقطة انصهار عالية‬since the heat produced when the electrons are stopped in the surface of the target is substantial. Nearly all X–ray tubes use tungsten ‫ التنجستن‬targets. The atomic number (Z) of tungsten is 74, and its melting point is about 3400. There are two different mechanisms by which X-rays are produce. One gives rise to bremsstrahlung (continuous) X-rays and the other characteristic X-rays. Note: Bremsstrahlung means "braking radiation" ‫ أشعاع الكبح‬to describe the radiation which is emitted when electrons are decelerated or "braked" when they are fired at a metal target. ‫تنشأ عند إبطاء (تقليل مقدار السرعة) جسيم ذو شحنة كهربية مثل إلكترون أو‬: (Bremsstrahlung ‫أشعة انكباح (باأللمانية‬ ‫ للحصول على هذه األشعة بشكل مصطنع يجري تسريع الجسيمات بوساطة تسليط مجال كهربائي أو مجال مغناطيسي‬. ‫بروتون‬.‫ ثم بإجراء عملية الكبح‬،‫ كما يحدث في معجالت الجسيمات األولية مثل السيكلوترون‬، ‫على الجسيم‬ X-ray Energy Spectra - X-rays photons produced by an X-ray machine are heterogeneous in energy. ‫غير‬ ‫متجانسة في الطاقة‬ 34 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy - The spectrum of X-rays produce by a modern X-ray generator is shown in Figure (2-12), the broad smooth curve ‫ المنحنى العريض األملس‬is due to the bremsstrahlung and the spikes represent the characteristic X-ray. - Many of the low energy (soft) X-ray photons produced are absorbed in the glass walls of the X-ray tube. - If no filtration inherent or added, of the beam is assumed, the calculated energy will be a straight line (shown as dotted line in Figure: 2-11). - The purpose of added filtration is to enrich the beam with higher energy photon by absorbing the lower energy components of the spectrum, and hence improving the penetration power of the beam. Figure (2-11): diagrams the energy of K-characteristic X-ray of tungsten, superimposed on the continuous spectrum (Bremsstrahlung). Absorption of X-rays - X-rays absorption depends on the composition of the matter penetrated. ‫المادة‬ ‫المخترقة‬ - Heavy elements ‫ العناصر الثقيلة‬such as Ca are much better absorbers ‫ أفضل أمتصاص‬of X-rays than light elements such as C, and. - So the bones are the best, while the soft tissues ‫ األنسجة الرخوة‬like fat, muscles and tumors ‫ واألورام‬all absorb X-rays equally ‫متساوية األمتصاص‬, thus they are difficult to distinguish from each other on an X-ray image. - The attenuation ‫ التوهين‬of an X-ray beam is its reduction due to absorption and scattering of some of photons out of the beam. ‫التوهين لحزمة األشعة السينية هو تقليلها بسبب امتصاص وتشتت بعض الفوتونات خارج الحزمة‬ 35 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy Figure (2-12): X-rays absorption. - A simple method of measuring the attenuation of an X-ray beam is shown. I= where: I = an attenuated (transmitted) beam intensity = intensity of incident beam. μ= linear attenuation coefficient. e = 2.718 x = Thickness of the attenuator such as (brain tumor, bone, aluminum). UV, Visible, and IR Wavelengths The three general categories of light-UV, Visible, and IR are defined in terms of their wavelengths; see Figure (2-9).  Ultraviolet ‫ فوق البنفسجية‬light has wavelengths from 100 to 400 nm. UV-A has wave lengths from 320 – 400 nm, (photon energy between 3.10 – 3.94 ev and Long-wave, black light, not absorbed by the ozone layer: soft UV). ‫ال تمتصه طبقة األوزون‬ UV-B has wavelengths from 290 - 320 nm, (photon energy between 3.94 – 4.43 ev and Medium-wave, mostly absorbed by the ozone layer: intermediate UV). ‫تمتصها طبقة‬ ‫األوزون في الغالب‬ UV-C has wavelengths from 100 – 290 nm, (photon energy between 4.43 – 12.4 ev and Short-wave, germicidal, completely absorbed by the ozone layer and atmosphere: hard UV). ‫تمتصها بالكامل طبقة األوزون والجو‬  Visible light ‫ الضوء المرئي‬has wavelengths 400 to 700 nm.  IR ‫ تحت الحمراء‬light has wavelengths from 700 to 104 nm. Each of these categories subdivided according to wavelength. Visible light is measured in photometric units the quantity of light. 36 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy  Illuminance ‫اإلنارة‬: striking a surface.  Luminace: the intensity of a light source.  UV and IR radiation can be measured in radiometric units. ‫بوحدات قياس اإلشعاع‬  Irradiance ‫تشعيع‬: the quantity of light striking a surface.  Radiance ‫أشعاع تألق‬: the intensity of a light source. Applications of Visible Light in Medicine - Endoscope ‫المنظار الداخلي‬: a number of instruments are used for viewing internal body cavities. - Cytoscopes ‫منظار الخاليا‬: are used to examine the bladder. - Bronchoscope ‫منظار القصبات‬: Are used for examining the air passages into lungs ‫الرئتين‬. - Flexible endoscopes ‫المناظير المرنة‬: can be used to obtain information from regions of the body that cannot be examined with rigid endoscopes, such as the small intestine ‫ األمعاء الدقيقة‬and much of large intestine. - Some endoscopes are rigid tubes with a light source to illuminate the area of interest. Applications of UV and IR Light in Medicine - UV photons have energies greater than visible and IR light. Because of their higher energies, - UV photons are more useful than IR photons..‫تعد فوتونات األشعة فوق البنفسجية أكثر فائدة من فوتونات األشعة تحت الحمراء‬ - UV light has even shorter wavelengths than the visible light and is scattering more easily. - UV light cannot be seen by the eye because it absorbed before it reaches the retina. ‫تمتص قبل أن تصل إلى الشبكية‬ - UV can kill germs and used to sterilize medical instruments. ‫تقتل الجراثيم وتستخدم لتعقيم األدوات الطبية‬ - UV produces more reaction in the skin ‫ تفاعالت أكثر في الجلد‬some of these reactions are beneficial, and some are harmful. - A beneficial effect of UV light from the sun is the conversion of molecular products in the skin into vitamin D.‫تحويل المنتجات الجزيئية الموجودة في الجلد إلى فيتامين د‬ - Harmful effects of UV light can produce sunburn ‫ حروق الشمس‬as well as tan skin and also cause the skin cancer in humans, which many be related to the fact that the UV wavelengths that produce sunburn are also absorbed ‫ أمتصاص‬by the DNA in the cells. 37 Dr. Mustafa Q. Al Habeeb Medical Physics Department of Pharmacy - The IR rays are not usually hazardous ‫ ليست خطرة في العادة‬even though they are focused by the cornea and lens of the eye onto the retina. However, looking at the sun through a filter (e.g., plastic sunglasses) that removes most of the visible light ‫ يزيل معظم الضوء المرئي‬and allows ‫ يسمح‬most of the IR wavelengths through can cause a burn ‫ يسبب حروقًا‬on the retina. - Heat lamps that produce a large percentage of IR light with wavelengths of 1000 to 2000 nm are often used for physical therapy purposes ‫ألغراض العالج الطبيعي‬. Two types of IR photography are used in medicine: 1- Reflective ‫ العاكسة‬IR photography, which uses wavelength of 700 to 900 nm to show patterns of veins just below the skin. ‫إلظهار أنماط األوردة تحت الجلد مباشرة‬ 2- Emissive ‫ األنبعاث‬IR photography, which uses the long IR heat waves emitted by the body ‫ المنبعثة من الجسم‬that give an indication of the body temperature ‫درجة حرارة الجسم‬, is usually called thermograph. 38 Dr. Mustafa Q. Al Habeeb