RADIOPHYSICS SHORT NOTES FOR RADIOGRAPHER

          RADIOPHYSICS SHORT NOTES RADIOGRAPHER 

RADIOPHYSICS IS A BRANCH OF PHYSICS THAT CONTAINS                                                                  X-RAY, CT SCAN, AND MRI, etc. RELATED SUBJECT.

• Collimators are used to reduce the radiation beam spread.
• Wilhelm Roentgen discovered X- rays in 1895.
• X-ray and gamma rays are forms of electromagnetic radiation.
• Computed tomography x-ray technique used to test various cross-sectional slices.
• The tip of the match stick contains red phosphorus.
• The material is added to the anode disc of the rotating x-ray tube to prevent the crazing effect of rhenium.
• The inner envelope of an x-ray tube is usually made from perspex / Pyrex glass.
• The interaction of electrons (cathode) with atoms of the anode 1% x-rays and 99% heat generated.
• Absorbed dose measured by TLD .
• The image file format is used commonly in digital medical imaging is DICOM.

• The effecting quality of x-rays is KvP & mAs.
• TLD cards are sent to which place for their analysis- Ultra tech lab.
• Lead material is used for radiation protection.
• Annual effective dose limit for occupationally exposed workers in radiology 20 mSv.
• A specific radioactive source will always produce gamma rays at the same energy levels.
• 8 Nov 1895 X-rays discovered.
• The three major principles assisting the ALARA concept- Time, Distance, Shielding.
• The term ALARA stands for As low As Reasonably Achievable.
• Proper use of PPE (personal protective equipment) helps in reducing internal radiation exposure.
• In a radiography quality control procedure that is usually done once in a year- Safe light test.

• Unit of energy is – Jule.
• Geiger counters detect nuclear emissions.
• Short wavelength electromagnetic waves are x– rays.
• The photosensitive layer in the film is made of silver halide
• The normal body temperature is 37 °C /98.6 °F.
• Sound travels fastest in – steel.
• The main source of heat is Sun .
• Cathode rays are used also known as electrons.
• A hygrometer is used in measuring relative humidity.
• Energy is the ability to do work.

• The penetrating ability of an x-ray beam is governed by wavelength.
• In film radiography, penetrameters are usually placed on the source side of the test object.
• KvP stands for kilo energy volt.
• The two most common causes for excessively high-density radiographs are over-exposure and over-developing.
• Cobalt 60 used in non-destructive testing emits – gamma rays.
• Mass is not a property of x-rays.
• R/hr- roentgen/hour.
• The darkroom should have three types of illumination.

• In x- ray developing tempreture 20-22°c(68-72°f)time 5 minutes .
• Rinsing –time 30 sec.
• Fixation temperature 18-20°c,time -2-3 minutes .
• Washing time – 5 minutes.
• Drying temperature 35°c
• RGU(Retrograde urethrogram) x-ray procedure to study urethra.
• MCU (Micturating cystourethrogram) x-ray procedure to study any abnormalities in the bladder neck, narrowing urethra.
• The function of the grid is to reduce scattered radiation.

• MRI stands for magnetic resonance imaging.
• Magnetic field strength is measured in Tesla.
• CT scan stands for Computed Tomography/Computerized Tomography.
• CAT scan for computerized axial tomography.
• CT scan invented by Godfrey Hounsfield in 1972
• In MRI iv contrast medium used Gd-DTPA (Gadolinium-diethyl triamine penteacetic acid)

Initially, Gd-DTPA was the only contrast medium available, but recently other companies have completed trials using their own version of Gadolinium-based compound using different chelate GdDTPA-BMA, This is a non-ionic compound.

• Normally iv contrast medium does not cross the blood-brain barrier such as choroid plexus, pituitary stalk & nasal mucosa.
• RF (Radiofrequency effect )is used to excite the hydrogen protons in the body tissues during MRI.
• MRCP stands for  Magnetic Resonance Cholangiopancreato Graphy.
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