Diagnostic Radiology - Radiography by zerosoul

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									Integrated Block: Radiography

Topics
Conventional radiography Fluoroscopy Mammography IVU Angiography Computed radiography

Dr. Pek-Lan Khong Department of Diagnostic Radiology Queen Mary Hospital The University of Hong Kong

Electromagnetic spectrum

Ionising radiation
If a photon has 15eV or more of energy, it is capable of ionising atoms and molecules – ionising radiation. An atom is ionised when it loses an electron. Gamma rays, x-rays – ionising radiation.

The invisible light
Wilhem Conrad Roentgen Professor of physics at the University of Wurzburg, Germany 8th Nov. 1895
Roentgen’s lab at Wurzburg

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Discovery of X-rays
Behavior of cathode rays (electrons) in high energy cathode ray tubes. High-voltage discharge – ionization of remaining gas – faint light from fluorescence of paper coated with Barium platinocyanide.
Radiograph of Roentgen’s hand

Portable X-ray units

1901

1896

War-time radiographs

CXR of pTB in early 1896 exposure time: 45 mins

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How X-rays are created
The three main parts of any X-ray tube are the anode, cathode and the tube.

How X-rays are created
When a filament is heated, electrons are ejected from the surface of the filament. A large electrical potential, voltage, between the cathode and the anode force electrons emitted from the filament to accelerate towards the anode.

How X-rays are created
X-rays are produced by energy conversion when a fast-moving stream of electrons is suddenly decelerated at the tungsten target of the anode.

Radiographs
The photons of an x-ray beam enter a patient with a uniform distribution and emerge in a specific pattern of distribution. Image formation depends on a differential attenuation between tissues.

Attenuation
Reduction in the intensity of x-ray beam as it traverses matter by either absorption or deflection of photons from the beam. Some tissues attenuate more x-rays than other tissues.

CXR (PA)

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Attenuation
The amount of attenuation depends on the energy of radiation and 3 characteristics of tissue (density, atomic no., electrons/gm) The size of this differential determines the amount of contrast in an X-ray image.

Radiation
No known safe radiation dose. Spontaneous genetic mutations and malignant diseases. Man-made radiation = 15%. Diagnostic medical exposures account for 97% of it.

Radiation
Somatic :
• carcinogenesis - leukemia. • long latent period.

ICRP (International Commission on RadiationProtection) principles No practice involving exposures to radiation should be adopted unless it produces sufficient benefit to the exposed individuals or to society to offset the radiation detriment it causes (justification of practice). As low as reasonably achievable (ALARA), optimisation of protection. Exposure of individuals subject to dose limits.

Genetic :
• mutations - pregnancy!!.

Reduce radiation!!
Shielding of organs. Filtration of x-ray beam. Control of irradiation and recording of irradiation time. Radiographic film processing. Quality assurance.

Reduce radiation!!
Avoid unnecessary requests. Decrease repeat exams. Decrease number of films taken. Limit size of x-ray beam.

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Radiation doses and their equivalent natural radiation period
Examination Effective dose (mSv) Equiv. no. Of CXRs Equiv. peroid of natural background radiation 3 days 2 weeks 14 months 9 months 2.5 years 4 years 1 year

CXR (PA film) Skull Lumbar spine Abdomen Ba meal Ba enema CT head

0.02 0.1 2.4 1.5 5.0 9.0 2.0

1 5 120 75 250 450 100

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X-ray = radiograph = roentgenogram
Radiograph = Still images shown on film or computer screen Fluoroscopy = Movie (dynamic) viewed on TV monitor or computer screen

Fluoroscopy
Video x-ray machine ‘real time’ contrast material some information about function

Fluoroscopy couch and machine

Common fluoroscopy examinations
Gastrointestinal tract :

Common fluoroscopy examinations
Gastrointestinal tract :

Barium swallow - hypopharynx and oesophagus Barium meal - stomach and duodenum

Barium follow-through - small bowel Barium enema - large bowel

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Common fluoroscopy examinations
Genitourinary tract: Micturating cystourethrogram bladder, urethra. Hysterosalpingogram - uterus, fallopian tubes.

Contrast Mediums
Barium. Water-soluble contrast medium. Air.

Barium: complications
Perforation
• Peritoneal adhesions and granulomata • For assessment of suspected gastrointestinal perforation, water-soluble contrast should be used instead

Water-soluble contrast mediums: complications
Pulmonary edema if aspirated – hypertonic contrast medium. Hypovolaemia – hypertonic contrast medium in GIT. Allergic reactions.

Aspiration
• Relatively harmless • Physiotherapy

Intravascular Contrast Medium (water-soluble) : Adverse reactions Mild
• Sneezing, nausea.

Prophylaxis for adverse reactions Steroid premedication
• oral methlyprednisolone/IV hydrocortisone

Moderate
• Pruritis, flush, fever/chills, increased/decreased blood pressure.

Change of contrast medium
• Low osmolar contrast medium

Severe
• Difficulty in breathing, periorbital edema, cardiac arrhythmia, pulmonary edema, death.

Reduction of anxiety

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All Radiological Procedures carry a RISK
Risk from Radiation. Risk from Contrast Medium. Risk due to technique.

Patient preparation
? admission ? pregnancy Informed consent Bowel preparation Fasting Previous films and notes Premedication

Barium Swallow
Indications: Difficulty/pain in swallowing. Preoperative assessment of oesophageal cancer.

Barium swallow

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Oesophageal cancer

Barium Meal
Indications: Dyspepsia/epigastric pain. Weight loss. Assessment for suspected stomach cancer.

Single contrast Barium Follow-through

Double contrast Barium Meal

Barium enema
Indications: Change in bowel habit. Pain. Mass. Blood in stools. Bowel obstruction.

Double-contrast Barium enema

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Barium enema: patient preparation
Bowel preparation
• Low residue diet, fluid diet, cleansing enema, Dulcolax

Micturating cystourethrogram (MCU)
Indications: Vesicoureteric reflux. Study of the urethra during micturation. Contraindications: Acute urinary tract infection.

Water-soluble contrast is introduced into the bladder using a Foley’s catheter

MCU

Vesico-ureteric reflux

Hysterosalpingogram (HSG)
Indications: Infertility. Recurrent abortions. Following tubal surgery. Contraindications: Pregnancy. Pelvic Inflammatory disease.

HSG

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IVU (Intravenous urogram)
Demonstrate the urinary tract for suspected urinary tract pathology

IVU (Intravenous urogram): patient preparation
Laxative. Fast for 4 hours. Hydration. Micturate before IVU.

IVU :
Preliminary KUB

50mls of water-soluble contrast injected into I/V cannula

0 mins

Release KUB

10 mins

Full bladder

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R ureteric stone causing obstruction

IVU (Intravenous urogram)
Contraindications: Pregnancy. Serious reactions to previous injections of contrast media. Diabetes with renal insufficiency.
• risk of acute renal failure.

Mammography
x-ray imaging used to create detailed images of the breast. x-ray system designed specifically for imaging the breasts. uses low dose x-ray; high contrast, high-resolution film.

Mammogram

Oblique view

Craniocaudal view

Mammography
Screening mammography :
Asymptomatic women - early detection of small breast cancers.

Diagnostic mammography :
Breast complaint.

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Angiography : indications
Assessment of arterial/venous disease. Localisation of site of haemorrhage. Investigation of malignant tumours.

Puncture sites
Femoral artery – most frequent. Axillary artery. Brachial artery.

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Angiography
Patient preparation:
Admission to hospital. Discontinue anticoagulants. Puncture site is shaved. Premedication.

General complications of catheter techniques
Due to contrast medium. Due to drugs. Due to technique:
• local • distant

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Computed Radiography
Conventional projection radiography, in which the image is acquired in the digital format using an imaging plate rather than film.

CR Suite

Digital Images:
Advantages
Complex image processing can be performed by computers Electronic storage possible Electronic image transmission possible Image management through connectivity to Picture Archiving and Communication system

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Topics
Conventional radiography Fluoroscopy Mammography IVU Angiography Computed radiography

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