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Radiology Lecture
By Dr Kebede(MD,Radiologist)
Learning objectives:
• Understand sources of radiation exposure• Discuss Ethical, professional and legal issues of
radiation exposure• Understand mechanisms of protecting patients and
the public from inappropriate radiation exposure• Discuss medical application of radiation and common
diagnostic imaging modalities • Discuss radiological approach to common diagnostic
imaging modalities
Mode of Assessment
• Progressive assessment (attendace,active participation)….25%
• Written exam : 75%
Responsibility of the students
• Attendance : 100%• Attentiveness • Active participation
Sources of radiation
Natural (70-85%,2.4 milisielvert/year)
• Inhalational(Radon gas)• Radionuclide from rock• Ingestion• Cosmic radiation
Man-made(15-30%,0.6milisilviert/year)
• Diagnostic medical exposure
• Atmospheric nuclear testing• Occupational exposure
Radiation exposure of the public
• 70-85% (2.4msV)natural background radiation• 15-30% (0.6msv)medical radiation exposure• Overall exposure : 3msV /Year• CT scan contributes for 4% of all diagnostic
imaging modality but shares 40% of all medical radiation exposures
Hazards of radiation exposure
• Carcinogenesis• Teratogenesis• Abortion• Burn
NB: Stochastic vs. Deterministic effects
Life time risk of fatal cancer after diagnostic medical radiation exposure
Guideline while imaging a patient
• A useful investigation is one in which the result - positive or negative – will alter clinical management and/or add confidence to the clinician's diagnosis.
• Significant number of radiological investigations do not fulfill these aims hence causing inappropriate patient radiation exposure.
Major causes of inappropriate patient exposure
1. Repeating investigations2. Investigation when results are unlikely to affect
patient management3. Investigating too often4. Doing the wrong investigation5. Failing to provide appropriate clinical information
and questions that the imaging investigation should answer.
6. Over-investigating
Mechanism to protect patients and the public
• Justification of the procedure• Optimization of a procedure• Dose reduction techniques
The field of Radiology and Imaging
• Young dynamic field on continuous changes and improvement
• Importance of radiology and its value for modern medicine
• Futures and Advances in Imaging• Risks ,medico-legal issues and public concerns
What did radiology Add to medicine?
• Imaging difficult organs(organs like Brain,mediastinum,retroperitoneum,.)
• Better surgical planning • Staging cancers• Interventional radiology• radiotherapy
Imaging Modalities• Radiation emitting
modalities– Radiographs (analogue,
computed Radiograph and digital)
– Fluoroscopy– Mammography– Computed Tomographic
(CT) Scan– Nuclear medicine
Imaging
• Non-Radiation emitting modalities
• Ultrasound • Magnetic Resonance
Imaging(MRI)
Mode of imaging
• Anatomical imaging– Radiographs– Mammography – Ultrasound – CT scan– MRI
• Functional Imaging– Nuclear medicine
(PET,SPECT)– Functional MRI
• Combined – PET-CT– PET-MRI
Conventional radiographs
• .
Fluoroscopy
CT scan
• . • .
Radiographic densities
• Air : blackest on a radiograph• Fat, which is shown in a lighter shade of gray than
air• Soft tissue or fluid (because both soft tissue and
fluid appear the same on conventional radiographs, it’s impossible to differentiate the heart muscle from the blood inside of the heart on a chest radiograph)
• Calcium (usually contained within bones)• Metal : appears the whitest on a radiograph
MRI
Systematic approach to common radiographs
By Kebede(MD,Radiologist)
LECTURE -2
Systematic Approach to CXR
Technique :
• Standard : PA and lateral• Critically ill patients, pediatrics: AP/SupineIndications : – Persitenent cough > 2weeks– In working up Complications of pneumonia – Congestive Heart failure, pulmonary edema– Pulmonary Thromboembolism– Lung cancer and ,metastatic work up– Preoperative work up– Follow up of treatment
1. Assessing Technical adequacy
• Labeling : Identification ,Technique, right/left, Date• Inspiratory /Expiratory : anteriorly 6 ribs, posteriorly
10 ribs has to be seen• Rotation : medial ends of the clavicle should be at
equidistance from the spinous process/ 1/3rd of the cardiac shadow should be in the right hemi chest and 2/3rd should be in the left hemi chest
• Penetration : above 4 thoracic vertebrae should be visualized…..underpenetrated if not visualized and over penetrated if lower vertebrae are visualized.
UNDER PENETRATED
OVER PENETRATED
NORMAL
APPA
AP film : apparent magnification of the cardiac and mediastinal outline is seen
ANTERIOR RIBS
POSTERIOR RIBS
Inspiratory Expiratory
Drawbacks of expiratory film
• cardiomegaly• Abnormal contour of the aorta and• patchy opacification in both lower zones.
Drawbacks of Underpenetrated film
• apparent cardiomegaly• apparent hilar abnormalities• apparent mediastinal contour abnormalities• the lung parenchyma tends to appear of
increased density, i.e. ‘white lung’.
….technical adequacy
• Field of view: should include the lung apices and the costophrenic angles
• Others: breast shadow should be outside of the lung field, foreign bodies like necklace should be removed
• Hence , before reading Chest film its technical adequacy has to be assessed whether it is adequate to read or not since technically inadequate film may mask or overcall findings and mislead to patient mismanagement.
INSIDE –OUT-APPROACH
• Air ways– Trachea : • Location : Central/slight shift to the right• Size : 13mm-23mm in females,15mm-27mm in males• Lumen: air field• Carinal angle : acute angle,72 degrees• Para tracheal strip < 4mm
Right partracheal strip
• Hilum
– Location : left is always higher than the right– Density : symmetric and concave outward; Contributed by :
pulmonary artery and veins,lymphatics not the air ways• Pulmonary vasculatures:
– Are the only white branching linear opacities in lung field which fade in peripheral 1/3rd of the lung field/first intercostal space
– In PA film lower lung zones are more vascularized than the upper lung zones
– If there is at least equalization of vascular diameter in upper and lower zone there is vascular redistribution or cephalization
….continued
• Lung Fields: – Compare both lungs zone by zone – Upper lung zone is more ventilated than the lower
lung zone– Upper lung zone : up to 2nd intercostal space– Mid lung zone : between 2nd and 4th intercostal
space– Lower lung zone : below 4th intercostal space
Cont…..
• Cardiac and mediastinal silhouette• Location : Central • Shape• Size : <50% in adult on PA ,<60% in pediatrics and
supine films• Outlines: Its borders should be well outlined
• Diaphragm • Well outlined• Dome shaped• Acute costophrenic angles
….cont
• Rib cage and soft tissue– Bones : osteolytic or sclerotic changes, missing
ribs, deformity– Soft tissue : swelling,gas,calcifications ,nodules,..
• Hidden Areas– Sub diaphragmatic areas,retrocardiac
areas,paratracheal areas and peripheral lung fields
Common terminologies• Opacification : increased density in the lung field• Luncency : increased blackness/transradiancy• Consolidation : ill-defined opacity with internal branching
tubular radiolucent areas representing patent terminal bronchioles……air bronchogramme .
• Collapse : well defined increased opacity due to blocked air ways; could be segemental,lobar,total…..no air bronchogramme.
• Reticulations : linear radio-opaque shadows• Nodules : discrete ,round radio-opaque shadows < 3cm• Mass: well defined radio-opacity >3cm
..cont
• Blebs : subpleura air containing lesions < 1cm in diameter having thin wall
• Pneumatocele: air containing lesions < 1cm in diameter having thin wall measuring <1mm
• Bullae : air containing lesions >1cm in diameter having thin wall <1mm
• Cavity : air containing lesions >1cm in diameter having thick wall <1mm(active infection >3mm,air fluid level in the cavity and adjacent consolidation)
…cont
• Silhouette sign : Loss of the normal radiologic definition/contrast between two adjacent structures
Consolidation with air-bronchogramme
REVERSED BATWING
• When the periphery of the lung is affected and the central areas are spared
Atelectasis with well defined increased opacity
Atelectasis
mass
Nodule
Reading assignment
• How to approach and differentiate air space VS. Interstitial lung Parenchymal diseases on chest X RAY (Learning radiology recognizing the basics chapter 5 and Radiology Assistant Chest X-Ray - Lung disease Four-Pattern ApproachInternet)
Lecture -3
Approach to spine X ray
Approach to cervical spine x ray
• Technique : AP and lateral• Supplementary views: Open mouth
view ,flexion and extension viewsTechnical adequacy: Skull base and C7/T-1
Junction should be includedSystematic Approach : ABCS
NORMAL : LATERAL
NORMAL : AP
NORMAL OPEN MOUTH VIEW
A-Alignment(assed on lateral film)
• Line 1 is in the prevertebral soft tissue……..10mm anterior to C-1 ,5-7mm between C-2-C-4, and 22mm between C-5-C-7. It should have smooth contour.
• Line 2 follows the anterior vertebral bodies and should be smooth and uninterrupted.
• Line 3 is similar to the anterior vertebral body line (line 2) except that it connects the posterior vertebral bodies.
• Interruption of the anterior and posterior vertebral body line is a sign of a serious injury
Cont…..
• Line 4, called the spino-laminal line, connects the posterior junction of the lamina with the spinous processes.
• The spinal cord lies between lines 3 and 4; therefore any offset of either of these lines could mean that a bony structure is impinging on the cord.
• Severe neurologic deficits can result from very little force against the cord, and any bony structure lying on
…cont
• Line 5 is not really a line so much as a collection of points—the tips of the spinous processes
• After visually inspecting these five lines on the lateral C-spine, inspect the C1–2 area a little more closely. Make certain that the anterior arch of C1 is no greater than 2.5 mm from the dens in adults and 5mm in children.
B-bones
• Height : Anterior and posterior vertebral body height should be equal
• Size : progressively increase downwards• Cortical outline should be smooth• End plates : smooth• Density (normal trabecullar pattern ,accentuated
trabecullar pattern….osteoporosis)• Look for any osteolytic or sclerotic changes• Look for osteophytes
C-Cartillage/Disc spaces
• The disc spaces are examined next to check for any inordinate widening or narrowing, either of which could indicate an acute traumatic injury.
• If a disc space is narrowed, it will usually be secondary to degenerative disease. Make certain that associated osteophytosis and sclerosis are present.
• Look also for facet joints and neural foramina
Vertebral columns
Stable Vs Unstable Fracture
• Stable : Fracture involving only one column• Unstable fracture : Fracture involving more
than one column
Terminologies
• Spondylosis : bony Overgrowth over the vertebral bodies(osteophytosis)
• Spondylolisthesis : sliding of vertebral bodies over one another(Grade -1 < 25% of the vertebrae has slided over, Grade 2 25-50%,Grade 3 50-75% and Grade 4 mores than 75% of the vertebral body is sliding over the inferior)
• It could be posterior or anterior• Spondylolisis : Fracture of the vertebrae
Common Indications for cervical spine x ray
• Trauma• Radiating neck pain• Infection(vertebral and soft tissue)• Metastasis• Degenerative changes• Neoplastic conditions• Upper air way obstruction• Foreign body,..
Thoracic and Lumbar spine
Technique : AP and lateral Normal vertebral curvature in adults• Cervical and lumbar : lordosis• Thoracic and sacral spine : Kyphotic• 5-lines are used in cervical spine only • The size of vertebral body and the height of
disc spaces will gradually increase downwards• Otherwise systematic approach is the same
Lumbar spine : AP
NB:
• For systematic approach of thoracic and lumbar spine X ray please refer emergency radiology page 328-329
• Spine Tuberculosis is the most common musculoskeletal tuberculosis
• Thoraco-lumbar junction is the most common site• Paravertebral collection/abcesses with
calcification is pathognomonic for Tuberculoses spondylodiscitis
Role of MRI in spine
• MRI is superior for evaluation of degenerative vertebral and disc diseases, disc prolapse ,for assessing central canal and neural foraminal stenosis, for diagnosis of spondylodiscitis
• MRI has also superior efficacy for spinal cord neoplasms,infection and inflammatory condition of the spine, and for assessing spinal cord injury and compression.
Role of CT in spine
• Gold standard for bony lesion• For assessing trauma• For assessing Bone
neolasms(Primary/secondary)• Assessing Osteoporosis
Lecture -4
Systematic approach to extremity radiographs
Indication
• Infection • Inflammatory conditions like rheumatoid
arthritis• Bone neoplasm's
Systematic approach: ABCS
• A-Adequacy and alignment– View : Atleast two views – Areas of interest should be included– Adequately penetrated film– Normal alignment in specific region
B-Bone
• Cortex : have smooth cortical outline ,fracture lines
• Normal medullary cavity• osteolytic or sclerotic changes• Density : normal or osteoporotic
C-Cartillage /joint
• Articulating surface : smooth outline with no irregularity
• Joint space : look for asymmetric widening or narrowing
• Look for any intra-articular foreign bodies/loose bodies
S-Soft tissue
• Look for swelling• Fat planes….obliteration/displacement• Gas in soft tissue(indicates gas forming
infections/abcesses), foreign bodies
Imaging modalities of choice
• MRI and Nuclear medicine scan : detect osteomyelits at earlier stage(in the first 3 days)
• Conventional Radiographs: There is radiological lag of 10days -2weeks for osteomyelits
• MRI : Is helpful to know the extent of bone and soft tissue involvement in sarcomas of the bone and soft tissue
• CT : Better for assessing and grading fracture• Ultrasound : cellulites ,soft tissue abscess, Pyomyositis,
joint effusion
LECTURE -5
Plain Abdominal X ray ,normal and abnormal bowel gas distribution, signs of extra luminal gas…well discussed in class
Plain Abdominal X ray
• Standard : Erect plain abdominal X ray• Other views: Supine and cross table lateral
decubitus
Systematic approach to plain abdominal x ray
• Look for normal bowel gas distribution• Look for abnormal bowel gas distribution• Look for abnormal soft tissue density• Look for abnormal calcifications
Normal bowel gas distribution
• Stomach : air is always seen except in NG tube decompression or excessive vomiting
• Small bowel : 2-3 non-dilated bowel loops• Large bowel: Normally seen in rectum and
sigmoid
Abnormal bowel gas distribution
• The presence of > 3 air fluid levels in small bowel
• The presence of one air-fluid level in large bowel is abnormal
• Absence of gas in the rectum• Dilated bowel loops(>3cm in small bowel,>6cm
in large bowel and > 9cm in cecum==rule of 3)• Signs of extralumnal gas.
References
• Learning radiology recognizing the basics 3rd edd
• Emergency radiology 1st edd• Fundamentals of skeletal radiology 4th edd• Internet : Radiology Assistant