Chest Radiography - Aditya Nagrath

8/4/2019 Chest Radiography - Aditya Nagrath

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CHEST RADIOGRAPHY

Moderator:Mr. S.C. Bansal

Lecturer,

Department of Radiodiagnosis & Imaging

P.G.I.M.E.R., Chandigarh.

Speaker:Mr. Aditya NagrathFinal Year B.Sc MT (X-Ray)


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INTRODUCTION

Chest x-ray is the most commonly performed diagnostic x- rayexamination. Approximately half of all x-rays obtained in medicalinstitutions are chest x-rays. A chest x-ray is usually done for theevaluation of lungs, heart and chest wall.

Pneumonia, heart failure, emphysema, lung cancer and othermedical conditions can be diagnosed or suspected on a chest

x-ray. Traditionally, chest x-ray have been taken prior toemployment, prior to surgery or during immigration. The use ofroutine chest x-ray is being re-evaluated because there is a lack of

evidence for their usefulness. Routine x-rays are obtained inabsence of specific signs symptoms or Medical conditions.


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ANATOMY

The trunk of body is divided by the diaphragm into an upper

and lower part. Upper part is called thorax and lower part iscalled abdomen.

Thorax is formed by following bones

: Anteriorly by sternum

: Posteriorly by the 12 thoracic vertebra and intervertebral disc

: On each side by 12 ribs


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THORACIC CAVITY:

The cavity of the thorax contains the right and

left pleural cavities which are completely

invaginated and occupied by the lung. The

right and the left pleural cavities are separated

by a thick median portion called themediastinum. The heart lies in the middle

mediastinum.

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Structure lies inside the mediastinum

1 Trachea and its bronchus2 Oesophagus

3 Muscles

4 Heart enclosed in pericardium

5 Aorta

Trachea: It is fibro elastic tube about 11cm long

extending from the larynx at the level of 6thcervical vertebra to lower border of 4th thoracic

vertebra where it is divided in the

right & left bronchi one for each lung.


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Lung: The lungs are pair of respiratory organs

and spongy in texture. Each lung is conical inshape. The right lung is divided into 3 lobes

a) Superior

b) Middlec) Inferior by the two fissure a) Oblique b)

Horizontal

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Structure lies inside the mediastinum Contd

Left lung is divided into two lobes by the oblique

fissure.

A. Superior

B. Inferior

Heart: The heart is a conical, hollow muscular organsituated into the middle mediastinum. It is enclosed with in

pericardium.

The heart is placed obliquely behind the body of

the sternum so that 1/3 of its lies the right and 2/3 to the left ofthe median plane.


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Indications of the Chest Radiography

1. Pulmonary diseases such as Kochs disease.

2. Pleural disease Pleuritis. Pleurisy - inflammation of plural.

Pleural effusion - fluid in pleural cavity..

3. Pericarditis

4. Chest x-ray are done for follow up pts.

5. Pre-operative and post-operative cases

6. To see the heart disease like cardiomegally7. To see diaphragm movement.

8. Blunt Trauma Chest


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9. Bronchial asthma

10. Bronchial pneumonia


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Equipment and Accessories

X-ray Unit

High Power Generator

Chest stand or vertical bucky, Air Gap Stand

Cassettes


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- X-Ray Unit: The heart cycle is completed in about 0.08

second. So the exposure time should be lesser than

0.08 sec to prevent the blurring of heart shadow due to

involuntary movement of heart. This type of exposure

can be achieved by high mA and high KV X-ray units

with output in the range.

800mA 1000mA40KV - 150 KV

Exposure time can be reduced further by the use of

high speed screen faster film combination. It can also be achieved with the added advantage of

selecting a smaller focal spot within the tube rating.


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- High Power Generators:

The essential function of H.T generator in x-ray

tube is to provide such power which is needed byX-ray tube so an important specification in the

description of any generator is a statement on its

power out put. Unit 70KW 100KW generator isused which can give 1000- 1250mA and upper

voltage limit 150KV.


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- CHEST STAND OR VERTICAL BUCKY

The chest stand is a holder for cassettes that is

used to examine patients in erect position, for

chest or other radiography. It must hold the

size of cassette used for chest examination

and rigidly.


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Preparation For The Chest Radiography

This procedure requires no special preparation. But a brief

explaination to patients with a rehearsal of the procedure shouldensure a satisfactory result. Respiratory movement should berepeated several times before the performance Is considered to

be satisfactory.Patients will also be asked to remove all metallic jewellery or

undergarments that may contain metal that may interfere withx-rays.


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Basic Projections

PA (Postero -anterior) Erect

AP ( Anteroposterior ) Erect or supine

Lateral (Erect or sitting)


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Additional Projections

OBLIQUE

a. PA Oblique

- Left PA Oblique

- Right PA Oblique

b. AP Oblique

- Left AP Oblique

- Right AP Oblique

2. Apicogram

3. Lordotic

4. Decubitus


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PA View

Position of patient :

Patient is made to stand in PA position, facing the cassette, infront of vertical chest stand.

Chin of the patient is placed over the cassette

The cassette is adjusted 1 above the upper border of theshoulder.

Position of part :

Hands of the patient should be placed on waist level below thehips , so that they will not be superimposed on CP angles.

Palms should face upwards and arms are rotated internally to

throw out the scapula out of lungs. Shoulders sould lie in the same transverse plane and

depressed to carry the clavicles below the apices.


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Cassette Size: The cassette size is chosen so that it

must include the apices and lower region of the

diaphragm and chest wall. It must includes thecostophrenic angle (CP)

Central Ray: C.R. is directed at right angle to

thefilm at the Junction of 4th & 5th thoracicvertebra,

FFD: generally 5 feet (6 feet for Heart size).

Breathing Instructions: The exposure is given inarrested inspiration phase, to show the greatest

possible area of lung structure.


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P.A Position


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P.A. Resultant Image

L


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Structures shown

Air filled trachea

Lungs

Diaphragmatic domes Heart

Aortic knob


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Evaluation CriteriaPosition wise: It must include whole of the

lung field.

Apices

C.P. Angle

Any rotation is easily detected by the position of medial

end of the clavicle. Scapula should not over shadow the lung field

Exposure Wise

a. Trachea & bifurcation of trachea must be seen

in the midline.b. Vertebral bodies should be faintly visible but not

inter vertebral space.

c. Heart & diaphragm show a sharp outline.

d. Peripheral lung vessels must be seen.


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Processing wise: Put a finger under the

darkest

area of the film. If finger is not seenproperly, then

it is properly developed.


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PA in expiration

This view is done in two conditions.

For pneumothorax, PA is done in expiration to

confirm the disease. This has effect of intra pleural

pressure which result in compression of lung makinga pneumothorax bigger.

This technique also demonstrates the effect of

inhaled foreign body obstructing the passage of air in

lung segment and extent of diaphragmatic

movement.


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AP Projection (Erect or sitting)

This view is done as an alternative to PA erect

projection. When the patients shape or

medical condition makes it difficult or unsafe

for the patient to stand or sit for basicprojection. For the latter, the patient is usually

supported sitting erect on a

trolley or bed side.


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Positioning of patient & film for AP erect

projection

The patient may be standing or sitting with their back againstthe cassette which is supported vertically with the upper edgeof the cassette above the lungs apices.

The median sagittal plane is adjusted at right angle to the

center of the film. The shoulders are brought downward & forward with the

back of the hands below the hip & elbow forward

Central ray: Is directed at right angle to the film and

towards the sternal notch. The central ray is then angled

until it is coinciding with the middle of the film. The

exposure is taken on normal full inspiration


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AP Supine projection (on bedside)

Positioning of patient & film:

With assistance, a cassette is carefully positioned

under the pts back with the upper edge of

cassette above the lung apices. The median

sagittal plane is adjusted at right angle to themiddle of the film & pts pelvis is checked to

ensure that it is not rotated. The arms are laterally

rotated. Chin slightly raised.

Central Ray : Is same as erect AP projection

Exposure: is taken on normal full inspiration


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Lateral projection

Positioning of patient and film: Patient is made to stand

in lat position in front of the vertical cassette holder withside to be examined touching the film. Both arms are raisedover the head. Distance between film & xiphisternum equalto the distance between line joining spinous process. Mid axillary line should be 2 posterior to midline of grid.Central Ray: Is directed through axilla at the level of D5.FFD is generally 40. Grid is used because KVP is morethan 70. To prevent the scatter Rad.Note: For diaphragmatic abscess (to see the movement of

diaphragm) Two exposures are given on single film. 1st in inspiration 2/3mAs. 2nd in expiration 1/3 mAs. Alternate procedure - Fluoroscopy


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Lateral projection Cont

Lateral view is done to see the: Depth of tumors.

Part of the lungs overlapped by heart.

To demonstrate the inter lobar fissures

To localize the pulmonary lesion.

Evaluation Criteria: Posterior rib superimposed

Sternum should not be rotated

C.P. Angle and apices should be included.

Hilum should approx in centre.

Exp. Should penetrate the lung field of heart.


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Lat. Position


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Resultant Image


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Penetrating View Of Chest

It is done to see rib & heart.

It is done when one side appears opaque on normalchest radiograph.

Opacity due to hydrothorax or pyothorax. Thus topenetrate through these densities more exposure

is required. Grid is used one side which is normal

will be over exposed so wedge filters can be used

to see both sides with same opacity.


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Oblique projection

Mediastinum & lung fields, incase of

asbestosis pleural plaques not seen in PA

projection.

Rt. Middle lobe Ant. oblique

Both lower lobe - Post oblique


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a. Right anterior oblique: The patient in PA position & the

Rt. Side of the trunk is kept in contact with the cassette &

patient is rotated to bring the left side away from the films so

that the coronal plane is at an angle at 450 to the film.

Central rays: Directing at right angle to the middle of film.

or at the level of 6th thoracic vertebra.

b. Left anterior oblique: The patient in PA position & the

left side of the trunk is kept in contact with cassette & the

patient is rotated to bring the right side away from the film so

that the coronal plane is at an angle of 450 to the film.

Central Ray: Is directing at right angle to the middle of film or

at the level of 6th thoracic vertebra.


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Structure shown: Lung field usually appear

shorter due to

magnification of diaphragm.

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Left posterior oblique: The patient in AP position &

the left side of the trunk is kept in contact with the

cassette. Patient is rotated to bring the right side

away from the film. So the coronal plane is an angle

of 450 to the film.

Central Ray: at right Angle to the middle of the film orat the level of 6th thoracic vertebra.

Structure shown:

The maximum area of lung. Trachea & its bifurcation.

Heart descending aorta and arch of Aorta.


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Right posterior oblique: The patient in AP position

and right side of the trunk is kept in contact with the

cassette and patient is rotated to bring the left side

away from the film so the coronal plane is an angle

of

450 to the film

Central ray at right angle to the middle of the film or

at

the level of 6th thoracic vertebra.


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Structure shown:

Maximum area of right lung & mediastinal

content.

Also shown trachea & entire left branch of

bronchial tree.

Left atrium, left main branch of the pulmonary

artery.

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APICOGRAM

Apicogram is done when there is doubt of T.B. T.B mostlybegins in apex region where the lesion is superimposed by

clavicle.

Apicogram can be done in two ways:

Tube angle, patient straight Patient angle, tube straight

Tube angle, patient straight (Axial projection) patient in AP

position. Patient is made to stand in front of tube & back

touching to the film. Film is placed 4-5 above the upperborder of shoulder

Central ray is directed just below sternal notch with

150 to 200 angulation towards head.

Patient in PA Position : Patient is made to stand in PA


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Patient in PA Position : Patient is made to stand in PA

position in front of vertical cassette holder. A cassette is

placed 4 to 5 above the border of shoulder.

Central ray is directed at level of C7 with 15-20 angulationtoward the feet.

Patient angle & tube straight method :

The patient is made to stand facing the tube 6 to 8 away

from the film. Patient is asked to lean backward touching thehead and neck on the cassette. So the clavicle is thrown

away from the apex of the lung.

Central ray: is directed at the sternal notch.

Structure shown :The apices lying below the shadow of clavicles.


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Evaluation criteria:

The clavicles should lie superior to the apices.

Sternal ends of clavicle should equidistance

from the vertebral column.

The apices should be included.

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Apicogram Axial Projection


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Clavicle

Apex

L

Resultant Image

L


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Lordotic View

This projection is done to see Middle lobe collapse of R Lung

Demonstrate the magnified interlobular effusions

Positioning of patient & Cassette:

Patient is made to stand in PA position in frontof a vertical cassette holder, patient is asked to

hold stand with hand and he is made to lean back

Ward i.e. approx 300 inclination.

Central ray: is directed at level of D5


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Lordotic Position


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L

Resultant Image


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Decubitus Projection

Lat Decubitus: Patient is made to lie in lateral position

on affected side, Film is placed either touching to

anterior or posterior aspect. Tube is brought horizontal.

Both Decubitus should be done. Fluid will come to the

side which is lowered.

Cassette Position: The cassette is placed posteriorly or

anteriorly in contact with the chest and adjustedapproximately 2 above the shoulder. Central ray is

directed at right angle to D5 Make the exposure at the

end of full inspiration.


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Structures shown : This projection demonstrates the

change in fluid position and reveals any previously

obscured pulmonary areas or in case of suspectedpneumothorax, presence of any free air.

Evaluation criteria

The patient should not be rotated from a true frontalposition.

The affected side should be included.

The apices should be included.

Proper identification should be visible.


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Decubitus Position


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Resultant Image


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Ventral or dorsal Decubitus position

Patient is made to lie down in prone or supineposition. Elevate the thorax 2-3 on foam pad.

Arms are kept over the head, cassette is placed

against the affected side. The cassette is adjusted

so that it extends to the level of laryngealprominence.

Make the exposure at the end of full inspiration

Central ray: is directed center to the mid axillary

line at the level of the 6th thoracic vertebra.


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PEDIATRIC CHEST RADIOGRAPHYAlthough there are many similarities in pediatric and Adult

chest radiography in basic positioning and image quality. To

maintain the proper positioning and image quality, it is

essential to immobilize the child by using immobilization devices.

Some time we have to take help by parents for immobilization ofpatient during radiography.

We have to provide radiation protection by using lead apron,thyroid shielding to the childs parent as well as child.

If patient is cooperative then immobilization device is not used.

Basic positioning of child is as adult PA. AP. LAT. Exposure time should be lesser about 0.08 sec.


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AP Projection


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Resultant Image

L


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Selection Of Kilovoltage

In general 60-70kvp is adequate for the Posterio-

anterior projection. In which case there will be

minor penetration of the mediastinum and heart.An increase in kilovoltage however is necessary

for penetration of the denser mediastinum and

heart to show the lung behind those structures andbehind the diaphragm as well as the lung bases in a

very larger or heavy breasted patient


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High KV Technique

We used KV in the range of 90-140. Which reduce contrastbetween the lung field and mediastinum. However, using

this technique there is loss of inherent contrast and

visualization small lesion of soft tissue density because

possibility of photoelectric effect is decreased at the sametime possibility of Compton effect is increase. The purpose

of high KV technique, we make use of Compton effect

which is independent of atomic number.

Purpose: The application of high kilovolgate technique is

primarily with a view to obtaining exposure time in the

region of milliseconds. The effect control to blur the image

by involuntary movement.


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Airgap Technique

The technique of leaving a gap between the patient and

film during radiography is called air gap technique.

AIM : The aim of this technique like grid, is also reduce the

effect of scattered radiation produced on the film.Principle : The scatter radiation arising in the patient, from

compton scattering travels in all directions. When an air

gap is left between the patient. Some of scatter radiation

will not be able to reach the film. Some will be reduced in

intensity due to inverse square law, some will be deflectedin other direction before reaching the film e.g. in chest

x- ray, cervical spine lateral projection.


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Newer Developments

Due to higher radiation dose and cost involved asbigger size of films are being used. There is growingneed to look into this aspect. Thus newerdevelopments have taken place as following

Mass miniature radiography (Odelca camera)

To reduce the cost of film because a small film is used(100to 70mm) for follow up cases at T.B. inspecialized T.B. Hospitals.


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2. High KV Technique

3. Image intensifier system (D.F. System)4. Digital chest radiography

This is done by two methods.

Flat panel detector system

Using imaging plate system

F.P.D. System: There is detection at the outer endwhich picks up signal and passes to analogconvertor. In this analogue data is converted as:

Disadvantagea. High radiation doseb. Information is less

Advantagea. It is less costly

b. Storage problem solvedc. It is done for TBscreening


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Imaging plate Method:

Advantage :

Post processing.

Radiation dose less.

Tele radiography.

Image can be store.

Cost reduce.

Better edge enhancement.

Disadvantage : Initial investment cost high.


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Computed tomographyAfter development of CT technology CT is done

for chest to visualize the mass lesion in the lungfield as well as mediastinal mass, so we candistinguish, The tumour or pleural effusion,cavitation by giving intravenous contrast media

to enhance the lesion for better visualization fordiagnosis whether it is malignant or benigntumor.

Bronchography is replaced by thedevelopment of HRCT chest it is done tovisualize the bronchiactasis, as well as theinterstitial parenchymal lung lesion.

R di ti t ti


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Radiation protection

The radiation protection can be achieved byapplying ALARA Principle As low as reasonably

achievable) Distance Time Shielding1. Limitation of filed size by using collimators.

2. Directing the beam.3. Use of gonad shields.4. Careful preparation of the patient.5. Use of the high speed film, screen, high mA

and short exposure time.

6. Presence of essential staff only.7. Use of protective apron or protective screen

C l i


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Conclusion

Chest x-ray is the basic investigation whichmay reveal more information about the patientsdisease.Approximately of the all x-ray examination isobtained in medical institution are chest x-ray.The quality of Chest x-ray is of utmostimportance but it is difficult to maintain it as

slight variation in exposure factors, processingtime and slight rotation due to malpositioningmay result into loss of the information. So thechest radiography is to be done very carefully.


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we can say in other words that proper chest

radiography is a challenge for Radiological

technologist. This challenge is met more

effectively with the help of digital radiographyand more information is being gathered by

other new modalities like CT scan, MRI etc

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Chest Radiography - Aditya Nagrath