Note - The Society for Pediatric Radiology

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15 Νοε 2013 (πριν από 3 χρόνια και 8 μήνες)

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www.WFPIweb.org

World Federation of
Paediatric

Imaging

R
ADIOLOGY
:

C
OLLIMATION

What is the WFPI?

Copyright 2012 World Federal of Pediatric Imaging All Rights Reserved

2


Launched during IPR 2011, in London


Founding Members: SPR, ESPR, SLARP, AOSPR


Purpose: to provide an international platform for
pediatric radiology organizations united to address
the challenges in global pediatric imaging training
and the delivery of services


WFPI Goals

Copyright 2012 World Federal of Pediatric Imaging All Rights Reserved

3


The promotion of the status and standards of
pediatric imaging and pediatric image
-
guided
intervention for the benefit of child health
worldwide


The advancement of internationally
-
driven
education and/or research in pediatric imaging
and pediatric image
-
guided intervention


The encouragement of global child imaging safety
and radiation protection


WFPI Goals (
cont
)

Copyright 2012 World Federal of Pediatric Imaging All Rights Reserved

4


The stimulation of transnational resource
allocation for pediatric imaging and pediatric
image
-
guided intervention, focusing on places with
acute needs


The fostering of opportunities for communication
and collaboration between pediatric imaging
practitioners across
nations, and


Collaboration with other global health
organizations for the dissemination of pediatric
imaging and pediatric image
-
guided intervention
best practices and appropriate imaging
guidelines


Copyright 2012 World Federal of Pediatric Imaging All Rights Reserved

R
ADIOLOGY
: C
OLLIMATION

5

Objectives

Copyright 2012 World Federal of Pediatric Imaging All Rights Reserved

6


To understand the role of collimation


To recognize collimation’s significance in
radiographic quality


To become aware of collimation’s importance in
radiation protection

What Are Collimators?

Copyright 2012 World Federal of Pediatric Imaging All Rights Reserved

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Collimators are x
-
ray beam
-
restriction devices that
control the size and shape of the radiation field


The field size can be manipulated by turning the hand
controls:


To the correct number on the dial in relation to the film size


Visually to size of the body part being imaged


Increasing collimation makes the radiation field smaller


The x
-
ray field should be
no larger

than the film/image
receptor(IR) size

Collimator Parts

Copyright 2012 World Federal of Pediatric Imaging All Rights Reserved

8

Collimation Bulb

Anode

Electrons

Upper Jaws

Lower Jaws

Hand Controls:
Open/Close Jaws
& Light
-
Field

Light Reflecting
Mirror

X
-
Ray Beam
(and light
-
field)

Collimator Part’s Role

Copyright 2012 World Federal of Pediatric Imaging All Rights Reserved

9


Anode


Converts electrons to x
-
ray photons


Jaws


Shape the radiation field


Bulb & Mirror


Show light
-
field on patient; light
-
field corresponds to same size and shape as
radiation field


Hand Controls


Move jaws in/out to shape


the size of the radiation beam


Where Collimators Are Located

Copyright 2012 World Federal of Pediatric Imaging All Rights Reserved

10


Collimators are located
just below the x
-
ray tube


The x
-
ray light
-
field
switch is located on
collimator


This light will
serve as a guide to
demonstrate whether the
field is opened to the
proper amount

















X
-
Ray Beam

Collimator

X
-
Ray Tube

Hand Controls

Light
-
Field
“On”
Switch

Reading The Collimation Device

Copyright 2012 World Federal of Pediatric Imaging All Rights Reserved

11


First follow the hemi
-
circle of the distance used


Distances as well as smaller field size numbers are indicated
in inches


Turn each dial (X & Y) according to the patient body part
size and IR size


Setting should not be larger than IR size and should
closely match the size of the body part



Note:

Dial appearance
will vary based on vendor;
c
urrent dials are digital

X

Y

Collimation Field Design

Copyright 2012 World Federal of Pediatric Imaging All Rights Reserved

12


Collimators have two separate field changing
controls ( x and y)


Changing the dimensions allows technologists to
produce radiation fields in square or rectangle
patterns


The two x jaws (diaphragms) move together and the
two y jaws move together

Copyright 2012 World Federal of Pediatric Imaging All Rights Reserved

Collimation Field Design


The picture describes centering
and jaw movement


Centering point/Central Ray
(CR) goes through point (0,0);
indicated with a


A 10x12” field is
demonstrated in the shaded
region

13

Note:
For to 10” x
-
Axis
see that the Field extends
5” on both sides of the CR
and for the 12” y
-
Axis see
that the field extends 6”
on both sides of the CR

x
-
axis

-
9
-
8
-
7
-
6
-
5
-
4
-
3
-
2
-
1

9
8
7
6
5
4
3
2
1

1 2 3 4 5 6 7 8 9

-
1

-
2

-
3

-
4

-
5

-
6

-
7

-
8

-
9

y
-
axis

X1

Y
1

X2

Y
2

Copyright 2012 World Federal of Pediatric Imaging All Rights Reserved

Collimation Field
Comparison

14

10x12” Field
Size

8x10” Field
Size

Note:
X1 and X2 jaws
move together; Y1 and
Y2 jaws move together;

CR will always be (0,0)


Both on these field sizes are common for
paediatric

patients

x
-
axis

-
9
-
8
-
7
-
6
-
5
-
4
-
3
-
2
-
1

9
8
7
6
5
4
3
2
1

1 2 3 4 5 6 7 8 9

-
1

-
2

-
3

-
4

-
5

-
6

-
7

-
8

-
9

y
-
axis

X
1

X
2

Y
2

Y
1

Proper Centering & Collimation

Copyright 2012 World Federal of Pediatric Imaging All Rights Reserved

15


In order to collimate effectively, centering must be accurate


therefore, technologists must center right in the middle of the
body part being imaged

-
9
-
8
-
7
-
6
-
5
-
4
-
3
-
2
-
1

9
8
7
6
5
4
3
2
1

1 2 3 4 5 6 7 8 9

-
1

-
2

-
3

-
4

-
5

-
6

-
7

-
8

-
9

y
-
axis

X
1

X
2

Y
2

Y
1

Correct
Method

Incorrect

Method

Note:
Off
-
centering forces
the technologist to open
the field size wider than
necessary to prevent
clipping off anatomy

Bird’s Eye View of Collimator
Jaws

Copyright 2012 World Federal of Pediatric Imaging All Rights Reserved

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The x and y jaws are
independent of each
other


however the x
jaws work together
as do the y jaws


The x
-
ray field is in
the center cream
area

X

X

Y

Y

Why Is Collimation Important?

Copyright 2012 World Federal of Pediatric Imaging All Rights Reserved

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Collimation is important to:


Improve radiographic image quality


R
educe radiation exposure to the patient by limiting the
field size to include only necessary anatomy


Generate less scattered radiation to lessen the
potential for occupational exposure

How Collimation Improves Image
Quality

Copyright 2012 World Federal of Pediatric Imaging All Rights Reserved

18


Closely collimating to the part of interest improves
image quality by reducing scattered radiation


Increases in field size yield greater amounts of
scattered radiation


The production of larger amounts of scattered
radiation in larger field
-
sizes subsequently reduces
overall image contrast

How Collimation Reduces
Paediatric

Radiation Exposure

Copyright 2012 World Federal of Pediatric Imaging All Rights Reserved

19


Appropriate collimation
reduces the amount of anatomy
exposed
to radiation


Appropriate collimation necessitates proper alignment
of the body part to
ensure essential anatomy
is
included
in the
image


Turning the tube head to align with the part may also
allow for additional collimation


Only the anatomy needed to make diagnosis should be
included in order to protect developing
paediatric

body parts

How Collimation Limits Occupational
Exposure

Copyright 2012 World Federal of Pediatric Imaging All Rights Reserved

20


Scattered radiation is the primary cause of
occupational radiation exposure


Collimation plays an important role in the reduction
of generated scattered radiation


Why Should
Paediatric

Patient’s
Radiation Exposure Be Limited?

Copyright 2012 World Federal of Pediatric Imaging All Rights Reserved

21


Paediatric

patient’s developing bodies dictates the
need for radiation protection measures (which
includes collimation)


Children’s cells that are immature and rapidly
dividing, making them more sensitive to radiation


This can make children
potentially

more susceptible
to radiation’s damaging effects (cancer).

Copyright 2012 World Federal of Pediatric Imaging All Rights Reserved

World Federation of
Paediatric

Imaging

22


Become

a
Member

Organization



Volunteer

by
providing

t
elereading
,
medical

imaging

training
,
and/or
education


Give

us
your

time, attention, and support


For more information contact us
at
:
wfpi.office@gmail.com