0:01

What are the factors affecting patient dose?

0:04

There are several factors. I'm going to show you the most

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important ones for fluoroscopy.

0:10

The factors influences are like the tube voltage, the tube current,

0:14

and beam on time. And the shorter the beam exposure, lesser

0:18

the chances. The tube voltage and tube current are also already

0:22

discussed in radiography lecture about the important factors influencing the

0:26

X-ray output. Filters and grids are very important.

0:30

Patient thickness and the projection, which angle the fluoroscopy

0:34

procedure is done, will also impact the radiation exposure.

0:38

Then the image receptor, is it image intensifier or a

0:42

flat panel detector? How it is optimally set and how

0:46

sensitive it is, is very critical, and that can influence

0:50

also the fact the radiation exposure to the patient.

0:53

Field size, magnification, and collimation we discussed

0:57

earlier, which makes a lot of difference in the total patient dose.

1:01

The distance between the patient, X-ray tube, and the image

1:05

receptor, such as II, is also equally contributes to the

1:09

factor affecting radiation exposure, and that also highlights the reason why

1:13

our education of fluoroscopy safety is very critical for anyone

1:17

doing fluoroscopy.

1:19

And the last one is the operator's training and experience will also cause towards

1:23

the factors affecting radiation exposure.

1:26

So now these are the three panels of cardiac image showing

1:30

basically the radiation dose versus the image noise.

1:35

So on the left-hand side, it is shown as like the

1:38

typical radiation exposure needed to create an image.

1:42

Two micro R per frame image in fluoroscopy shows images

1:46

like this. It's noisier. It is much noisier than the

1:49

radiographic image. However, if you increase the dose, let's say two

1:53

micro R to 15 micro R, the image

1:57

quality improves. If it is even 24, it's even better.

2:01

These are the frame rates typically used in cine

2:05

angiography and other purpose. We don't

2:09

have to use 15 micro R for fluoroscopy because it's not

2:13

done per frame. If you are doing 30 frame per second, the images are

2:17

already integrated, so the image noise seen on the screen

2:21

is much less than one individual frame.