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Today we are honored to welcome Dr.

0:32

M Mahesh for a lectured entitled Imaging Pregnant

0:34

and Pediatric Patients.

0:36

Dr. Mahesh is the professor of radiology

0:38

and cardiology at the Johns Hopkins University School

0:41

of Medicine, as well as the chair

0:43

of the Radiation Control Committee

0:45

for the Johns Hopkins Health Systems.

0:48

Prior to that, he served as chief physicist

0:50

for the Johns Hopkins Hospital for over 29 years.

0:53

Dr. Mahesh has published over 150 peer review publications

0:57

and given more than 150 international talks

1:00

and several grand rounds.

1:02

Is the associate editor for the Journal of American College

1:04

of Radiology and is a member

1:06

of numerous societies committees and council.

1:09

At the end of the lecture, please join him in a q

1:11

and a session where he will address questions you may

1:13

have on today's topic.

1:14

Please remember to use the q

1:16

and a feature to submit your questions so we can get to

1:18

as many as we can before our time is up.

1:21

And with that, we're ready to begin today's lecture. Dr.

1:24

Mahesh, please take it from here.

1:26

Thank you first of all for the, for you guys

1:28

for inviting me to speak on this important topic.

1:32

Um, I'm gonna be talking on imaging pregnant

1:34

and pediatric patients.

1:37

Here Are my disclosures

1:42

and this is where I work.

1:45

So let me start this lecture on two topics.

1:48

One is, um, just to get this out of the this, out

1:52

of the confusion, I'm gonna be focusing imaging on pregnant

1:56

patient and pediatric patient, um, with respect

2:00

to X-ray imaging.

2:02

So having need to go more detail into that, let me start

2:05

with what is the MRI, what is the, uh, the issues

2:10

or conditions for MRI during pregnancy?

2:13

So let me start with that one.

2:15

And I wanna start with sharing this particular, um, um,

2:18

statement by the American College of AB Gynecology

2:22

basically recommends

2:23

that pregnant patients should be reviewed on a case

2:26

to case basis and risk benefit ratio needs to be made

2:30

by the physicians involved.

2:33

They also state that the, as of now,

2:35

there are no known biological effect of MRI on the fetus.

2:39

So it's safe to do MRI on pregnant patient, um, um,

2:43

because of the statement, you can make it.

2:45

However, they also state

2:47

that the gadolinium contrast should be awarded when

2:50

examining pregnant patient to support the statement.

2:53

There is a big article published in JAMA in 2016, um,

2:57

which examined the MRI exposure during pregnancy

3:01

and fetal and childhood outcome.

3:04

They looked at more than 1.4 million pregnancies.

3:08

Um, and the, with respect to the safety of the use of MRI

3:13

during pregnancy and the, the findings basically concluded

3:17

as follows, exposure to MRI during first trimester

3:21

of the pregnancy compared

3:23

with non exposure was not associated with increased risk

3:27

of harm to fetus or in early childhood.

3:31

And this is a very strong statement,

3:32

and this is based on the signs we know based on the current

3:37

magnetic field strength we are using in clinic.

3:39

Basically pregnant patient can be scanned in MRI,

3:43

however, if the use of gadolinium is always associated

3:47

with adverse outcomes, so it should be awarded.

3:50

So I just want to put this, uh, share this information

3:53

regarding the pregnancy, um, uh,

3:56

imaging pregnant patient using MRI scanner.

4:00

Now let me come to the main focus of my lecture.

4:04

I want to discuss and do different topics.

4:06

One is what is the radiation exposure during pregnancy

4:09

and why should we concerned or not concerned?

4:12

And what is their exposure in pediatric imaging?

4:15

I want to focus the talk imaging in pregnant

4:17

and pediatric patient under these subheadings

4:21

because there is lot of, um, um, myths

4:25

and concern of pre imaging pregnant patient.

4:28

And I want to answer some

4:29

of these question through this lecture.

4:32

First and foremost is the question everybody can ask is why

4:36

and when should we be concerned?

4:38

Because the moment the word radiation comes into picture,

4:41

we always have this concept in our mind.

4:44

And of course the media does not help

4:46

because we are a lot of Marvel comics, uh, stories

4:50

medias are talking about all ill effect of radiation.

4:54

And when we see these things, when,

4:56

because radiation we cannot hear taste

4:59

or smell, there is always concern about radiation

5:03

that automatically translate to

5:05

what happens when we do an imaging on pregnant patient

5:09

using x-rays.

5:11

And that is the main concern a lot of the people has.

5:15

We have, and I'm trying to answer some of these questions,

5:18

um, based for this imaging x-ray imaging.

5:21

First of all, when you talk about radiation,

5:24

we can group the radiation, the biological effect

5:26

of radiation into two categories.

5:29

One is stochastic effect,

5:32

the other one is called non-ST stochastic effect,

5:35

stochastic effect.

5:36

They're also called as delayed effect

5:38

because you don't see this effect immediately.

5:41

And this is more example is cancer in exposed individual

5:45

radiation in ca induced cancers, um,

5:48

because of the radiation exposures.

5:50

And usually these are observed within three to 20 years

5:53

after exposure, or if the fetus is exposed to large quantity

5:58

of radiation, which I'm going to share later of

6:00

what is the quantity I'm talking about in general,

6:04

mutations in offsprings can happen

6:06

or it can impact the pregnancy.

6:08

This is the stochastic effect.

6:09

Stochasticity also implies probabilistic in nature.

6:13

You cannot quantify exactly,

6:16

but the chances, best analogy I can say

6:19

for stochastic effect is buying a lottery ticket.

6:22

When the jackpot increases, people rush to buy more tickets.

6:25

The reason is they want to increase the chances

6:28

of winning the jackpot.

6:30

Similarly, you can look at the radiation doses.

6:33

Exposure of for stochastic effect has

6:35

to be like every exposure will have certain chances,

6:38

but we cannot tell which has this, um,

6:41

which which is exactly we cannot, can, cannot be quantified.

6:46

The second type of, um,

6:47

biological effect is the nons stochastic effect,

6:50

also called this tissue effect also calls acute effect.

6:54

This acute effect occurs

6:56

because of the direct damage to tissue due

6:59

to local cell death

7:00

and usually it's observed within days to weeks.

7:03

And this non-ST stochastic effect, um,

7:06

in imaging we see is a little bit more quantifiable

7:08

with respiratory imaging, uh,

7:10

with respiratory radiation exposure

7:12

because the radiation effort such

7:15

as the deterministic effort only observe when the radiation

7:18

level exceeds certain threshold level.

7:21

Therefore, we can quantify

7:23

or at least expect any

7:24

of this effort if the radiation exposure

7:26

is at a certain level.

7:28

So broadly categorizing any type of radiation exposure,

7:32

there is stochastic effect

7:34

and there is non-ST stochastic effect.

7:37

What is the radiation exposure during pregnancy in order

7:40

to examine this aspect of radiation exposure,

7:43

if we do any imaging during pregnancy, let's examine

7:47

what is the, uh, impact, um, after radiation on pregnancy

7:51

and so forth For that.

7:53

Um, I wanna share

7:54

with you the radiation effects on the unborn

7:57

on this slide here.

7:58

Basically demonstrating the impact on the pregnancy

8:02

matched with respiratory.

8:03

The mouse model, the mouse model, the mice model does shows

8:07

as a very nice way

8:08

of explaining the radiation efforts on the fetuses.

8:12

On your left, on the right left, uh,

8:14

right hand side is shown a graft basically telling like

8:17

what are the chances

8:18

of a certain effect happening depending on the time

8:21

of the trimester or the time

8:23

of the pregnancy being exposed to radiation.

8:27

Again, warning is these numbers are very high numbers,

8:30

which we don't normally see in imaging.

8:33

Therefore, as you can see here, the most sensitive part

8:37

of the prior pregnancy is the first trimester

8:39

between two to 15 weeks.

8:41

And during that time, very large quantity

8:44

of radiation exposure can lead to prenatal

8:47

or embryonic death.

8:48

And that's kind of documented

8:49

with the experiments done on the development mice exposed

8:53

to 200 rats ranking of exposure.

8:56

That's a large quantity of exposure we see in imaging.

8:59

We don't see that level in the imaging.

9:02

So what I'm trying to convey here is like, in addition

9:04

to sharing with you the knowledge about what we know,

9:07

I'm also trying to put that in perspective.

9:09

How does that compare to

9:11

what the radiation doses we use these days in the imaging?

9:15

The other aspect is

9:16

that the pregnancy is a little bit in the second trimester

9:20

and then then there is a radiation exposure.

9:22

The effort we have known is decreasing head size

9:25

and mental retardation and so forth.

9:27

The chances are higher and that is documented in the people

9:32

who survived their Hiroshima Nagasaki bomb bomb

9:35

explosion at that time.

9:37

And, and every radiation exposure

9:39

to the features have some child slight increase

9:41

of the childhood cancer and so forth.

9:43

Having said that,

9:45

what is the level which we are typically

9:47

concerned in imaging?

9:50

So, and,

9:51

and this is again, this is not a strict, uh,

9:54

threshold level, but approximately conservative level is a

9:58

dose to the fetus of a hundred.

10:01

Milli c word during the first six weeks

10:03

of pregnancy is considered as a cutoff point

10:07

above which you can, one can consider

10:09

therapeutic abortion or so forth.

10:12

If I leave that statement right here,

10:14

it can cause further confusion.

10:16

So to put this in perspective, how does that compare

10:19

to the examination we do in the imaging?

10:21

A typical examination example, the CT of the abdomen

10:25

and pelvic, let's say the effective dose of one CT

10:29

and abdominal pelvic is about 10 milli ct.

10:32

These days, we are doing much at a much lower level

10:35

than 10 milli ct.

10:36

But in general, let's say let for easy

10:40

easy understanding 10 milli ct.

10:42

That means in order to reach a hundred milli ct,

10:46

one should get more than 10 CT of the abdomen

10:49

and pelvic during the first six weeks after conception.

10:53

If you look at this aspect, the chances

10:56

of a pregnant patient getting this amount of le level due

11:00

to pregnancy the during pregnancy is almost impossible

11:04

or almost very highly unlikely at the most.

11:08

Sometime the pregnant patient gets the CT

11:10

of the abdomen in pelvic week or

11:12

because of the emergency situation

11:14

or some clinical indicated nerves, the doses are much lower,

11:18

probably about 10 minutes, see what or even lesser.

11:20

So what I want

11:21

to convey here is like even though we know the radiation

11:24

exposures to the, to the pre

11:26

and during pregnancy can cas effect the amount

11:30

of imaging doses we use these days

11:32

or we use in imaging is far less

11:34

of a concern even if we are doing on a pregnant patient.

11:38

I'm gonna continue this particular discussion even further,

11:41

but demonstrating why.

11:43

So, so let's all, um,

11:46

the diagnostic imaging system utilizing radiations are the

11:50

following, following three radiography, fluoroscopy

11:54

and CT ultrasound does not use radiation and so is MRI.

11:58

So let's focus on these three things.

12:00

In order to examine these three things, we also need

12:03

to understand how is the radiation dose

12:05

pattern distribution in the body.

12:07

For that, we need

12:09

to understand what's the typical radiation dose distribution

12:13

in radiography and fluoroscopy

12:15

because the radiation enters the body

12:18

and the radiation comes outta the body, which is captured

12:20

by the detector to create an image,

12:23

the surface dose is always maximum.

12:26

So the, the highest dose is on the surface

12:30

and the dose decreases vertically going down.

12:34

So the rule of thumb, for an average size patient

12:37

to get a good image quality, only about 15%

12:40

of the dose is coming out of the patient,

12:42

which we capture with a detector.

12:44

So for radiography

12:46

and oscopy, the surface dose is very critical

12:49

and that is the maximum

12:51

and goes down as we go through the patient on a ct.

12:55

On the other hand, for the ct, the typical distribution,

12:59

the dose distribution is as follows,

13:01

because we are acquiring the data around the patient,

13:04

the surface dose will become the maximum

13:08

and the center dose will be the minimum

13:10

and that's what we see that

13:13

unifor uniform dose on the surface

13:15

and it decreases radially.

13:17

And for those who read the CT of a large patient,

13:20

you may have seen some time in the abdominal CT at the

13:24

center being lot of this art like lot of, um, study pattern

13:29

because of the photon starvation we call it

13:31

as photon starvation.

13:33

Why this understanding the dose

13:35

distribution is critical for us.

13:36

I'm gonna share with you next why this is important.

13:39

When we are examining what is the radiation exposure

13:43

to the pregnant patient, um, um,

13:45

with use these type of imaging modalities.

13:48

So in order to do that, I want to use a couple

13:51

of two, two different graphs.

13:53

One is when the fetus,

13:56

when when you are doing an imaging procedure, any type

13:59

of imaging x-rays where fluoroscopy r ct, um, this is

14:03

how, this is a typical examination of a chest x-ray.

14:06

Um, for example, the maximum dose is in the, on the entrance

14:10

of the patient in the, in the backside here

14:13

and the minimal dose coming out.

14:15

The dose coming out here is the

14:17

one captured by the detector.

14:19

As the X-rays pass through.

14:21

There is some of it is absorbed, some of it is scattered

14:24

and that scatter will move in all direction

14:27

and that's, we call it as internal scatter.

14:30

And that internal scatter goes down, get absorbed

14:34

and absorbed and absorbed.

14:36

Therefore, if a pregnant patient,

14:38

if you're doing a chest radiograph, um, and

14:41

or any type of ver graft outside the, uh, abdomen

14:45

and pelvic of a pregnant patient, the fetus is not

14:49

directly in the path of the x-ray beam.

14:52

That's the, that is the classification I like to show.

14:55

So here the fetus is not directly in the x-ray beam path,

15:00

therefore very few scatter radiation will reach the fetus

15:05

and the fetal dose can be as small

15:08

as 10 micro seaver.

15:11

What does it c word dose means?

15:13

Seaver is the quantity of the qu, the dose quantity we use

15:17

and micro seaver means 1000 micro seaver equal

15:21

to one milli C word.

15:23

And to put that in perspective, in the US the average

15:27

annual background radiation

15:30

for the everybody on this in the on here in the US

15:33

is about three milli C.

15:35

So if you look at here, any

15:37

of the fetal dose receiving from any

15:40

of these radiograph out, when the fetus is not

15:43

directly in the beam, the dose is very insignificant,

15:47

are almost very, very, very low.

15:50

That's one, one concept.

15:52

The second concept is

15:53

because of that we can say like this, the radiation goes

15:57

to the fetus when it is not in the path

16:01

of the primary x-ray.

16:03

Um, I want to, I want to kind

16:06

of nicely group into two different scenario

16:09

of any x-ray imaging exam when the fetus is not

16:13

directly in the path of the primary beam, we call this

16:17

as it's not in the path of the primary X-ray beam.

16:20

In that case the,

16:22

for diagnostic procedures X-rays procedure, the,

16:26

the fetal dose or internal dose is almost same

16:29

as the background radiation dose about 10 micro.

16:34

If the, if the procedure is a fluoroscopy

16:36

and ct, the dose is even lesser, uh,

16:39

when the fetus is not directly in the beam

16:41

because the c the the CT use small, small slices,

16:46

so therefore the intra scatter is even much lesser.

16:49

Therefore for fluoroscopy in ct,

16:52

the general understanding is the fetal dose is

16:54

approximately less than five micro.

16:57

To put this in perspective,

16:58

the average annual background

17:00

radiation is about three milli.

17:03

So the take home is if the fetus is not directly in the path

17:08

of the primary X-ray beam, either in x-rays, radiography,

17:13

fluoroscopy, or in ct,

17:15

the the radiation exposure fetus is almost very

17:19

insignificant or very small

17:22

or ins very insignificant is equal to almost equal

17:25

to the natural background radiation dose.

17:28

So now let's look at the exam in the situation where the,

17:32

the, the fetus is in direct path of the beam.

17:35

That happens if you're doing an abdominal radiograph,

17:38

abdominal fluoroscopy or abdominal ct.

17:42

When the abdominal radiograph,

17:44

I'm showing you an example here, the

17:47

for the abdominal radiograph and the con

17:49

and uh, during that time the fetus radiation is as follows.

17:54

Again, it depends on the way the fetus is located.

17:58

For radiograph, the surface dose is the maximum and

18:02

therefore the dose will decrease as it going through.

18:06

So depending on the location of the fetus,

18:09

the radiation dose can be quite small or go goes down.

18:13

Therefore, the fetus, when the fetus is directly in the path

18:17

of the X-ray beam, the x-ray intensity can reach,

18:21

can usually less than 50% of ward that is entering.

18:26

So what the pregnant patient is getting on the surface,

18:30

the fetus is receiving half of that to

18:33

and approximately the fetus dose may be

18:36

as much as 10 milligram.

18:38

Even that number when I'm sure other tables will then

18:41

demonstrate how smaller this relatively smaller compared to

18:45

what we are typically concerned

18:47

about the radiation exposure.

18:50

So this one is at the,

18:52

when the fetus is directly in the path of the beam,

18:55

it is exposed to, um, radiation,

18:58

but that radiation to the fetus depending on the location

19:01

of the fetus and as the abdominal radiograph shows here,

19:06

the surface dose is the maximum,

19:08

the fetus doses can be almost half of

19:10

what the surface dose is.

19:13

Now what are the fetal efforts from low level

19:16

of radiation exposure?

19:18

So as I say, here's a table is a busy table.

19:22

I'm not going to read through the table

19:24

or expect you to know,

19:25

but I wanna highlight some of a couple of things

19:28

in the earlier chart I showed, um, on, on the mouse model,

19:32

the very large quantity of exposure

19:35

during the first trimester can cause spontaneous abortion

19:38

or embryonic death in order to occur

19:41

that the dose level needed is more than 200 milligram.

19:45

So we have seen that in atomic bomb survivor

19:49

who received more than 200 milligram had some type

19:53

of effect congenital formation

19:55

that is in the second trimester.

19:57

But what we know is like the most sensitive part

20:01

of the pregnancy, we do not have any data for human studies

20:06

and especially absolute incident studies.

20:09

Therefore, if the concept survive, it is thought

20:12

to develop fully with no radiation damage

20:14

or any radiation exposure if it is occur,

20:18

if the radiation exposure is in the second trimester,

20:20

let's say abdominal radiograph CT

20:22

or any of these things, animal studies have shown

20:26

if the fetus has visited more than 50 to a hundred

20:29

or 250 gra of dose, that's when um, and,

20:33

and human studies has shown,

20:35

especially from the atomic bomb survivor,

20:37

if it is more than 200 gra it is shown to have some type

20:41

of a, um, congenital mal formation

20:44

or a smaller head circums and so forth.

20:47

But I also show shared earlier

20:50

that if the fetus is directly in the path of the beam

20:53

for abdominal radiograph, the fetus exposure can be as low

20:56

as 10 milligram.

20:58

Put that in perspective to 250 milligram.

21:01

We don't have much evidence on the data to be of

21:04

of which demonstrate any type of a risk with respect

21:08

to the fetus and even when it is directly exposed

21:11

to the radiation in the abdominal radiograph and so forth.

21:14

This table is basically demonstrating some of the dose level

21:18

and amount of D data we have and what it can imply.

21:23

But if to draw your attention, all of them

21:26

is the radiation doses is in the order of a hundred

21:30

or 200 milli K

21:32

or milli milli K of levels,

21:34

which we normally don't see in a single radiograph

21:37

or a single uh ct.

21:40

So to put it in another perspective,

21:44

the potential radiation effect on the fetus

21:47

by gestational age

21:49

and radiation exposure is can be discussed here in this fall

21:53

following if the, during the gestation age between zero

21:57

to two weeks or three to four weeks, the potential effect

22:01

by radiation exposure, if it is less than 50 milligram

22:06

we have it is demonstrated there's no effect on the,

22:09

on the, on the fetus.

22:12

If it is only more than a hundred milligram,

22:15

that's when there is some understanding that can lead

22:18

to some type of spontaneous abortion

22:21

possible deficient in IQ or mental reation and so forth.

22:25

And this basically demonstrate during the pregnancy

22:28

if the dose is anytime during the first trimester

22:31

or the second or the trim trimester, if the patient gets,

22:35

um, if the fetus is dose is less than 150 milligram,

22:39

we don't have any evidence to show any risk

22:42

to the radiation exposure

22:44

and that's the take home message I want to convey.

22:47

So 50 milligram

22:48

or even a hundred milligram below a hundred milligram,

22:51

we don't have any evidence with respect

22:53

to the radiation effect on the, on the fetus.

22:58

So any imaging of the pregnant patient as long

23:02

as is clinically relevant, can be done safely

23:06

and we don't have to deny the pregnant patient from the

23:09

valuable information one gets from doing an imaging.

23:13

One way, the other way to look at it,

23:15

we can also communicate the risk, um,

23:18

who requires x-ray imaging when we counsel pregnant patient

23:22

about this x-ray imaging,

23:23

we can look at this in a different way also.

23:26

One is every pregnancy carries some risk even with no,

23:31

um, no mal formation

23:33

or even with a zero zero dose means no exposure.

23:37

The the probability of at birth with no mal formation

23:41

or no childhood cancer is about 96% or 99.93%.

23:46

In total, about 96% means every pregnancy have about four 4%

23:51

chance of mal formation of childhood cancer.

23:54

Now on top of it,

23:55

if you have any fetal doses receiving about five,

23:59

let's say 10 mg,

24:01

they individual risk will only go from 95.95

24:06

to 95.83.

24:08

So as you can demonstrate, shown here is

24:10

that the risk from imaging pregnant patient

24:15

is quite small compared

24:16

to all the other risk involved in the pregnancy.

24:19

So therefore, pregnant patient can be imaged safely as long

24:24

as it's clinically relevant and needed.

24:28

The recommendation from the American College of Obby

24:31

and gynecology and the a CR on the use

24:35

of CT is demonstr listed here, according

24:38

to the American College of Obstetric

24:40

and Gynecology, um,

24:42

they recommend is perform necessary examination only

24:46

after clinical workup and it,

24:50

and they also recommend counsel for radiation exposure.

24:53

And the reason is like you can, uh,

24:55

you can automatically try to answer any concern

24:58

to the patient because the patient

25:00

or the general public get a lot

25:02

of misinformation about radiation.

25:04

Therefore, they recommend any type of imaging done

25:07

during pregnancy to have some type

25:09

of a counseling for radiation exposure.

25:11

They also state that iodinated contrast agent is safe is is

25:15

considered safe during pregnancy.

25:17

The American College of Radiology recommendation is keep the

25:21

radiation low levels as low as reasonably achievable

25:25

and that is possible by following multiple ways

25:28

of dose optimization technique,

25:30

which I'm gonna discuss later, um, which can be done

25:33

with the work of a team of radiologists, medical physicist

25:37

and technologist den contrast material is also likely to,

25:41

is safe in pregnancy

25:43

and a CR also recommend for any type of a counsel

25:46

for addition exposure, allowing an opportunity

25:48

to answer any likely question the patient might have.

25:54

So now let's say, let's examine here is a data

25:57

for various fetal dose from imaging procedure.

26:01

Yeah, as I as you shown here is like radiography

26:04

and fluoroscopy exposure, CT and nuclear medicine procedure.

26:09

If you look at the radiography

26:10

and fluoroscopy exposure, the typical fetal dose,

26:14

even from the double contrast variant anima study,

26:17

which includes a lot of radiograph

26:19

around the abdominal region,

26:20

even there the typical fetus dose is about seven milligram.

26:24

To put that in perspective, we have data of any, um,

26:29

now on any risk only when the doses is about 250 milligram

26:34

or even symptom more than a hundred milli grade.

26:36

So suffice to say that any radiograph

26:40

and fluoroscopy procedures can be done safely on pregnant

26:44

patient as long as the clinical indication is very critical

26:49

and benefits, uh, for outweigh any of the risk.

26:53

When you look and examine the nuclear medicine procedure,

26:56

the typical fetal dose, uh, is about the, the,

27:00

the largest dose is about when you do the whole body pet PET

27:04

imaging studies about 15 milligram even

27:07

that is lower than the 50 milligram,

27:09

which demonstrate there is no possible effects on the

27:13

pregnancy in ct.

27:15

If you look examine any exam,

27:17

it does not include fetus directly in the path of the beam.

27:21

The radiation dose to the fetus is very, very small

27:24

or almost insignificant,

27:27

but those exams would include directly in the path

27:30

of the beam such as abdominal or abdominal pelvic

27:34

or routine pelvic uh, CT exams that can go as much

27:38

as 25 milligram,

27:39

but there are a number of steps one can take

27:41

to minimize this radiation exposure even further.

27:48

So before I move into radiation exposure to the uh,

27:50

the pediatric patient, I wanna uh,

27:52

take a couple of take home message.

27:54

One is as long, if the fetus is not directly in the path

27:59

of the radia path of the primary beam of x-ray fluoroscopy

28:02

or CT one should um,

28:05

understand any radiation exporter features is very small,

28:09

almost same level as the NAB background radiation

28:12

and that's caused due to some internal radiation scatter,

28:15

not any external radiation scatter.

28:18

That's also one

28:19

of the reason why we don't recommend putting any apron on

28:23

the patient, even when you're doing the pregnant patient

28:26

for any of the radiograph

28:27

because that's only gives only psychological comfort

28:31

but not any additional protection from any internal

28:34

scatter take on.

28:36

Two, if the radiation exposure involves the fetus directly

28:40

in the path of the primary beam, then there is some exposure

28:44

to the fetus and that depends on the depth of the fetus

28:48

and as a medical physicist can do a fetal dose exposure

28:52

or estimation taking into a variety of parameters which,

28:57

um, uh, which are taken into consideration

29:00

for estimating the fetus dose.

29:02

In my experience of all these 30 years, I have never, um,

29:06

encountered a situation

29:08

where the fetus exposure was more than uh, um, reached even

29:13

to 50 milligram of exposure.

29:16

Most of the cases when the pregnant patient are scanned is

29:19

in the emergency room when they are either brought

29:21

as a trauma patient or are they come in the middle

29:24

of the night for lower abdominal pain where they can,

29:27

they are immediately gut a CT scan

29:30

and the medical physicist as such as mine,

29:32

we can calculate the fetal dose estimation

29:35

and most of the time is much less than 25 milli grade.

29:39

Therefore, it is suffice to say that

29:42

even though people are totally worried about radiation

29:45

and not to and about radiation exposure during pregnancy,

29:49

it can be imaging can be done very safely during pregnancy,

29:53

especially those which, um,

29:56

and so we need to evaluate the risk versus the benefit

30:00

ratio, the, the benefit for outweigh any

30:03

of the risk associated with radiation exposure.

30:06

Now with respect to radiation exposure in pediatric patient,

30:10

I'm going to focus on few things

30:12

because of the time limitation

30:14

and we are gonna take lot more questions to answer any

30:17

of your questions you have.

30:18

First of all, why children are more vulnerable

30:22

to radiation than adults.

30:24

Of course we all know that um, for the same amount

30:26

of radiation exposure,

30:28

the the chi children will have larger effect dose means

30:32

higher risk compared to adult effect dose

30:35

because the anger bodies are more sensitive to radiation,

30:39

they are longer lifetime for radiation efforts to, to impart

30:43

that is the stochastic effect to show up

30:45

and for the same technique,

30:47

kids will observe more radiation than others

30:50

in because of this.

30:51

We have a general understanding on this particular graph

30:55

shown, um, as the um, attributable lifetime risk,

31:00

which is what um, cancer epidemiologists use

31:03

to estimate radiation risk shown on this one is attributable

31:08

lifetime risk per perceived dose over the period of aging.

31:12

And generally for epidemiological risk estimation we use

31:17

a model called 5% perceived for males

31:21

and females are slightly risk

31:23

and that is estimated pretty much same across the age,

31:26

but in reality children are two

31:29

to three times at a higher risk than the adults

31:32

because they're living for a longer time,

31:34

their bodies are developing and so forth.

31:36

So one has to make sure we take special precaution when we

31:40

are doing imaging of the prep, uh, of the pediatric patient

31:43

and that's why from past 20 years we are seeing lot more

31:47

development, um, towards developing protocols specifically

31:52

for pediatric patient both in CT in fluoroscopy

31:56

and in radiography.

31:57

To put this in perspective, the natural incident

32:01

of fatal cancer in the US is about 25%.

32:05

In fact, some of these uh, uh,

32:06

studies even caught even higher than that.

32:09

Therefore, if somebody get a CT

32:12

or an radio X-ray examination

32:14

of 10 milli say their individual lifetime risk is only

32:18

increased by 0.4% compared

32:21

to the natural incident of fatal cancer.

32:23

So what I meant to say is like as long as the studies

32:27

is providing clinical value, the radiation exposure,

32:33

what the pregnant patient

32:34

or to the pediatric patient, um, is,

32:37

the risks are much smaller

32:39

and that risk can further mitigate by adopting number

32:42

of optimization principle.

32:44

So where are we in the US approximately?

32:46

This is one of the data which I have we to show the number

32:50

of CT we use we do in the us.

32:53

Among all the number of CT done in the US in 2016,

32:56

approximately 82 million CT procedure, 10% of

33:00

that was on pediatric.

33:01

And if you look in among the pediatric, we did uh,

33:05

dwell more deeply into radiation exposure

33:07

to the US population from medical exposure.

33:10

This was published in this NCRP and 180 4 report.

33:14

We look in among the 10, uh, among the pediatric population,

33:18

majority of the doses come from CT because,

33:21

and the rest of it, the other procedures are fluoroscopy,

33:25

interventional and nuclear medicine.

33:27

Among the ct, majority of that comes from head CT

33:30

because among the CT procedure done, majority

33:33

of the pediatric uh, x-ray imaging or CT done is in the head

33:38

and the abdomen pelvic can contribute this amount of dose.

33:41

What I'm trying to convey here is like the the,

33:45

if we are trying to optimize a protocol,

33:48

examining the CT protocol specifically should be designed

33:51

for pediatric patient.

33:53

And what can be done in that one is we need to make sure

33:57

that the imaging provides a clear benefit

34:00

and that is the bottom line for any imaging.

34:03

The risk the benefit should fall outweigh the risk.

34:07

In addition for a pediatric patient these days

34:10

with the technology advanced, we have to use what is called

34:14

as a dose modulation.

34:15

In ct all the advanced CT scanner we are using these days

34:20

above 16 slice multi detector ct.

34:22

The radiation dose modulation technique have matured.

34:26

So adapting the dose modulation technique will

34:30

minimize radiation exporter patient

34:32

because the scanner will automatically lower the dose

34:36

or change the dose based on the patient thickness.

34:39

So one doesn't have to have to kind of like gauge

34:43

and adjust the technique.

34:44

The mission will do it for yourself.

34:47

They change the technique based on the patient thickness.

34:51

In addition, the pediatric patients typically can be done at

34:55

a lower tube voltage within ct.

34:58

There is no longer needed

35:00

to acquire all cts in the same tube voltage, which was what

35:04

majority of the places did 20 years ago.

35:06

But now with a lot of understanding

35:08

and knowledge we have lowering using low tube voltage

35:12

a hundred kv 82 voltage

35:15

and 70 kilo voltage automatically have even further

35:19

reduction in the radiation dose.

35:21

Adapting these things, the dose modulation

35:24

and the use of low tube voltage, the radiation dose given

35:27

to the pediatric patient in CT has significantly dropped

35:32

from past 15, 20 years

35:34

and this needs to be done to undo

35:36

for while you're imaging the p pediatric patient.

35:39

The other aspect which is very important for uh,

35:42

imaging in either child

35:44

or in pregnant is to limit the area of imaging area.

35:48

One doesn't have to um, expose region, which is not needed

35:52

for diagnostic studies.

35:54

For example, for the chest ct, it doesn't have

35:57

to cover the entire head and neck or the abdomen.

36:00

It has to be limited to the area of diagnosis required.

36:06

The second is we want

36:07

to make sure the study is done on the pediatric is done the

36:10

right way the very first time,

36:12

therefore we minimize multiple scan.

36:16

That's also one of the reason why we are now advocating not

36:21

to not to use any type of a shielding on pediatric patient

36:24

or any patient because those shields can inert inadvertently

36:28

results in repeating the studies.

36:31

If, if it has to be avoided, one can always examine using,

36:35

doing the study, using ultrasound or MRI.

36:38

So why is CT done most commonly in pediatric patient?

36:42

And there are for a number of reason.

36:44

One is it is quick

36:45

and fast, it can be done in less than the time required

36:49

to put the patient on the table

36:52

and that is a major advantage.

36:54

Second is you can minimize the motion, motion artifact by

36:57

because of the fast scanning in the ct,

37:00

the scans can be done less than one second.

37:04

We have now advanced CT scanners such

37:06

as the three 20 detector scanner,

37:08

which covers an area about 16 centimeter,

37:11

which means small babies,

37:13

the entire chest CT can be done in half of the rotation

37:16

or one rotation, which is about 0.3.

37:18

Second, we can also get very high quality images.

37:22

We can because of the fast scanning

37:24

and the larger area, we can minimize the use of contrast.

37:29

Seldom we use sedation.

37:31

So one of the argument which I have with some

37:33

of my colleagues is like in order to avoid radiation,

37:36

they try to redo it on on MRI.

37:39

So my call quality is, my argument is one should not avoid

37:44

or hesitate to use CT

37:47

or radiation of course just for radiation's sake

37:50

and perform MRI because MRI has its own has its own issues.

37:55

So what I'm trying to convey is like

37:59

avoiding CT in pediatric patient or pregnant patient

38:02

because of radiation, um,

38:05

and moving them away to just to MRI

38:08

or other studies just to, our radiation has

38:10

to be examined more closely because there are other issue.

38:14

For example in MRI we have the scan time is a big issue.

38:19

It can take a long time.

38:21

In order to address this,

38:22

we in the past we wrote this paper called

38:25

if MRI examination time is considered equivalent

38:30

to X-ray dose in CT

38:32

and put the limitation on the exam time.

38:36

One can result in creating LA shorter MR studies

38:40

in a shorter time and it can become less expensive

38:44

and more studies and more patients can be

38:46

accommodated to MRI.

38:47

Again, this is a just a, um, just a, um, one

38:51

of the points which I wanted to make,

38:53

but in general there are a number of resources available

38:58

for, uh, what one has to do for imaging.

39:01

Um, so social media campaign like an image gently

39:05

has a valuable resources available, um,

39:08

which basically the aim is to increase awareness for need

39:12

to decrease radiation dose to children

39:14

and adults with a medical imaging.

39:17

And we have seen this image gently

39:19

campaign similar thing has been mimicking

39:21

now across the globe.

39:23

Um, in Europe we have eurosafe in, uh,

39:26

in South America we have Latin safe.

39:28

Um, in Asia we have Asia safe, which all have the same uh,

39:33

uh, objective is to bring awareness.

39:36

There is a need to examine imaging protocol

39:39

to minimize the risk from radiation

39:42

and uh, MR safety and so forth.

39:44

There is also, similarly, there is image wisely.

39:47

And um, for those who are doing,

39:49

have questions about radiation have uh,

39:52

are question about a procedure one can also check out this

39:56

radiology info.org, which is dialed between radiologist

40:00

and medical physicist housed by RSNA

40:02

and a CR has a very valuable website which is geared towards

40:06

answering these questions to the patients

40:09

and so anybody can understand, get a lot

40:11

of valuable information from these websites.

40:15

Before I conclude the lecture, I also want to show some

40:18

of the policy statement regarding imaging pregnant patient.

40:22

One of the policy statement is from this NCRP,

40:25

the National Council

40:26

of Radiation Protection and Measurement.

40:28

This is a advisory body to the US government.

40:32

NCRP put out various reports on radiation exposure

40:35

to the paper, the to to the patients

40:38

or PO to the population according to the NCRP,

40:41

they do may have the statement telling like

40:44

risk is considered to be negligible at 50 milligram

40:47

or less when compared to other risk of pregnancy

40:51

and risk of mal formation is significantly increases

40:55

only when radiation doses the fetus is above 150 milligram.

40:59

And they also says like exposure of fetus to radiation

41:03

arising from radio diagnostic procedure

41:06

would very rarely be the cause by itself

41:09

for terminating pregnant.

41:10

Because there is a tendency sometime when when patients get

41:14

imaging done and they're pregnant, there is like, they're

41:17

so much worried they try to looking

41:19

for all these other option to terminate a pregnancy,

41:23

worrying about the radiation exposure.

41:25

In that regard, they need to understand these policy,

41:27

this knowledge we have about this, uh, imaging during,

41:31

during the pregnant patient.

41:33

Similarly, the ICRP,

41:35

the International Body on radiation protection,

41:38

they also have a statement telling like

41:40

prenatal doses from most properly done

41:43

diagnostic procedures present no measurable

41:46

or increased risk of, of fatal cancer, of prenatal death

41:51

or more formation or other entities.

41:54

Fetal doses below a hundred milligram should not be

41:58

considered a reason for terminating a pregnancy.

42:00

And that is important statements

42:02

to be understood when we are examining

42:05

or worried about imaging pregnant patient.

42:07

Are a pregnant patient getting an imaging done

42:10

again, tore, confirm again.

42:12

Uh, American College of Obstruct

42:14

and gynecologist made the all appalling statement.

42:17

Similarly, a CR has similar statement telling like

42:20

interruption of pregnancies rarely justified

42:23

because of the radiation risk to the embryo

42:25

or fetus from a radiological examination.

42:30

The reiterating the American College

42:32

of OB gynecology statement on regarding MRI again,

42:35

they say there are no no there are no known biological

42:39

effect of MRI and fetus.

42:41

So MRI in pregnant patient can be done safely except

42:45

that the gadolinium should not be,

42:47

should be awarded when examining the pregnant patient.

42:51

The American College of Radiology also has a lot

42:53

of practice parameters for variety of, uh,

42:56

topics in the field.

42:58

One of them is this, uh, um,

43:00

the joint statement from the American College of Radiology

43:03

and the Society of Pediatric, uh, radiology

43:06

practice parameter for the safe use of optimal, um,

43:10

optimal performance of fetal MRI has the following.

43:14

The present data have not conclusively documented

43:18

any deleterious effect on MRI at 1.5

43:22

and three T test on the developing fetus.

43:25

So this statement confines to 1.5 to three Tesla

43:28

and lower than that one.

43:30

Therefore, they also make a statement

43:31

that there is no special consideration is recommended

43:35

for any trimester in pregnancy.

43:38

And they also tell like pregnant patients can be accepted

43:41

to undergo MS scanner at any stage

43:43

of the pregnancy if the risk to benefit ratio warrants

43:47

that the study be performed.

43:50

They also warrants about the other things,

43:53

the theoretical consideration

43:54

for the radiofrequency power consideration

43:57

and the gradient used in the study

44:00

regarding the specific absorption ratio

44:03

that needs to be evaluated.

44:05

So the key points during x-ray imaging of pregnant patient

44:09

benefit of medical x-ray imaging procedure should be weighed

44:14

as part of the risk assessment

44:16

and counseling the patient who are found to be pregnant

44:19

and is radiation counseling.

44:21

When the fetus is outside the primary path,

44:25

the radiation dose to the fetus is generally negligible

44:28

and that's because of the internal scatter.

44:30

It's going to vary less, almost same

44:32

as the natural bigger daily background radiation dose level.

44:36

When the fetus is in the path,

44:39

one can take optimal techniques

44:41

to minimize the radiation exposure to patient

44:44

and that can be a lecture by itself.

44:46

Uh, in future, in conclusion,

44:50

imaging pregnant patient,

44:52

if the fetus is not in the X-ray beam

44:56

exposure is minimal or negligible.

44:58

If it's in the path of the X-ray beam, those can be lowered

45:03

by dose optimization strategies.

45:05

Imaging pregnant patient one needs

45:08

to use the optimization strategies

45:10

to minimize radiation exposure.

45:13

In conclusion, imaging including CT should not be avoided

45:18

because the patient is pregnant

45:20

or pediatric when the procedure is clinically appropriate.

45:24

Let me stop here and I will take any questions. Thank you.

45:30

Thank you so much for that lecture Dr.

45:32

Mahesh, we do have a couple questions, so I will

45:36

read those to you now.

45:38

Should I stop sharing the screen?

45:41

Sure. Okay, awesome.

45:44

What, what is the MSV dose

45:46

for the whole body X-ray like skeletal survey?

45:51

So, um, it's interesting question.

45:53

Skeletal survey, um, includes different part of the body,

45:58

um, and depends on the technique.

46:00

Again, if you're doing in a pediatric patient,

46:03

it can be different adult, it can be different.

46:05

So it is not, it's, there's no one number to tell you,

46:09

but the radiograph with the digital radiography technique we

46:13

are using these days, the dose are getting quite smaller,

46:16

but I don't have one number to say

46:19

what is the Millie word from skeletal x-ray,

46:20

because that can be a false number

46:23

and it can vary from patient size and what are the,

46:26

and the patient, uh, age also.

46:31

Great. What is the best way to put the lead apron

46:36

when we do CT chest

46:37

for non-pregnant patient including pediatric?

46:41

I mean we should put the apron interior

46:43

or wrap it around the pelvis like skirt.

46:46

Okay, two things.

46:47

First of all, um, the American College American,

46:50

a association physicist in medicine

46:52

and now even the NCRP have come against the use of any type

46:55

of lead apron during any type of imaging.

46:58

First we made a statement for gonadal imaging.

47:01

There is no need for shielding during gonadal,

47:04

especially for a couple of reason.

47:06

One is it can be misplaced

47:08

and even if it is correctly placed,

47:10

it can obscure the needed area for diagnostic.

47:13

Third is use of the digital radiography technique

47:17

with the shield in the path

47:18

of the beam can actually increase the dose to the patient

47:21

because the system will automatically think the patient is

47:25

thick, it increase the dose.

47:27

So there is no lead la there is no lead

47:29

apron required for imaging.

47:31

The other other point is like, let's say for the ct, um, lot

47:35

of the time you only you give this apron was

47:39

for psychological comfort.

47:41

And if you're doing that, if you're ct, you have

47:44

to really wrap the patient, which again becomes impossible

47:47

and becomes very futile attempt.

47:49

Let's say for example, a pregnant patient comes

47:51

for a CT chest CT and she's getting a chest ct.

47:55

And typically by practice, by conventional practice

48:00

or uh, legacy practice, we have apron rapid it on the,

48:04

on the pra, on the on the belly, assuming that

48:08

that apron is protecting the uh, uh, fetus,

48:11

not necessarily it can give you false comfort

48:14

and also it can come in the path of the beam.

48:17

In those situations, make sure

48:19

that you're not unnecessarily radiating the abdominal area

48:22

limit the area, uh, area.

48:24

So the use of apron is almost becoming, um, which almost,

48:29

um, being made around the world not to be used

48:33

during the imaging purpose.

48:34

In fact, when a PM

48:36

and a CR, we came up with a statement, um,

48:39

about the gonadal dose.

48:40

NCRP has now have a study,

48:42

have a statement telling there's no need for use of apron.

48:46

Similarly, the UK Radiology Society also commences against

48:49

the use of this lead apron.

48:51

And recently you, many

48:53

of you may know the American Dental Society has come out

48:58

with the study telling that use of lead apron even

49:01

during the left, um, when you visit the dentist is of no use

49:06

and it can be discontinued.

49:11

That was great. Okay, why is it safe

49:16

to use iodine but no gadolinium in pregnant patients?

49:19

So the iodine studies in ct, um,

49:22

has been studied exhaustively

49:24

and found to have no, uh, no effect on patient.

49:28

On the other hand, for the gadolinium, it had the,

49:31

some studies has shown there is a transformation

49:33

of this gadolinium through the placenta

49:35

that can impact the pregnant patient.

49:37

And that's why they're, they're, they're considered a non,

49:40

uh, non, uh, they recommend not to use a contrast in MRI

49:45

because galium is the only contrast used in MRI.

49:51

Great. About

49:52

how many c TPAs can a first trimester mother have?

49:55

What's the dose estimate versus safety?

49:58

So let's say I, I just give a ballpark figure CT

50:01

of the abdomen and wig.

50:03

Let's say it's 10 milli C word.

50:05

These days with the advanced techno technique we have, we,

50:08

we are getting even lower than that.

50:10

Let's, for easy convenience,

50:12

let's say it is 10 milli C word,

50:14

unless the patient, a pregnant patient gets 10 CT

50:19

of the abdomen wig, that's when one can see

50:22

that dose can go up to a hundred.

50:27

Unless you have like 10 ct, you have to be worried.

50:31

And seldom is the case a pregnant patient gets 10 CT

50:35

or even one CT or two or three cts during pregnancy.

50:42

Got it. In breastfeeding women,

50:45

does gadolinium have an effect on milk?

50:46

Is it safe to breastfeed the baby immediately

50:48

after the MRI exam?

50:51

Um, I am going to defer this question for the,

50:55

my colleagues were more expert in MRI, um, but

50:59

however, the pre during pregnancy, the gadolinium is not,

51:03

is, uh, is used as a is not, is counter contraindicated

51:08

and that's one of the reason why they recommend not to use,

51:11

uh, contrast during pregnancy.

51:14

Got it. Okay. We have a specific question here.

51:17

Which protocol does your institution use

51:18

to image a pregnant patient

51:20

with suspected pulmonary embolism?

51:22

What do you I'm not sure

51:25

how I can tell very specific protocol

51:27

because we have a number of protocol actually for a ct.

51:31

I would recommend you to visit hopkins cts as.com.

51:34

My colleague Elliot Fishman has had a website which he,

51:39

we shares the protocols, uh, for a variety of more, uh, uh,

51:45

uh, indications and you can, I would recommend you guys

51:48

to visit that website to look at

51:50

what particular protocol we use

51:52

and in, in any of these things.

51:54

One thing I can make a general, as a physicist

51:57

with the advanced technology we have with the ct,

52:00

we are advising every protocol to use

52:04

as thinnest detector slice as possible so

52:07

that you can acquire the data as the thinnest slices

52:10

and you can always reconstruct it to thick slices.

52:13

But if you acquire the data, the thick slices,

52:16

thick detector, you cannot reconstruct into thin slices.

52:20

So that is the, um, uh, the rule of thumb, I can use it,

52:23

but for a specific protocol our institution uses,

52:27

I would recommend you to check out our c.com

52:29

where my colleague Elliot Fishman has shared many

52:32

of the protocol he has been using

52:34

in routinely in the clinic.

52:37

Great. Okay. Let me see.

52:43

What is the dose reduction technique in a pediatric

52:46

patient and CT scan?

52:47

Which parameter is measuring DLP or CDI volume

52:51

or other parameter?

52:52

Okay, here is a, uh, the couple of things.

52:56

First of all, whatever the dose information we have in the

52:59

ct, it's all based on the phantom measurement.

53:02

We are measured, so it's a, there is,

53:03

we don't directly measure on the patient.

53:05

It is estimated on the patient based

53:07

on the phantom measurement.

53:09

So in general, in order to estimate a long-term risk DLPs,

53:13

the cons, the measure, we wanted those length product

53:17

because, because that will demonstrate

53:19

what is the anatomical area was scanned actually.

53:23

However, right now the two main dose descriptors we used in

53:27

CT is the CTDI wall and DLP.

53:30

Both of them are required to be displayed for each patient.

53:34

So you can actually take a look at these

53:36

numbers under each patient.

53:38

For example, any radiologist reading,

53:40

reading a radio ct, uh, studies.

53:42

If you go back to the last image,

53:44

there is a CT dose image basically showing an A abbreviated

53:49

information on the CTDI volume and the DLP.

53:52

So you can use this DLP information

53:55

and there are some conversion factors to create

53:58

that into an effect dose.

54:00

And those effect dose, you can then examine

54:03

what is the level is and there are conversion factors.

54:06

Um, one set of conversion factor for the adult size

54:10

and there are a little bit more different conversion

54:12

factor for the pediatric.

54:13

And again, there are a variety of sources.

54:15

One, one source, which I would highly recommend is the

54:18

American Association of Physicists in Medicine.

54:21

We have task group reports

54:23

and one of the report task group report 96 clearly have a

54:28

table of this conversion factor for pediatric patient

54:31

compared to the other patient to be used

54:34

to estimate the effect you dose

54:36

for based on the DLPI would highly recommend you

54:39

to take a look at that one because

54:40

they're also freely available.

54:43

Awesome. All right, one more question

54:45

and it's out of my own curiosity.

54:47

In your experience, when has,

54:49

when has it been absolutely necessary

54:51

to image pregnant women?

54:53

Best example is one is trauma case that is different.

54:56

TRA trauma case is, uh, patient brings in, they want

54:59

to save the patient, they wanna, the second most common

55:02

thing done in the pregnant patient is um, uh,

55:05

lower abdominal pain.

55:07

Let's say a second trimester.

55:09

The patient, um, is uh, fully pregnant

55:11

and she experienced lower abdominal uh, pain

55:14

and they come to the emergency room

55:16

and in the middle of the night,

55:18

the best way is like ideally speaking you

55:20

to get an ultrasound.

55:22

If not get an MRI, if not a CT ultrasound.

55:25

A lot of the time we don't have a tech in the middle

55:27

of the night, so it's not possible.

55:28

Second thing is like you want do, do you want

55:30

to go into an MR MRI or a CT MRI can do

55:33

but it'll take 45 minutes.

55:35

The doctor wants the answer in the next minute

55:38

to award any type of abdominal appendicitis rupture so

55:42

that they can go for surgery.

55:43

In those cases, the best answer is get a CT done.

55:47

And that's why most of the hospital now have a CT scanner in

55:51

the emergency room so

55:52

that they can get a quick CT scan of the pregnant patient.

55:55

And that usually takes about less than two seconds

55:58

or three seconds at the most.

56:00

Now you have an answer right off the bat whether the uppers

56:03

is, the lower abdominal pain is caused

56:05

by the ruptured appendicitis.

56:07

If that is the case, they

56:08

can immediately rush to the surgery.

56:09

And I find that that scenario to be the most, um,

56:14

effective scenario using a CT

56:16

because you are getting the answer in a second

56:19

and you can rule out the patient to get either get a,

56:22

a surgery or not.

56:23

And in that cases that becomes really important

56:26

and a lot of the time physicists, we get a call next day

56:28

to like, hey, the patient was scanned, tell you,

56:31

can you tell the estimation when we estimate the fetal dose

56:34

estimation, I have never seen doses more than 10 milligram

56:37

or 20 milligram to the fetus.

56:39

And a lot of the time I have volunteered to consult

56:42

with the patient to explain what that means and why he

56:46

or she, she should, he

56:47

or her, her family should not be worried

56:49

from the radiation exposure.

56:50

Rather they should be keeping their focus on their whole

56:54

pregnancy and other issues.

56:58

Amazing. Thank you so much. Yeah.

57:00

Um, and one more question, uh, the recommended CT website

57:03

that you just threw out, what was the name of that?

57:06

So this is the website.

57:07

My, my colleague, um, has, uh, has it, it's called CT is us.

57:13

So CT IS us.com.

57:15

It is a freely available website, uh, which has lot

57:20

of information and in fact in that, in that, in

57:23

that website, I also have a 16 lecture short lecture on

57:28

CT physi CT physics, CT physics, um, on various topic.

57:33

And it's not a self advertisement,

57:34

but if you're interested you can always take check it out.

57:37

It's about, it's not more than 15 minutes each.

57:41

So you can understand more more about the CT physics.

57:44

But my under my, my take home message

57:46

to the audience here is like there is lot

57:49

of misunderstanding about radiation

57:51

and lot of the time we completely block

57:54

of using CT on pregnant patient

57:57

or pediatric patient for unnecessary reason,

58:00

even when the value is very highly valuable.

58:03

So in that aspect I hope to, I hope I conveyed the message.

58:08

What is about imaging pregnant patient?

58:11

What is about imaging pregnant pediatric patient either

58:14

with MRI or with CT or x-ray?

58:16

That's what, um, I wanted to uh, um, answer some

58:21

of these unanswered these uh, questions which are difficult

58:25

and it can lot of confusion are there in the field

58:28

and only by um, sharing this information we are trying

58:32

to reduce some of this concern.

58:34

Well, I think you did that,

58:36

you definitely illuminated a lot of information for,

58:38

for me and for the audience.

58:39

So thank you so much for being here

58:41

and for doing a, a talk on such an important

58:43

and, and tricky topics.

58:44

Really appreciate it.

58:47

Um, there's one more question.

58:49

Should I take it for this, uh,

58:50

from one of the person for flu?

58:52

Yeah. So The question here is like Flo fluoro exam,

58:56

do you report time imaging numbers

58:58

are, this is a good question.

59:01

So in historically when you say about fluoroscopy procedure,

59:05

any hospital, they always document just the

59:07

Fluor fluoroscopy minutes.

59:09

And in the, in the past that was fine because in fluoroscopy

59:13

or interven fluoroscopy

59:15

or interventional cardiology fluoroscopy procedure,

59:18

we were only, were focused on the fluoroscopy minutes.

59:21

Now fluoroscopy time is only one part

59:24

of the total radiation exposure

59:26

because the patient is not only getting fluoroscopy,

59:29

they also get c imaging.

59:32

The little subtraction angiography imaging,

59:35

therefore it is important is the just documenting

59:39

fluoroscopy time becomes almost less of a mute.

59:42

On the other hand, they need to focus on the total dose

59:46

to the patient and

59:48

that's available now on all the advanced

59:50

fluoroscopy machine.

59:52

The machine automatically creates a dose report

59:54

and display two things.

59:56

One is cumulative dose are Air Karma expressed in gra.

60:01

The second one is DAP or air, um, karma air product

60:05

or dose area product expressed in GRA centimeters square.

60:09

The, the DAP reading can be used

60:11

for effective dose estimation,

60:13

but more important in fluoroscopy,

60:16

the number which I am interested is the cumulative Air Karma

60:19

cumulative dose to the surface.

60:22

Because if that number reaches certain,

60:25

certain exceeds certain threshold,

60:27

I know the patient have a, a good possibility

60:30

of certain type of deterministic effect.

60:32

So we track based on the accumulative dose to the patient

60:36

and see if the patient needs to be examined

60:39

or alerted about any type of skin injury and so forth.

60:42

So for fluoroscopy cumulative Air Karma is

60:45

an important metric.

60:46

The second one is the D dap reading

60:49

for estimating long-term risk.

60:52

Thank you so much for answering

60:53

all those questions you got too.

60:55

That was very nice and, and,

60:56

and for, for spending more time, uh, with us.

60:59

Appreciate it. Yeah, and you can access today's recording

61:02

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61:04

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61:06

And be sure to join us next week on Thursday,

61:09

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61:12

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61:14

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61:16

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61:18

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61:22

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61:25

Thank you.