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SEMINAR 1Radiological Protection Of PatientsRadiological Protection Of Patients

Radiation Protection in Paediatric Cardiology

Dra. Patricia Miranda González

CARDIOVASCULAR DEPARTMENT , CALVO MACKENNA’S HOSPITAL SANTIAGO CHILE


Pediatric patients have special features, they are not small adults.


Paediatric cardiology is absolutely different from the adult cardiology not only in the age of the patients (newborns until fifteen years old) but also because of the diversity of structural anomalies in congenital heart diseases

• This is important to understand because paediatric procedures are longer than procedures in adults (Lock 2000).

• In certain times need to be studied before each surgery, even up to three times before the age of two years old.

• More complex congenital heart diseases have the possibility of cardiac surgery, complex diagnostic studies are necessary including several biplane angiographic recordings, measurement of local pressure curves and oxygen saturation (with and without oxygen), before and after cardiac surgery.

PART 1

1. They have congenital diseases of the heart

Mean values of Pka for different procedures

Type of examination Pka Gycm²mean

Pulmonary angioplasty with stent 8.10

Diagnostic complex (D) 6.47

Closure atrial septal defect 5.14

Other 4.54

Aortic valvuloplasty 3.63

Pulmonary angioplasty 3.56

Diagnostic “normal” (d) 3.46

Therapeutic (global) 3.44

Aortic angioplasty 2.98

Diagnostic (global) 2.44

Pulmonary valvuloplasty 2.00

Patent ductus arteriosus closure. 1.27


A PILOT PROGRAMME ON PATIENT DOSIMETRY ON PAEDIATRIC INTERVENTIONAL CARDIOLOGY IN CHILE


2. Children have especially radiosensitive tissues


Dosis

Efec

t

Deterministic Deterministic efectefect

Cancer and Genetic efects

Probability ∝ dosis

EstocasticEstocastic(Probabilistic)(Probabilistic)

RxRx

CataratasEsterilityEritemaEpilationFetal Malformations


3. Their have longer life span makes the stochastic effect manifest

674 childrens undergoing cardiac catheterization due to congenital heart desease between 1950-1970 The expected number of cancer was 4.75, but the real number was 11.0


Dosis

Efec

t

Deterministic Deterministic efectefect

CataratasEsterilityEritemaEpilation

Fetal Malformations

Cancer and genetic efects

Probability ∝ dosis

EstocasticEstocastic(Probabilistic)(Probabilistic)

RxRx


According to the International Commission Radiological ptrotection (ICRP)the probability of cancer iduction by ionizig radiation is a factor 2-3 higherfor infants and children in comparision with adults (ICRP 1991).

0,00

0,04

0,08

0,12

0,16

0,20

0 15 30 45 60 75 90

Edad de exposicion

Muerte por

Sievert (Sv)

FemaleMale


4. The age of the patients is very different (newborns until fifteen years of age) even their weight.

Air kerma area product retains a strong dependence on patient weight

kerma area product v/s body weight

y = 78,531e0,4495x

R² = 0,8974, R=0,9473

0

100

200

300

400

500

600

700

800

900

< 10 10 ‐ 20 20 ‐ 30 30 ‐ 40 > 40Weight (kG)

kkerma area

produ

ct KAP (cGycm^2



Kerma area product per minute fluoroscopy versus body weight

FLUOROSCOPY

y = 2.3857e0.4386x

R2 = 0.9994

0

5

10

15

20

25

< 10 10 ‐ 20 20 ‐ 30 30 ‐ 40 > 40Weight (kG)

kerm

a area

pro

duct / tim

eflu

oros

copy

(cGycm^2

min‐ 1

Kerma area product per cine frame versus body weight

CINE ACQUISITION

y = 0.0356e0.5386x

R2 = 0.9863

0

0.1

0.2

0.3

0.4

0.5

0.6

< 10 10 ‐ 20 20 ‐ 30 30 ‐ 40 > 40Weight (kG)

kerm

a area

pro

duct / fr

ame

(cGycm^2

)





HDO Biplane A 11Nov04 paediatric

0

50

100

150

200

250

4 8 12 16 20

cm PMMA

mic

roG

y/fr

ame

Cine 25 cmCine 20 cmCine 16 cm


RADIATION DOSE AND IMAGE QUALITY FOR PAEDIATRIC ITERVENTIONAL CARDIOLOGY E. Vañó. C. Ubeda. F Leyton and P. MirandaPublished 8 july 2008


PART 2

Paediatric Interventional Cardiology (PIC) has a challenge¿ How to reduce the doses in PIC?

1. Formation in RP


Support Programs of the IAEA

• Regional Workshops in Chile 2006 and Costa Rica 2007.

• Attending cardiologist from all Latinamerica.• Several works at the workshop to evaluate

patient dose in interventional Cardiology in Latin America.


2. The equipment

¿What is the best Image intesifier or Flat Panel?

Both sistems are adecuated, but flat panel have became the most “popular” because the market offers a better image quality and dose reduction, nevertheless the experince show that at least at this “inicial point” is different.


Biplane Siemens Flat panel

Biplane Siemens with image itensifiers


Dose rate reaching the

patient is meassured or

calculated (usually expresed

in mGy/min)


Flat Panel sistemDose rate reaching

the metacrilatpatient is

meassured or calculated (usually

expressed in mGy/min)


3. Operation modes

Sometimes, interventionists do not have clear criteria to select

the different operation modes. Thus, the characterization of the

systems in dose and image quality using test objects offers a set

of useful data to help cardiologists to select the most appropriate

operation modes for the different procedures and patient sizes.






0

10

20

30

40

50

16 20 24 28PMMA thickness (cm)

Scat

ter d

ose

rate

(mSv

/h)

lowmedhighcine


Important factors in the dose rate for fluoroscopy

• Number of pulses per second (pulsed fluoroscopy).• Dose per puls (o dose per “frame”).• Added Filter (normaly the low dose modes use cupper

filters of 0,4 to 0,8 mm).


HDO Biplane A 11Nov04 paediatric0.

2

0.3 0.7 1.

4

3.4

0.3 0.6 1.

3 3.1

7.4

0.5 1.

5 2.8

6.7

17.3

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

4 8 12 16 20

cm PMMA

mG

y/m

in Fluoro low 25 cmFluoro med 25 cmFluoro high 25 cm


HDO Biplane A 11Nov04 paediatric vs adult

3.4

7.4

17.3

4.5

11.7

21.6

0.0

5.0

10.0

15.0

20.0

25.0

20

cm PMMA

mG

y/m

in

Fluoro low 25 cmFluoro med 25 cmFluoro high 25 cmFluoro low adultFluoro med 25 cm adultFluoro high 25 cm adult


CD-1 1 fluoro 5860895


CD-1 4 cine 5861107


Comparison between median KAP (Gy.cm2) for paediatric cardiology procedures reported by different authors (figures adapted by theauthors of this paper).

Age bands (years)

Boothroyd et al.

[10] (1997)

Rassow et al. [11]

(2000) (Gycm²)

Bacher et al. [12]

(2005) (Gycm²

)

Martinez et al. [7] (2007)

(Gycm²)

*This paper (2008)

(Gycm²)

<1 12 3 1.9 1.01 - < 5 24 5 4.1 2.9 1.65 - < 10 48 10 4.5 1.810 - <16 98 18 15.4 5.1

*A PILOT PROGRAMME ON PATIENT DOSIMETRY ON PAEDIATRIC INTERVENTIONAL CARDIOLOGY IN CHILE


Pediatric interventional cardiologyst dose

HDO Biplane A 11Nov04 paediatric

0

1

2

3

4

5

6

4 8 12 16 20

cm PMMA

mS

v/h

Fluoro low 20 cmFluoro med 20 cmFluoro high 20 cmcine 30f/s 20 cm


Different C-arm angulations can modify the disperse dose in a 5factor


Operation modes tips

1. Use of fluoroscopy runs instead of cine

2. Use of “one shot” instead of cine

3. Use one projections instead of two if it is possible (PDA

closure with coil)


4. Reduce the operator doses

SUGGESTED ACTION LEVELS FOR STAFF DOSE

Body 0.5 mSv/monthEyes 5.0 mSv/monthHands/Extremities 15.0 mSv/month

Suggested action levels in staff exposure in interventional radiology (Joint WHO/IRH/CE workshop 1995)

References:• Radiation Safety in Interventional Radiology: BfS ISH 178/97. Proceedings of the 1995 Joint WHO/ISH Workshop. October 9-13; Munich-Neuherberg. Bundesamt für Starhlenschutz, Germany. 1997.• Efficacy and Radiation Safety in Interventional Radiology. WHO 2000. Geneva.


Lens dose, optional Finger dose, optional Second dosemeteroutside and above the apronat the neck, optional

Personal dosedosemeter behind the lead apron

X-ray tube

Image intensifier

Patient

Radiationprotectionmeasures

Dose limits of occupational exposure

(ICRP 60)

Effective dose 20 mSv in a yearaveraged over a period of 5 years

Anual equivalent dose in the lens of the eye 150 mSvskin 500 mSvhands and feet 500 mSv


Reduction in operator doses with the use of radiation protection tools

• Lead apron of 0.5; 0.35 or 0.25 mm lead equivalent (weight of the apron to be taken into account). Typical reduction 90% (or more).

• Thyroid protector. 0.5 mm lead equivalent

• Suspended ceiling screens, typically equivalent to 1 mm lead. Typical reduction > 90%.

• Under table lead equivalent protection

• Protective goggles, typically 0.5-0.75 mm lead.

• Tactile gloves, typically equivalent to 0.03 mm lead. Typical reduction > 15-55%.


0.50 mm lead

60 kV; 100% < 1 %

100 kV; 100% 3 - 7 %

Attenuation measured at the San Carlos University Hospital (lead aprons)

But, X ray beam filtration has a great influence!!


THYROID PROTECTOR

Avoid more than 90% of the scatter radiation


Sometimes, hands in the

direct beam!!


Vañó et al.Br J Radiol 1998;

71:954-960

Interventional cardiologist

Interventional radiologist

Mean values (µSv) per procedure

(using protection tools)


Give me a break !!!

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Microsoft PowerPoint - 5- patricia miranda.ppt [Sólo lectura]