International Atomic Energy Agency

Example of Practice of Radiation Example of Practice of Radiation Protection Protection

L 9.2

Lecture 9.2: Example of practice of radiation protection 2Radiation Protection in Cardiology

Educational ObjectivesEducational Objectives

1. How awareness of radiation protection and close cooperation with medical physics / radiation safety staff helps

2. Avoidance of skin injuries

Lecture 9.2: Example of practice of radiation protection 3Radiation Protection in Cardiology

IntroductionIntroduction• The evaluation of maximum local skin dose from an

interventional procedure is difficult: • On-line evaluation: dosemeter or computer code

• Off-line methods more accurate: use of large area detectors, time consuming (adopted for a limited number of patients)

• It should be important to periodically evaluate incidence of skin injuries in cardiac centres

• A follow-up protocol has been developed in Dimond European research project (www.dimond3.org):• Purpose to identify patients with an high probability of an

high localised skin dose to be submitted to a follow-up.

• The protocol adopts a trigger value in terms of dose-area product (DAP) as a dose quantity indicator of possible localised high skin dose.

Lecture 9.2: Example of practice of radiation protection 4Radiation Protection in Cardiology

Retrospective evaluation of skin injuries on Retrospective evaluation of skin injuries on patients of Udine cardiac centrepatients of Udine cardiac centre

• Patient can be submitted to repeated cardiac procedures in short period of time

• Methodology: • Analyse database of patients submitted to diagnostic and

therapeutic procedures in a 4 years period

• Detect patients with highest cumulative DAPs (due to repeated procedures) selecting an appropriate DAP trigger value

• Evaluate maximum local skin dose

• Submit selected patients to a clinical evaluation to detect possible skin injuries

Lecture 9.2: Example of practice of radiation protection 5Radiation Protection in Cardiology

Patient database: CA and PTCA in Udine hospital from 1998 to 2002

SAMPLE COLLECTION 21 April 1998 - 17 April 2002

NUMBER OF PROCEDURES 5517

N. OF PTCA PROCEDURES 1843

N. OF CA PROCEDURES 3674

N. OF PATIENTS 3332

Lecture 9.2: Example of practice of radiation protection 6Radiation Protection in Cardiology

CA and diagnostic procedures

No. of procedures 3674

Mean DAP37.5

Gycm2

Median DAP31.2

Gycm2

No. of procedures with

DAP>300Gycm2

1

DAP distribution of CA procedures

0

100

200

300

400

500

0 50 100 150 200 250 300

Gy cm^2

Fre

qu

en

cy

Lecture 9.2: Example of practice of radiation protection 7Radiation Protection in Cardiology

PTCA procedures

No. of procedures

1843

Mean DAP66.1

Gycm2

Median DAP48.3

Gycm2

No. procedures with

DAP>300Gycm2

13 (0.7%)

DAP distribution of PTCA procedures

020406080

100120140160

0 50 100 150 200 250 300 350 400 450 500

Gy cm^2

Freq

uenc

y

Lecture 9.2: Example of practice of radiation protection 8Radiation Protection in Cardiology

No. of procedures per patient

1 2 3 4 5 6 7 >7

No. of patients 1967 940 194 138 41 29 14 9

No. of patients 3332

Mean DAP78.6

Gycm2

Median DAP50.6

Gycm2

No. of patients with DAP>300Gycm2 87 (2.6%) 0

100

200

300

400

500

600

0 100 200 300 400 500 600 700

Gy cm^2

Fre

qu

ency

Frequencies of repeated procedures and cumulative dose

Lecture 9.2: Example of practice of radiation protection 9Radiation Protection in Cardiology

Sample of patients Sample of patients extracted for the follow-up studyextracted for the follow-up study

79 patients with a cumulative DAP>300 Gycm2 extracted from the databaseDistribution of number of procedures performed and cumulative DAP

0

5

10

15

20

25

30

35

40

DAPtotal (Gycm2)

No.

of p

atie

nts

024

68

1012141618

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Number of procedures/patient

No.

of p

atie

nts

Lecture 9.2: Example of practice of radiation protection 10Radiation Protection in Cardiology

Sample of patients Sample of patients extracted for the follow-up studyextracted for the follow-up study

Maximum local skin dose evaluated for the 79 patients

02468

1012141618

1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7Maximum Local Skin Dose (Gy)

No

. of

pat

ien

ts

Lecture 9.2: Example of practice of radiation protection 11Radiation Protection in Cardiology

Maximum local skin dose (MSD) Maximum local skin dose (MSD) assessmentassessment

• Correlation between DAP and MSD has been evaluated: operator and installation dependent

• Skin dose distributions measured on a sample of patients with radiochromic films

MSD= 0.0141*DAP Maximum local skin dose versus DAPfor PTCA

PSD= 0.0141*DAP

0.0

1.0

2.0

3.0

4.0

0 50 100 150 200 250DAP (Gycm2)

PSD

(Gy)

Lecture 9.2: Example of practice of radiation protection 12Radiation Protection in Cardiology

Skin dose assessment (patient no. 1)Skin dose assessment (patient no. 1)

• Patient no. 1: Total maximum local skin dose 6,7 Gy Procedure type DAP per

procedure(Gycm2)Maximum local skin dose

(Gy)

Diagnostic 86.9 0,416

Diagnostic 86.3 0,413

Diagnostic 26.8 0,128

Ad hoc PTCA 57.1 0,509

Diagnostic 108.6 0,520

Diagnostic 73.8 0,354

Ad hoc PTCA 135.6 1,208

Diagnostic 28.4 0,136

Ad hoc PTCA 33.8 0,301

Election PTCA 84.7 0,755

Diagnostic 58.4 0,280

Ad hoc PTCA 115.3 1,027

Diagnostic 27.2 0,130

Diagnostic 33.5

Ad hoc PTCA 39.2

Lecture 9.2: Example of practice of radiation protection 13Radiation Protection in Cardiology

ConclusionsConclusions

• 56 patients received medical examination with particular focus on the more exposed skin area.

• None of visited patients presented skin lesions that could be attributed to high dose X-ray irradiation

• The result assures cardiologists and medical physicists that, if proper quality assurance and radiation protection programme is established, the frequency of skin injuries can be very low also when repeated procedures are taken into account