1. Radiation safety in CT

2. RADIATION DOSES DURING CT EXAMS ARE CLASSIFIED AS:
LOW DOSE RADIATION
AS COMPARED TO DOSES GENERATED FROM NUCLEAR EVENTS

3. BODY RESPONE TO RADIATION:
SOMATIC EFFECTS
GENETIC EFFECTS

4. SOMATIC EFFECT
MANIFESTED IN THE INDIVIDUAL EXPOSED

5. ACUTE SOMATIC RADIATION SYNDROME STAGES:
PRODROMAL- NAUSEA, VOMITING, DIARRHEA
LATENT PERIOD – NO SYMPTOMS
MANIFEST – ORGAN DAMAGE, DEATH OR RECOVERY
HEMATOPOIETIC GI
CNS

6. MOST COMMON SOMATIC EFFECTS
CATARACT FORMATION
SKIN CANCER
THYROID CANCER
BREAST CANCER
LEUKEMIA

7. EFFECT ON AN EMBRYO OR FETUS
MOST PRONOUNCED DURING THE FIRST TRIMESTER!!!!

8. ALTERNATIVE EXAMS SHOULD BE SCHEDULED IF PATIENT IS PREGNANT
CT OR MRI ?

9. FETAL MRI

10. GENETIC EFFECT
MANIFESTED IN THE FUTURE GENERATIONS!

11. RADIATION DOSES FROM CT SCANNERS ARE THE HIGHEST IN DIAGNOSTIC RADIOLOGY!!!!
HOWEVER:

12. RADIATION EXPOSURE SHOULD OCCUR :
AFTER CONSIDERATION BY THE PHYSICIAN

13. ALARA

14. RADIOLOGIC UNITS (CUSTOMARY)
EXPOSURE, INTENSITY ROENTGEN (R)
ABSORBED DOSE RADIATION
ABSORBED DOSE (rad)
DOSE EQUIVALENT RADIATION EQUIVALENT MAN (rem)

15. RADIOLOGIC UNITS (SI) EXPOSURE, INTENSITY ------ C/kg
ABSORBED DOSE GRAY (Gy)
DOSE EQUIVALENT SIEVERT (Sv)
1 Gy = 100 rad
1 Sv = 100 rem

17. PENCIL IONIZATION CHAMBER METHOD OF MEASURING CT DOSE (CT DOSE INDEX---CTDI)

19. CT PHANTOM & IONIZATION CHAMBER

27. PRINCIPLE OF OPERATION OF IONIZATION CHAMBER

29. THE AMOUNT OF COLLECTED CHARGE IN I. C
THE AMOUNT OF COLLECTED CHARGE IN I.C. IS PROPORTIONAL TO THE AMOUNT OF IONIZATION WHICH IS PROPORTIONAL TO THE AMOUNT OF RADIATION PASSING THROUGH THE CHAMBER. THE TOTAL ELECTRIC CHARGE GENERATED BY AN X-RAY BEAM IS REPRESENTED BY Q AND IS MEASURED IN COULOMBS.

30. IN 1981 CENTER FOR DEVICES AND RADIOLOGICAL HEALTH SUGGESTED AN EASY AND ACCURATE METHOD TO MEASURE PATIENT DOSE IN CT. IT RELIED ON ON CTDI AND MSAD (MULTIPLE SCAN AVERAGE DOSE)

31. MSAD
SERIES OF CT SCANS ARE PERFORMED ON A PATIENT . BETWEEN EACH SCAN PATIENT IS MOVED A BED INDEX (BI) DISTANCE.

37. MSAD vs CTDI

39. FACTORS IN PATIENT PROTECTION
TIME
DISTANCE
SHIELDING

40. SHIELDING
IF PERSONNEL PRESENT IN THE ROOM DURING SCAN MUST BE SHIELDED AND STAND FAR FROM THE SOURCE
( INVERSE SQUARE LAW)

41. GONADAL SHIELDS
4-5 CM WITHIN THE X-RAY BEAM

42. CONTACT SHIELDS
360 ° AROUND PATIENT

47. CT DOSE IN SPIRAL SCANNING
CTDI CAN ALSO BE USED
PITCH
MSAD OR CTDI

48. MORE USEFUL MEASUREMENT IS
EFFECTIVE DOSE
TAKES INTO ACCOUNT QUALITY
OF RADIATION
AND ORGAN SENSITIVITY
EXPRESSED IN Sv

50. EFFECTIVE DOSE (mSv) HEAD------------ 2 CHEST ---------- 8
CONVENTIONAL
HEAD
CHEST
ABDOMEN
PELVIS
SKULL
CHEST PA
ABDOMEN --- 1
PELVIS

51. DOSE REDUCTION IN CT BED INDEX SPIRAL PITCH COLLIMATION (PREPATIENT)
NOISE
DOSE

52. DOSE REDUCTION IN CT
SID
OID
kVp (15 % RULE)
mAs
DOSE