Radiation safety in ct
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Radiation safety in CT. RADIATION DOSES DURING CT EXAMS ARE CLASSIFIED AS:. LOW DOSE RADIATION. AS COMPARED TO DOSES GENERATED FROM NUCLEAR EVENTS. BODY RESPONE TO RADIATION:. SOMATIC EFFECTS GENETIC EFFECTS. SOMATIC EFFECT. MANIFESTED IN THE INDIVIDUAL EXPOSED.

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Radiation safety in CT

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Radiation safety in ct

Radiation safety in CT


Radiation doses during ct exams are classified as

RADIATION DOSES DURING CT EXAMS ARE CLASSIFIED AS:

  • LOW DOSE RADIATION

AS COMPARED TO DOSES GENERATED FROM NUCLEAR EVENTS


Body respone to radiation

BODY RESPONE TO RADIATION:

  • SOMATIC EFFECTS

  • GENETIC EFFECTS


Somatic effect

SOMATIC EFFECT

  • MANIFESTED IN THE INDIVIDUAL EXPOSED


Acute somatic radiation syndrome stages

ACUTE SOMATIC RADIATION SYNDROME STAGES:

  • PRODROMAL- NAUSEA, VOMITING, DIARRHEA

  • LATENT PERIOD – NO SYMPTOMS

  • MANIFEST – ORGAN DAMAGE, DEATH OR RECOVERY

HEMATOPOIETIC

GI

CNS


Most common somatic effects

MOST COMMON SOMATIC EFFECTS

  • CATARACT FORMATION

  • SKIN CANCER

  • THYROID CANCER

  • BREAST CANCER

  • LEUKEMIA


Effect on an embryo or fetus

EFFECT ON AN EMBRYO OR FETUS

  • MOST PRONOUNCED DURING THE FIRST TRIMESTER!!!!


Alternative exams should be scheduled if patient is pregnant

ALTERNATIVE EXAMS SHOULD BE SCHEDULED IF PATIENT IS PREGNANT

CT OR MRI ?


Fetal mri

FETAL MRI


Genetic effect

GENETIC EFFECT

  • MANIFESTED IN THE FUTURE GENERATIONS!


Radiation doses from ct scanners are the highest in diagnostic radiology

RADIATION DOSES FROM CT SCANNERS ARE THE HIGHEST IN DIAGNOSTIC RADIOLOGY!!!!

HOWEVER:


Radiation exposure should occur

RADIATION EXPOSURE SHOULD OCCUR :

  • AFTER CONSIDERATION BY THE PHYSICIAN


Alara

ALARA


Radiologic units customary

RADIOLOGIC UNITS (CUSTOMARY)

  • EXPOSURE, INTENSITY ------ ROENTGEN (R)

  • ABSORBED DOSE ----------- RADIATION

  • ABSORBED DOSE (rad)

  • DOSE EQUIVALENT ---------RADIATION EQUIVALENT MAN (rem)


Radiologic units si

RADIOLOGIC UNITS (SI)

  • EXPOSURE, INTENSITY ------ C/kg

  • ABSORBED DOSE ----------- GRAY (Gy)

  • DOSE EQUIVALENT ---------SIEVERT (Sv)

1 Gy = 100 rad

1 Sv = 100 rem


Pencil ionization chamber method of measuring ct dose ct dose index ctdi

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


Ct phantom ionization chamber

CT PHANTOM & IONIZATION CHAMBER


Principle of operation of ionization chamber

PRINCIPLE OF OPERATION OF IONIZATION CHAMBER


Radiation safety in ct

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.


Radiation safety in ct

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)


Radiation safety in ct

MSAD

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


Msad vs ctdi

MSAD vs CTDI


Factors in patient protection

FACTORS IN PATIENT PROTECTION

  • TIME

  • DISTANCE

  • SHIELDING


Shielding

SHIELDING

  • IF PERSONNEL PRESENT IN THE ROOM DURING SCAN MUST BE SHIELDED AND STAND FAR FROM THE SOURCE

    ( INVERSE SQUARE LAW)


Gonadal shields

GONADAL SHIELDS

  • 4-5 CM WITHIN THE X-RAY BEAM


Contact shields

CONTACT SHIELDS

360 ° AROUND PATIENT


Ct dose in spiral scanning

CT DOSE IN SPIRAL SCANNING

  • CTDI CAN ALSO BE USED

PITCH

MSAD OR CTDI


More useful measurement is

MORE USEFUL MEASUREMENT IS

  • EFFECTIVE DOSE

TAKES INTO ACCOUNT QUALITY

OF RADIATION

AND ORGAN SENSITIVITY

EXPRESSED IN Sv


Effective dose msv

HEAD------------ 2

CHEST ---------- 8

ABDOMEN --10-20

PELVIS -------10- 20

SKULL -------- 0.07

CHEST PA ---- 0.02

ABDOMEN --- 1

PELVIS -------- 0.7

EFFECTIVE DOSE (mSv)

CT

CONVENTIONAL


Dose reduction in ct

BED INDEX

SPIRAL PITCH

COLLIMATION

(PREPATIENT)

NOISE

DOSE

DOSE

DOSE

DOSE

DOSE REDUCTION IN CT


Dose reduction in ct1

SID

OID

kVp (15 % RULE)

mAs

DOSE

DOSE

DOSE

DOSE

DOSE REDUCTION IN CT


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