Patient Radiation Dose Management Flashcards
Exposure to medical radiation is up by ___ in the U.S.
18%
Patient dose is usually estimated by
conducting simulated x-ray exams with human phantoms and test objects.
Patient dose from diagnostic x-rays can be reported in three ways
Exposure, Bone Marrow Dose and Gonadal dose
Bone Marrow is important because
it can indicate radiation-induced leukemia Bone.
calculated from ESE
Marrow dose is estimated by
Entrance Skin Exposure.
Entrance skin exposure
Most common way to report dose, easy to measure directly
Gonadal dose
target for genetic effects, easy to measure or estimate
Entrance Skin dose most often referred to as _____
“patient dose”
Entrance Skin dose(ESD)
- Easily measured with or without measurement devices
- Entrance Skin Dose is used to estimate Bone Marrow Does
- Efficiency of the radiology equipment will change these doses from facility to facility.
Thermoluminescence Dosimetry
- Like the film badge can be worn up to 3 mos.
- Must be processed – can measure as low as 1 millirem.
- Highly sensitive , compact
- Most accurate and not affected by humidy.
- Twice the price of a film badge.
Thermoluminescence Dosimetry uses
lithium fluoride (LiF)
what monitor is most frequently used to measure pt. exposure?
Thermoluminescence Dosimetry
disadvantage of Thermoluminescence Dosimetry (TLD)
- Higher cost
- Can only be read once and then reused
- Previous records are erased – therefore no permanent or legal record of exposure
We can Reduce Unnecessary Patient Dose by unnecessary exams of what kind?
-mass screening of TB
-hospital admission
-preemployment physicals
-periodic health exams
-emergency room CT
-Whole body multislice spiral CT screening
-
Reducing Unnecessary Patient Dose
unnecessary exams, repeat exams, technique and positioning
Frequency of repeats may range as high as __
10%
Repeat rate should NOT exceed ___
5%
major cause for repeats
Technologist error
Exams with high repeat rates:
- L – spine
- T – spine
- Abdomen
High Dose Examinations
- CT with an x-ray procedure.
- Helical CT – using multislice
- Fluoroscopy
- C – arm in surgery
CT accounts for ___ of the total patient effective dose
70%
Practices to reduce dose to patients: High kVp technique results in _______
reduced pt. dose
Practices to reduce dose to patients: Digital radiography can be conducted at higher kVp, resulting in ______
lower pt. dose
Practices to reduce dose to patients: Proper collimation is essential especially with________
pregnant patients.
____ screen-film combination should be used to reduce patient dose
Fast
What is most sensitive in early pregnancy?
Fetus
Pregnancy: Higher the dose the ______ will be the radiation response
more severe
Radiation & Pregnancy is ______& ____ dependence
time and dose
Major Organogenesis occur during
2nd – 10th week of pregnancy
First two weeks of pregnancy
- high exposure may cause resorption of the embryo
- no other response likely
- no possibility of the induction of congenital abnormalities
Second week to 10th week
- major Organogenesis
- major organ systems of the fetus developing
- high exposure may cause congenitial abnormalities
___ of all live births exhibit a manifest congenital abnormality.
5%
___ increase there after the exposure of radiation (10 rad).
1%
Spontaneous abortion in the absence of radiation – ____
25% – 50%
Protocol for patient safety
- Elective Booking
- Patient Questionnaire
- Posting
A dose >25 rads (250 mGy) must be acquired to see an increase of risk factors such as:
- Congenital abnormalities (skeletal deformities)
- Neurologic deficiencies
NCRP recommendations:
- No recommendations for abortion after diagnostic x-ray exposure.
- Manifest damage to the new born is unlikely at fetal doses below 25 rad.
Safeguard against the irradiation of unsuspected pregnancy
elective booking
For average fluoro exam, one can assume an ESD of ____
40 mGyt/min
The higher the multislice value, the __________
lower the patient dose will be
