Ch 37 Patient dose Flashcards
Exposure to medical radiation is up ___% in the U.S
18%
Patient dose is usually estimated by conducting simulated x-ray exams with human ________ and test objects.
Phantoms
What are the (3) ways patient dose from diagnostic x-rays can be reported?
- Entrance Skin Exposure
- Bone Marrow Dose
- Gonadal Dose
What is Entrance Skin Exposure?
- Most common way to report dose
- Easy to measure directly
What is Bone Marrow Dose?
- Target area for Leukemia
- Cannot be measured directly
- Calculated from ESE
What is Gonadal Dose?
- Target for genetic effects
- Easy to measure or estimate
What is ESD (Entrance Skin Dose) most often referred to as?
Patient Dose
How long can a TLD (Thermoluminescence Dosimetry) be worn?
Up to 3 months
TLD’s are highly ______ and compact.
Sensitive
_____ use a Lithium Fluoride sensing agent
TLD’s
What type of monitor is used to frequently measure patient exposure.
TLD’s
TLD’s are ____ the price of a film badge.
Twice
TLD’s can measure as low as ____ millirem.
1
What are the disadvantages of TLD’s?
- Higher cost
- Can only be read once and then reused
- Previous records are erased
- No permanent record of exposure
What are examples of some unnecessary exams?
- Mass screening for tuberculosis
- Hospital admission
- Preemployment physicals
- Periodic health examinations
- ER CT
- Repeat exams
- Technique and positioning
What are the exams with the highest repeat rates?
- L-spine
- T-spine
- Chest and Abdomen
What is the major cause for repeats?
Technologist error
Repeat rate should not exceed ___%
5%
Frequency of repeats may range as high as ___%
10%
What are some examples of high dose examinations?
- CT with an x-ray procedure
- Helical CT- using multi slice
- Fluoroscopy
- C arm in surgery
CT accounts for ___% of the total patient effective dose.
70%
Proper ________ is essential, especially with pregnant patients.
Collimation
Digital radiography can be conducted at ____ kVp, resulting in lower patient dose.
Higher
Fast screen film combination should be used to ____ patient dose.
Reduce
When is Major Organogenesis?
2nd- 10th week of pregnancy
The higher the dose the more _____ the radiation response.
Severe
What is major organogenesis?
The major organ systems of the fetus developing
The most likely biologic response to irradiation during the first 2 weeks of pregnancy is ______ of the embryo, and therefore no pregnancy
Resorption
What time during pregnancy is the least hazardous to receive irradiation?
The first two weeks
Early in organogenesis if radiation dose is sufficiently high what is the most likely abnormality to occur?
Skeletal deformities
Later in organogenesis if radiation dose is sufficiently high what type of abnormalities can occur?
Neurologic deficiencies
___% of all live births exhibit a manifest congenital abnormality
5%
What is the chance of a spontaneous abortion in the absence of radiation?
25-50%
A 1% increase in congenital abnormalities happen after the exposure of a ___.
10 rad
What is the protocol for patient safety to check for pregnancy?
- Elective Booking
- Patient Questionnaire
- Posting
What is the dose required to see an increase in risk factors such as congenital abnormalities and neurologic deficiencies?
Greater than 25 rads
Manifest damage to the new born is unlikely at fetal doses below…
25 rad
After a diagnostic x-ray exposure, what is the recommended dose before an abortion is recommended?
There is none
For the average fluoroscopic exam, one can assume an ESE of …
40 mGy/ min
Glandular dose is approximately ___% of ESE.
15%
