Exam 4 Ch 37- Radiation/Fluoroscopy Patient Radiation Dose Flashcards
types of imaging (3)-
-projection imaging
-emission imaging
-reflection imaging
projection imaging-
x-rays emitted from a source, projected on a subject, & captured remnant beam
projection imaging ex.-
radiography, fluor, & CT
emission imaging ex.-
PET & MRI
reflection imaging ex.-
DMS
2 reasons for patient radiation dose concerns-
-med. imging. plays larger role in diagnosis
-stochastic effect risk increase
stochastic effects ex.-
cancer & non-expected life span shortening
4 ways to express pt. dose-
-enterance skin exposure (ESE)- equated w: pt. dose
-mean marrow dose (MMD)
-genetically significant dose (GSD)
-tissue dose
MRI & DMS-
has no radiation concerns at all
Entrance skin exposure (ESE) reporting pt. dose most often used due to-
ease of measurement (easiest to measure)
mean marrow dose (MMD) reporting pt. dose-
-radiation-induced leukemia
-estimated not measured
gonadal dose reporting pt. dose-
-exposure to reproductive organs
-can be measured/estimated
reporting pt. dose most likely response of human tissue to x-radiation is-
no response
Enterance Skin Exposure (ESE) most often referred to as-
pt. dose
Enterance Skin Exposure (ESE) measured by-
TLD/OSL- if in control setting it’s accurate within 5%
Enterance Skin Exposure (ESE) estimated by using a-
nomogram (must be specific for each system)
Enterance Skin Exposure (ESE) uses inverse square law IF-
ESE is known at 1 distance
in digital radiography, ESE is-
30%-50% lower than film screen
in digital radiography, ESE is due to the advantage of-
receptor response
ESE exit skin dose is appx.-
1% ESE
mean marrow dose Is estimated bec of-
possible hematologic effects of radiation exposure
avg. pt. dose in US is-
appx. 1 uGy(t)/yr (100 mrad/yr)
pt. dose should present-
no hematological response
pt. dose used for research due to-
cumulative dose & specific late effect: leukemia
gonadal dose is more important to understand as-
a population/offspring than as an individual
genetically significant dose-
-radiation dose to gene pool
-if received by every member. would produce total genetic effect on population
genetically significant dose in US is-
0.2 mGyt/yr
tissue dose-
computer generated anthropomorphic phantom
each tissue type & organ has-
level of radiosensitivity
tissue dose in skin is-
relatively radio resistant, but is of primary concern
skin burns from-
fluoro procedures
Digital Radiographic Tomosynthesis-
newest imging. modality
Digital Radiographic Tomosynthesis may reduce-
number of CT exams
Digital Radiographic Tomosynthesis approved for-
mammo
Fluoro Patient Radiation Dose increases w:-
high level fluoro use
ESE estimation is difficult-
-directly related to exposure time
-should be measured
digital fluoro reduces-
pt. dose- time is decreases
sentinel event is the center for-
devices & radiation health
sentinel event determines-
any fluoro event where pt. receives more than 15 gray in tissue should be documented & considered a sentinel event
sentinel event measurement-
15 Gyt
dose area product-
quantity of radiation & amt. of tissue exposed
increasing field size increases-
DAP even if dose remains the same
DAP meters are positioned-
b/w collimator & pt.
DAP expressed in-
units of mGya-cm^2