Lecture 19 - Management of Patient and Personnel Dose in Diagnostic X-Rays and Radiation Therapy

ONCOL 243 - Radiation Safety

What can poor communication with the patient cause

repeat exposures, improper treatment and increased patient uneasiness

ways to reduce patient exposure to radiation

use proper immobilization, adequate filtration, shielding, motion reduction, etc

consequences of blurred x-ray images

examination needs to be repated, causing additional exposure

• or improper dose delivery with radiation therapy

how to reduce patient motion

motion reduction techniques or immobilization

two types of patient motion

1. voluntary motion

2. involuntary motion

why is protective shielding needed

to minimize radiation exposure to patients and healthcare personnel.

what areas of the body should be shielded

1. lens of eye

2. breasts

3. reproductive organs

4. thyroid gland

female reproductive organs recieve about _____ more exposure after pelvic irradiation than men

3 times more

if an x-ray machine doesnt have automatic exposure control, what should it have?

a standardized technique chart

____ kVp and ____ exposure time reduces patient dose

higher kVp, lower mAs

What is the air gap technique

A method to reduce patient dose in radiography by increasing the distance between the patient and the image receptor, which minimizes scatter radiation.

Consequences of repeat images

include increased patient exposure to radiation and potential delays in diagnosis.

• double dose

3 examples of uneccessary radioloc proceures

1. CXR for admission to hospital

2. CXR for preemployment physical

3. CXR for routine health checkup

what type of dosimeters are used to directly measure skin dose

thermoluminescent dosimeters (TLDs)

why is ESE (entrance skin exposure) the most reported dose

simplest to determine

if a patient is pregnant but needs an x-ray, what do you do

Assess risks and benefits, consult a physician, and use shielding when possible.

• consult the RSO

most medical procedures result in fetal doses less than

0.01 Gy

what should you do if patient who is unknowingly pregnant is irradiated

Monitor fetal exposure and evaluate potential risks; consult with a specialist for further guidance.

• figure out as much of the informtion on the x-ray exam as possivle

• contact RSO

• determine EqD

how often should women 50-69 be screened with mammos

every 2-3 yearsto detect breast cancer early.

what CT scan gives the higest dose

multi slice spiral CT scanners with small slice thicknesses

is there more or less scattered radiation in CT

less

• due to tight beam collimation

what is the risk of cancer from a dose from a CT scanner

The risk of cancer from a dose from a CT scanner varies but is generally considered low. It is estimated that the lifetime risk of developing cancer increases by about 0.1% for each CT scan.

who is more radiosenstive, adults or children

Children are more radiosensitive than adults due to their rapidly dividing cells and greater susceptibility to radiation effects.

• CT scans early in life increase cancer incidence in adults

are men or women more radiosensitive

Women are generally more radiosensitive than men due to biological differences in tissue composition and hormone levels.

what is the image gently campaign

three categories of radiation in an x-ray room

1. primary

2. scatter

3. leakage

scatter and leakage radiation are known together as

secondary radiation

imaging procedures that have increased risk of exposure to radiographers

EfD does not include

personal medical exposure and natural background exposure

annual occupational EfD

50 mSv

three basic principles of ALARA

1. time

2. distance

3. shielding

what is the major source of scattered radiation to the radiographer

the patient

• via compton interactions

where should a radiographer stand if he needs to be in the x-ray

90 degrees from primary x-ray beam

technical parameters that impact exposure

Effectiveness of shielding material depends on what 3 things

• atomic number

• density

• thickness

purpose of primary protective barriers

prevent direct unscattered radiation from reaching personnel

purpose of seconday protective barrier

protect against leakage and scatter radiation

• ensure maxmimal protection for personnel

• can have observation window made out of lead

what can lead-acrylic overhead barriers be used for

to provide open view during special procedures

• 0.5 mm lead equivalent protection

when are lead gloves used

if the patient needs to be restrained during imaging

when are thyroid shields used

during fluoroscopy

protective eyeglasses

used to reduce scatter radiation to lens of eye

what is the protective tube housing on x-ray machines used for

what is a spot fil device used for ?

minimize exposure to technologists during fluoroscopy

what is a bucky slot

protects radiographer at gonadal level

which imaging procedures result in technologist receiving highest dose

where is the safestly place to position C-arm fluoroscope

x-ray tube of arm under table and image intensifer over the table

ways to minimize exposure during c-arm fluoroscopy

ways to reduce dose in interventional procedures

where should the radiographer stand during the procedure

90 degrees from beam

are pregnant radiographers permitted to assist in holding patient during treatment

no, never

protocol for pregnant radiographers

see last 5 slides

• essentially try to minimize dose as much as possible

how much lead must be in the doors to x-ray rooms

at least 0.8 mm