RADPRO II

PRIMARY RADIATION

• The most intense, most hazardous and difficult to shield. It is also called the useful beam.

PRIMARY BARRIER

• is any wall to which the useful beam can be directed

COMPOSITIONS: Lead bonded to sheet rock or wood panelling –

Concrete, concrete block or brickb can also be used instead of lead.

1/16 of lead.

Rule of thumb is 2 inches of masonry is equivalent to _______

SCATTER

Results when useful beam intercepts at any object.

LEAKAGE

• Radiation emitted from the xray tube housing in all directions over than that of the useful beam.

SECONDARY BARRIERS

Protective barriers desined to shield areas from secondary radiation and less thicker than primary protective barriers.

• Usual materials used are conventional gypsum board, glass,or lead acrylic is adequate.

5/8

Walls can be protected adequately with 4 thicknesses of _______ in gypsum board.

DISTANCE

The ______ to the adjacent room not to the inside of the wall of the x-ray room.

MIDDLE

X-ray Imaging System: must be position in the ______ of the room

CONTROLLED

area occupied by the radiology personnel and patients. Barrier must reduce the exposure of workers to this area to less than 1 mSv/wk or 100 mRem/week.

UNCONTROLLED

maximum exposure rate allowed is based on the recommended dose limit for the public of 1mSv/year or 100 mRem/yr. It is equivalent to 20 uSv/wk or 2 mRem/wk.

25 uSv or 2.5 mRem

Barrier should ensure that no individual will receive

more than _________ in single hour.

WORKLOAD

• Expressed in mAmin/wk.

• Product of the maximum mA & the number of x-ray examinations performed per week

500 mAmin/week

Busy, General Purpose X-ray Room WORKLOAD

<100 mAmin/week

Private Office WORKLOAD

USE FACTOR (U)

The percentage of time during which the x-ray beam is on & directed toward a particular protective barrier

1/4 - 1

The use factor of walls is______ while floor has a use factor of ___.

100KVP

General Radiography KVP

30KVP

Mammography KVP

150 kVp

Modern X-ray Imaging System

75 KVP

Most Examination KVP

dosimetry - dosimeters

Instrument designed to measure intensity of radiation operates at integrate mode

PHOTOGRAPHIC EMULSION

The earliest radiation detection device

personnel radiation monitoring

• Provides an indication of the working habits and working conditions of diagnostic imaging personnel.

• Determines occupational exposure by detecting and measuring the quantity of ionizing radiation to which the dosimeter has been exposed over a period of time.

COLLAR LEVEL

When a protective apron is not being used, the primary personnel dosimeter should be attached to the clothing on the front of the body at _______

GAS FILLED DETECTORS

• Based on the principle of ionization of gas.

• Used to measure radiation intensity and detect

radioactive contamination.

CYLINDER OF GAS

• USUALLY AIR OR ANY NO. OF GASSESS

XENON

• (UNDER PRESSURE)

• USED TO MEASURE X-RAYS IN SOME CT SCANNERS

CENTRAL ELECTRODE

• RIGID WIRE POSITIONED ALONG CENTRAL AXIS OF THE CYLINDER

Region of Recombination

If voltage across the chamber of the ideal gas filled detector is increased slowly from 0 to high level, the signal with fixed intensity

will increase in stages

Region of Continuos Discharge

• Because of high voltage, electrons continue to stripped off from atoms of the filling gas, producing a continuous currrent or signal from the chamber.

• Instrument is useless for detection of radiation and continuous use can result to damage

ION CHAMBER

• a level where electrons released in ionization is attracted to the electrode.

Cutie Pie

• A portable instrument used for diagnostic and therapeutic beams and used principally for radiation area surveys.

• It can measure a wide range of intensities from 1mR/hr to several thousands R/hr

• It is usually the instrument of choice when determining exposure rates from patients containing therapeutic doses of radioactive materials and when assessing the exposure rates in radioisotope storage facilities

Dose Callibration Ion Chamber

• Used to accurately measure quantities of radioactive material use in nuclear medicine laboratories.

PROPORTIONAL COUNTERS

• ARE SENSITIVE INSTRUMENTS USED PRIMARILY FOR ASSAY OF SMALL QUANTITIES OF RADIOACTIVITY

• Used primarily as stationary laboratory instruments for the assay of small quantities of radioactivity. They have the ability to distinguish between alpha and beta radiation.

Geiger-Muller Detector

• detector serves as the primary portable radiation survey instrument for area monitoring in nuclear medicine facilities

• A quenching agent is added to the filling of the G counter to enable the chamber to return to its original condition.

• Used for contamination control in nuclear laboratories.

• Not useful as dosimeters because they are difficult to calibrate

• Does not have a very large wide range.

• WORK IN PULSE MODE

• It can be used to locate a lost radioactive source or low-level radioactive contamination

• may also be employed to scan radiation barriers for any shielding defects

• With the exception of alpha particle emission, the unit is sensitive enough to detect individual particles

Geiger Muller Region

the region where GM counters operate

SCINTILLATION DETECTORS

• Basis of gamma camera used in NucMed, detector arrays in CT, and image receptor for several types of digital imaging systems.

• are used most often to indicate individual ionizing events and are incorporated into fixed or portable radiation detection devices

• They can be used to measure radiation in the rate mode or the integrate mode.

Liquid scintillation counters

• have nearly 100% detection efficiency for beta radiation

• used frequently in the research laboratory to detect low energy beta emission from Carbon 14 and Tritium

SCINTILLATION PROCESS

• When a material is irradiated, it emits a flash

of light in response to absorption of xray.

• Only those materials with a particular

crystalline structure will scintillate.

• At the atomic level, the process involves the

rearrangement of valence electrons into

traps. The return of the electron from the trap

to its normal position is immediate in

scintillation and delayed in luminiscence./

Thallium activated Sodium Iodide (NaI:Tl)

crystals are incorporated in gamma cameras

Thallium activated Cesium Iodide (CsI:Tl)

phosphors are incorporated into image intensifier tubes as the input phosphor and into flat pannel digital radiography IRs.

Hermetic seal

prevents crystal from coming into contact with

air

Glass envelope

provide structural support and maintains

vacuum inside the tube.

Optical coupling

sandwiched between the PMT and the

window so light is transmitted with minimul loss.

Photocathode

metal coating consist of cesium, antimony

and bismuth; it is where electrons are emitted.

Dynodes

first series of plate like elements where electrons

are accelerated. .

Film Badges

Film badges are economical and can be used to

monitor large numbers of personnel in a cost

effective manner.

3 PARTS

● A durable, lightweight plastic film holder

● An assortment of metal filters

● A film packet

FILM HOLDER

should be made of a plastic material of a low

atomic number to filter low energy x-radiation, gamma radiation,

and beta radiation

metal filters

Inside the plastic holder are ______of aluminum or copper

that are secured in a permanent position.

0.1 - 5000 mSv

The radiation-dosimetry film contained in the radiographic film

packet is similar to dental film. This film is sensitive to doses

ranging from as low as _____ mSv (10 mrem) to as high as _____

DENSITOMETER

used to measure this density. It measures optical density, the intensity of light transmitted through a given area of the dosimetry film, and compares it with the intensity of light incident on the anterior side of the film

ADVANTAGE OF FILM BADGE

• The main advantage of the film badge is that the radiographic film

itself, constitutes a permanent legal record of personnel exposure

• The film badge is reasonably economical

• It can be used to record exposure to x-radiation, gamma radiation,

and all but very low-energy beta radiation in a reliable manner.

• Another advantage is its mechanical integrity.

DISADVANTAGE OF FILM BADGE

Temperature and humidity extremes or wetting can

cause fogging of the dosimetry film over long periods

of time

THERMOLUMINISCENCE DOSIMETRY

• Emission of light by a thermally stimulated crystal following

irradiation.

• Lithium fluoride is the most widely is widely used material. It

has Z of 8.2 and exhibits xray absorption properties similar

to those of soft tissue.

• Lithium fluoride is relatively sensitive. It can measure doses

as low as 50 uGyt with modest accuracy ;at doses excededing 100 mGyt, accuracy is better than 5%

CALCIUM FLUORIDE

_______activated with manganese has a higher Z (16.2) than LiF making it more sensitive to ionizing radiation. It can measure radiation doses of less than 10 uGyt, with moderate accuracy.

ADVANTAGE OF TLD

• It has an advantage in terms of size.

• It can be obtained in its powdered form: allowing irradiation in nearly configuration.

• It is reusable.

• It responds proportionally to dose.

• It is rugged,useful in monitoring dose in small areas.

• It does not respond to single ionizing event: cant be used in rare meter type of instrument.

• It is suitable only for integral dose measurements but doen't give immediate results.

TLD ANALYZER

measures the amount of ionizing radiation to which a TLD badge has been exposed by first heating the crystals to free the trapped, highly energized electrons and then recording the amount of light emitted by the crystals (which is proportional to the TLD badge exposure)

OPTICALLY STIMULATED LUMINISCENCE DOSIMETRY

• Developed in 1990 by Landauer.

• It uses aluminum oxide as the radiation detector.

• The intensity of light emission is proportional to the dose received by the Aluminum Oxide.

• This radiation monitor is the most common type of device used for monitoring of occupational exposure in diagnostic imaging

• provides a new degree of sensitivity by giving an accurate reading as low as 1 mrem for x-ray and gamma ray photons with energies ranging from 5 keV to greater than 40 MeV

● Aluminum (Al)

● Tin

● Copper (Cu)

ADVANTAGE OF OSL

• More sensitive than TLD.

• Has a precision of 10 uGya

• Reanalysis ofor confirmation of dose, qualitative information about exposure conditions, wide dynamic range, long term stability.

laser light

The OSL dosimeter contains an aluminum oxide (Ah03) detector

(thin layer). The dosimeter is "read out" by using ________ at

selected frequencies

Pocket Ionization Chamber

• is the most sensitive type of personnel dosimeter

• Resembles an ordinary fountain pen, but it

  contains a slender cylindrical (thimble) ionization

  chamber that measures radiation exposure.

self-reading type

which contains a built-in electrometer (a device that measures electrical charge

non-self-reading type

which requires a special accessory electrometer to read the device

Special Charging Unit

required for pocket ionization chambers.

• Each dosimeter must be charged to a predetermined voltage

before use so that the quartz fiber indicator shows a zero (0)

reading

ADVANTAGE OF POCKET IONIZATION CHAMBER

• _______was used to provide immediate

exposure readouts

• ________ were compact, easy to carry, and

convenient to use.

• Reasonably accurate and sensitive, they were useful monitoring

devices for procedures of relatively short duration.

DISADVANTAGE OF POCKET IONIZATION CHAMBER

• _______ are fairly expensive, costing $150 or

more per unit

• If not read each day, the dosimeter may give an inaccurate reading

because the electric charge tends to escape

• In addition, _______ can discharge if they are

subjected to mechanical shock, which again would result in a false

high reading.

Extremity Dosimeter/TLD ring

be worn by an imaging professional as a second monitor when performing fluoroscopic procedures that require the hands to be near the primary x-ray beam.

Entrance Skin Dose

-referred to as patient dose.

widely use To measure:

you can use TLDs, nomograms, knowing the output intensity in

at least one condition

-ESD in fluoroscopy is difficult to estimate

40 mGya/min

For an average fluoroscopic examination, one can assume an ESD of _______.

Mean Marrow Dose

-average radiation dose in the entire bone marrow.

Genetically Significant Dose (GSD)

Is the gonad dose that if received by any member of the population, would produce the total genetic effect on the population as the sum of the individual doses actually received.

1.0mGyt

The ESD for CC view is mGya and the dose to the midline of the breast is only

8 mGyt.

ESD MLO view is

2.4 mGyt

Total Dg of mammogram

1mGya/view - 3 mGya /view

Glandular dose should not exceed _______ with contact mammography and _________ with grid.

50%

CT dose is approximately ______ of the ESD for thebody.

30-50 mGyt

Head imaging: CT dose ranges from

20-40 mGyt.- 10 mSv.

body imaging in CT. Effective dose for each examination is approx ______

UNNECESSARY EXAMINATION

• Mass Screening for TB

• Hospital Admission

• Preemployment Physicals

• Periodic Health Examinations

• Emergency room CT

• Whole Body Multi Slice Helical CT

REPPEAT EXAMINATION (5%)

The rate of _________ should not normally

exceed________

• Examination with high repeat rates include lumbar

spine, thoracic spine, chest, and abdomen.

IMAGE RECEPTOR

Fastest speed screen film combination consistent with nature of examination should be used.

PATIENT POSITIONING

Make sure that xray beams are not directed to

gonads and provide protected apron as a

shield.

CONTACTS SHIELDING

positioned directly to patient such as lens, gonads, breast

SHADOW SHIELDING

better for adult patients;used for surgery in which

sterile procedure is required. Improper positioning of the

shallow shield can result to repeat examination and

increased patient dose.

USE GONADAL SHIELD

• patient is younger than 40 years old and even older men.

• gonads lie in or near the useful beam.

• Proper positioning and beam collimation should not be relaxed

when gonad shields are used.

• does not interfere with obtaining required diagnostic procedure

250 mGy

spontaneous abortion after irradiation is unlikely at radiation doses less than

10 DAY RULE

• A guideline used to minimize the possible exposure to

an embryo in the earliest days of a pregnancy.

• Elective abdominal x-ray exams of fertile women

should be postponed until the _____ period following

the onset of menstruation .

Elective Booking

• Most direct way to ensure agains the irradiation of

suspected pregnancy; Ask the patients LMP

Patient Questionnaire

• Patient is given an information form that must be completed first before doing the examination.

• Include question like "Are you or could you be pregnant?" or "When was the date of your LMP?"

Postings

• Considered as equally successful method.

• Ex: Are you pregnant or could you be? If so, inform the radiologic

technologist,”

• We meet our responsibility to the pregnnat patient by posting signs in the waiting room.

FLUOROSCOPY

• Contributes to the highest occupational exposure of diagnostic x-ray personnel.

• Personnel exposure is related directly to the xray beam-on time

• In remote _____, personnel exposures were low because personnel is not in the examination room.

INTERVENTIONAL RADIOLOGY

• Personnel receive higher exposures : longer beam on time, absence of protective curtain on the image intensifier, use of cineradiography.

• REQUIREMENTS: lead gloves and extremity monitoring

SURGERY

• Occupational exposure for nursing personnel & other working in the operating room & intensive care unit is near zero.

• Not necessary to provide occupational radiation monitors for such personnel.

MOBILE RADIOLOGY

• Contributes to the highest occupational

exposure of diagnostic x-ray personnel.

• Dose Limit: 50 mSv/yr (5000 mrem/yr) •

Smaller Hospitals, Emergency Centers &

Private Clinics: rarely exceeds 5 mSv/yr (500

mrem/yr)

• Average Exposures: <1 mSv/yr (100 mrem/yr)

In most facilities

MAXIMUM PERMISSIBLE DOSE

Dose of radiation that would

be expected to produce no significant radiation effects.

• It is now obsolete and is replaced by Dose Limits.

500 mSv/week - 1 mSv/wk.

The first DL recommended in 1902 was ________ The

current DL is_______

50 mSv (5 rem)

ANNUAL OCCUPATIONAL EXPOSURE

10 mSv x age

CUMULATIVE OCCUPATIONAL EXPOSURE

150 mSv(15rem)

LENS OF THE EYE OCCUPATIONAL EXPOSURE