Module 6

Réussis tes devoirs et examens dès maintenant avec Quizwiz!

A single step back from the patient during a fluoro exams would decrease the dose exponentially and the bucky tray slot cover must have a lead cover for this area of at least ____________________.

.25 mm Pb.

Fetus one month occuptional exposure=

0.05 rem (0.5 mSv).

Public frequent exposure=

0.1 rem (1 mSv).

Student < 18 years old=

0.1 rem (1mSv).

Public infrequent exposure=

0.5 rem (5 mSv).

Fetus nine month occuptional exposure=

0.5 rem (5mSv).

Lead aprons must have a min. lead thickness of ________________.

0.5mm.

The recommended cumulative lifetimes exposure for technologists is __________________________.

1 rem X age in years.

In the 1930s and 1940s an exposure of ________________ per day was permissible. This is double the amount today's radiographers are allowed in one year.

1 roentgen.

The dose limit for general public is _______ of occupational.

1/10.

All personnel who have the potential to recieve ________ of the annual effective dose must be monitored.

10%.

Source to tabletop distance must not be less than _________ or 38 cm for fixed fluoro units.

15 inches.

lens of eyes occuptional exposure=

15 rem (150mSv).

When wearing a lead apron if facing the primary X-ray beam ___________ of the body's active bone marrow is covered.

3/4.

Whole body occuptional exposure=

5 rem (50mSv).

Annual occupational exposure limit for dosimetry report=

5 rem.

Skin/ extremities occuptional exposure=

50 rem (500mSv).

HVL: the lead thickness will reduce the intensity of the radiation to __________.

50%.

Lead aprons should be worn at all time during mobile radiography, and the mobile unit switch must allow for __________________ of distance from the unit.

6 Feet.

The radiographer must be at least ____________ away from the X-ray source during mobile radiography.

6 feet.

A ______________ has a skin dose of 250-500m a mean marrow dose of 30, and a gonad dose of 125.

AP abdomen.

______________ of film badges are: simple to use, inexpensive, readily processed by commercial labs, provide a permanent record by lab and in radiology dept.

Advantages.

_________________ of Optically stimulated luminescence OSL are: bimontly readout offered, tamper proof sealed badges, not affected by heat, moisture, or pressure and complete re-analysis available.

Advantages.

_________________ of Thermoluminescent dosimeters TLD are: can be very small, sealed in teflon, minimizing chance of damage, low exposure limit to 5mrem, responsible to X-rays proportional up to 4R, less sensitive to heat, can be worn for 3 months, and are resusable.

Advantages.

_____________________ of pocket dosimeters are: that they provide an immediate exposure reading, they are sensitive to exposures up to 200 mR, and can be reset to record individual exposure readings.

Advantages.

Persons holding during an exam must wear a ____________ and under no circumstances should a pregnant female hold a patient.

Apron.

ALARA=

As low as reasonably achievable.

A _____________ has a skin dose of 150, a mean marrow dose of 10, and a gonad dose of <1.

Cervical spine.

__________ is controlled by positive beam limitation and the automatic adjustment to field size must be accurate within 2% of the SID.

Collimation.

Geiger-mueller detector and ionization chamber type survey meter are ______________________ radiation survey instruments.

Commonly used.

When different mA is used (100 vs. 200) but the exposure time is compensated so that the mAs is the same the output radiation intensity should be _____________.

Constant.

______________ must indicate the conditions of exposure and must be clearly indicated when the beam is on.

Control panel.

____________________ must be provided that produces an audible signal when 5 minutes of fluoroscopic time have been used. This timer is reset with each 5 minutes of use and also with each new fluoroscopy procedure.

Cumulative timing divide.

In the inverse square law:______= original distance from source.

D1.

In the inverse square law:_______= new distance from source.

D2.

_________________= a hand or foot petal controlled by the radiologist , must only be on where there is constant pressure.

Deadman type switch.

_________________ of Thermoluminescent dosimeters TLD are: cannot be stored as a permanent record, and they are more expensive than film badges.

Disadvantages.

_________________ of film badges are: are not reusable, low limit of sensitivity (10 mrem), accuracy limited, and susceptible to heat, humidity, and light leaks.

Disadvantages.

_________________ of pocket dosimeters are: they do not provide a permanent legal record of exposure and bumping or shock to the unit can cause false high readings.

Disadvantages.

____________________ of Optically stimulated luminescence OSL are: more expensive than film badges and TLDs.

Disadvantages.

The best way to reduce radiation exposure to personnel during fluoro by increasing your _____________ from the table. The radiographer should step back from the table whenever not immediately needed and assistance is not required.

Distance.

For a ________________________ badges are collected monthly and reports are sent back and posted where they can be viewed. This report shows the occupational exposure received during the past month. An "m" on the report means minimal or no exposure detected. When you change employment these records will be transferred to your new employer so they can look at each past report.

Dosimetry report.

Measurement of ionizing radiation doses to personnel is termed _______________.

Dosimetry.

______________________ or rationale for radiation protection occurs if human cells respond to a high dose of radiation within days or weeks.

Early effects.

Personnel dosimeters record _____________________.

External doses.

A ______________ has a skin dose of 10-200, a mean marrow dose of 2, and a gonad dose of <1.

Extremity.

____________________ measures occupational radiation exposure and consists of small piece of special radiation dosimetry film, similar to dental film, contained in a light proof packet. Film is changed monthly and shallow and deep doses can be calculated according to the amount of darkening of the film after processing. Usually worn at the collar level and if a apron is worn it must be outside the apron. They should be stored away from sources of radiation, excess heat, and humidity.

Film badges.

All general purpose diagnostic X-ray beams must have a total _______________ (inherent plus added) of at least 2.5 mm Al when operated above 70 kVp. This requirement changes based on the kVp capabilities of the equipment.

Filtration.

____________________: lead aprons must be worn by anyone in the room besides the patient.

Fluoroscopic exam considerations.

_____________ is known as the geiger counter and is normally used to detect alpha and beta radiation.

Geiger Muller.

In the inverse square law: ______= the original distance exposure intensity.

I1.

In the inverse square law: ______= new distance exposure intensity.

I2.

___________________ must be used on patients who are not able to cooperate. The use of this must be explained to the patient, as a last resort this should only be used.

Immobilization.

Radiologists are trained to use ______________ or pulsed fluoro and to collimate to only the area of interest to reduce radiation exposure to the patient.

Intermittent.

I/1 = D2 (2) _____________ I/2 = D1 (2).

Inverse square law formula.

By increasing the distance between the radiation source and the radiographer =, the radiation dose is decreased dramatically. The exposure dose is calculated by using the _________________.

Inverse square law.

The inverse square law states that the intensity of radiation at a given distance from a point source is _______________________ to the square of the distance of the object from the source.

Inversely proportional.

___________________ measures exposure rate from X-ray, gamma, alpha, and beta radiation.

Ionization chamber type survey.

_____________________ of rationale for radiation protection include damage to human cells not detected for months or years. Radiation induced cancer and genetic effects.

Late effects.

The maximum acceptable variation in _______________ is 10% from one mA station to an adjacent mA station.

Linearity.

A _____________ has a skin dose of 300, a mean marrow dose of 60, and a gonad dose of 225.

Lumbar spine.

reduce time, increase distance, and utilize shielding during ________________.

Mobile procedures.

No one tech should always hold the patients, the first choice is a friend or family member preferably male so there is no chance of pregnancy. The second choice should be _____________________.

Non radiology personnel.

_________________________ contains filters composed of aluminum, tin or copper. Also a thin strip of aluminum oxide that is stimulated by a laser light and becomes luminescent in relation to the amount of radiation it has received. Desired for use by pregnant workers as it can measure as small a 1 mrem.

Optically stimulated luminescence OSL.

a ____________ has a skin dose (mrad) of 10-20, a mean marrow dose (mrad) of 2, and a gonad dose (mrad) of <1.

PA chest.

Primary source of exposure to the radiographer during fluoroscopic exam considerations is the ________________ . The tube should be under the patient.

Patient.

A ___________has a skin dose of 150, a mean marrow dose of 20, and a gonad dose of 150.

Pelvis.

Types of _______________ include: film badges, thermoluminescent dosimeters (TLD), optically stimulated luminescence (OSL), and pocket dosimeters.

Personnel dosimeters.

________________ are very sensitive and can provide an instantaneous reading but must be re calibrated daily. They are only capable of a predetermined range if exposure exceeds this range, any additional amounts of exposure cannot be documented. It looks like a fountain pen and has an ionization chamber inside. They are normally used only in emergency situations in which all immediate reading is necessary. They might give false readings if subjected to trauma or high humidity.

Pocket dosimeters.

There are two types of structural shielding construction: 1. 2.

Primary & secondary.

_______________________ of rationale for radiation protection include: hematologic depression, skin erythema, epilation, chromosome damage, gonad dysfunction, and death. Doses at this level are not in modern diagnostic.

Primary early effects.

_________________ structural shielding construction = perpendicular to the line of travel for primary X-rays, should consist of 1/6 inch lead and extends up at least 7 feet from the floor.

Primary.

Three basic principals to reduce an individuals exposure to radiation: 1. reduce the amount of time spent in the vicinity of the radiation source while it is operating. 2. increase the distance between the radiation source and the individual to be protected. 3. interpose a shielding material which will attenuate the radiation from the source.

Principles of personnel exposure reduction.

When using different mA (100 vs. 200) and the time is not changed the increase in output radiation intensity should be ____________________ to the increase in mA.

Proportional.

__________________ serves to reduce radiation assigned safe level and leakage from the X-ray tube housing should not exceed 100 mR/hr at 3 feet (1 meter) away.

Protective tube housing.

The inverse square law is the most effective means of protecting the radiographer from _____________________.

Radiation exposure.

During the inverse square law if the radiographer moves further away from the tube the intensity of radiation decreases. If the radiographer moves closer to the tube the intensity of ______________.

Radiation increases.

_________________________ are used to detect and measure radiation.

Radiation survey instruments.

________________ should be the last preference for holding patients.

Radiographers.

________________________ lessens the likelihood of damage to humans from ionizing radiation.

Rationale for radiation protection.

For any given radiographic technique the output intensity should be constant. This is checked by making repeated exposures with the same technique ( done by a physicist) and the variation in X-ray intensity should not exceed 5%.

Reproducibility.

During a mobile exam, the tech should stand at a _______________ from the patient, less scatter radiation.

Right angle.

Leads high atomic number ensures that most _________________ are absorbed so it is the material most often chosen for shielding.

Scatter photons.

If possible during a mobile exam, the tech should stand around a corner, any radiation that reaches the tech will have _________________.

Scattered twice.

______________________ structural shielding construction= located parallel to the line of travel of the primary X-ray beam, and covers areas exposed only to scatter and leakage radiation, requires 1/32 inch lead and control booths are secondary barriers. X-rays must scatter twice before reaching control console wall.

Secondary.

Early radiographers only acknowledged _________________.

Short term effects.

Voluntary motion may require immobilization, involuntary motion is dealt with by using ______________.

Shorter time.

A _______________has a skin dose of 100-200, a mean marrow dose of 10, and a gonad dose of <1.

Skull.

First fluoroscope users displayed elevated occurrences of skin cancer, cataracts, and lesions of the hands and fingers. In order to minimum health risks _____________ had to be instituted.

Standards.

During a mobile exam, the radiographer would receive the greatest amount of radiation by standing besides the X-ray machine due to the scatter radiation from ____________________.

The patient.

________________ contains lithium fluoride or calcium fluoride crystals and when exposed to radiation these crystals store radiant energy in the form of excited electrons. When these are heated they release light which is measured by a machine that documents the radiation exposure. They are commonly worn as finger rings by nuc med techs.

Thermoluminescent dosimeters TLD.

Three cardinal rules=

Time, distance, shielding.

Age X 1 rem (age X 10 mSv)=

Whole body cumulative life


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