radiation safety

The HU for fat is

-100 HU

1 rad is equivalent to how many Gray?

0.01 Gy

The tolerance for gantry rotation check is

1 degree

Exposure is 400 mR at 90 cm. What will the exposure be at 180cm?

100 because of inverse square law

10 Sieverts is equivalent to how many rem?

1000 rem

What is the tolerance for the daily check of linac output constancy?

3%

Beyond which atomic (Z) number do elements generally exhibit increasing instability and become predominantly radioactive?

82

The point on a dose-response relationship graph that shows the cells radiosensitivity:

D0

Under established quality assurance protocols (such as those recommended by AAPM TG-142), at what minimum frequency must safety indicator lights—such as treatment room 'beam on' lights and warning signals—be tested?

Daily

In the context of quality assurance, what describes the recommended tolerances for safety interlock tests, and why are these tolerances critical for maintaining both patient and staff safety?

Door interlock systems must prevent beam activation when the treatment room door is open, with functional tolerances

A Sievert (Sv) is a unit used to measure which of the following, and how does it relate to the biological effects of radiation?

Dose equivalent, considering both the energy deposited and the biological impact of different radiation types.

The point on a dose-response relationship graph that represents the cells capability to repair:

Dq

What type of radiation dose is typically monitored using personnel dosimeters?

Equivalent dose

what does HU mean??

Hounsfield Units

The brachytherapy application method in which the radioactive source is placed within a body tube is:

Interluminal

In the context of brachytherapy for gynecological cancers, tandem and ovoid applicators are classified as which type of implantation technique, and what key characteristic distinguishes this method in terms of source placement within the patient's anatomical cavities?

Intracavitary brachytherapy, using applicators positioned within a natural body cavity.

In modern brachytherapy, a remote afterloader can be used to position a radioactive source embedded in a flexible nylon ribbon for targeted dose delivery. Which radionuclide is commonly employed in this configuration?

Iridium-192

Atoms that have the same number of protons, but differ in number of neutrons is referred to as a(an):

Isotope

How often should emergency switches be checked?

Monthly

What fundamental role does the beam flattening filter serve in shaping the photon beam?

Produce a uniform photon beam

What is the primary source of background radiation?

Radon gas released from the decay of uranium in soil and rock

What can be used as a tissue compensator?

Shaped bolus Wedge Cerrobend Dynamic MLC

In radiation dosimetry, which device detects absorbed ionizing radiation by releasing stored energy as visible light upon controlled heating, thereby providing a quantitative measure of the accumulated dose?

TLD (Thermoluminescent dosimeters)

Which radiation instrument is used to calibrate ion chambers in a linac?

Thimble chamber

What is the purpose of the safety questionnaire during magnetic field screening?

To identify any potential safety concerns or contraindications

What type of radiation area has radiation levels that are expected to be within regulatory limits and poses minimal risk to individuals?

Unrestricted area

The average or median of all the shades of gray on a CT image is:

Window level

The spectrum of different shades of gray or contrast on a CT image is:

Window width

Which radioactive source has the shortest half-life?

Yttrium

The power source for the waveguide is:

modulator

How often should emergency switches be checked?

monthly

Which of the following radiation areas is typically accessible only to authorized personnel with specific training and authorization?

restricted and controlled

Radiation therapist control room is considered...

restricted and controlled area

Which of the following examples requires a secondary radiation barrier?

scatter radiation and leakage

Which exposure factor primarily controls the quality or penetrating power of the x-ray beam in the diagnostic range?

kVp