Dosimetry Test 1

When did Wilhelm Conrad Roentgen discover x-rays?

Who discovered radioactivity?

Who discovered radium & polonium? When?

Artificial radioactivity was discovered in ______ by __________

Dose fractionating to achieve the same tumor response with less injury to normal tissue was discovered by

The first therapeutic use of x-rays was on _________.

What is the half-life of Cobalt-60

The gross palpable extent and location of malignant growth:

The tissue volume that contains the GTV and subclinical microscopic malignant disease:

Contains the tumor and adjacent tissues:

The dose at a point that has been "forced" to 100%

What are the limitations of isodose curves?
(3)

The region in which the dose gradually increases until it reaches a certain depth and then falls off due to the increasing thickness:

What is the major factor in determining the depth (d_max) at which dose maximum occurs?

When a photon beam encounters a surface obliquely, D_max moves _________ to the surface.

For electron beams, the D_max and actual dose on the skin surface ________ with beam energy. 
(increase or decrease)

To calculate the energy needed to treat along 90% isodose line for electrons multiply the depth by ______.

To calculate the energy needed to treat along 80% isodose line for electrons multiply the depth by ______.

The angle separating the two central axes:

SSD + depth =

TFD or FFD

EPI

What is the formula used to calculate the MU for electrons?

What is the formula used to calculate the wedge angle?

Rule of Thumb:

When in doubt when calculating energy to for an electron treatment the energy (MeV) should be ____ the maximum depth of the tumor.

The energy of a photon beam divided by four will give you the depth of the beam's _______ in most cases.

What does the RT (T) stand for?

The first linear accelerator was developed by ____________ in ______.

The purpose of this machine is to duplicate the geometry & mechanical movements of radiation therapy machine, what is it?

What are the three primary methods of dose determination in a radiation therapy department?

The ________ expresses the penetration and the quality or hardness of a beam.

The thickness of a material that reduces the intensity of the beam to half of its original value:

What is the ratio of the absorbed dose at a given depth to the absorbed dose at a fixed reference point, usually D_max ?

What is the ratio of the absorbed dose at a given depth in tissue to the dose at the same point when it is at D_max ?

The region near the edge of the field margin where the dose falls rapidly:

The angle through which an isodose curve is tilted at the central axis of the beam at a specified depth.

What is the correction factor of the lung?

When a tumor is not situated at mid-depth, it can be beneficial to deliver a higher dose from the field where the tumor is shallower by ________ the beams.

The wedge angle needed depends on the:

What is the formula used to find the necessary gap size?

Define:
BSF

Dose rates _________ with field size.
(increase or decrease)

What is the ratio of the dose rate of a given field size to the dose rate of the reference field size?

The intersection of the horizontal and vertical axes of rotation is referred to as the ___________.

The _____ axis represents the patient's left-to-right direction.

The ______ axis represents the cephalad-to-caudal direction.

The _____ axis represents the anterior-to-posterior direction.

What is the name of a tissue equivalent material used to eliminate the skin sparing effect?

Tissue-equivalent materials used in megavoltage radiation therapy to reduce the depth of the Dmax is called:

A sheet of Lucite placed in the beam to reduce it's depth of D_max is called a ___________.

What energy range does a conventional simulator operate in?

The dose delivered to a patient is dependent upon these six factors:

What was the only measure of exposure for the early pioneers of xrt

The Manchester system of radium distribution was developed by:

The pentrometer to measure the quality of x-rays was introduced by:

The Roentgen was internationally accepted as a unit of measure for x-rays and gamma rays in:

The rad as a unit of absorbed dose was recommended by the ICRU in:

The use of betatrons in XRT became unpopular because:

Radiation therapy units operating at approx 50-120 kVp are:

Insertion pf aluminum, copper & tin filter into the x-ray beam causes ________ to be absorbed

Orthovoltage units usually operate at:

Orthovoltage units usually operate in the energy range of :

Orthovoltage beams are generally _______ penetrating than superficial beams

LINACs were first developed:

LINACs produce high energy beams by accelerating CHARGED particles in a ___________

Because electrons scatter readily in air ________ extending close to the patient's skin are used

A collimator _____ the beam.

The photon beam from a LINAC is intercepted by:

A flattening filter reduces the __________ in the center of the unfiltered beam

The first Co-60 machine was introduced in:

The average energy of a Cobalt 60 beam is:

The half-life of Cobalt 60 is:

The penumbra of a LINAC is ______ than that of a Cobalt 60 machine

The point around which the source of the beam rotates

The secondary collimators are largely responsible for the _________ of the beam edges

Simulators are primarily used to:

A HVT is a way of expressing the _______ of a beam.

Dose rates in air express:

Dose rates ________ with increased field size & ________ with increased distance.

Increasing the distance from 80 to 90 cm causes the dose rate to change by:

Percentage depth dose is dependent on:

The TAR at 5 cm depth for a 10x10 field minus the TAR at 5 cm depth for a 0x0 field gives the:

The width of penumbra increases with:

In a fixed SSD technique, the dose is usually normalized: 

In an isocentric technique, the dose is usually normalized:

In a typical electron beam, only the ______ to ______ isodose lines bulge out in the penumbra region, causing great difficulties in matching adjacent electron fields uniformly

Photon isodose curves used in dose calculations on a patient usually require corrections for:

Electron isodose curves used in dose calculations on a patient usually require corrections for:

The depth of Dmax for any photon beam energy is reduced by:

Treatment fields should always be shaped so that the beam edge:

In port films of parallel opposed isocentric fields of a lung tumor, the _________ field will appear to include a longer segment of the spinal cord than in the _________ field.

To minimize the gap between two adjacent fields a ___________ can be used.

When adjacent areas must be treated, it is best to calculate the _____ necessary between fields to prevent overlap.

When an isodose curve of about 22° is needed, isodose charts for an ______ and a _____ are used.

In an electron beam, the _____ isodose curve bulges and the _____ isodose curve constricts.

When parallel opposed 6 mV photon beams are used in a 20 cm thick patient, the maximum dose will occur at:

When a 4 mV and a 15 mV photon beam are used to treat parallel opposed fields in a 20 cm thick patient, the dose in the entrance/exit region is highest when the _____ beams are used.

When a sector is skipped in an arc technique, the high dose area is shifted away from the __________.

When parallel opposed fields are used with the isocenter at mid-depth & one field is weighted twice as much as the other, the maximum dose is in the:

To minimize the risk of hot or cold spots in the junction between photon fields, the gap should be:

Matching of electron beams on a chest wall is more difficult because some isodose curves _______ and others ______.

The angle of beam divergence is ________ farther from the central axis

When parallel opposed fields are used & the isocenter is at mid-depth in the chest, the length of the spinal cord is:

The three planes in a patient are across the body, along the body in a lateral view & along the body in an anterior view. Respectfully, these are referred to as:

When a patient is re-aligned with a laser alignment system, it is necessary to align:

Treatment planning CT's are different diagnostic CT's because:

The anterior & posterior skin surfaces seen on a lateral radiograph of a patient's pelvis does not represent the patient's:

Discrepancies in the patient/beam alignment between the first port film & the simulation film may be due to:

When the location of a contrast-filled bladder is transported from a set of orthogonal films to a transverse contour of the pelvis, the _______ film yields info in the right/left & cephalad/caudal directions while the ______ film yields info in the ant/post & cephalad/caudal directions

Uncertainties associated with delivering XRT can be totally avoided by:

When the treatment fields are designed by the RadOnc, margins are always added around a tumor to account for: