Chapter 22 CT Sim Procedures

Question 1

It may be used in a variety of forms, including
EPID, an in-room CT scanner, kV cone beam computed tomography, MV cone beam computed tomography, ultrasound and others. Rational for IGRT is to image the patient just prior to treatment, compare the position of external set-up marks and internal anatomy to the treatment plan.

Answer 1

image guided radiation therapy (IGRT)

Question 2

Diagnostic, nonionizing means of visualizing

internal anatomy through noninvasive means. Imaging is based on the magnetic properties of the hydrogen nuclei.

Answer 2

magnetic resonance imaging (MRI)

Question 3

Nuclear medicine procedure that has become
useful in oncology to examine the biochemical or physiological (functional) aspects of a tumor. This diagnostic tool is useful in determining the physiology of the organ in question. Beneficial diagnostic
tool that may be useful in determining differences
between necrosis and malignancy, which are associated with areas of high metabolism.

Answer 3

positron emission tomography (PET)

Question 4

Single-photon emission computed tomography

Answer 4

Single photons are imaged from gamma ray source. SPECT can be used to assess lung perfusion and assess amount of functional lung tissue.

Question 5

Devices that restrict movement but require a patient’s

voluntary cooperation.

Answer 5

immobilization devices

Question 6

Geometrical definition of the tumor and anatomic structures using surface and/or fiducial marks for
reference

Answer 6

Localization

Question 7

Process carried out by the radiation therapist under the supervision of the radiation oncologist. It is part of the treatment planning procedure, which delineate
the treatment fields and construct any
necessary immobilization or treatment devices.

Answer 7

Simulation

Question 8

Final check that each of the planned treatment beams does cover the tumor or target volume and does not irradiate normal tissue structures.

Answer 8

Verification

Question 9

Material with a high atomic number used to document structures radiographically.

Answer 9

Radiopaque marker

Question 10

High-density substances used radiographically to visualize internal anatomy for imaging.

Answer 10

Contrast media

Question 11

Measurement of the thickness of a patient along the central axis or at any other specified point within the
irradiated volume.

Answer 11

Separation

Question 12

Dimensions of a treatment field at the isocenter (usually represented by width ¥ length)

Answer 12

Field size

Question 13

Based on acquired CT information, these are images that render a beam’s eye view display of the treatment field anatomy and areas of treatment interest. These images resemble conventional radiographs

Answer 13

Digitally reconstructed radiograph

Question 14

This is the change in target position from one fraction to another

Answer 14

Interfraction motion

Question 15

Changes or motion during the treatment administration.

Answer 15

Intrafraction motion

Question 16

Gross palpable or visible tumor

Answer 16

Gross tumor volume (Refer to picture on table sheet)

Question 17

indicates the gross palpable or visible
tumor (GTV) and a surrounding volume of tissue that
may contain subclinical or microscopic disease

Answer 17

Clinical target volume

Question 18

indicates the CTV plus margins for geometric uncertainties, such as patient motion, beam penumbra, and treatment setup differences.

Answer 18

Planning target volume

Question 19

indicates the CTV plus and internal margin that accounts for tumor motion.

Answer 19

Internal target volume

Question 20

Devices that place the patient in a particular position for treatment but do not ensure that the patient does not move.

Answer 20

Patient positioning aids

Question 21

Use of a high-energy photon beam with multiple

ports of entry convergent on the target volume.

Answer 21

Stereotactic radiosurgery (SRS)