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RT 209 > 11. Modality Exploration and Radiation Therapy > Flashcards

11. Modality Exploration and Radiation Therapy Flashcards

1
Q 
A radiologic examination that involves 
the use of strong magnets, 
radiofrequency waves, and computer to 
create an image of the internal 
structures of the body
A

Magnetic Resonance Imaging

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2
Q

Magnetic Resonance Imaging discovered simultaneously in ____ by :

A

1947
o Felix Bloch
o Edward Mills Purcell

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3
Q 
In \_\_\_\_, provided an impetus to the 
development of actual clinical imaging 
using strong magnetic fields by 
suggesting that radio wave signal 
relaxation times of different tissues 
might be indicative of tumour 
malignancy
A

Raymond Damadian (1971)

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4
Q

Provided the first 2D MR image of

chemical sample in ____

A

Paul Lauterbur (1973)

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5
Q

MRI Components

A

o Primary magnets
o Gradient magnets
o Radiofrequency (RF) Coils
o Computer system

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6
Q

MRI Image Formation

A

o Large magnet produces a strong
magnetic field around the body
o Nuclei in the body precess at the larmor
frequency
o Gradient coils vary the magnetic field
across the body
o A slice of the body is specified by the
magnetic field variation along the Z-axis

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7
Q

The slow movement of the axis of a
spinning body around another axis due
to a torque acting to change the
direction of the first axis

A

Precession

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8
Q

refers to the rate of precession of
the magnetic moment of the proton
around the external magnetic field

A

Larmor or precessional frequency in

MRI

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9
Q

MRI Image Formation (1)

A 
o Gradient coils also vary magnetic 
field along the x and y directions to 
select a tiny volume
o The magnetic field in that volume is 
set so that only the nuclei in that 
volume are at resonant Larmor 
frequency
o The procedure that follows will 
identify the tissue type in that 
volume
o This small volume will form one 
pixel of the final image
o During the scan, many small 
volumes will be scanned
o Nuclei in the volume precess at the 
specified Larmor frequency
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10
Q

MRI Image Formation (2)

A 
o A pulse of radio photons is 
transmitted into the body 
o Nuclei absorb energy and resonate, 
they flip into higher energy state
o After a period of time the nuclei 
relax: flip back to their normal 
energy state
o When they relax, they emit a radio 
photon
o The emitted photons form the 
signal received by the RF coils
o The mean time that elapses 
between switching off the 
transmitted RF pulses and receiving 
a signal from relaxing nuclei is the 
relaxation time
o The tissue type at the specified 
volume is identified from the 
relaxation time
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11
Q 
is a mathematical 
technique that allows an MR signal to 
be decomposed into a sum of sine 
waves of different frequencies, phases, 
and amplitudes
A

Fourier Transform

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12
Q 
is a specialized are of 
radiology that uses very small amounts 
of radioactive amounts, or 
radiopharmaceuticals, to examine 
organ function and structure
A

Nuclear Medicine

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13
Q

Three-stage process of radionuclide imaging

A 
o Introduction of suitable radionuclide 
into the patient
o Concentration of radionuclide in the 
specific organ
o Scanning of organ using appropriate 
scanner
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14
Q

Common ways in How to Produce Artificial

Radionuclide

A

o Irradiating materials in a nuclear
reactor
o Using technetium generator
o Using a medical cyclotron

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15
Q

Gamma Camera first developed by _____ in

___

A

Hal Oscar Anger,

1958

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16
Q 
Specialized type of scintillation counter 
where the position as well as the count 
of the scintillations within a thin Nal 
Crystal (or multiple crystals) are 
obtained using a number of 
photomultipliers
A

Gamma Camera

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17
Q 
is a diagnostic medical 
procedure that uses sound waves to 
produce images on a screen which 
allows medical providers to view 
internal structures of the body
A

Ultrasonography

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18
Q

Approximate speed of sound in Air

A

340 m/s

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19
Q

Approximate speed of sound in Lung

A

650 m/s

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20
Q

Approximate speed of sound in Fat

A

1460 m/s

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21
Q

Approximate speed of sound in Pure water

A

1500 m/s

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22
Q

Approximate speed of sound in Salt water

A

1530 m/s

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23
Q

Approximate speed of sound in Kidney

A

1560 m/s

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24
Q

Approximate speed of sound in Blood

A

1570 m/s

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25
Q

Approximate speed of sound in Muscle

A

1580 m/s

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26
Q

Approximate speed of sound in Bone

A

3000 m/s

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27
Q

is the

ability to bounce an echo

A

Echogenicity or echogeneity

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28
Q

Echogenicity or echogeneity

A

o Hypoechoic
o Hyperechoic
o Anechoic

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29
Q 
A device that produces sound waves 
that bounce off body tissues and make 
echoes. It also receives 
the echoes and sends them to a 
computer that uses them to create a 
picture called a \_\_\_\_\_
A

Transducer,

sonogram

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30
Q

is the ability of
certain materials to generate an electric
charge in response to applied
mechanical stress

A

Piezoelectric Effect

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31
Q

The word Piezoelectric is derived from
the Greek _____, which means to
squeeze or press, and ___, which is
Greek for push.

A

piezein,

piezo

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32
Q

Piezoelectric Effect

Strengths

A 
o Inexpensive
o Quick
o Mobile
o Non-invasive
o Can depict free fluid and aneurysms, 
e.g. in acute aneurysms
o Can differentiate between solid and 
fluid structures
o Can depict flow and motion
o Good for shallow structures
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33
Q

Piezoelectric Effect

Weaknesses

A 
o Operator dependent
o Images may be hard to interpret
o Suffers from image artifacts
o May be prone to giving “false positives”
o Not good for deep structures
o Cannot penetrate through bone or air
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34
Q

Began in 1930s with angiography

A

Interventional radiology

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35
Q

pionerred
transbrachial selective coronary
angiography

A

Mason Jones (Early 1960s)

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36
Q

introduced coronary

angiography

A

Melvin Judkins

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37
Q

introduced visceral

angiography

A

Charles Dotter

38
Q

Refers to the opacification of vessels

through injection of contrast media

A

Angiography

39
Q

Imaging Procedures

A
  • Angiography
  • Aortography
  • Arteriography
  • Cardiac catheterization
  • Myelography
  • Venography
40
Q

Interventional Procedures

A
  • Stent Placement
  • Embolization
  • Intravascular stent
  • Thrombolysis
  • Balloon angioplasty
  • Atherectomy
  • Electrophysiology
41
Q

Embolization

A
  1. Narrow neck aneurysms
  2. Aneurysm catheterization
  3. Coil development
  4. Microcatheter removal
42
Q

described
a method of arterial access in which
catheter was used

A

Sven Ivar Seldinger (in 1953)

43
Q

18 gauge hollow

needle with stylet

A

Seldinger needle

44
Q

Allows safe introduction of the catheter

into the vessel

A

Guidewires

45
Q

Fabricated of stainless steel and contain
an inner core that is tapered at the end
to a soft flexible tip

A

Guidewires

46
Q

are 145 cm

long

A

Conventional guidewires

47
Q

Catheters - categorized in French (Fr) sizes; __ Fr

equal to __ mm in diameter

A

3,

1

48
Q

used for femoral

approach to the brachiocephalic vessels

A

H1 or headhunter tip- (designed by

Vincent Hinck)

49
Q

highly curved

designed for cerebral angiography

A

Simmons catheter

50
Q

has angled tip for

celiac, renal, and mesenteric arteries

A

C2 or Cobra Catheter

51
Q

have side holes for ejecting

contrast media into a compact bolus

A

Pigtail

52
Q

Procedure room should not be less than
20 feet along any wall and not less than
500 ft^2

A

Interventional Radiology Suite

53
Q

Control room must be large, perhaps

100 ft^2

A

Interventional Radiology Suite

54
Q

2 or 3 radiographers, interventional

radiologist, radiology nurse

A

Interventional Radiology Suite

55
Q

More massive, flexible and expensive
than conventional; radiographic and
fluoroscopic imaging

A

X-ray Apparatus

56
Q

Small target angle

A

X-ray Tube

57
Q

Large diameter massive anode disc

A

X-ray Tube

58
Q

designed for magnification

and serial radiography

A

Cathodes (X-ray Tube)

59
Q

X-ray Tube Small focal spot size

A

not greater than

0.3 mm

60
Q

X-ray Tube SID

A

100 cm

61
Q

X-ray Tube OID

A

40 cm

62
Q

The use of high-energy radiation from xrays, gamma rays, neutrons, protons,
and other sources to kill cancer cells
and shrink tumors

A

Radiation therapy

63
Q

Teletherapy other name

A

External beam radiation therapy (EBRT)

64
Q

EBRT

A

External beam radiation therapy

65
Q

Radiation delivered from a distant
source, from outside the body and
directed at the patient’s cancer site

A

Teletherapy

66
Q 
involves placing 
radiation sources as close as 
possible to the tumor site. 
Sometimes, they may be inserted 
directly into the tumor
A

Brachytherapy

67
Q

Sometimes, they may be inserted

directly into the tumor

A

Brachytherapy

68
Q

The use of high-energy radiation
from x-rays, gamma rays, neutrons,
protons, and other sources to kill
cancer cells and shrink tumors

A

Radiation therapy

69
Q

Energies up to 150 Kv with beam
filtration of 1-8 mm al at an FSD
(focal skin distance) of 10-30 cm

A

Superficial units

70
Q

with energies of
150-500 kV with 0.5-3 copper
filtration at a 50 cm FSD

A

Orthovoltage unit or “deep therapy”

71
Q

Accelerate electrons in a straight

path

A

Linear Accelerator (LINAC)

72
Q

Energies up to 5 MeV

A

Linear Accelerator (LINAC)

73
Q

LINAC

A

Linear Accelerator

74
Q

Linear Accelerator (LINAC) - Divided into two large structures

A

o Floor-mounted stand

o Motor-driven gantry

75
Q 
An evacuated cylindrical structure, 
consisting of hollow, indirectly heated, 
oxide-coated cathode surrounded by a 
copper anode containing equidistant 
cavities that communicate with the 
space surrounding the cathode
A

Magnetron

76
Q

Anode and cathode are supplied by
pulse direct current supply from the
modulator

A

Magnetron

77
Q

AFC

A

Automatic Frequency Control

78
Q

Maintains the frequency with

an accuracy of +- kHz

A

AFC- Automatic Frequency Control

79
Q

AFC- Automatic Frequency Control

A

Magnetron

80
Q

Simple hollow tubes that carry the RF
waves from the magnetron to the
accelerator section waveguides

A

Waveguides

81
Q

are sealed at both ends by ceramic discs that are transparent to
microwave radiation

A

Waveguides

82
Q

Waveguides are filled with ______ to

improve its power-handling capabilities

A

sulphur hexafluoride

83
Q

Situated between the magnetron and

the waveguide

A

RF Circulator

84
Q

Act as a one-way valve permitting the
RF radiation to pass into the waveguide,
but preventing any from passing back
into the magnetron

A

RF Circulator

85
Q

Situated in the gantry of LINAC

A

Accelerating Waveguide and Accelerator

86
Q

Uses RF to accelerate electrons to

very high velocities

A

Accelerating Waveguide and Accelerator

87
Q

Electron gun injects electron into
the guide impulses under the
control of modulator, in
synchronization with the RF waves

A

Accelerating Waveguide and Accelerator

88
Q

at the entrance and
exit of the waveguide ensure that
the electron beam is centered to
the center of the guide and target

A

Focusing coils

89
Q

Deflects the electron beam through a

270 degree angle

A

Bending Magnet and Treatment Head

90
Q

is an evacuated
structure situated externally to the
accelerator structure

A

Bending magnet

91
Q

Attached to an external
opening on the treatment
head

A

Electron applicator

92
Q

Designed to produce a

“flat” electron beam

A

Scattering foil

RT 209 (11 decks)

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