Brachy

Question 1

is a method of treatment in which sealed radioactive sources are used to deliver radiation at a short distance by interstitial, intracavitary, or surface application.

Answer 1

Brachytherapy

Question 2

With this mode of therapy, a high radiation dose can be delivered locally to the tumor with rapid dose falloff in the surrounding normal tissue.

Answer 2

Brachytherapy

Question 3

In the past, brachytherapy was carried out mostly with ____ or ___ sources.

Answer 3

radium, radon

Question 4

Currently, use of artificially produced radionuclides in brachytherapy such as _______ is rapidly increasing

Answer 4

137Cs, 192Ir, 198Au, 125I, and 103Pd

Question 5

New technical developments have stimulated increased interest in brachytherapy: the introduction of _____ to reduce personnel exposure, and automatic devices with remote control to deliver controlled radiation exposure from high-activity sources.

Answer 5

artificial isotopes, afterloading devices

Question 6

is the sixth member of the uranium series, which starts with 238U-92 and ends with stable 206Pb-82.

Answer 6

Radium

Question 7

Radium disintegrates with a half-life of about ____ to form radon

Answer 7

1,600 years

Question 8

As a result of the decay process from radium to stable lead, at least 49 γ rays are produced with energies ranging from _____ MeV.

Answer 8

0.184 to 2.45

Question 9

The average energy of the γ rays from radium in equilibrium with its daughter products and filtered by 0.5 mm of platinum is ____ MeV.

Answer 9

0.83

Question 10

The radium is supplied mostly in the form of _____ that is mixed with an inert filler and loaded into cells about 1 cm long and 1 mm in diameter.

Answer 10

radium sulfate or radium chloride

Question 11

The radium is supplied mostly in the form of radium sulfate or radium chloride that is mixed with an inert filler and loaded into cells about _____

Answer 11

1 cm long and 1 mm in diameter.

Question 12

These radium cells are made of ____ and are sealed to prevent leakage of radon gas.

Answer 12

0.1- to 0.2-mm-thick gold foil

Question 13

Radium sources are specified by

Answer 13

Active length
Physical length
Activity or strength of source
Filtration

Question 14

Three types of radium needles used for implants:

Answer 14

Needles of uniform linear activity, needles with higher activity at one end (Indian club), and needles with high activity at both ends (dumbbell).

Question 15

is a γ-ray–emitting radioisotope that is used as a radium substitute in both interstitial and intracavitary brachytherapy.

Answer 15

Cesium-137

Question 16

The main advantages of 60Co is its ____, which allows fabrication of small sources required for some special applicators.

Answer 16

high specific activity

Question 17

Cesium-137 is supplied in the form of _____, labeled with 137Cs, and doubly encapsulated in stainless steel needles and tubes.

Answer 17

insoluble powders or ceramic microspheres

Question 18

The advantages of 137Cs over radium are

Answer 18

it requires less shielding and is less hazardous in the microsphere form

Question 19

With a long half-life of about 30 years, these sources can be used clinically for about 7 years without replacement, although the treatment times have to be adjusted to allow for radioactive decay (2% per year).

Answer 19

Cesium-137

Question 20

137Cs emits γ rays of energy____ MeV

Answer 20

0.662

Question 21

has been used for brachytherapy but is rarely used now

Answer 21

60Co

Question 22

Disadvantages of Cobalt-60

Answer 22

more expensive than 137Cs and has a short half-life (5.26 years)

Question 23

Cobalt brachytherapy sources are usually fabricated in the form of a ___ that is encapsulated in a _____.

Answer 23

wire, sheath of platinum iridium or stainless steel

Question 24

Curie-sized cobalt sources have also been used in a unit called the ____

Answer 24

Cathetron (11,12,13)

Question 25

This is a remote-loading device and provides high dose rates for intracavitary therapy, for example, 250 to 300 cGy/min at point “A”

Answer 25

Cathetron

Question 26

sources are fabricated in the form of thin flexible wires that can be cut to desired lengths.

Answer 26

Iridium-192

Question 27

192Ir has a complicated γ -ray spectrum with an average energy of ____

Answer 27

0.38 MeV

Question 28

192Ir has the disadvantage of a short half-life ____

Answer 28

73.8 days

Question 29

198Au has a half-life of ____ and emits a monoenergetic γ ray of energy _____

Answer 29

2.7 days, 0.412 MeV

Question 30

has gained a wide use for permanent implants in radiation therapy.

Answer 30

125I

Question 31

Advantages of 125I

Answer 31

long half-life (59.4 days) low photon energy which requires less shielding

Question 32

seeds have recently become available for use in brachytherapy.

Answer 32

103Pd

Question 33

Half-life of Palladium-103

Answer 33

17 days

Question 34

was developed to deliver uniform dose (within ±10%) to a plane or volume.

Answer 34

Paterson-Parker or Manchester system

Question 35

The system specified rules of source distribution to achieve the dose uniformity and provided dosage tables for these idealized implants.

Answer 35

Paterson-Parker or Manchester system

Question 36

In the case of planar implants the uniformity of dose is achieved in parallel planes at ____ from the implanted plane and within the area bounded by the projection of the peripheral needles on that plane.

Answer 36

0.5 cm

Question 37

The spacing of the needles ____ from each other or from the crossing ends.

Answer 37

should not be more than 1 cm

Question 38

is composed of belt, four parts; core, two parts; and each end, one part

Answer 38

Cylinder

Question 39

is made up of shell, six parts, and core, two parts

Answer 39

Sphere

Question 40

consists of each side, one part; each end, one part; and core, two parts.

Answer 40

Cuboid

Question 41

•Uses sources of uniform linear activity •Sources distributed uniformly over the area or volume •Result is non-uniform dose distribution, higher in the central region

Answer 41

Quimby System

Question 42

is an extension of Quimby system.

Answer 42

Memorial system

Question 43

was used for manual intra-operative planning of I-125 implantation

Answer 43

Memorial Nomogram

Question 44

Developed based on experience with Ir-192 interstitial implants by afterloading techniques

Answer 44

Paris System

Question 45

forms the basis for dosimetry

Answer 45

BASAL DOSE (BD)

Question 46

Similar to Paris and Quimby techniques

Answer 46

Computer System

Question 47

Brachytherapy sources are applied in three ways:

Answer 47

1.External applicators or molds 2.Interstitial implantation 3.Intracavitary therapy

Question 48

are used to treat small superficial areas, such as the ear or the lip.

Answer 48

Surface molds

Question 49

is indicated when the tumor is well localized and can be implanted directly according to accepted rules of distribution;

Answer 49

Interstitial therapy

Question 50

is used when applicators containing radioactive sources can be introduced into body cavities. In all these cases, owing to the short treatment distance, the geometry of source distribution is critical.

Answer 50

Intracavitary therapy

Question 51

two types of interstitial implants:

Answer 51

1.Temporary 2.Permanent

Question 52

–The sources are removed after the desired dose has been delivered (e.g., radium needles, iridium wires, or iridium seeds). –Provides better control of source distribution and dosimetry than a permanent implant

Answer 52

Temporary implant

Question 53

–The sources are left permanently in the implanted tissues (e.g., 198Au and 125I seeds). –A one-time procedure and is a preferred method for some tumors such as those in the abdominal and thoracic cavities.

Answer 53

Permanent implant

Question 54

This procedure eliminates exposure in the operating room, the x-ray room, and the areas through which the patient is transported. “Dummy” sources are used for radiographic localization and dosimetry.

Answer 54

Interstitial Therapy

Question 55

is mostly used for cancers of the uterine cervix, uterine body, and vagina. A variety of applicators have been designed to hold the sources in a fixed configuration.

Answer 55

Intracavitary therapy

Question 56

–Applicator is pre-loaded and contains radioactive sources at time of placement into the patient.

Answer 56

Hot loading

Question 57

–Applicator is placed first into the patient and the radioactive sources are loaded later –Either by hand (manual afterloading) –Or by machine (automatic remote afterloading)

Answer 57

Afterloading

Question 59

Radium is the sixth member of the uranium series, which starts with ____ and ends with stable ____

Answer 59

238U-92 206Pb-82

Question 60

The product nucleus ___ is a heavy inert gas that in turn disintegrates into its daughter products.

Answer 60

radon

Question 61

○ The distance between the ends of the radioactive material

Answer 61

Active length

Question 63

○ The distance between the actual ends of the source

Answer 63

Physical length

Question 64

○ Milligrams of radium content

Answer 64

Activity or strength of source

Question 65

○ Transverse thickness of the capsule wall, usually expressed in terms of millimeters of platinum

Answer 65

Filtration

Question 66

Linear activity of a source can be determined by

Answer 66

dividing the activity by the active length

Question 67

○ needles with higher activity at one end

Answer 67

INDIAN CLUB

Question 68

○ needles with high activity at both ends

Answer 68

DUMBBELL

Question 69

Uniform linear activity needles may be _____

Question 70

Needles also are constructed with linear activities of ____

Answer 70

0.5 and 0.25 mg/cm