Quiz 1 (PPT2 & 3)

Question 1

IM

Answer 1

Internal Margin

Question 2

ITV

Answer 2

Internal Target Vol

Question 3

SM

Answer 3

Setup Margin

Question 4

TV

Answer 4

Treated Vol

Question 5

PRV

Answer 5

Planning Organ at Risk Vol

Question 6

IrV

Answer 6

Irridiated Vol

Question 7

Visible mass to include lymphadenopathy and metastasis.

Answer 7

GTV

Question 8

Subclinical malignant disease.

Answer 8

CTV

Question 9

expanded margin for volume differences (bladder, rectum respiration, swallowing).

Answer 9

IM, internal margin

Question 10

to include motion (CTV+IM).

Answer 10

ITV, internal target vol

Question 11

Variation in daily patient positioning.

Answer 11

SM, setup margin

Question 12

to include all geometric variations (ITV+SM).

Answer 12

PTV

Question 13

Volume to encompass prescribed dose.

Answer 13

TV, treated vol

Question 14

Similar to PTV except for OAR’s

Answer 14

PRV, Planning Organ at Risk Vol

Question 15

Tissue that receives a dose that is considered significant in relation to normal tissue tolerance.

Answer 15

IrV

Question 16

Isodose levels are modified by changing the ___, ___, ___, ___, etc., to produce a desired dose distribution.

Answer 16

energy
field size
beam arrangements
beam modifiers

Question 17

Isodose levels are modified by changing the energy, field size, beam arrangements, beam modifiers, etc., to produce a desired dose distribution.

Answer 17

Isodose Distributions

Question 18

Isodose Level Parameter: Isodose levels are lines that pass-through points of equal dose expressed as a ___ relative to a ___ ___.

Answer 18

%, reference point

Question 19

Two-dimensional graph showing dose delivered to volumes of interest.

Answer 19

DVH

Question 20

Physical penumbra= ___ + ___ + ___

Answer 20

Geometric, Transmission, Scatter

Question 21

the lateral distance between two isodose lines at a specified depth

Answer 21

Penumbra

Question 22

Penumbra Formula

Answer 22

s(SSD+d-SDD)/SDD

Question 23

Penumbra Formula:

s=

Answer 23

Source size

Question 24

Penumbra Formula:

SDD=

Answer 24

MLC, Block distance

Question 25

Penumbra Formula: | D=

Answer 25

Depth

Question 26

Effect on Penumbra: | Increase source size

Answer 26

Increase

Question 27

Effect on Penumbra: | Increase SSD

Answer 27

Increase

Question 28

Effect on Penumbra: | Increase depth

Answer 28

Increase

Question 29

Effect on Penumbra: | Increase SDD

Answer 29

Decrease

Question 30

Collimators produce scatter and ___ (increase/decrease?) penumbra.

Answer 30

increase

Question 31

___ ___ contribute to penumbra due to partial transmission through the ___ end

Answer 31

MLC leaves, leaf

Question 32

Some MLC’s create little penumbra when the leaves are mounted on ___ ___

Answer 32

diverging carriages

Question 33

___ leaves create constant penumbra with changing field sizes

Answer 33

Rounded

Question 34

DVH types: | (most often used) graphs the volume(in the Y-axis that receives the corresponding dose or more in the X-axis

Answer 34

Cumulative DVH

Question 35

DVH types: | graphs the volume of a structure receiving dose within a specified dose interval

Answer 35

Differential DVH

Question 36

When choosing an energy consider the following: (6)

Answer 36

- Tumor location - Tumor size - Surrounding tissues - Skin sparring - Depth - Exit dose

Question 37

Two considerations when selecting beam arrangements:

Answer 37

OARs | Homogeneous dose within planning target

Question 38

How to get a homogeneous dose?

Answer 38

more beams

Question 39

Beam arrangements that are asymmetric usually require ___ or ___ to be homogenous

Answer 39

wedges, compensators

Question 40

Field Shape: | Cerrobend blocks have ___ (more/less?) field conformality than MLC’s due to the leaf size

Answer 40

more

Question 41

Field Shape: | The blocking must always be ___ than the target volume to account for ___

Answer 41

larger, penumbra

Question 42

Single field advantages: (3)

Answer 42

Simple setup Uses SSD technique Decreased treatment time

Question 43

Single field disadvantages: (2)

Answer 43

Limited treatment depth | Max doses

Question 44

Parallel opposed fields advantages: (4)

Answer 44

Simple setup Decreased chance of geometric miss Homogeneous dose Ability to weight beams

Question 45

Parallel opposed fields disadvantages: (2)

Answer 45

Entry and exit doses | Difficult to avoid critical structures

Question 46

Multiple fields advantages: (3)

Answer 46

Dose conformality Decreased max dose Avoidance of critical organs

Question 47

Multiple fields disadvantages: (2)

Answer 47

More integral dose (total dose in body) | Difficult to avoid critical organs

Question 48

``` Rotational therapy: 1, Best suited for ___, ___ tumors 2. Able to shape dose distribution based on ___ of arcs and ___ of arcs 3. ___ treatment time 4. ___ Conformality of doses 5. Varian linacs - type of arc: 6. Elekta linacs - type of arc: ```

Answer 48

1. small, deep-seated 2. number, degree 3. Decreased 4. Increased 5. Rapidarc 6. VMAT

Question 49

Partial arc therapy may require “Past-pointing” where the isocenter is placed ___ than the target

Answer 49

deeper

Question 50

Wedge field technique common uses: 1. Can account for ___ anatomy such as a chestwall or breast 2. ___ a beam such as a in a 3 field rectum 3. Use as tissue ___ 4. Use for a ___ ___ target such as a rt sided brain tumor Wedge/ Hinge angle 180 - 2(wedge angle)= hinge angle

Answer 50

1. sloping 2. Omit 3. compensator 4. one sided

Question 51

Matching fields techniques: (3)

Answer 51

Half beam on central axis Angling adjacent beams Match at desired depth (use gap calc)

Question 52

Matching fields used when: (5)

Answer 52

1. Prior treatment to adjacent area 2. 3-field head and neck treatment technique 3. 3-field breast sclav treatment technique 4. Craniospinal 5. Mantle

Question 53

Wedge/ Hinge angle formula:

Answer 53

hinge angle = 180 - 2(wedge angle)

Question 54

___ ___ advantages: Simple setup Uses SSD technique Decreased treatment time

Answer 54

Single Field

Question 55

___ ___ disadvantages: Limited treatment depth Max doses

Answer 55

Single Field

Question 56

``` ___ ___ advantages: Simple setup Decreased chance of geometric miss Homogeneous dose Ability to weight beams ```

Answer 56

POP Fields

Question 57

___ ___ disadvantages:

Answer 57

Entry and exit doses | Difficult to avoid critical structures

Question 58

___ ___ advantages: Dose conformality Decreased max dose Avoidance of critical organs

Answer 58

Multiple Fields

Question 59

___ ___ disadvantages: More integral dose (total dose in body) Difficult to avoid critical organs

Answer 59

Multiple Fields