Skin And Breast Flashcards
(144 cards)
1
Q
What are the types of non melanoma skin cancers
A
- basal cell carcinoma
- squamous cell carcinoma
- mycosis fungoides
- kaposi’s sarcoma
- merkel cell
2
Q
How many of cancers diagnosed are skin
A
1/3
3
Q
What is the ratio of male to female of those diagnosed with skin cancers
A
2:1
4
Q
What are the most common reasons for skin cancer
A
Fair skin
History of excessive sun exposure
5
Q
Which skin cancer is most common
A
Basal cell carcinoma
6
Q
Where do basal cell carcinomas arise from
A
Basal layer of epidermis
7
Q
Where do basal cell carcinomas occur most
A
Head and neck
8
Q
Compare the likely hood of metastasis from BCC to SCC
A
BCC (rare) and SCC (likely)
9
Q
Where do SCCn arise from
A
Epidermal keratinizing cells
10
Q
What is a SCC in situ known as
A
Bowen’s diease
11
Q
What is a benign SCC known as
A
Keratocanthoma
12
Q
What reasons would surgery be preferred over RT
A
- four small lesions and primary closure is possible
- mainly preferred over Rt
13
Q
Why would RT be preferred over surgery
A
- cosmetically or functionally sensitive area (nose, canthus of the eye)
- comorbid disease
- primary closure not possible
- patient preference
14
Q
What are the advantages of radiotherapy in skin cancers
A
- better for older and in poor health
- better for people on anticoagulants with bleeding tendency
- preserves anatomic contour
- no reconstructive surgery required
- no anesthesia required
15
Q
What are the disadvantages of radiotherapy in skin cancers
A
- potential cataract or carcinogenesis in the young patient
- many visits for optimal cosmetic result
- some degree of chronic effects expected which worsen with time
- takes 3-4 weeks to heal (acute morbidity)
16
Q
What would be a reason to choose RT
A
- improve local control ( post operative positive margin , extensive nodal disease found at dissection)
- used as a primary where lesion could be deep
- lesion could be nose, lip, eyelid, ear
- to preserve normal tissue contours
- if margins were not examined microscopically
17
Q
What are some reasons for RT that are not primary or local control related
A
- large primary size >5cm
- recurrent disease
- incompletely excised primary (positive surgical margins)
- perineural invasion, lymphovascular invasion
- regional nodal involvement
18
Q
What are some reasons RT would not be used
A
- young age (scar worsens with time)
- area is exposed to other hazards (sunlight, poor blood supply, trauma/friction)
- hair hearing skin
- previous high dose RT
- peripheral limb lesions in an edematous leg or with vasculopathy
- fair fragile or damaged skin
19
Q
What are the most common sites XRT will be used
A
- eyelids
- lip
- nasal pyramid
- canthal regions
- pinna of the ear
20
Q
Once radiation is chosen, what are the 8 steps that are taken to choose the treatment
A
- Determine extent and size of lesion
- Delineate surface depth/size
- Select beam type and energy
- Tailor field defining devices (margins)
- Tailor beam blocking devices if any
- +/- bolts
- Tailor immobilization / machine / set up
- Document all of the above
21
Q
How’d you determine extent, size, and depth of the lesion
A
palpation
- bidigital (assess depth but is imprecise and requires safety margins)
- CT / MRI (assess depth of invasion (infiltrative/perineural))
22
Q
What is the T staging for BCC and SCC
A
T1 - greater and equal to 2cm
T2 - 2-5cm
T3 - greater than 5 cm
T4 - tumour involves deep structures (cartilage, muscle, bone)
23
Q
What are the CTV margins for BCC
A
< 2cm = 5mm
> 2cm or distinct/morphea or recurrent = 1cm
> and equal to 6cm plus advanced grade = 2cm
24
Q
What is the margin for SCC
A
1 cm or more
25
What are the types of XRT used for skin
Superficial / ortho photons (single SSD field)
Electrons with bolus
Brachy
MV external beam
26
What are superficial X rays energy
50-150 Kip
27
Fill in these blanks for superficial x rays
Useful for _____ T_ lesions
Maximum dose on surface with ____% of dose is at ___mm of depth
___ dose fall off at ___ depth
After ___ mm dose drops off significantly
- excellent for _____ tumours
- small T1
- 90% at 5mm
- rapid at 5mm
- 5mm
- superficial
28
What is the energy range for ortho
150-400 Kip
29
Fill in the blanks for ortho voltage x rays
Useful for
- more ____ disease T__
- involvement of ___ or ____
- involved _____
- maximum dose on ____
- additional _______ power
- 90% of dose at ____ depth
- excellent for lesions ________ the skin surface
- bulky disease T1/2
- bone or cartilage
- lymph nodes
- surface
- penetrating
- 2.0 cm
- slightly below
30
What are the advantages of orthovoltage
- easy shielding
- narrow penumbra
- relatively flat beam
- low cost
31
What are the disadvantages of orthovoltage
- F factor (increases absorption in bone compared to soft)
- dose drop off (dose not uniform for thick tumour)
- significant dose to underlying normal tissues, bone
- availability of orthovoltage units
- Dosimetry issues with small/shielded fields
32
When are ortho and electron preferred to one another
- superficial/ortho are for T1-T2
- superficial/ortho are for tumours greater than 4cm and 1cm thick
- electrons are favoured for T2-T4 tumours and tumours on scalp to reduce exit dose to brain
33
What is now being more frequency being chose for T4 lesions
Megavoltage
34
Where at the isodose line is the therapeutic range given
90%
35
What are the advantages of electrons
- good for deeper skin tumours as uniformity is better at depth than orhtovoltage
- bolus can be utilized to increase surface dose
- rapid dose drop off at desired depth
- very available
- lower absorption in cartiledge and bone
36
What are the disadvantages of electrons
- wide field margin
- lateral scatter of electrons makes shielding difficult
- air spaces are harder to treat
37
Why is a wider field margin needed for electrons
Bowing of isodose lines
38
What does more side scatter at shallow depths and less at deeper depths result in
Higher isodose lines shifting more to surface. Decreasing therapeutic depth of beam
39
Is RBE lower or higher for electrons compared to low energy photons
Lower
40
What would be a sample dose for electrons with bolus? Include energy of beam
55/20 and 6 or 9 MeV
41
How much does dose need to be increased by if megavoltage is being used compared to superficial photons
10-20%
42
What would be the common fractionation for megavoltage T4 tumours
60/30
43
What would clinicians balance to determine fractionation ? What do each favour
- convenience (short regimen)
- retards proliferation (short regimen)
- better cosmesis (longer regimen)
44
What is the general fractionation for small superficial tumours
20 in one fraction
45
What is the general fractionation for <3 cm, cosmesis unimportant ?
30-35 Gy/5
46
What is the general fractionation for <5 cm, cosmesis unimportant ?
45 GY/10-25fx
47
What is the general fractionation for most indications and is also the preferred
50/15-20
48
What is the general fractionation for a large volume with nodal areas
60-70/30-35
49
What is the minimum dose for SCC for all lesions
50gy
50
What is the TD5/5 for 10/10cm
70 GY (necrosis)
51
What is the electron fractionation schedule for less than or equal to 5cm
45/10
52
What is the electron fractionation schedule for less than or equal to 8cm
50/20
53
What is the electron fractionation schedule for greater than 8cm (large)
60-70/30-35
54
What is the electron fractionation schedule for post adjuvant RT
50/25
55
How much transmission should field defining devices allow
No more than 5%
56
How is orthovoltage therapy shielded
Pb cutout behind tumour as well
57
What are some examples of orthovoltage eye shielding
Lead (1.4-1.7 +coating)
Gold (18 Karat , 2.0mm)
58
How much transmission goes through each beam with eye shielding
225 kv 4%
100 kv < 4%
75 kv <4%
59
What is the dose threshold for cataract formation
5-10Gy (or 0-0.08)
60
What is the usual lead thickness for ortho and what does it depend on
1-3 mm over possible energy range and depends on filter type in beam
61
What should high atomic number shielding be coated with
- aluminum
- dental acrylic
- paraffin wax
62
What is the eyeshielding for electrons
Tungsten with thickness of 2.8 mm coated with acrylic with 9MeV
63
How is bolus different to tantalum wire mesh
Bolus: acts as a tissue equivalent and shifts isodose lines superficially
Wire: increases scatter to skin surface and dose not shift isodose lines
64
What is the atomic number and density of wire mesh
73
16.6g/cc
65
How thick is the wire and open area fraction
T= 0.51
F = 0.706
66
What is the distance between wires in tantalum wire
3.2 mm
67
What are examples of measurements and setup references
- ink marks on skin
- written set up instructions
- photos of treatment setup
- acetate template
-patient data
- orientation
- scar
- moles
- previous tattoos
68
What is positive and negative standoff
Positive: skin lesion is below the surface
Negative: skin lesion is above the surface
69
How do you compensate for ISL in ortho
- longer FSD
- compensating attenuator
70
What is mucous is fungoides a common form of
Cutaneous T cell lymphoma
71
What is a common fractionation for mycosis fungoides / T cell lymphoma (cutaneous)
- 10/5 with 3MeV
72
What is a common fractionation for mycosis fungoides / T cell lymphoma (cutaneous) with multiple lesions
- total body electron therapy (TBE)
- extended SSD : 120cm
- 45x45 field using 3MeV
- 30/10 fractions biweekly
73
What does TSET stand for and what is it also known as
Total skin electron therapy is also known as total body electrons TBE
74
Where is the gantry and what is the position of the patient in TSET
- 270 degrees
- patient is standing
- modified flattening filter
75
What is the presentation of kaposi’s sarcoma
Multiple flat or raised purple lesions
76
What is the fractionation of kaposi’s sarcoma
3 MeV: 10gy /1
TBE: 4Gy per week for 6-8 weeks with an average of 30Gy
77
What is the fractionation of kaposi’s sarcoma
3 MeV: 10gy /1
TBE: 4Gy per week for 6-8 weeks with an average of 30Gy
78
What is the use of RT in melanoma
- palliation, bleeding, ulceration
79
What is the fractionation of melanoma with and without nodal involvement
Without: 30 giving 6-8 weekly
With: 50/25
80
How is ocular melanoma treated if the disease is inside the eye and outside
Inside: enucleation. Conservative RT treatment with some chemo
Outside: brachytherapy or proton
81
What does ABCDE stand for
Asymmetry
Boarders
Colour
Diameter
Evolving or elevation
82
Where is the breast sitatuated approx
- superiority 2nd rib
- inferiority 6th rib
- medial lateral sternum
- laterally- mid axillary line
Anterior - skin
Post - Pectoralis major
83
What is the biggest prognostic factor of the breast
Nodal involvement
84
Describe the pathway of nodal involvement starting with level I (axilla level)
Axilla level I (lateral axillary lymphnode)
Mid axillary II (central axillary lymphnode)
High axillary III (apical axillary lymphnode)
Supraclavicular
Internal mammary chain
85
Define each stage in breast cancer
I: tumour confines to the breast or at least one micromet
II: tumour is greater than 5cm in diameter or spread is to 1-3 movable ipsilateral axillary node
III: tumour is greater than 5cm or has spread to skin or chest wall or IMC nodules are involved or more than 3 axillary lymphs or SC nodes are involved
IV: metastasis present
86
Is RT needed is risk recurrence is less than 5%
No
87
What is the role of radiaiton in early breast cancer
Conserving
Reduce local recurrence following lumpectomy
88
What is the typical treatment for stage I
Lumpectomy + sentinel node biopsy
RT to ipsilateral breast
Hormone treatment if hormone positive
Chemo if high risk
89
What is the typical treatment for stage II
Lumpectomy + sentinel node biopsy +- axillary lymphnode dissection if positive sentinel nodes
Cx
RT to ipsilateral breast +- regional nodes
Hormone treatment if hormone positive
90
What are some immobilization accessories for breast cancer
Vacuum bags
Immobolization uvex cast
Breast board
Raised styrofoam board
91
What are breast “immobilization” devices (large pendulous breast)
Aquaplast
Thermoplastic shell
Styrofoam wedge
Wireless bra
Sock
92
If patient is in breath hold should it be inhale or exhale
Inhale: moves chest wall away from heart
93
How to do breath hold
- ABC
- reflective marker
- VBH
- surface rendering
94
What are the typical breast techniques
- 2 beams
- tangential field
95
What is the most common technique
- isocenter is, half beam, parallel opposed tangential technique
96
What are the tattoos on the breast patient (not diamond)
1. ASU (medial C/A)
2. Straightening Tattoo
3. Lateral boarder C/A
4. Levelling Tattoo
97
What are the tattoos on the breast patient (diamond)
1. Medial
2. Inferior CAX (1.5-2cm inf to palpable breast tissue)
3. Lateral TTH (medial of TTH)
4. Sup CAX (1.5-2cm inf to palpable breast tissue)
98
What is the commonality between both tattoo setups on breast
Tattoos placed on stable surfaces to localize
the breast tissue
Laterals may be on one
side or on both sides
99
What are the typical boarders of a standard tangent field
SUP: SSN (1.5-2.0cm sup to breast)
INF: 2cm inf to inframammary fold
MED: midline
LAT :mid axillary line
100
What are the typical boarders of a standard tangent field
SUP: SSN (1.5-2.0cm sup to breast)
INF: 2cm inf to inframammary fold
MED: midline
LAT :mid axillary line
101
What does the CTV include in a breast
entire breast with 2cm clearance
Chest wall with 1-3cm lung volume included
Field boarders must include
- tumour bed (surgical clips)
- surgical scar (scar marked by wire)
- margins to ensure a 2cm margin beyond
102
When does moist desquamation occur
4000 Cgy or earlier for larger breasts
103
When does acute pericarditis with subsequent fibrosis occur
4000cgy
104
For average size patients with separation between 18-21cm, what would the energy be
4-6MV photons
105
What MV should be used for separations over 22cm
10-18MV
106
When would beam energies be mixed in breast cases
- ensure adequate dosage to entire breast
- improve cosmesis
107
What are the common dose regimes for breast
4240 (4256) cGy/16#/3.5 weeks
•265 (266) cGy / day
4005 cGy/15#/3.5 weeks
•267 cGy / day
5000 cGy/25#/5weeks
•200 cGy / day
•Latest one 2600 cGy/5#/1week
108
Where is the isocenter located in a breast setup
Mid way along posterior field border
109
How is collimator angle beam aligned
Slope of chest
110
How is field width defined
Asymmetrically by anterior jaw
111
What are the everyday checks
- covering all breast tissue with anterior clearance
- covering lumpectomy scar
- arm out of field
- separations or depth
Reference to tattoos
Acccessories
Lung volume with portal imaging
112
What are some set up correction strategies
Gantry
Vertical
Vert and lat
Tape
113
What are some other techniques used to treat breast cancer (RT)
Intraopertive (irradiate open cavity with 20/1)
Breast permanent seed implant (u/s guided)
Accelerated partial breast irradiation (EBRT 30/5 , 38.5/10) brachy HDR
114
What is APBI and what does it stand for . What is the dose regime
- CBCT guided non co planar beams for early stage patients with no LVI, great margins
- uses 38.5/10 BID
- accelerated partial breast irradiation
115
What is the fractionation for post tangent radiotherapy boosts for EBRT
10-16Gy in 4-5 fractions for EBRT
116
What are the types of seroma.tumour bed boosts
Electron beam
Electron / photon
Cone down photon
Non co planar photon
Boost with interstitial implant
117
What are the types of seroma.tumour bed boosts
Electron beam
Electron / photon
Cone down photon
Non co planar photon
Boost with interstitial implant
118
What is the typical energy for an electron boost to the breast and to which isodose line
10-16 MeV
To 90%
119
When are cone down photons used and what are they also known as
- aka mini tangents
- reduced to only include the tumour with a 1-2cm margin
Suited for large deep seromas
120
What is the margin for a non co planar photon/vmat
- 2cm
121
What are the characteristics of iridium 192 as a boost
- fractionation
- type of catheter
- advantage
- 10/2
- interstitial or intracavity balloon
- improved cosmetic result
122
How many lymphnodes in each axilla
10-38 or more
123
What percentage drain to the axilla and IM chain
>75% : axillary
<25% : IM
124
About how much breast cancer occurs in the outer upper quadrant
40%
125
How many breast cancer cases are locally advanced
10-15%
126
What makes a breast locally advanced ? How is it usually cured
More advanced - large tumour, nodal disease, extension onto chest wall or skin, inflammatory
Cured through with multimodality therapy
127
What is axillary node sampling
- small number of nodes removed (minimum of 4)
128
What is axillary lymphnode clearance
Removal of the first two levels of lymph nodes
129
What is______ for XRT in locally advanced breast cancer
Intent
Beam arrangement / energy
Dose:
Dose homogeneity
Radical / curative intent
Tangential obliques / 4-6MV or mixed with 10-18MV / AP and PA pair to cover supclav and axilla
5000/25 for 5 weeks with a boost
Wedges/IMRT , bolus
130
What is the scan range for LABC
- mandible to cover entire thorax plus 4cm inf
131
What’s is the four field technique
- 2 AP PA POP to supraclav and axilla
- 2 POP tangents to breast and chest wall
132
What are the advantages of dual asymmetry
Perfect match line
Equivalent field definition
Superior absorption
Cost effective
Minimal junction inconsistency
133
4 field dual asymmetric technique isocenter s
1 iso centre: tangents and supraclavicular
2 isocenter: tangents/anterior field and posterior field
3: tangents, ant supraclavicular and post supraclavicular
134
What is the fraciationation and beam energy for axilla and supraclav fields
5000/25
4-6MV
135
What are the boarders of the supraclavicular field
Medial : 1cm of M/L cord
Lateral: cover humeral head and surgical neck
Sup: thryocricoid groove
Inf: inf clavicular head
136
What are the boarders of a four field tangent field
Med: approx: M/L
Lateral: cover breast tissue
Sup: inf clavicular head
Inf: 2cm inf to fold
137
How do you define post border for 2 and 4 field tangents
2: rotate collimator and half beam block , non divergent posterior boarder
4: do not rotate and and defined using MLC , divergent posterior boarder
138
How do you define post border on chest wall
With bolus
139
What are the setup correction strategies for tangents and supraclav
- couch shifts
- gantry rotation (3 degrees for SC)
140
What are the pros and cons to RT to the IMC with photons using wide tangents
Pro: treats IMC, technique is easy and no field matching
Cons: treats more normal tissue
141
What are the boarders for a separate IMC field
Sup: abutting the inf boarder of the SC field
Right boarder: 1cm across midline
Left boarder: 4cm lateral to midline
Inferior: xiphoid or 4th intercostal space to spare heart
142
Describe each for the separate IMC field
- energy for electrons
- dose
Critical structures
12-16MeV
5000/25
Ipsilateral lung and heart
143
What is the isocentric, half beam, parallel opposed tangential technique ?
- eliminates beam divergence into underlying lung and contralateral breast
- most common
- affords optimal coverage of breast tissue and chest wall
144
What are some challenges in bilateral breast cancer
- large breasts
- immobilization
- confusing references
- gap between volumes
