Techniques Quiz 3

Skin & Melanoma, Soft tissue sarcomas, Bone Tumors, Lymphoreticular System

3 types of skin cancer

basal cell

squamous cell/cutaneous squamous cell

malignant melanoma

basal cell

slower growing

doesn’t metastasize

not aggressive

very prevalent

(can cause damage if untreated)

squamous cell/cutaneous squamous cell

faster growing than basal

higher chance of metastasis

common on face, hands, shoulders, etc

malignant melanoma

not just dependent on sun exposure

tendency to move to a depth

legs of women

trunk & face of men

eyelids, anus, mucosa

radioresistant most often

merkel cell

rare tumor

more lethal than malignant melanoma

raised lesion - pinkish/reddish

chemo/radiation/surgery

treatment for melanoma

surgery for complete cure (hence, early diagnosis = best prognosis)

chemo or immunotherapy to make sure it doesn’t spread

• key is to treat before it spreads

rad therapy usually only used for palliative

superficial e-

• total skin e- radiation (standford technique)

standford technique

total skin e- radiation

angle 15-30 degrees

6 dual fields (12 total fields)

36 Gray in 9 weeks

1 Gray per fraction

3 treatment techniques for skin cancer

Surgery - best if pt is ok w/ scar in that area

• Mohs procedure = good, but expensive and scarring can be significant

Radiation therapy - used on places where surgery may be difficult, recurrence, or pt. preference)

• lips, eyelids, ears, face

• expensive

Chemo - 5-FU & solution of creams

Pros of rad therapy for skin cancer

• better cosmetically

• treats involved lymph nodes better

e- treatment for skin ca

e- = LINAC (monoenergetic)

• doesn’t get good coverage b/c high dose region doesn’t spread to sides

• falls off rapidly (no deep dose)

• higher E = brings surface dose higher to skin

• can easily dose surrounding structures (e- repel eachother)

kv photon treatment for skin ca

kV photons = orthovoltage (polyenergetic)

• tightess field/sharpest beam edge (lowest penumbra)

• higher dose at depth (higher E = lower surface dose/goes deeper)

• depends on z (can affect bones more than skin)

• photoelectric interaction

MV use in skin ca treatment

rarely used unless lesion is very deep

bolus

brings surface dose higher

isodose lines

e/4 = 90%

e/3 = 80%

e/2.5 = 50%

e/2 = 10% (practical range) (R_p)

Practical range

no more dose goes past this point

e- applicator/e-cone

focus beams

relationship of SSD and penumbra

smaller distance (SSD) = smaller penumbra

small basal cell margin

0.5 - 1 cm

chondritis

inflammation of cartilage

what body parts would you use a bolus for

ear

lips

nose

eye

eyelid

what single dose can cause cataracts

2 Gy

(200 cGy)

key point when treating

want to create a flat surface for treatment so dose falls off the same

dose for ears

10 Gy or less

(1000 cGy or less)

downside to using lead or dense metals to protects gums, nose, eyes

increases scatter

• can use something like wax in front of shield

cosmesis is worse when

higher single dose compared to spread out doses

total dose for malignant melanoma

60-65 Gy

• (50 Gy in 25 treatments)

  • (10-15 Gy for boost where surgery was)

soft tissue sarcoma

outside of bone

most often extremities

retroperitoneum

trunk of body

how long to wait post radiation for surgery

3-6 weeks

pre vs post op vs alone (rad therapy for sarcomas)

pre

• smaller volume of tissue can be treated due to lack of seeding from surgery

• going in blindly because havent seen in surgery

• better biological effect because no scar tissue (scar tissue has no O2)

• lower chance of fractures due to less radiation to bones

post

• less seeding in surgery because pseudo capsule from rad therapy

• have seen the tumor (not going in blindly)

initial volume around scar for sarcomas

3-6 cm

boost volume margins around scar for sarcomas

2-3 cm

scar should be treated w/

higher dose b/c disease was there

• can do tangential or e- w/ bolus to boost it

how much tissue should be left untreated during circumferential treatments

1-3 cm strip of normal tissue

prevents permanent lymphedema

preserves lymphatic drainage

what can’t be done with MLCs but only with cerebrum block

island blocking

kaposis sarcoma

• blotches on skin

• common in AIDS/HIV pts

dose for kaposis sarcoma

10 to 25 Gy

(has high lasting effect)

Hypofractionation dose for kaposis sarcoma

7 Gy

how long to wait after surgery before starting interstitial therapy

3 days

allows healing

common chemo drug for sarcomas

doxorubicin

dose for unresectable tumors (sarcomas)

75 Gy

(7500 cGy)

dose for tumor plus minimal margins of sarcomas

60 Gy

(more than 6000 cGy)

dose for preop w/ post op boost of sarcomas

50 Gy

3 options of post op boost for sarcomas

brachy

IORT (intraoperative radiotherapy)

EBRT (external beam radiotherapy)

dose for brachy (post op boost) for sarcomas

62-76 Gy

(12-26 about 3 days after surgery)

dose for IORT (post op boost) for sarcomas

60-66 Gy

(10-16 Gy immediately after tumor removal)

dose for EBRT (post op boost) for sarcomas

66-68 Gy

• (16-18 Gy for microscopic disease)

70-76 Gy

• (20-26 Gy for gross residual disease)

Post op dose for sarcomas

60 to 66 Gy

dose of interstitial therapy for sarcomas

45 Gy - primary

2000 at 40 cGy/hr (dwell time 50 hrs) - boost

• done 3 days after surgery using Iridium 192

2 types of bone cancer

primary

metastic (common)

most common symptom of bone tumors

PAIN

swelling

engored (bulging) veins

osteosarcoma

most common bone tumor in general

radioresistant

chemo drugs to treat osteosarcoma

cisplatin

doxorubicin

high dose methotrexate

leucovorin

chondrosarcoma

most common bone tumor in adults

radioresistant qualities

fibrosarcoma

rare form of bone malignancy

• arise from fibroblasts (active cells in connective tissue)

locally aggressive

high rate of recurrence

use wide excisional method when doing surgery

ewings sarcoma

affects first decade of life most

2nd to osteosarcoma in 2nd decade of life

starts in diaphysis of bone

multiple myeloma

affects the plasma

disseminated disease

lytic lesions (increase chance of fractures)

no cure (treating symptoms)

chemo and rad therapy (when localized)

giant cell tumor

aggressive benign tumors

arise in metaphysis or epiphysis of long bones

young adults

metastatic bone disease

bone lesion resulting from primary site located elsewhere in the body

• common primary sites include: prostate, breast, lung, kidney, and thyroid

fractures due to the disease

neurologic issues (disease affects the spine) (sensation loss, paralysis)

MRI pros for bone tumors

accurate detail between normal tissue, neurovascular structures, tumor tissue

Dose for TBI (total body irradiation)

7-8 Gy

HBI

hemi/half body irradiation

upper or lower part first & then switch after break

treatment of vertebral bodies for multiple myeloma

want to treat 2 vertebral bodies above and 2 below disease

dose to treat pain for multiple myeloma

30 Gy

radionecrosis occurs at what dose

80 Gy in 20 days or less

what does the reticule help with

helps w/ shift method and to know if we are magnified or not

en face “on fos”

beam is directed directly at tumor at a 0 degree angle

(perpendicular to skin)

dose for osteosarcoma

60 to 65 Gy in 30 to 35 fx in 8 weeks

Post op dose for osteosarcomas

64 to 68 Gy to high risk sights

dose to uresectable tumors

soft tissue vs osteosarcoma

75 Gy vs 70 Gy

dose for chondrosarcoma

60 Gy in 4-6 weeks

pre op dose for chondrosarcoma

20 to 50 Gy

dose for fibrosarcoma

66 to 70 Gy w/ shrinking field technique

dose for giant cell

35 Gy in 15 tx is good

45 to 55 Gy in 5-6 weeks

50 to 60 Gy where surgery is not possible

dose for ewing’s sarcoma

45 Gy and 2 boosts of 5 Gy (1st w/ 5 cm margin, 2nd w/ 1 cm margin)

Tx to 55 to 60 Gy

pre and post op = 36 to 45 Gy

dose for metastatic bone disease

30 Gy in 10 to 15 tx’s and a boost of 10 Gy

• 30 Gy in 10 fx or 20 Gy in 5 fx

1 fx of 8 Gy = provides adequate pain relief

SBRT group got 18 Gy in 1 fx, 30 Gy in 3 fx, or 35 Gy in 5 fx

Hodgkins disease

systemic pattern

reed sternburg cell (determines if Hodgkin’s or non-Hodgkin’s)

treatment for hodgkins

surgery = to stage (biopsy)

chemo does most (may be used with radiation, especially if advanced)

chemo drugs for hodgkins disease

ABVD, BEACOPP, Standford V, MOPP

(don’t use MOPP when pt has heart issues)

Involved field radiation

treating area that has lesion

(known to have gross disease and affected lymph nodes)

chemo usually done before radiation

dose for bulky disease (Hodgkins)

30 to 36 Gy

dose for subclinical sites (not bulky) (Hodgkins)

25 to 30 Gy

types of irregular field treatments

mantle field

inverted Y

clarkson algorithim

calculates the scatter dose within a medium for an irregular field

sequentially

different parts of the field are treated at different times

entire field is not treated at the same time

prophylactically

preventative

akimbo postion

“superhero”

hands on hip and elbows out to the sides

helps open up axillary region for treatment

Flash

seeing light beyond pt border when lining them up

Mantle

upper border - follows the line of the mandible

lower border - usually stops at level of diaphragm (T9-T10)

lateral border - extends to include fall off of the axilla

seminoma

unilateral testicular disease

2 types of treaments field for seminoma

“hockey stick”

“chimney”

upper - inferior border of mantle

lateral - 5cm off midline

• includes spleen or if resected 2 cm margin around clips

• aortic bifurcation = L4-L5

treatment field for hodgkins

“inverted y”

upper - L5

lower - 2cm below BIT or BOF

lateral - 2 cm beyond pelvic inlet

how do we want pt in simulation to ensure reproducibility

flat & straight

field sizes when chemo & rad vs just rad

chemo & rad = smaller field sizes

only rad = larger field sizes

what is always tattooed

inferior border of gap on mantle field

(where the lower treatment field is allowed to begin)

usually around T10

Gap calc

½ L1 (d/SSD) + ½ L2 (d/SSD)

what is L1 and L2 in the gap calc

it is the length part in the width * length of each field

involved node/site therapy vs mantle field

involved node/site therapy = only treats the original nodes affected plus a margin

mantle = treats large upper body region regardless of individual node location

margin for initial involved field radiation

1 cm

what views are done for initial mantle field

AP & PA

what does the initial mantle field block

lungs, humeral heads, larynx (on AP), cervical cord (on PA)