Orbital Lymphoma Part 1

What is lymphoma

blood cancer that develops in the lymphatic system

in what cells does lymphoma arise from

lymphocytes (b cells and t cells)

what are the types of orbital lymphoma

hodgkins and non-hodgkins lymphoma

hodgkin's lymphoma epidemiology (2)

one of the most curable cancers

predictable patterns of spread

what is a requirement for hodgkin's lymphoma

the reed-sternberg cell must be present

Hodgkin's lymphoma age group

young adults (20s-30s)

the subtypes of non-hodgkins lymphoma are based on (3)

if the disease is fast growing or slow growing

certain cell features

presence of proteins on cell surface

non-hodgkins lymphoma spread

NHL tends to spread randomly

Hodgkins lymphoma spread

predictable patterns of spread

Non-Hodgkin's Lymphoma Age group

older individuals with median age of 60-65

Symptoms of Non-Hodgkin's Lymphoma (6)

orbital bulging

Eye pain and redness

Painless orbital mass

Eyelid prolapse

blurry vision/double vision/floaters

Enlarged lacrimal gland

MALT Lymphoma (mucosa associated lymphoid tissue) is a subtype of

NHL

what is the second most common type of cancer worldwide

MALT Lymphoma

MALT Lymphoma characterisitcs

indolent and radiosensitive

where is malt lymphoma most commonly found

Asia and Europe

Malt Lymphoma and Vision

MALT lymphoma does not generally cause vision loss

what is the most common cause of MALT lymphoma

immunosuppression (immunosuppressive drugs, autoimmune disorders, HIV)

MALT lymphoma is associated with infections from

Epstein-Barr Virus, Helicobactor Pylori, Chlamydia Psittaci

what are the treatment options for orbital lymphoma

radiation therapy

surgery

antibiotics

chemotherapy

b cell vs t cell lymphoma commonality

b cell lymphoma is more common than t cells

where does orbital lymphoma develop

socket in conjunctiva or in the adnexa

not in the eye

what is the primary treatment for orbital lymphoma

radiation therapy

when is chemo used as a TM option for orbital lymphoma

metastatic orbital lymphoma

what is rarely used as a TM option for orbital lymphoma and why

surgery- can damage the eye/optic nerve

orbital lymphoma simulation (6)

supine

head rest

head mask

bolus

knee wedge

a-bar for hands

what does the physician contour for orbital lymphoma (6)

GTV/CTV

lacrimal glands

parotids

pituitary gland

optic chiasm

brain stem

what does the dosimetrist contour for orbital lymphoma (7)

PTV

brain

eyes

lenses

optic nerve

cord

cochlea

what should be included in the CTV for orbital lymphoma

the entire orbit is contoured for the ctv

how is the PTV created from the CTV

the ptv is expanded 3-5 mm from the CTV

use a 5 mm margin for the practicum

optic nerve dose limit

54 Gy

optic chiasm dose limit

54 Gy

lens dose limit

5 Gy

cochlea contouring

contour just the cochlea, not the auditory canal

5-8 slices

field arrangement, how far are the wedge pairs from each other

60-80 degrees apart

what is dose prescribed to in orbital lymphoma

final iso or calc pt

the wedge pair angle is chosen based on

PTV shape and pt anatomy

field arrangement- beam entrance and exits

avoid entering through the contralateral eye, exiting through the contralateral eye is ok

why is exiting through the contralateral eye acceptable

exit through the contralateral eye to spare exit dose to the brain

what is a wedge angle

angle through which the isodose curve is tilted at the central ray of a beam at a specific depth

tilt of the isodose curve to a line perpendicular to the central axis

what is the range of wedge angles

15-60 degrees

wedge size and wedge angle

a larger wedge produces a deeper wedge angle

hinge angle

the angle between the central rays of two fields

wedge angle formula

90-(hinge angle/2)

hinge angle formula

180 - 2(wedge angle)

what beam energy is used for orbital lymphoma and why

6x, shallow depth of orbital cavity

what is something to keep in mind when using wedges

using wedges may result in less robust anterior coverage

what is the common side effect of RT for orbital lymphoma

cataracts

what is the prescribed dose and fractionation for malt lymphoma

4 Gy in 2 fractions

why is a low dose recommended for malt lymphoma

MALT lymphoma is indolent and radiosensitive

low dose prevents side effects such as conjuctivitis, dry eye, retinopathy for doses above 30 Gy

where is the marked isocenter placed for orbital lymphoma

somewhere in the brain