CH139 Bologna Radiotherapy

Question 1

X-rays are often referred to as electrons

Answer 1

False - photons

Question 2

When x-rays are absorbed by biological matter, an electron may be ejected from an atom with local release of large amounts of energy

Answer 2

True

Question 3

Replicating malignant cells undergo mitotic death with XRT

Answer 3

True

Question 4

Hypofractionation refers to delivering smaller doses per fraction

Answer 4

False - larger

Question 5

Low energy electrons offer an alternative to low energy photons when treating cutaneous tumours, but the former do have some disadvantages

Answer 5

True

Question 6

Photons offer the advantage of a rapid linear decline in dose beyond a well defined tissue depth that is a function of the selected beam energy

Answer 6

False - electrons

Question 7

Tumours treated with electrons require 10-20mm margins as a consequence of a wider penumbra

Answer 7

True

Question 8

Brachytherapy is delivered by direct application of a radioactive source to involved tissues

Answer 8

True

Question 9

Suitable lesions for brachytherapy need to be deeper >3-4mm in depth and well defined

Answer 9

False - superficial <3-4mm in depth

Question 10

Radiotherapy has a significant risk of inducing in field malignancy

Answer 10

False - very small risk ~1 in a 1000

Question 11

In field malignancy is often soft tissue/bone sarcoma 30-40y or more after exposure

Answer 11

False 10-15 years after exposure

Question 12

How soon after surgery should keloids be treated with radiotherapy?

Answer 12

24-48 hours

Question 13

Radiotherapy for keloids 12-16Gy delivered in 3-4 fractions

Answer 13

True

Question 14

Keloids on anterior neck should avoid tx with radiotherapy

Answer 14

True, proximity to thyroid

Question 15

For SCC on lip, surgery is far superior to XRT

Answer 15

False - similar outcome

Question 16

Formication, dysesthesias, parasthesias, numbness but not pain are symptoms suggestive of perineural invasion

Answer 16

False - also pain

Question 17

Transplant patients have a greater degree of acute toxicity from XRT

Answer 17

False - usually tolerate XRT well

Question 18

Merkel cell ca WLE 10-15mm margins

Answer 18

False 15-20mm or Moh’s

Question 19

Adjuvant locoregional radiotherapyfor merkel cell ca improves recurrence rates and disease-free survival

Answer 19

True

Question 20

List advantages of total skin electron beam therapy:

Answer 20

1. Comprehensive coverage of the entire skin surface
2. Can be repeated should other modalities fail to control the CTCL
3. An acceptable toxicity profile when given over a 6-9 week period

Question 21

What does total skin electron beam therapy comprise of?

Answer 21

4-6MeV beam with patents often treated standing at distance of 7m away from the linear accelerator

• lead contact lenses to shield eyes during first 18 fractions of TSEBT and external shielding for second portion .
• hands and feet shielded 50% of the time during TSEBT
• 4 days per week for 9 weeks (36 fractions)

Question 22

List acute reactions of XRT

Answer 22

Dry desquamation, with moderate erythema

Moist desquamation, and mild bleeding

Question 23

Late radiotherapy reactions

Answer 23

Hypo and hyperpigmentation
Telangiectasias
Epidermal atrophy and fragility
Alopecia, sweat gland atrophy
Necrosis of soft tissue, cartilage and/or bone
Subdermal fibrosis
Benign tumours — eccrine Poromas
Radiation induced malignancy

Question 24

Eccrine Poroma can occur as a result of XRT

Answer 24

True

Question 25

Better long term cosmetic results are more likely if a high dose per fraction is administered

Answer 25

False - low dose per fraction

Question 26

What is EPPER syndrome

Answer 26

Eosinophilic, polymorphic and pruritic eruption associated with radiotherapy syndrome

Question 27

What is EMPACT syndrome

Answer 27

Erythema multiforme associated with phenytoin and cranial radiation therapy