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Oncology + Palliative > Radiotherapy > Flashcards

Radiotherapy Flashcards

1
Q

What is radiotherapy - how is it delivered, what effect does it have on cancer?

A

Strongly targeted rays of ionising radiation

Destroys or inactivates cancer Disrupts cell division Invisible, silent + pain free

Delivered by a linear accelerator - delivering high energy, short wavelength x rays

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2
Q

Electrons vs photons

A

Photons = high energy x ray treatments = penetrate deep. Cause DNA damage

Electrons = used for skin tumours

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3
Q

What is a differential cell kill?

A

Kills more cancer cells than healthy cells Due to cancer cells having ineffective DNA repair pathways

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4
Q

Units of measurement + dose

A

Gray (Gy)

Delivered as series of small doses (fractions)

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5
Q

What is IMRT?

A

Intensity modulated radiotherapy

Given continuously as it moves in arc around the patient - delivered quicker + greater accuracy

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6
Q

What is VMAT?

A

Volumetric modulated arc therapy - type of IMRT

Protects more healthy tissue MLC movement throughout beam delivery so head can move around (patient not fixed)

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7
Q

What is MLC?

A

Multi leaf collimator Part of RT machine, helps to shape beam of radiation

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8
Q

What is the margin for setting up?

A

Extra margin added due to tumour moving slightly

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9
Q

Treatment schedule for category A cancers

A

5 days a week throughout treatment as can’t give cancer cells time to regenerate

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10
Q

What is the toxicity skin reaction in RT?

A

Radiation dermatitis

Eventually causes fibrosis Borders are defined

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11
Q

Side effects of RT

A

Mucositis

Cystitis

Proctitis

Long term urinary frequency + urgency due to bladder fibrosis

Bronchitis/ pneumonitis (can occur 4 weeks - 6 months post treatment)

Fatigue

Diarrhoea

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12
Q

Grading for radiation dermatitis

A

Grade 1 = faint erythema, dry desquamation 2 = moderate erythema, moist desquamation, confined to skin folds 3 = moist desquamation other than skin folds 4 = skin necrosis or ulceration 5 = death

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13
Q

RT in prostate pts - requirements, SE

A

Need to have a full bladder, empty bowels

SE: skin reaction, fatigue, diarrhoea, tenesmus, cystitis, urinary frequency

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14
Q

RT in head and neck cancer - SE

A

Worst SE - intensive mouth care needed

Held in place by thermoplastic shells

SE: skin reaction, fatigue, mouth soreness, difficulty swallowing, voice changes, hair loss, tinnitus Long term risk of tooth decay, hearing changes, difficulty swallowing + xerostomia (dry mouth)

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15
Q

What is brachytherapy + what are the types?

A

Inserting radioactive material into affected area

intracavity = into body cavity eg uterus

intrastitial = into target eg prostate

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16
Q

What cancers use brachytherapy?

A

Prostate, cervical + womb, head and neck

17
Q

What is the skin sparing effect?

A

X rays penetrate deep into body tissue, sparing overlying skin Reduces skin toxicity reactions

18
Q

Which cancers are more radio sensitive?

A

Seminoma Hodgkins disease

19
Q

Which cancers are radio resistant?

A

Glioblastoma multiforme

20
Q

Why is concurrent chemo helpful?

A

Acts as radiosensitiser

Improves efficacy

21
Q

What is the radiotherapy pathway?

A

Diagnosis

MDT discussion

Patient consents

Immobilisation CT scan

Disease delineation by oncologist

Margins added

Treatment plan developed

Pt has daily treatments

Review + monitoring

Follow up

22
Q

What is the most common type of RT used?

A

External beam - 3D conformal RT Treatment based on 3D shape of their tumour

23
Q

What is the GTV, CTV + PTV?

A

GTV = gross tumour volume CTV = clinical target volume (margin has been added) PTV = Planning target volume (added margin due to patient + tumour movement)

24
Q

Long term toxicity effects of RT

A

Lung fibrosis, skin atrophy + infertility

Secondary malignancy

25
Q

What are radioisotopes + what is it commonly used for?

A

Unstable form of chemical element

Emits radiation when it decays

Commonly used is radiactive iodine I-131 - used in thyroid cancer

26
Q

What is stereotactic RT?

A

Delivered using VMAT technique

Image guided radiotherapy

works for small + well defined tumours

Large dose of RT given in small number of large fractions

Oncology + Palliative (23 decks)

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