Wk 11 Proton Therapy Flashcards

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1
Q

Radiation cause damages to DNA through __________ and _______________.

A

Direct action and indirect actions

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2
Q

DNA damages include ________________ and ___________________

A

Single strand break (SSB) and double strand break (DSB)

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3
Q

DNA damages that cannot be paired caused ______________.

A

Cell death

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4
Q

What is therapeutic ratio?

A

The ratio of radiation damages to cancer cells vs to normal cells

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5
Q

What forms the Bragg peak?

A

Energy loss via ionisation and atomic excitation

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6
Q

What do a proton therapy system consist?

A
  1. Accelerator (cyclotron or synchrotron)
  2. Energy selection and beam transport system
  3. Beam delivery system (fixed beam or gantry)
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7
Q

What is the function of a cyclotron or synchrotron?

A

Produce and accelerate protons suitable for cancer treatment (230MeV, 66% of light speed)

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8
Q

What is the function of energy selection system in proton therapy system?

A

It changes the beam energy to that needed for tumour depth in patient.

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9
Q

What is the function of the beam transport system in the proton therapy system?

A

-focuses beam
- maintain protons in beam to uniform energy (discrepancy <1%)
- transport beam to individual treatment rooms

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10
Q

What is the weight, diameter and degree of rotation of proton gantries?

A

Weight >100 tons
Diameter >10m
Rotation >360 degrees

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11
Q

What do a proton therapy treatment room consist?

A
  1. 360 rotating gantry
  2. Nozzle (treatment head)
  3. Orthogonal X-ray and CBCT imaging panels
  4. 6D rotating robotic couch
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12
Q

What are the particle beam delivery techniques?

A

3D conformal proton therapy technique
- double scattering beam
- single scattering beam
- uniform scanning beam

IMPT technique
- pencil beam scanning (PBS)

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13
Q

What consist in the universal nozzle?

A
  • 1st scatterer
  • range modulator and focusing magnets
  • scanning magnets
  • 2nd scatterer
  • variable collimators
  • monitor chambers
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14
Q

What equipment is used to conforming dose to target laterally?

A

Metal apertures
Made of brass or low-melting point alloys

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15
Q

What equipment is used to conform dose to target distally?

A

Range compensators

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16
Q

Why adaptive proton therapy plan is needed?

A

Plan revision is required due to tumour shrank and target changed due to patient weight loss

17
Q

How is offline plan adaptive performed?

A

Repeat CT scan after the start of treatment —> image registration and contouring —> dose calculation and evaluation —> revision required? If yes, conduct plan revision and QA, then use the revised plan

18
Q

What are the advantages of proton therapy?

A
  1. Volumes of patient body receiving low dose is significantly reduced, reduced early and late complication of treatment
  2. For shallower tumours, the nearby critical organs are better protected