Megavoltage machines

Question 1

Tomotherapy

Answer 1

• fan beam radiation, rotational RT
• rotates through 5 resolutions per min or 6 if images are getting taken
• single energy (6MV)
• narrow gantry, rotates 360
• less narrow bore
• MRI & CT components
• helical and direct projection for treatment
• 1, 2, 5cm movements into the bam path
• ONLY couch moves
• IGMRT
• connected to a magnetron
• standing wave accelerator
• can treat a 135cm field length, max couch movement is 40ck
• one rotation = 51 beams at 7 degrees

Question 2

Cyber knife

Answer 2

• 6 MV linac
• imaging system
• tracking system
• 70 cm standing WG
• delivers 100cGy
• small fields (max 5 x 5)
• small and defined volumes
• robotic monitoring and movement

Question 3

Haylcon

Answer 3

• water cooling system
• dual layer of MLC’s, 100% movement
• varian ring gantry
• standing wave
• single energy, 6MV
• 100cm bore
• direct transfer from CT scanner
• 360 rotation
• provides VMAT and IRMT
• patient observation
• FFF (increases beam)

Question 4

how many fractions is stereotactic radio surgery

Answer 4

1

Question 5

how many fractions is stereotactic radiotherapy

Answer 5

multiple

Question 6

what is the degree of freedom for a positional movement

Answer 6

six