Stereotactic RT

Question 1

What is the purpose of sterotactic RT?

Answer 1

• Precisely targeted radiation
• Fewer high-dose treatments
• Can help to preserve healthy tissue

Question 2

What is SRS?

Answer 2

Stereotatic radiosurgery
[treatment to brain in 1 fraction]

Question 3

What is SRT?

Answer 3

Stereotactic radiotherapy
[fractionated treatment to brain]

Question 4

What is SBRT?

Answer 4

Sterotactic body radiotheray
[treatment to body outwith brain]

A.K.A SABR

Question 5

What benign brain conditions can be treated with SRS/SRT?

Answer 5

• Vestibular Schwannoma
• Meningioma
• Pituitary Adenoma
• Trigeminal neuralgia
• Ateriovenous malformation [AVM]

Question 6

What malignant brain conditions can be treated with SRS/SRT?

Answer 6

• Gliomas
• Small, low grade brina tumours [clear margin]
• Chordoma
• Residual tumour after surgery
• Metastatic brain tumours

Question 7

Name 3 treatment machines used for SRS/SRT

Answer 7

• Gamma Knife
• Cyber Knife
• Linac with micro MLCs

Question 8

Describe Gamma Knife

Answer 8

• Focused array of intersecting beams of gamma radiation
• 192 separate Colbot-60 sources
• Extremely high radiation at focus point
• Dose very low short distance from focus point
• Requires light sedation and local anaesthetic
• Frame attched to patient’s head
• Planned and delivered in one day

Question 9

Describe Cyber Knife

Answer 9

• Linac mounted on robotic arm
• High engery photons
• Can be used for brain, prostate, and lung tumours
• Respiratory tracking system syncs beam delivery to tumour movement
• Increase in number of treatment angles

Question 10

What is the precribed dose for Vestibular Schwannoma

Answer 10

• 1300 cGy [80% isodose] 1#
• 3000 cGy [90% iso] 6# [2 weeks]
• 2500 cGy [80/90% iso] 5# [1 week]

Question 11

What is prescribed dose for brain mets?

Answer 11

Lesions < 7cm3: 2100 cGy [80% iso] 1#
7-13cm3: 1800 cGy [80% iso] 1#
> 13cm3: 1500 cGy [80% iso] 1#

Question 12

What is the prescribed dose for Meningioma?

Answer 12

Lesions < 7 cm3: 2100cGy [80% iso] 1#
Lesions 7-13cm3: 1800cGy [80% iso] 1#
Lesions > 13cm3: 3000cGy [90% iso] 6# [2 weeks]

Question 13

What is the prescribed dose for pituitary adenomas?

Answer 13

V small lesions: 2100 cGy [80% iso] 1#
Rest: 4500-5400 cGy [90% iso] 1.8Gy per #

Question 14

What are the main OARs for SRS/SRT?

Answer 14

• Brainstem
• Optic chiasm
• Optic nerves
• Eyes
• Lens
• Cochlea
• Trigeminal nerve
• Facial nerve

Question 15

What are the advanatges of SRS/SRT?

Answer 15

• Non-invasive
• Can treat inoperable tumours
• Higher dose given in fewer fractions
• Increased tumour control
• Less damage to surrounding tissues

Question 16

What are the disadvantages of SRS/SRT?

Answer 16

• Planning is time consuming
• Staff training
• Cost
• Availablity of machines