Lower GI technique

Question 1

What do you need to consider when deciding whether the patient should be treated prone or supine?

Answer 1

What is more stable?
? Colostomy bag
Patient comfort
? IMRT

Question 2

What is the prone immobilisation equipment?

Answer 2

Prone Pillow
Straight & level
Arms “up”
Bolster under ankles

Question 3

Why do we use a belly board?

Answer 3

The small bowel can be displaced anteriorly by the use of devices such as a bellyboard, which allows it to fall forwards into the bellyboard aperture
Modern bellyboard devices are more comfortable, improve immobilisation and reduce set-up errors in the prone position.

Question 4

How is the small bowel position affected by the belly board?

Answer 4

• Small bowel is moved superior outside of the treatment field
• Without belly board Small bowel within treatment field

Question 5

What is the supine immobilisation equipment?

Answer 5

Supine, straight & level
	Arms on chest
	Headrest
	Knees bolster (indexed)
	Foot-stocks (indexed

Question 6

Why is pre-op RT used?

Answer 6

Pre-operative radiotherapy becoming increasingly common as it has been proven useful in down staging tumours, making surgical excision easier and more successful. Also useful for inoperable or recurrent tumours.

Question 7

What are some other pre-op RT advantages?

Answer 7

The patient is well when attending RT – this is often easier for the patient rather than feeling unwell post operatively
Imaging techniques – including CT, MRI and PET – allow for more accurate staging of the tumour which means it is easier to assess which patients are suitable for EBRT
Studies show that results are similar pre vs post op EBRT in terms of reduction of pelvic recurrence

Question 8

What are some considerations for rectum CT/stimulation?

Answer 8

Pre-treatment considerations
A full bladder protocol is used for planning and treatment as this displaces small bowel superiorly – helps to reduce toxicity

Question 9

What are the OAR for the rectum?

Answer 9

Small bowel
Bladder
Femoral H&Ns
Genitalia

Question 10

Rectal – field arrangement & technique

Answer 10

3 field technique

Posterior beam and 2 lateral wedged fields

Question 11

Rectum - Dose Fractionation Schedules?

Answer 11

• Pre-operative RT- Short Course 25Gy in 5#
• Long Course- Phase 1 45Gy in 25#, Phase 2 (optional) 5.4 – 9Gy in 3-5#
• Adjuvant chemo: 5FU

Question 12

What is an advantage of short course pre-operative RT?

Answer 12

has been shown to reduce pelvic recurrences in patients with resectable disease

Question 13

What is an advantage of long course pre-operative RT?

Answer 13

has been shown to downstage tumours when the resection margin is threatened and to improve margin negative resection and local recurrence rates

Question 14

Post operative RT dose fractionation schedules for the rectum?

Answer 14

Phase 1- 45Gy in 25#
Phase 2 - (optional) 5.4 – 9Gy in 3-5#
(less common)

Question 15

What are the acute radiation side effects for the rectum?

Answer 15

Chemo patients - increased severity.
Acute:
Erythema/ Moist desquamation
Diarrhoea
Tenesmus
Rectal bleeding
Cystitis & Dysuria
Fatigue

Question 16

What are the late radiation side effects for the rectum?

Answer 16

Late (6-18 months)
Ulceration
Fistula
Risk of obstruction in small bowel
Chronic diarrhoea

Question 17

Patient care considerations for rectum patients?

Answer 17

Skin care – aqueous creams apply 2-3 times per day (avoid powders, other creams unless approved by RO)
medication to reduce diarrhoea
reduce fibre intake
dietitian consultation
Dysuria – urinary alkalisers
Booked to see RO weekly and when necessary.

Remember chemo will increase severity

Question 18

Anus - Patient consideration CT simulation?

Answer 18

Patients are treated in the prone position, which displaces small bowel superiorly to reduce toxicity and allows easy visualisation of the anal verge for the application
Full bladder to displace small bowel

Question 19

Anus - OAR?

Answer 19

Small bowel
Bladder
Genitalia
*Transplanted kidneys may lie in
the pelvis and should be excluded from the treatment volume or repositioned

Question 20

Anus – Field Arrangements & technique?

Answer 20

Ph 1: Large Pelvis
(plus nodes)
Ph 2:Lymph node negative or lymph node positive

Question 21

Anus - Dose Fractionation Schedules?

Answer 21

Curative or adjuvant chemoradiotherapy
Phase 1
30.6 Gy in 17 daily fractions of 1.8 Gy given in 31⁄2 weeks.

Phase 2
19.8 Gy in 11 daily fractions of 1.8 Gy given in 21⁄2 weeks
or
Single phase
50.4 Gy in 28 daily fractions of 1.8 Gy given in 6 weeks

Question 22

Anus – Side effects?

Answer 22

Grade 3 and 4 toxicity
Perineal & inguinal tissues are particularly sensitive to irradiation
Skin reactions - often brisk and painful.
Regular review and use of hydrocolloid dressings, nutritional support, analgesia and antidiarrhoeal medication are essential.
During concomitant chemotherapy, patients should receive appropriate antiemetics, and prophylactic antibiotic cover is advised for the duration of treatment.
Blood tests are monitored regularly for myelosuppression -any sign of infection treated promptly.

Question 23

Treatment set up(For rectum, Anus)? (part 1)

Answer 23

Ensure all necessary equipment is available and checked.
Ensure Patient has full bladder
Floor Rotation = 0o Gantry Rotation = 0o
Prepare bed, get patient in and explain treatment procedure and expectations.
Position patient as in CT simulation (as per instructions)
Straightened along midline using laser
Level patient using lateral levelling tattoos to match lateral lasers on machine.
Set to isocentre as per treatment instruction, (i.e. Set DOB (distance off bed) )

Question 24

Treatment set up(For rectum, Anus)? (part 2)

Answer 24

Check SSD (post field if patient prone) & post field and shielding.
Then rotate gantry around to check field, shielding, SSD and wedge orientation for other fields. (i.e. 3 field if Rectum, 2/3 field anus)
Check all set up parameters before leaving treatment room.
At console area, double check all set up parameters against the plan and treatment sheet.
Take kV/MV images prior to treatment to verify the isocentre position (check isocentre position if out of tolerance 3mm or dept policy) move to match, recapture image, record the move required).
Treat all fields double checking and verbalising console settings, jaw sizes, mlc’s, wedge orientation and MU’s for all fields
Record all necessary information

Question 25

QA images for anus and rectum?

Answer 25

Minimum - first 3 days and weekly

Daily if required for IMRT or VMAT patients