EXTERNAL BEAM RADIOTHERAPY TREATMENT for cervical cancer

Question 1

EXTERNAL BEAM RADIOTHERAPY TREATMENT recommended for

Answer 1

-stages IB3,II,III and IVA-chemoradiation
-Pelvic RT with brachy (Pt not fit for surgery)
-CRT can be given in early stages (Pt not fit for surgery)

Question 2

Dose Defintive chemoradiotherapy

Answer 2

1.8Gy (50.04Gy) + single agent radiosensitizing chemotherapy cisplatin (weekly 40mg/m2 )

followed by intra-cavitary brachytherapy

Question 3

Dose Post-op:

Answer 3

-45-50.4Gy/25-28#/5-5.5wks
-not vaginal vault brachy unless +ve vaginal margin

Question 4

CT Simulation- bladder filling

Answer 4

displaces small bowel and reduces volume of bladder

Question 5

CT Simulation- Patient Position: prone

Answer 5

-bellyboard
-displace small bowel
-arms above head

Question 6

PRE-TREATMENT- CT SCAN

Answer 6

-intraoital marker
-vaginal contrast
-contrast if no renal impairment(helps in visualizing pelvic blood vessels , uterus and primary tumour)

Question 7

PRE-TREATMENT- CT SCAN scanning levels

Answer 7

T12- below the perinum

Question 8

Possible Plans

Answer 8

-2 fields :ant and post (when patient has
extensive disease-palliation)
-3 fields ( anterior and wedged fields on lateral)
-4 field block (obese patients , to give better dose distribution)

Question 9

PLANNING-IMRT/VMAT

Answer 9

decrease in acute toxicities - GI ,GU and haemotogical toxicities

Equivalent efficacy to conventional techniques with lower toxicity burden

Question 10

Para-aortic Treatment

Answer 10

-extended field( now to T12 to L1 space) with concurrent cisplatin
-associated with high risk of high rate acute and late toxicity

Question 11

possible doses for Palliative Treatment

Answer 11

-single 8Gy fraction
-20GY/5#/1 week
-30Gy10#/2 weeks

Question 12

IGRT-WHAT NEEDS TO BE CONSIDERED?

Answer 12

INTACT UTERUS:
-whole uterus in volume
-the uterine movement (can be up to 3cm a/p)
-independent of bone
-bladder-filling has been shown to influence uterine motion a/p and s/i
-Movement of the cervix in AP direction for rectal filling

Question 13

Post-op Pelvis

Answer 13

-vaginal vault moves in A/P direction w rectal filling
-little movement of vagina in LT/RT
-empty bladder might be easier to reproduce, however this increases dose to small bowel and bladder

Question 14

imaging protocols for IGRT

Answer 14

IGRT protocols that visualize soft tissue at the time of radiotherapy

Question 15

imaging protocols for Target motion in the cervix

Answer 15

significant changes in shape and position in CTV anatomy can occur due to changes in bladder and rectal and tumour volume.

Adaptive RT can be used to reduce margins and/or avoid dosimetric insuffiency

Question 16

imaging protocols on treatment verification

Answer 16

3d volumetric vertification is gold standard imaging modality particulary when using IMRT

Question 17

Adaptive Planning Strategies: Post-operative pelvis

Answer 17

two planning scans , one with a full bladder and one with a empty bladder.

images are fused and planning can create a ITV(internal tumour volume) and take account of the position in two extremes

Question 18

Adaptive Planning -Uterus motion model

Answer 18

-create library of plans where the uterus is in different positions due to bladder filling
-take CBCT before tx and select the most apropiate plan for that day
-reduces dose in OAR

Question 19

BRACHYTHERAPY :HDR-Iridium Ir192

Answer 19

-outpatient
-shorter tx times
-minimises radiation to staff (afterloading)
-allows tx dose optimisation with greater control and less morbidites
-intregration of EBRT and HDR - reduction in overall tx time

Question 20

BRACHYTHERAPY :LDR- Cesium Cs 137

Answer 20

-inpatient
-strict bed rest
-radiation exposure to staff - manual loading
-high reliance for vaginal packaging -potential for displacement

Question 21

Brachytherapy aim

Answer 21

give higher dose to tumour and sparing normal tissues

Question 22

Brachytherapy usually combined

Answer 22

EBRT and also post-op and /or pre-op surgery

Question 23

Brachytherapy dose can be delivered

Answer 23

Low dose rate=0.4-2Gy/hr
medium dose rate= (2- 12Gy/hr)
high dose rate=(>12Gy/hr)

Question 24

Brachytherapy- conditions prior to implant

Answer 24

-optimal tumour reduction/shrinkage must. be achieved
-tumour regression usually occurs 2-5wks of EBRT
-review all patients before brachy
-FBC before insertion

Question 25

Duration of EBRT and brachy

Answer 25

shouldnt exceed 56 days

-EBRT and chemo should be stopped on days of brachy
-In Ireland, intracavity brachytherapy given once EBRT has been completed. Keeping to within 56 days

Question 26

Intracavity Procedure- Theatre

Answer 26

-general Anaesthesia, spinal or epidural
-in dorsal lithotomy position
-EUA asses :
a) residual
b)cervical and fornices anatomy
c)select appropiate applicators
-contrast or saline to visual on imaging
-dilate cervix and use ultrasound to check uterine length

Question 27

Intracavity Procedure

Answer 27

-insert applicators
-pack vagina to keep applicator in place (vaseline soaked gauze)
-rectum retracter to minimize dose to rectum and bladder
-can suture applicator to restrict movement if needed
-transfer bed to CT or MRI
-CT scanned w applicators in place and then 3D planned

Question 28

target volumes notes

Answer 28

-interstital brachy or a combo of interstital and intracavity brachy if tumour volume cannot be achieved by conventional brachy

Question 29

Point A allows

Answer 29

uniformity of treatment delivery between institutions

Question 30

Total Doses from Point A and external beam radiotherapy

Answer 30

◦80 Gy- small tumours
◦ 85 Gy or higher- larger tumours