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Annex 3: BOC quality system document number WI 13.26.06, written procedures for 'Medulloblastoma Calculations'.
BEATSON ONCOLOGY CENTRE - QA CONTROLLED DOCUMENT
WI 13.26.06
MEDULLOBLASTOMA CALCULATION AND INPUT TO VARIS GENERATION 7.
1. Pre-Treatment Staff should be aware that on the prescription page will be Eclipse dose prescription and the status will be unapproved. This will not be used as prescription plan.
2. Check that all data has been co-ordinated e.g.
- Both the plan and the prescription have been signed.
- The dose on the Booking Slip corresponds with the dose on the prescription.
- The Booking Slip has been signed by the relevant IR(ME)R Practitioner.
- The patient has been consented.
- The images/x-rays has been signed by the relevant IR(ME)R Practitioner.
- Check the image or x-ray printout parameters correspond with the plan.
- Check what Treatment Machine the patient is due to attend. Check the plan has been run for the correct machine.
3.Obtain the physics plan and the prescription from the Clinical Oncologist and check that all the information has been completed correctly
4. The head fields are treated isocentrically and the information for calculation is given on the physics-planning sheet. ie. weighting, and output - output denoted in MU/100cGy.
The daily machine units remain the same throughout the treatment irrespective of changing field size.
It may be specified as a 100% incident dose or, more commonly, it is specified as a dose to the spine at depth. In this case the radiographer will have to calculate the 100% incident dose before calculating the daily machine units.
The daily machine units remain the same throughout treatment irrespective of changing field size. Spine fields to be treated at fixed FSD.
6.Complete the Varis 7 Data Confirmation Sheet. (Note that three separate sheets will be required, specifying the changes in field size as the junctions are moved)
a) Patient's name and I.D.
b) Jaw settings
c) Tolerance (F)
d) F.S.D
e) Gantry angles
f) Collimator rotation
g) Floor rotation
h) Daily machine units (in red ink)
i) Patient position and set up details-including instructions for the use of a wax compensator and shielding
j) Sign the data sheet
7.Pencil on the appropriate line on the treatment record sheet when the field size should change and the BDS and wax compensator adjusted.
8.In RT Chart, Prescription Page;
This plan will not be downloaded so all treatment data will need to be manually entered.
9. A new prescription will be required for each site ie. Rename PSI as
MEDULLA1
MEDULLA2
MEDULLA3
SPINE-UPPER1
SPINE-UPPER2
SPINE-UPPER3
SPINE-LOWER1
SPINE-LOWER2
SPINE-LOWER3
It will be necessary to keep the same volume site as medulla throughout for the brain fields and for the spine fields use Spine-Upper and Spine-Lower. For each plan key in the number of fractions to each junction. Key in the daily TD as normal.
10. The following parameters should be entered into RT Chart;
Field I.D.
Field Name
Technique
Energy/Mode
Dose Rate
M.U's; as calculated by the Radiographer from physics output.
Tolerance Table (Tolerance F)
F.S.D.
Gantry Rotation.
Collimator Rotation.
Field X1 and X2.
Field Y1 and Y2.
MLC
Couch Vertical.
Couch Longitudinal.
Couch Lateral.
Couch Rotation.
(Key in any additional data e.g. set-up note, in RT Chart as per W.I 13.26.03).
Refer to W.I 13.26.03.
The Start Delay will need to be entered for each junction change
i.e. MEDULLA1 start delay is 0
MEDULLA2 (if the junction change is after 7 fractions) start delay is 7
MEDULLA3 start delay is 14.
This will also be the case for the start delay for the Spinal Upper and Spinal Lower.
In the Dose Contributions section, the following will be entered;
M.U's
Field Dose
The Total Dose Limit is the total dose prescribed for the treatment i.e. total dose for all junctions.
(The Daily Dose Limit and Session Dose Limit will need to be entered as W.I 13.26.03).
Refer to W.I 13.26.03.
(The Interval Days and if necessary, a Sequence Template will need to be entered as W.I 13.26.03).
6. The patient's data should be scheduled on Varis 7 Time Planner as W.I 13.26.02.
7. Have the prescription, the VARIS 7 Data Confirmation Sheet and all the data entered on VARIS 7 Patient Manager, RT Chart and Time Planner checked by another radiographer. The radiographer checking the plan must ensure all boxes are 'ticked' on the data confirmation sheet. After checking the plan must be set to treatment approved. One of these two must be Senior or Superintendent grade.
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