Using the CRW Frame for the Stereotactic Biopsy of Cerebral Lesions Mr D Eagle & Mr S Ushewokunze Using the CRW Frame for the Stereotactic Biopsy of Cerebral Lesions

Objectives Familiarity of components of the CRW frame Ability to fit the base plate and localiser Ability to obtain a usable scan Familiarity with iPlannet system for planning trajectories and obtaining co-ordinates Set up of the frame from co-ordinates to obtain an accurate biopsy ***?add brief

Key Steps General anaesthetic (if being used) Fit base plate & localiser Obtain CT scan with localiser in-situ Plan biopsy using iPlannet system Assemble CRW frame using co-ordinates from iPlannet Check co-ordinates using phantom frame (if necessary) Fit frame to base plate on patient Drill burr hole and perform biopsy

Base Plate & Localiser Fit carbon uprights vertically in 2 most anterior holes... ...and 2 most posterior holes. Set-up of the base plate and localiser is non-sterile and can be done while the patient is being put to sleep.

Base Plate & Localiser Insert 4x disposable nylon screws - use 2x long screws anteriorly (to give more space over the nose) and 2x short screws posteriorly. Tighten the screws to being ‘hand-tight’ using the spanner. If under local can use the ‘hat’ to help hold the frame in position over the patient.

Base Plate & Localiser Fit the localiser frame. Note: the triangular cut outs anteriorly on the localiser match triangular projections on the base plate. It is normal that there is a 2-3mm gap between the localiser frame and base plate. Always keep the spanner with the patient for transfer to scan in case of an emergency. Phone CT before transfer.

Scanning Fit the bracket into the CT scan bed and screw down the top clamp so its rigid. This bracket is equivalent to the bracket you will use in theatre to secure the patient to the table Note this is Mr Rowe’s bracket! Mr Jellinek’s bracket is slightly different but at present doesn’t work in the new scanner.

Scanning Transfer the patient onto the scan bed and secure the base plate to the scanner bracket using the 2x bolts. The frame should be exactly perpendicular to the bed and rigid.

Scanning During scanning, the frame should appear perfectly straight in the scout images. If they’re not straight, adjust the clamp and re-scan.

Planning Open Window’s Explorer (no Internet Explorer) Type: Iplannet in the address bar (For access email: itservicedesk@sth.nhs.uk , request standard access to BrainLab/Iplannet) Follow the Iplannet steps to load the patient, assign the localiser, plan the trajectory and obtain the co-ordinates The Anterior-Posterior, Vertical and Lateral co-ordinates gives the position of the TARGET The Ring and Arc settings, gives the position of the ENTRY POINT However, could all requests for access be made to the IT Service desk on 15369 or by email to itservicedesk@sth.nhs.uk. To help our staff grant you the correct access please state that you need access to: System: Brainlab (Iplannet) Role: Standard Access

Clamping to the Theatre Table Transfer the patient onto the theatre table. Take the table bracket out of the sterile tray and fit it between the base plate on the patient to the clamp. Take the square ring out of the sterile tray and fit to the base plate. If this squashes the nose the anterior section of the square ring can be removed.

Prep’ing and Draping Scrub. Prep the patient and square ring WITH CLEAR PREP ONLY. Drape keeping all the square ring exposed.

Assembling the Frame Take the large ring bracket and rotate both rings so they are at 90 degrees.

Assembling the Frame Take the angle brackets and slide the SHORT side into the grooves on the ring, with the long side of the angle brackets facing away from you. The numbers on the angle brackets should align with numbers on the ring bracket.

Assembling the Frame Take the arc frame, slide it onto the ring frame from the side. ‘Dimples’ in both frames should be facing down and the numbers should line up.

Assembling the Frame Take the arc bracket, slide it onto the arc frame from the side (you will have to move the arc frame over to fit it) The arrow should line up to the numbers on the arc frame.

Assembling the Frame Take the biopsy needle sleeves, inserts and chuck. Left to right: chuck, short insert for needle, short sleeve, long insert for needle, long sleeve and drill insert

Assembling the Frame Choose between either the long or short needle insert and sleeve depending on how high the frame will sit on the head. Put the insert in the sleeve and screw into the chuck. Put the biopsy needle down the insert and measure exactly 16cm from the SHOULDER of the chuck to the middle of the biopsy needle aperture.

Assembling the Frame Place the chuck into the arc bracket and secure with the grub screw. Replace the needle insert with the drill insert ready for drilling.

Fitting the Frame Slide the whole frame onto the square ring, the long sides of the angle brackets should slide down the grooves on either side of the square ring. For most biopsies it will be easiest to have the patient head-up.

Setting the Co-Ordinates Left to right setting the co-ordinates for: - Anterior-Posterior (posterior is negative) - Lateral (left is negative) - Vertical (inferiorly is negative) Example setting: A-P -13.3mm, Lateral -10.7mm, Vertical -47.6mm Note: co-ordinates can be set prior to fitting the frame and checked on the phantom

Setting the Arc & Ring Left to right setting the co-ordinates for: - Arc (iplannet will specify left or right) - Ring (iplannet will specify anterior or posterior) Example setting: ring 56.7 A, arc 14.3 L Note: the arc and ring can be modified to suit a different entry point without affecting the target

Drilling Slide the twist drill down the drill insert, give local and make a stab incision at the point of entry. Set the collar on the drill to prevent plunging and drill through the skull.

Biopsy Replace the drill insert with the needle insert. Slide the biopsy needle down the needle insert to the preset collar. Take biopsies as required.