1. Peripatetic Prostates and Fiducial Markers – a Simple Solution to a Complex Problem? Jo Treeby Radiographer Advanced Practitioner Urology Addenbrooke’s Hospital Cambridge With help from Donna Routsis and Yvonne Rimmer

2. The Problem It is widely recognised that the prostate is not a static organ We do really clever planning techniques with IMRT to maximise dose to target and minimise dose to surrounding tissue BUT Where exactly is it today?????

3. 3 Prostate - The Movie 8 cm Sup Ant

4. Peripatetic Prostate The same patient’s scans 1 week apart 4

5. What causes prostate movement? The level of gas or faeces in the gut Bladder filling, or not Patient positionPatient position IGRT minimises the risk of missing part or whole of the prostate Can be done in a variety of ways Newer equipment has better OBI, but is hugely expensive in a cash short NHS, and takes time to install

6. 6 Treatment verification Traditionally done using portal images: based on bone anatomy based on bone anatomy information gained is 2 dimensional information gained is 2 dimensional out-of-plane rotational information not gained out-of-plane rotational information not gained assessed retrospectively assessed retrospectively Using radio-opaque markers: markers inside the prostate markers inside the prostate 3 dimensional information 3 dimensional information rotational information available rotational information available assessed prospectively assessed prospectively

7. 7 Radio-Opaque Seeds 1.2mm x 3mm

8. Gold Marker Placement Gold grains inserted in 3 separate locations, apex, centre and tip (approx.) Implanted via transrectal ultrasound Takes about l0 mins Could be done by a radiographer Antibiotic cover given (usually 5 days oral ciprofloxacin)

9. Benefits of fiducial markers No need for an expensive new machine Software System quick & easy to install No extra imaging dose, reducing the risk of long term iatrogenic consequences Staff training not difficult, well within the capability of treatment staff Radiographer led image assessment

10. Planning Localisation CT planned as standard Gold grains are easily identifiable Co-ordinates of seeds measured relative to planned isocentre

11. Pair of Images Obtained on Treatment Set Images can be taken from any two gantry angles separated by at least 30 degrees 4 MU’s per image approx on beamview TI

12. 12 Identifying Gold Grains Just click on markers and software finds equivalent density

13. Automated analysis Analysis takes seconds Identifies seeds positions in 3D space Calculates vector displacement and 3  rotational displacement

14. Couch moves to 0.1 mm Intermarker comparison Rotational information Treatment Couch Adjustment and Target Verification

15. 15 Treatment durations Treatment fractions were timed from patient entering to exiting the maze and treatment and patient-related parameters recorded (Burnet 1999) Standard prostate radiotherapy sessions were timed on the same unit with the same parameters Treatment durations were compared

16. 16 Treatment duration comparison Treatment duration (mins) AcculocStandard Average12.610.0 SD1.72.0 n122202

17. 17 Results Mean translational displacements were 1.3mm (SD 3.0, max 14.4mm) Mean rotational displacements were 2.4  (SD 3.9, max 21.7  ) Systematic errors in the antero-posterior direction and pitch were detected Most displacements appear random Largest variations were in the AP direction and pitch

18. 18 Comparison with bony anatomy Standard PI analysis results did not agree with seed displacements Smaller displacements seen with PI Pt1 acculocPI Left/Right-2.9-1.2 Sup/Inf1.20.1 Ant/Post3.72.7 X (pitch)-21.77 Z (roll)3.12 Y (yaw)-0.4

19. 19 Interobserver variability

20. Patient Perspectives After a pilot study of 6 patients, we did a study on 50 men Well tolerated by patients Well tolerated by patients Among other things, we asked how they felt about the process OK, but - “Like being shot up the arse with a shotgun” (how does he know how that feels?) (how does he know how that feels?) All “would recommend to a friend” None regretted seed implantation 20

21. The next 50 patients intrafraction movement 21

22. The down side RESOURCES! Staff, equipment, space for seed insertion Staff, equipment, space for seed insertion Cost of seeds, antibiotics, disposables Cost of seeds, antibiotics, disposables Patients taking anticoagulant drugs need extra care, preferably stop if safe Infection risk – low, but exists Patient reluctance to have rectal probe Trauma post biopsy may mean seed insertion is contra indicated Occasional seed loss 22

23. 23 Conclusions Interventional imaging and decision making can be implemented in routine clinical practice with only small increases in treatment times Real-time interventional imaging reduces the risk of a geographical miss and permits slightly tighter margins Radiographer led process highly successful

24. If you’re still wondering “Peripatetic” means “walking about” Usually refers to a teacher Comes from the Greek “peripatos” a walk THANK YOU ANY QUESTIONS? 24