Sheffield Teaching Hospitals NHS Foundation Trust Teaching the Basic Craft of Radiotherapy Treatment Planning Stephen Tozer-Loft Radiotherapy Physics Department Weston Park Hospital Witham Road Sheffield S10 2SJ bleep 315 Featuring Interactive Radiotherapy Planning for Students (IRPS)

Sheffield Teaching Hospitals NHS Foundation Trust Radiotherapy in Practice SHU, October 2010 Outline how and why IRPS came about computer-based planning teaching how IRPS works

Sheffield Teaching Hospitals NHS Foundation Trust Radiotherapy in Practice SHU, October 2010 Existing teaching method 4 hand-planning with tracing paper 4 teaches physical principles 6 unconnected with clinical planning 6 boring 6 25-year-old book – ‘The Planning Manual’

Sheffield Teaching Hospitals NHS Foundation Trust Radiotherapy in Practice SHU, October 2010 Why not use real planning system ? knowledge gained is not generic availability security complexity peripherals and/or real patient data required

Sheffield Teaching Hospitals NHS Foundation Trust Radiotherapy in Practice SHU, October 2010 Initial considerations replace existing ‘planning manual’ PC-based self-guiding allow students’ progress to be monitored use existing planning algorithms  Part 1 (1994)

Sheffield Teaching Hospitals NHS Foundation Trust Radiotherapy in Practice SHU, October 2010 IRPS Part 1 very easy to use teaches fundamental principles tests knowledge interactively eg: adding up isodose values on screen selecting wedge monitor unit calculations

Sheffield Teaching Hospitals NHS Foundation Trust Radiotherapy in Practice SHU, October 2010 Subsequent developments interest from School of Radiography (Sheffield Hallam Uni) In use since 1994 requirement for assessed free planning Part 2 produced in 1997 commercial version (v2) available 1998

Sheffield Teaching Hospitals NHS Foundation Trust Radiotherapy in Practice SHU, October 2010 IRPS Part 2 contours, targets selected from list use simple menus to create a plan test for “clinical acceptability” user scores points if required, guide user towards acceptable plan

Sheffield Teaching Hospitals NHS Foundation Trust Radiotherapy in Practice SHU, October 2010 IRPS Part 2 in action

Sheffield Teaching Hospitals NHS Foundation Trust Radiotherapy in Practice SHU, October 2010 The dose algorithm simple 2-D dose calculation algorithm up to 2 inhomogeneities - effective depth method physical wedges

Sheffield Teaching Hospitals NHS Foundation Trust Radiotherapy in Practice SHU, October 2010 IRPS aims to expose the underlying craft by keeping it very simple: No 3D, 4D, MLC, IMRT, IGRT, VMAT, DRR, REV, BEV, EDW, CTV, GTV, ITV, MC, AAA, DICOM, HL7 Deliberately simple approach

Sheffield Teaching Hospitals NHS Foundation Trust Radiotherapy in Practice SHU, October 2010 Testing for ‘clinical acceptability’ needs to be (at least) site-specific embed clinical experience output to help user achieve acceptability yes-no result

Sheffield Teaching Hospitals NHS Foundation Trust Radiotherapy in Practice SHU, October 2010 Manitoba’s score functions based on analysis of DVHs based on volumes not areas parameters are not combined into ‘cost-function’ - each test must be passed Int. J. Rad. Onc. Biol. Phys. 20 (1991) Shalev et al. ibid 23 (1992) Viggars et al.

Sheffield Teaching Hospitals NHS Foundation Trust Radiotherapy in Practice SHU, October 2010 Overdose score function where D max = maximum dose limit (105% of intersection) V 1 = volume of target over D max T 1 = tolerance volume for D max (10%)

Sheffield Teaching Hospitals NHS Foundation Trust Radiotherapy in Practice SHU, October 2010 Expert planners input 36 real contours planned ‘adequately’ by experts calculate S 0, S 1, S 2, R f, and dose to critical organs clinically acceptable values ‘derived’ IRPS user’s values compared

Sheffield Teaching Hospitals NHS Foundation Trust Radiotherapy in Practice SHU, October 2010 Dose gradient

Sheffield Teaching Hospitals NHS Foundation Trust Radiotherapy in Practice SHU, October 2010 IRPS Part 2 - scoring system start with 100 points per contour lose 10 for a hint (up to 5 per plan) lose 4 for recalculation points allocated only when ‘acceptability’ has been achieved

Sheffield Teaching Hospitals NHS Foundation Trust Radiotherapy in Practice SHU, October 2010 Scores achieved by our experts IRPS Part 2 Scores - Means, Maxima, and Minima Number of complete plans

Sheffield Teaching Hospitals NHS Foundation Trust Radiotherapy in Practice SHU, October 2010 Conclusions IRPS seems useful (>50 centres bought) clinical acceptibility has been assessed imperfectly learning the craft of planning can be computer-aided and self-guided