title: Comparison of Oncentra® Brachy IPSA and graphical optimisation techniques: a case study of HDR brachytherapy head and neck and prostate plans.
abstract: There are a number of different dwell positions and time optimisation options available in the Oncentra® Brachy (Elekta Brachytherapy Solutions, Veenendaal, The Netherlands) brachytherapy treatment planning system. The purpose of this case study was to compare graphical (GRO) and inverse planning by simulated annealing (IPSA) optimisation techniques for interstitial head and neck (HN) and prostate plans considering dosimetry, modelled radiobiology outcome and planning time. Four retrospective brachytherapy patients were chosen for this study, two recurrent HN and two prostatic boosts. Manual GRO and IPSA plans were generated for each patient. Plans were compared using dose-volume histograms (DVH) and dose coverage metrics including; conformity index (CI), homogeneity index (HI) and conformity number (CN). Logit and relative seriality models were used to calculate tumour control probability (TCP) and normal tissue complication probability (NTCP). Approximate planning time was also recorded. There was no significant difference between GRO and IPSA in terms of dose metrics with mean CI of 1.30 and 1.57 (P > 0.05) respectively. IPSA achieved an average HN TCP of 0.32 versus 0.12 for GRO while for prostate there was no significant difference. Mean GRO planning times were greater than 75 min while average IPSA planning times were less than 10 min. Planning times for IPSA were greatly reduced compared to GRO and plans were dosimetrically similar. For this reason, IPSA makes for a useful planning tool in HN and prostate brachytherapy.
authors.affiliation: Liverpool and Macarthur Cancer Therapy Centres Liverpool, New South Wales, Australia ; Centre for Medical Radiation Physics, University of Wollongong Wollongong, New South Wales, Australia ; Ingham Institute of Applied Medical Research Liverpool, New South Wales, Australia.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Jameson
authors.affiliation: Liverpool and Macarthur Cancer Therapy Centres Liverpool, New South Wales, Australia.
authors.forename: Lucy
authors.initials: L
authors.lastname: Ohanessian
authors.affiliation: Liverpool and Macarthur Cancer Therapy Centres Liverpool, New South Wales, Australia ; Ingham Institute of Applied Medical Research Liverpool, New South Wales, Australia ; South Western Sydney Clinical School, School of Medicine University of New South Wales, Australia.
authors.forename: Vikneswary
authors.initials: V
authors.lastname: Batumalai
authors.affiliation: Liverpool and Macarthur Cancer Therapy Centres Liverpool, New South Wales, Australia.
authors.forename: Virendra
authors.initials: V
authors.lastname: Patel
authors.affiliation: Liverpool and Macarthur Cancer Therapy Centres Liverpool, New South Wales, Australia ; Centre for Medical Radiation Physics, University of Wollongong Wollongong, New South Wales, Australia ; Ingham Institute of Applied Medical Research Liverpool, New South Wales, Australia ; South Western Sydney Clinical School, School of Medicine University of New South Wales, Australia ; Institute of Medical Physics, School of Physics, University of Sydney Sydney, New South Wales, Australia.
authors.forename: Lois C
authors.initials: LC
authors.lastname: Holloway
keywords: IPSA; head and neck; optimisation; prostate