DIFFERENT TECHNIQUES: A SURVEY OF THE EMERGING PARTIAL BREAST IRRADIATION TECHNIQUES DISCLOSURES. Gregory K. Edmundson, M.Sc. Consulting Physicist

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1 DIFFERENT TECHNIQUES: A SURVEY OF THE EMERGING PARTIAL BREAST IRRADIATION TECHNIQUES Gregory K. Edmundson, M.Sc. Consulting Physicist DISCLOSURES Consulting clients include: Cianna Medical (mfr of SAVI) CR Bard (mfr of Contura MLB) Nucletron BV (mfr of afterloaders and planning systems) Varian Brachytherapy (mfr of afterloaders and planning systems) Former employers: Nucletron Cytyc Corp (now Hologic, mfr of MammoSite) BACKGROUND BACKGROUND DEFINITION OF APBI Accelerated Partial Breast Irradiation Key features: Treatment duration 2 12 days Replacement for conventional whole breast irradiation Targets ¼ or less of breast Any modality HISTORY OF APBI First interstitial series begun 1992 (King, 2000) MammoSite 2001 (Edmundson, 2002) APBI via external beam 3D-CRT 2001 (Baglan, 2003) Other breast applicators: SAVI 2006 (Yashar, 2010) Contura 2008 (Arthur, 2010) Other external techniques: Tomotherapy (Patel, 2007) IMRT (Moon, 2009; Jagsi, 2010) CyberKnife Protons (Moon, 2009) IORT IntraBeam Xoft Axxent 1

2 EMERGING BRACHY SPECTRUM INTERSTITIAL Conventional APBI Modalities (1993) Intracavitary (MammoSite, 2001) Sources (and hot spots) distributed throughout volume Catheters Cavity Target These methods have qualitatively different philosophies and strategies, strengths and limitations INTERSTITIAL INTERSTITIAL Sources (and hot spots) distributed throughout volume Each position has relatively low weight (1 2% of total) Advantages Flexible shape High gradient at edge Highest modulation potential Large experience 2

3 INTERSTITIAL CLASSICAL INTRACAVITARY: MAMMOSITE Disadvantages Possible poor distribution More trauma Complex Possible geometric miss* Target Cavity Single catheter, as far as possible from applicator surface (maximize applicator size) Cavity Catheter Target *Peterson, 2007(10) Edmundson, 2002 (2) CLASSICAL INTRACAVITARY: MAMMOSITE CLASSICAL INTRACAVITARY: MAMMOSITE Single catheter, as far as possible from applicator surface (maximize applicator size) Few dwell positions, each with high weight Depends upon distance from source to reduce hotspots Advantages Simple placement Less trauma Balloon positions tissue Certainty of location (no geometric miss) (Xoft Axxent similar) What is the cavity extent? 3

4 CLASSICAL INTRACAVITARY: MAMMOSITE EMERGING BRACHY SPECTRUM Disadvantages Subject to asymmetry Size limitations Very low modulation potential No asymmetric margin Skin dose Asymmetry Simpler Intracavitary (MammoSite Classic ) MammoSite ML (Multi-Lumen) SenoRx (now Bard) Contura MLB NAS ClearPath (bankrupt) BioLucent (now Cianna Medical) SAVI More Modulation Skin Dose with MammoSite HYBRID APPROACHES: MAMMOSITE ML Similar to classic intracavitary Distends cavity 3 Fixed catheters + central Catheters parallel, 3 mm offset HYBRID APPROACHES: MAMMOSITE ML Intermediate # dwells, weights Asymmetric margin possible Modest modulation potential 4

5 HYBRID APPROACHES: CONTURA MLB HYBRID APPROACHES: CONTURA MLB Similar to classic intracavitary Distends cavity Suction ports 4 Fixed catheters (curved, 5mm offset) + central Intermediate # dwells, weights Asymmetric margin possible Moderate modulation potential Arthur, 2010 (5) HYBRID APPROACHES: SAVI HYBRID APPROACHES: SAVI Similar to interstitial Several sizes: 6 10 outer catheters + central Sources load in central and/or outer tubes Distends cavity to some extent Many dwells, low weights High modulation potential Asymmetric margin possible Yashar, 2010 (4) 5

6 THE BRACHY SPECTRUM THE BRACHY SPECTRUM MammoSite Classic Contura MLB and Intracavitary use qualitatively different strategies and tradeoffs Hybrid devices: Form a spectrum between IT and IC All provide some skin dose reduction Have higher dose gradients in PTV Provide some geometric assurance MammoSite ML Increasing modulation SAVI EXTERNAL BEAM Several methods available 3D-CRT IMRT Tomotherapy Cyberknife Protons 3D-CRT started at William Beaumont 2001 Compared to brachy at ASTRO 2003 BRACHY VS EXTERNAL BEAM MammoSite 3D-CRT ASTRO 2003 Weed, 2005 (9) 6

7 BRACHY VS EXTERNAL BEAM BRACHY VS EXTERNAL BEAM PTV 3D-CRT MammoSite 3D-CRT MammoSite ASTRO 2003 ASTRO 2003 BRACHY VS EXTERNAL BEAM BRACHY VS EXTERNAL BEAM: UPDATED TECHNIQUES Ipsilateral Breast MammoSite 3D-CRT Bovi (2007) (ref 11) v MammoSite v 3D Better coverage for brachy methods Same pattern in uninvolved breast Patel (2007) v 3D v TOMO (prone, supine) Similar pattern in uninvolved breast TOMO intermediate between brachy and 3D Moon (2009) 3D, IMRT, TOMO, Proton Proton looks best, but is it real? ASTRO

8 IORT IORT There are two intracavitary devices marketed for IORT: Xoft Axxent (balloon + mini x-ray tube) also used for APBI Zeiss IntraBeam (mini x-ray + rigid applicators) Both of these systems use ~50 kvp (i.e. low energy) x-rays, for ease of shielding IORT may also be delivered using dedicated electron accelerators (not discussed here) IORT CONCLUSIONS Brachy techniques have evolved significantly Multi-lumen applicators, improved planning systems Skin doses near 100% possible for most patients Better coverage routine (V95>95%) External techniques expose large volumes of uninvolved breast to high dose GTV CTV expansion of 15 mm excessive?* 10 mm CTV PTV margin really necessary? Would true image guidance (Cyberknife?) resolve these issues? *Shaitelman, 2010 (12) 8