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Title: MO-FG-CAMPUS-JeP2-05: MRI-Guided Single-Fraction Boost Delivery On Individual Axillary Lymph Nodes

Abstract

Purpose: The Utrecht MRI-linac (MRL) design enables new MR-guided radiotherapy (RT) approaches. This is a feasibility study for a single-fraction high dose (boost) to individual lymph nodes (LNs) in breast-cancer patients, after breast-conserving surgery (BCS) and hypofractionated whole-breast irradiation (WBI) with conventional axillary RT (AxRT). Methods: After written informed consent, 5 breast-cancer patients (cT1-3N0) were enrolled (NL500460.041.14 trial) and underwent 1.5T MRI in supine RT position, after BCS. Axillary levels, based on ESTRO guidelines, and organs-at-risk (OARs) – including lungs, chest wall, plexus and neurovascular bundle (NVB) – were delineated. Pseudo-CT scans (pCTs) were generated by HU bulk-assignment of water, lung, and air. With Monaco treatment-planning software (TPS Elekta), VMAT plans were generated for simultaneous WBI and AxRT, prescribing 16×2.66=42.56Gy (V95%>99% V107%<2cc). Two scenarios were considered: AxRT of levels I–II; AxRT of levels I–IV, depending on boost location. Per patient, 4 LNs with varying axillary locations were selected, delineated, and expanded to PTV with 2-mm margin. Using dedicated MRL TPS, accounting for magnetic-field effects, an IMRT 1×8.5Gy boost was simulated for each LN, to achieve a total target dose of 66Gy EQD2 (α/β=3.5Gy). WBI/ART doses and boost doses were added, and evaluated in EQD2. Results: For all scenarios, 1×8.5Gy boostsmore » could be simulated within clinical constraints for a 66Gy total dose, in addition to WBI/AxRT. LN target coverage was excellent (V95%>95%, mean >8.5Gy). Additional dose to OARs was limited. Conclusion: Our study explored the concept of LN boosting using on-line MRI guidance. It is feasible to boost individual axillary LNs – with 2-mm margin – with an additional 1×8.5Gy, in all axillary levels, within clinical constraints. This may lead to more personalized RT approaches for patients with involved LNs and may reduce RT-induced toxicity, or the need for axillary surgery. Other LN boost strategies, including dose escalation, are under investigation.« less

Authors:
; ; ; ;  [1]
  1. University Medical Center Utrecht, Utrecht (Netherlands)
Publication Date:
OSTI Identifier:
22653904
Resource Type:
Journal Article
Journal Name:
Medical Physics
Additional Journal Information:
Journal Volume: 43; Journal Issue: 6; Other Information: (c) 2016 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-2405
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; 61 RADIATION PROTECTION AND DOSIMETRY; COMPUTER CODES; COMPUTERIZED TOMOGRAPHY; FEASIBILITY STUDIES; LYMPH NODES; NMR IMAGING; PATIENTS; RADIATION DOSES; RADIOTHERAPY

Citation Formats

Heijst, T C F van, Hoekstra, N, Philippens, M E P, Eschbach, D, Lagendijk, J J W, Bongard, H J G D van den, and Asselen, B van. MO-FG-CAMPUS-JeP2-05: MRI-Guided Single-Fraction Boost Delivery On Individual Axillary Lymph Nodes. United States: N. p., 2016. Web. doi:10.1118/1.4957358.
Heijst, T C F van, Hoekstra, N, Philippens, M E P, Eschbach, D, Lagendijk, J J W, Bongard, H J G D van den, & Asselen, B van. MO-FG-CAMPUS-JeP2-05: MRI-Guided Single-Fraction Boost Delivery On Individual Axillary Lymph Nodes. United States. doi:10.1118/1.4957358.
Heijst, T C F van, Hoekstra, N, Philippens, M E P, Eschbach, D, Lagendijk, J J W, Bongard, H J G D van den, and Asselen, B van. Wed . "MO-FG-CAMPUS-JeP2-05: MRI-Guided Single-Fraction Boost Delivery On Individual Axillary Lymph Nodes". United States. doi:10.1118/1.4957358.
@article{osti_22653904,
title = {MO-FG-CAMPUS-JeP2-05: MRI-Guided Single-Fraction Boost Delivery On Individual Axillary Lymph Nodes},
author = {Heijst, T C F van and Hoekstra, N and Philippens, M E P and Eschbach, D and Lagendijk, J J W and Bongard, H J G D van den and Asselen, B van},
abstractNote = {Purpose: The Utrecht MRI-linac (MRL) design enables new MR-guided radiotherapy (RT) approaches. This is a feasibility study for a single-fraction high dose (boost) to individual lymph nodes (LNs) in breast-cancer patients, after breast-conserving surgery (BCS) and hypofractionated whole-breast irradiation (WBI) with conventional axillary RT (AxRT). Methods: After written informed consent, 5 breast-cancer patients (cT1-3N0) were enrolled (NL500460.041.14 trial) and underwent 1.5T MRI in supine RT position, after BCS. Axillary levels, based on ESTRO guidelines, and organs-at-risk (OARs) – including lungs, chest wall, plexus and neurovascular bundle (NVB) – were delineated. Pseudo-CT scans (pCTs) were generated by HU bulk-assignment of water, lung, and air. With Monaco treatment-planning software (TPS Elekta), VMAT plans were generated for simultaneous WBI and AxRT, prescribing 16×2.66=42.56Gy (V95%>99% V107%<2cc). Two scenarios were considered: AxRT of levels I–II; AxRT of levels I–IV, depending on boost location. Per patient, 4 LNs with varying axillary locations were selected, delineated, and expanded to PTV with 2-mm margin. Using dedicated MRL TPS, accounting for magnetic-field effects, an IMRT 1×8.5Gy boost was simulated for each LN, to achieve a total target dose of 66Gy EQD2 (α/β=3.5Gy). WBI/ART doses and boost doses were added, and evaluated in EQD2. Results: For all scenarios, 1×8.5Gy boosts could be simulated within clinical constraints for a 66Gy total dose, in addition to WBI/AxRT. LN target coverage was excellent (V95%>95%, mean >8.5Gy). Additional dose to OARs was limited. Conclusion: Our study explored the concept of LN boosting using on-line MRI guidance. It is feasible to boost individual axillary LNs – with 2-mm margin – with an additional 1×8.5Gy, in all axillary levels, within clinical constraints. This may lead to more personalized RT approaches for patients with involved LNs and may reduce RT-induced toxicity, or the need for axillary surgery. Other LN boost strategies, including dose escalation, are under investigation.},
doi = {10.1118/1.4957358},
journal = {Medical Physics},
issn = {0094-2405},
number = 6,
volume = 43,
place = {United States},
year = {2016},
month = {6}
}