Impact of field number and beam angle on functional image-guided lung cancer radiotherapy planning. (11th August 2017)

• Record Type: Journal Article
• Authors: Tahir, Bilal A; Bragg, Chris M; Wild, Jim M; Swinscoe, James A; Lawless, Sarah E; Hart, Kerry A; Hatton, Matthew Q; Ireland, Rob H
• Is Part Of: Physics in medicine & biology. Volume 62:Number 17(2017:Sep.)
• Page Start: 7114
• Page End: 7130
• Publication Date: 2017-08-11
• Subjects: IMRT -- NSCLC -- radiation therapy -- lung avoidance -- hyperpolarized helium-3 MRI; Biophysics -- Periodicals; Medical physics -- Periodicals; 610.153
• DOI: 10.1088/1361-6560/aa8074
• Languages: English
• ISSNs: 0031-9155

Abstract

Abstract: To investigate the effect of beam angles and field number on functionally-guided intensity modulated radiotherapy (IMRT) normal lung avoidance treatment plans that incorporate hyperpolarised helium-3 magnetic resonance imaging ( 3 He MRI) ventilation data. Eight non-small cell lung cancer patients had pre-treatment 3 He MRI that was registered to inspiration breath-hold radiotherapy planning computed tomography. IMRT plans that minimised the volume of total lung receiving ⩾20 Gy (V20 ) were compared with plans that minimised 3 He MRI defined functional lung receiving ⩾20 Gy ( f V20 ). Coplanar IMRT plans using 5-field manually optimised beam angles and 9-field equidistant plans were also evaluated. For each pair of plans, the Wilcoxon signed ranks test was used to compare f V20 and the percentage of planning target volume (PTV) receiving 90% of the prescription dose (PTV90 ). Incorporation of 3 He MRI led to median reductions in f V20 of 1.3% (range: 0.2–9.3%; p = 0.04) and 0.2% (range: 0 to 4.1%; p = 0.012) for 5- and 9-field arrangements, respectively. There was no clinically significant difference in target coverage. Functionally-guided IMRT plans incorporating hyperpolarised 3 He MRI information can reduce the dose received by ventilated lung without comprising PTV coverage. The effect was greater for optimised beam angles rather than uniformly spaced fields.