Optimizing radiation treatment plans for lung cancer using lung perfusion information

Functional image-based radiotherapy planning for non-small cell lung cancer: A simulation study

“…Examination of the characteristics of these simulations suggests that the size of the functional deficit identified could be an important factor in determining the value of the functional information in treatment planning, with scenarios where defects exceeded approximately 25% of the total lung volume showing larger potential reductions in FV 20 . This is in keeping with the findings of previous SPECT studies, such as that performed by Seppenwoolde et al [10], who demonstrated greater improvements in functional lung irradiation parameters with large functional deficits, hypothesising that larger non-functional volumes allow greater potential to select beam arrangements that enter or exit through a non-functional "window" of lung.…”

“…These defects were selected to represent a subgroup of situations in NSCLC that could be potentially favourable for functional planning based on previous published work, and are not representative of the entire NSCLC patient spectrum. A previous radiotherapy planning series utilising perfusion SPECT has demonstrated that such localised functional deficits are present in a significant proportion of patients undergoing radiotherapy for NSCLC, with even large deficits such as hypo-function of the entire ipsilateral lung present in 16% of cases [10]. However, a significant number of patients had defects only at the target tumour itself, or varied patterns of inhomogeneous function spread throughout the lung, and therefore whilst it is likely that these simulations correspond to patterns present in real NSCLC patients, they may only be a small subset of the population as a whole.…”

“…Early SPECT studies using conformal planning concluded that the greatest benefits were observed in patients with large localised defects in lung function [10,17], a view supported by the findings of a more recent study using IMRT [12]. However, another recent study comparing SPECT-based IMRT with functional 3D conformal planning failed to identify significant benefits in this group, suggesting instead diffuse inhomogeneity of lung function as the most favourable setting for the use of this combined technique [11,19].…”

“…However, a significant proportion of NSCLC patients have defects in regional lung function caused either by local tumour effects or by concurrent pulmonary disease [9][10][11][12]. This observation has prompted investigations of functional image-based radiotherapy planning, utilising physiological information from either single-photon emission computed tomography (SPECT) [10][11][12][13], four-dimensional X-ray computed tomography (4D-CT) [14] or hyperpolarized helium-3 magnetic resonance imaging ( 3 He-MRI) [15,16].…”

“…The use of perfusion SPECT in facilitating lung radiotherapy treatment planning has been investigated over a number of years, with results demonstrating that incorporation of SPECT functional information into standard conformal radiotherapy planning can allow reductions in the V 20 for functional lung (FV 20 ) of 3-17% in individual cases, particularly where discrete non-functional regions of significant size are detected [10,17]. In addition, the combination of SPECT imaging data with IMRT techniques has shown the potential to improve functional lung avoidance when compared to both SPECT-based 3D conformal plans [11], and standard anatomical IMRT plans [12,13], permitting average reductions in FV 20 of 3-10.6% in patients with locally advanced disease, although this benefit has not been demonstrable in early stage patients [11][12][13].…”