2-[18F]Fluoro-2-Deoxy-D-Glucose Positron Emission Tomography Definition of Lung Targets in Vero Stereotactic Body Radiation Therapy Workflow

Charles A Kunos John P Shanahan

doi:10.4172/2155-9619.1000227

Abstract

This retrospective study explored 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) as an aid in target delineation among a first-group of five patients with single or multiple moving lung tumors planned for Vero stereotactic body radiation therapy (SBRT). Computed tomography (CT)-based free-breathing, end-inspiration, and end-expiration lung target volumes generated a single internal target volume (ITV). ITVs were compared to a thresholded 40% maximum standard uptake value FDG-PET target volume (CTVpet), a contour assumed to be a surrogate for lung target motion during quiet breathing. Planning target volumes (PTV) and relevant lung planning constraints determined clinical execution of Vero SBRT. A mean 28% PTV expansion by adding in a CTVpet contour to the CT-based ITV converted two (40%) of five cases from SBRT fractionation (40 Gy in four every other day fractions) to conventional fractionation (30 Gy in ten daily fractions). In all five cases, CTVpet contours captured target motion not enclosed by the CT-based ITV. Vero SBRT radiation plans achieved effective normal tissue sparing without compromise of PTV target coverage. A single instance of less than 30-day posttherapy grade 2 fatigue occurred; no pulmonary toxicity has been observed in the 3-month follow-up period. Thresholded CTVpet contours impacted target delineation and clinical delivery of Vero SBRT treatment.

Highlights

This study investigates the use of 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) images for delineation of pulmonary tumor targets when treating sites of recurrent lung cancer or lung oligometastases by Vero stereotactic body radiation therapy (SBRT)
The first five Vero SBRT patients with moving lung targets had histologically-confirmed diagnoses of either recurrent lung cancer previously treated by chemotherapy (n=2) or by radiochemotherapy (n=1), or a limited number (≤3 targets) of pulmonary oligometastases (n=2)
Vero SBRT workflow and adverse events Vero treatment involved both static fields and dynamic arcs delivered over a total of 32 fractions (Table 1 and Figure 1)

Summary

Introduction

This study investigates the use of 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) images for delineation of pulmonary tumor targets when treating sites of recurrent lung cancer or lung oligometastases by Vero stereotactic body radiation therapy (SBRT). Because intracellular hexokinase traps 18F-FDG as a sugar lookalike, PET has assisted in the spotting of and in the contouring of cancer targets for radiation treatment through image fusion, overlay, or side-by-side viewing [1,2,3,4]. As highly precise radiation delivery platforms become more mainstream, there has been a need for accurate anatomic and metabolic exactness of cancer targets [5]. SBRT has an emerging role in palliative management of recurrent lung cancer or treatment of a limited number oligometastases to the lung [10,11,12]. The gimbaled Vero linear accelerator nested in a rotational gantry (±185°) and pivoting O-ring (±60°) represents a first-in-class radiation platform for delivery of ablative radiation dose with submillimeter accuracy [13,14,15,16]

Methods

Results

Conclusion