RapidArc, intensity modulated photon and proton techniques for recurrent prostate cancer in previously irradiated patients: a treatment planning comparison study

Damien C Weber,Haleem G Khan,Raymond Miralbell,Giovanna Dipasquale,Michel Rouzaud,Hui Wang,Hansjoerg Vees,Luca Cozzi,Osman Ratib,Habib Zaidi

doi:10.1186/1748-717x-4-34

Abstract

BackgroundA study was performed comparing volumetric modulated arcs (RA) and intensity modulation (with photons, IMRT, or protons, IMPT) radiation therapy (RT) for patients with recurrent prostate cancer after RT.MethodsPlans for RA, IMRT and IMPT were optimized for 7 patients. Prescribed dose was 56 Gy in 14 fractions. The recurrent gross tumor volume (GTV) was defined on 18F-fluorocholine PET/CT scans. Plans aimed to cover at least 95% of the planning target volume with a dose > 50.4 Gy. A maximum dose (DMax) of 61.6 Gy was allowed to 5% of the GTV. For the urethra, DMax was constrained to 37 Gy. Rectal DMedian was < 17 Gy. Results were analyzed using Dose-Volume Histogram and conformity index (CI90) parameters.ResultsTumor coverage (GTV and PTV) was improved with RA (V95% 92.6 ± 7.9 and 83.7 ± 3.3%), when compared to IMRT (V95% 88.6 ± 10.8 and 77.2 ± 2.2%). The corresponding values for IMPT were intermediate for the GTV (V95% 88.9 ± 10.5%) and better for the PTV (V95%85.6 ± 5.0%). The percentages of rectal and urethral volumes receiving intermediate doses (35 Gy) were significantly decreased with RA (5.1 ± 3.0 and 38.0 ± 25.3%) and IMPT (3.9 ± 2.7 and 25.1 ± 21.1%), when compared to IMRT (9.8 ± 5.3 and 60.7 ± 41.7%). CI90 was 1.3 ± 0.1 for photons and 1.6 ± 0.2 for protons. Integral Dose was 1.1 ± 0.5 Gy*cm3 *105 for IMPT and about a factor three higher for all photon's techniques.ConclusionRA and IMPT showed improvements in conformal avoidance relative to fixed beam IMRT for 7 patients with recurrent prostate cancer. IMPT showed further sparing of organs at risk.

Highlights

A study was performed comparing volumetric modulated arcs (RA) and intensity modulation radiation therapy (RT) for patients with recurrent prostate cancer after RT
The gross tumor volume (GTV) coverage was optimal with volumetric modulated arcs radiation therapy (RA)
All the volume and dose metrics for these organ at risk (OARs) were substantially decreased with intensity modulated proton therapy (IMPT) and RA when compared to intensity modulated radiation therapy (IMRT) (Table 4)

Summary

Introduction

A study was performed comparing volumetric modulated arcs (RA) and intensity modulation (with photons, IMRT, or protons, IMPT) radiation therapy (RT) for patients with recurrent prostate cancer after RT. CapSURETM (Cancer of the Prostate Strategic Urologic Research Endeavor) data have demonstrated a biochemical failure rate following radiation therapy as high as 63% [3]. Curative treatment is still an option if the patient presents organ-confined disease only, no consensus exists on the optimal salvage therapy modality for these patients. Therapeutic management of these patients includes salvage radical prostatectomy, cryotherapy, brachytherapy or high-intensity focused ultrasound, with or without hormonal deprivation therapy. Re-irradiation techniques must minimally deliver radiation dose to pre-irradiated organ at risk (OARs) in the direct vicinity of the target volume

Methods

Results

Discussion

Conclusion