Comparative treatment planning for proton therapy of eye tumours with EYEPLAN and OCTOPUS

About 600 patients with eye tumours have been treated with protons at the Hahn Meitner Institut since 1998. For treatment planning the conventional software EYEPLAN is being used, which has several well known functional restrictions non intuitive user interface, adequate imaging not provided, spherical eye model with fixed structures, simplified dose calculation . The imaging supported 3 D planning software OCTOPUS developed in co operation with the Deutsches Krebsforschungszentrum Heidelberg is designed to improve these deficiencies. An adequate quantity of clinical treatment plans were compared with OCTOPUS plans. We identified weak points of the applied conventional plans in eye modelling and dose calculation. OCTOPUS enabled improvement of anatomical comprehension by direct 3 D imaging of the whole eye and its structures leading to a better adaptation of the model to the real eye. The use of a pencil beam algorithm allowed a more accurate calculation of dose distributions. Thus, more realistic dose volume histograms especially for the structures at risk i.e. macula, optic nerve, optic disc were available

Computer aided patient positioning in proton therapy of eye tumours

Purpose To improve and accelerate patient positioning during proton treatment of eye tumours using an automated monitoring procedure Methods and Materials Proton therapy of eye tumours requires positioning in the sub millimetre range. For this purpose, small tantalum clips sutured to the eye globe serve as landmarks. While the patient is immobilised in the treatment chair and keeps looking at a fixation light, clip and eye positions can be determined with a digital X amp; 64979;ray system providing orthogonal images. The clip projections derived from the treatment plan are superimposed with the present X ray images for position control. By the correction of chair and fixation light coordinates the patient is repositioned until both actual and target clip projections match with each other. In order to avoid a time consuming trial and error correction approach, a novel procedure has been implemented in the image processing software that compares both projections with each other. By automatically calculating the necessary corrections of chair and light coordinates it is aimed to facilitate adjustment to the final treatment position. Results Perpendicular X ray views provided precise patient positioning with an accuracy of below 0.3 mm. By use of the automated procedure, the mean positioning time could be reduced. Discussion and Conclusions To date, the installation of an on amp; 64979;site digital X ray system for patient positioning is unique in proton therapy. Reduced positioning time due to the use of image processing to full capacity makes therapy more tolerable for the patient and may result in higher patient throughput

Proton therapy of uveal melanomas intercomparison of MRI based and conventional treatment planning

Background and Purpose Proton therapy for uveal melanoma provides high conformal dose application to the target volume and, thus, an optimal saving of the organs at risk nearby. Treatment planning is done with the model based treatment planning system EYEPLAN. Tumor reconstruction is based only on a fundus composite, which often leads to an overestimation of the clinical target volume CTV . The purpose was to exploit MRI on trial in a proton therapy planning system by using the novel image based treatment planning system OCTOPUS. Patients and Methods Ten patients with uveal melanomas received both a high resolution planning CT and MRI of the eye. MR examinations were made with an eye coil. EYEPLAN requires eye geometry data for modeling, and tantalum marker clips for submillimeter positioning and additional information from ultrasound and 3 D imaging. By contrast, OCTOPUS provides the full integration of 3 D imaging e.g., CT, MRI . CTVs were delineated in each slice. For all patients, CTVs EYEPLAN vs. OCTOPUS were compared intraindividually. Results OCTOPUS planning led to a mean reduction of the target volume by a factor of 1.7 T1 weighted [T1w] and 2.2 T2w without compromising safety. The corresponding field size could be scaled down on average by a factor of 1.2 T1w and 1.4 T2w , respectively. Conclusion Compared with the conventional EYEPLAN, MRI based treatment planning of ocular tumors with OCTOPUS could be a powerful tool for reducing the CTV and, consequently, the treatment volume and the field size. This might be translated into a better patient compliance during treatment and a decreased late toxicity. Key Words Proton therapy Uveal melanoma Radiotherapy EYEPLAN OCTOPU

Salvage Proton Beam Therapy in Local Recurrent Uveal Melanoma

Purpose To evaluate survival and ocular outcome in recurrent uveal melanoma treated with proton beam therapy as salvage therapy. Design Retrospective, interventional case series. Methods We evaluated 48 patients with local recurrence of uveal melanoma after primary treatment with brachytherapy, transpupillary thermotherapy, proton beam therapy, laser photocoagulation, CyberKnife radiation, or photodynamic therapy. All patients received proton beam therapy as a salvage therapy at the Helmholtz Zentrum Berlin between July 2000 and December 2010. Kaplan Meier analysis was used to obtain survival rates. Results The Kaplan Meier estimator for local tumor control was 92.1 at 10 years after secondary treatment with proton beam therapy. Local recurrence developed in 3 patients; 1 of them underwent enucleation. During follow up, 20.8 of the patients died 16.7 of metastasis, 4.1 of other causes or not specified . The most frequent surgical interventions were phacoemulsification 20.8 and pars plana vitrectomy 10.4 . The Kaplan Meier estimators were 77.4 for survival and 70.1 for the absence of metastasis 10 years after the primary treatment. Conclusions Proton beam therapy as a salvage treatment resulted in high local tumor control rates in recurrent uveal melanoma, especially if the primary therapy was transpupillary thermotherapy or plaque brachytherapy. Preservation of the globe was possible in most patients. Enucleations were indicated only in case of re recurrences of uveal melanoma, but not because of secondary complications like intractable pain or secondary glaucoma. Retreatment was associated with vision deterioration, but loss of vision remained exceptional. Further larger prospective studies are needed to confirm the presented results of our retrospective analysis. Inquiries to Aline I. Riechardt, Augenklinik Department of Ophthalmology, Charit Universitätsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, D 12203 Berlin, German