We describe a projection system that presents a 20 megapixel image using a single XGA SLM and time-division multiplexing. The system can be configured as a high-resolution 2-D display or a highly multi-view horizontal parallax display. In this paper, we present a technique for characterizing the light transport function of the display and for precompensating the image for the measured transport function. The techniques can improve the effective quality of the display without modifying its optics. Precompensation is achieved by approximately solving a quadratic optimization problem. Compared to a linear filter, this technique is not limited by a fixed kernel size and can propagate image detail to all related pixels. Large pixel-count images are supported through dividing the problem into blocks. A remedy for blocking artifacts is given. Results of the algorithm are presented based on simulations of a display design. The display characterization method is suitable for experimental designs that may be dim and imperfectly aligned. Simulated results of the characterization and precompensation process are presented. RMS and qualitative improvement of display image quality are demonstrated.

We hypothesized that use of a true 3D display providing easy visualization of patient anatomy and dose distribution would lead to the production of better quality radiation therapy treatment plans. We report on a randomized prospective multi‐institutional study to evaluate a novel 3D display for treatment planning.The Perspecta® Spatial 3D System produces 360° holograms by projecting cross‐sectional images on a diffuser screen rotating at 900 rpm. Specially‐developed software allows bi‐directional transfer of image and dose data between Perspecta and the Pinnacle planning system.Thirty‐three patients previously treated at three institutions were included in this IRB‐approved study. Patient data were de‐identified, randomized, and assigned to different planners. A physician at each institution reviewed the cases and established planning objectives. Two treatment plans were then produced for each patient, one based on the Pinnacle system alone and another in conjunction with Perspecta. Plan quality was then evaluated by the same physicians who established the planning objectives. All plans were viewable on both Perspecta and Pinnacle for review. Reviewing physicians were blinded to the planning device used. Data from a 13‐patient pilot study were also included in the analysis.Perspecta plans were considered better in 28 patients (61%), Pinnacle in 14 patients (30%), and both were equivalent in 4 patients. The use of non‐coplanar beams was more common with Perspecta plans (82% vs. 27%). The mean target dose differed by less than 2% between rival plans. Perspecta plans were somewhat more likely to have the hot spot located inside the target (43% vs. 33%). Conversely, 30% of the Pinnacle plans had the hot spot outside the target compared with 18% for Perspecta plans. About 57% of normal organs received less dose from Perspecta plans. No statistically significant association was found between plan preference and planning institution or planner.The study found that use of the holographic display leads to radiotherapy plans preferred in a majority of cases over those developed with 2D displays. These data indicate that continued development of this technology for clinical implementation is warranted.PACS numbers: 87.55.D

We describe PerspectaRAD, the first tool for the review and modification of external-beam radiation therapy treatment plans with a volumetric three-dimensional display (Perspecta 1.9, Actuality Medical, Bedford, MA, USA) and a dedicated software application (PerspectaRAD, Actuality Medical). We summarize multi-institution retrospective studies that compare the system's efficacy to the incumbent 2-D display-based workflow. Contributions include: visualizing the treatment plan in a volumetric 3-D display, modifying the beam locations and performing point-and-click measurement in 3-D with a 3-D physical interface, and simultaneously viewing volumetric projections of the native CT data and isodose contours. The plans are synchronized with the hospital treatment planning system, Pinnacle 3 (Philips Medical, WI, USA). In the largest of five studies, 33 plans were retrospectively randomized and replanned at three institutions, including 12 brain, 10 lung, and 11 abdomen / pelvis. The PerspectaRAD plan was as good as or better than plans created without PerspectaRAD 70% of the time. Radiation overdose regions were more likely to be obvious inside the target volume than when reviewed in the 2-D display alone. However, the planning time was longer with PerspectaRAD. The data demonstrate that PerspectaRAD facilitates the use of non-coplanar beams and has significant potential to achieve better plan quality in radiation therapy.

To design and implement a set of quality assurance tests for an innovative 3D volumetric display for radiation treatment planning applications. A genuine 3D display (Perspecta Spatial 3D, Actuality‐Systems Inc., Bedford, MA) has been integrated with the Pinnacle TPS (Philips Medical Systems, Madison WI), for treatment planning. The Perspecta 3D display renders a 25 cm diameter volume that is viewable from any side, floating within a translucent dome. In addition to displaying all 3D data exported from Pinnacle, the system provides a 3D mouse to define beam angles and apertures and to measure distance. The focus of this work is the design and implementation of a quality assurance program for 3D displays and specific 3D planning issues as guided by AAPM Task Group Report 53. A series of acceptance and quality assurance tests have been designed to evaluate the accuracy of CT images, contours, beams, and dose distributions as displayed on Perspecta. Three‐dimensional matrices, rulers and phantoms with known spatial dimensions were used to check Perspecta's absolute spatial accuracy. In addition, a system of tests was designed to confirm Perspecta's ability to import and display Pinnacle data consistently. CT scans of phantoms were used to confirm beam field size, divergence, and gantry and couch angular accuracy as displayed on Perspecta. Beam angles were verified through Cartesian coordinate system measurements and by CT scans of phantoms rotated at known angles. Beams designed on Perspecta were exported to Pinnacle and checked for accuracy. Dose at sampled points were checked for consistency with Pinnacle and agreed within 1% or 1 mm. All data exported from Pinnacle to Perspecta was displayed consistently. The 3D spatial display of images, contours, and dose distributions were consistent with Pinnacle display. When measured by the 3D ruler, the distances between any two points calculated using Perspecta agreed with Pinnacle within the measurement errorPACS number: 07.07.Hj, 87.55.Qr, 87.56.Da, 87.55.D‐; Radiation Treatment Planning

Purpose: To develop a procedure for conducting true 3D treatment planning and evaluation using a novel 3D display device integrated with a conventional treatment planning system for a multi‐institutional planning study. Method and Materials: The 3D display device, Perspecta, includes 3D cursor and beam placement tools and renders auto‐stereoscopic images with a resolution of about 100 million voxels. Treatment planning calculations occur within Pinnacle and scripts are used to transfer all plan information bidirectionally between Pinnacle and Perspecta. Perpsecta includes software (PerspectaRad) to integrate information for displaying and planning. The procedure includes: 1) Transfer of contour information from Pinnacle to Perspecta; 2) Determining or refining beam orientations utilizing Perspecta; 3) Transferring the plan back to Pinnacle for dose calculation; 4) Transferring the dose distribution to Perspecta for evaluation in 3D. Results: By using this procedure, true 3D treatment planning and evaluation has been conducted for the first 11 cases in a multi‐institutional study. Beam placement was readily accomplished on the 3D device. Geometric relationships of beams and target volumes were reproducible and consistent after transfer between the devices. All relevant target volumes and doses were visualized on both devices and evaluated on both 3D and conventional devices. Conclusions: We have successfully established reliable, bi‐directional integration of a true 3D display with a treatment planning system that calculates dose in 3D. We believe that this results in enhanced understanding of anatomic, dosimetric, and geometric relationships which can in turn be used to more readily improve and/or optimize DVH and isodose distributions beyond what can be done with multiplanar 2D and pseudo 3D displays on flat CRT screens. We are in the process of confirming this impression with a prospective, multi‐institutional study designed to test this issue. Conflict of Interest: Actuality Systems Inc. provided the 3D display Perspecta used in this study.