Manfred Kranzinger

“Augmented Reality” in Conventional Simulation by Projection of 3-D Structures into 2-D Images

Background and Purpose:In this study, a new method is introduced, which allows the overlay of three-dimensional structures, that have been delineated on transverse slices, onto the fluoroscopy from conventional simulators in real time.Patients and Methods:Setup deviations between volumetric imaging and simulation were visualized, measured and corrected for 701 patient isocenters.Results:Comparing the accuracy to mere virtual simulation lacking additional X-ray imaging, a clear benefit of the new method could be shown. On average, virtual prostate simulations had to be corrected by 0.48 cm (standard deviation [SD] 0.38), and those of the breast by 0.67 cm (SD 0.66).Conclusion:The presented method provides an easy way to determine entity-specific safety margins related to patient setup errors upon registration of bony anatomy (prostate 0.9 cm for 90% of cases, breast 1.3 cm). The important role of planar X-ray imaging was clearly demonstrated. The innovation can also be applied to adaptive image-guided radiotherapy (IGRT) protocols.Hintergrund und Ziel:Es wird ein Verfahren vorgestellt, das die Einblendung von dreidimensionalen Strukturen, die zuvor z.B. auf axialen Schnittbildern segmentiert wurden, in Durchleuchtungsaufnahmen am konventionellen Simulator in Echtzeit erlaubt.Patienten und Methodik:Mit dieser Technologie wurden an 701 Patientenisozentren Lagerungsunterschiede zwischen der Schnittbildgebung und der Simulation visualisiert, vermessen und korrigiert.Ergebnisse:Im Vergleich der Genauigkeit mit der rein virtuellen Simulation, bei der auf Röntgenbildgebung verzichtet wird, zeigte sich eine deutliche Überlegenheit der neuen Methode. Im Mittel wurden virtuell simulierte Prostatabestrahlungen um 0,48 cm (Standardabweichung [SD] 0,38) und jene der Mamma um 0,67 cm (SD 0,66) korrigiert.Schlussfolgerung:Das vorgestellte Verfahren erlaubt die einfache Bestimmung entitätsspezifischer Sicherheitsränder für Lagerungsungenauigkeiten von knöchernen Strukturen (Prostatabestrahlung 0,9 cm für 90% der Fälle, Mamma 1,3 cm; Tabelle 2). Die Bedeutung von planarer kV-Bildgebung konnte gezeigt werden. Das innovative Verfahren ist auch im Rahmen von Protokollen zur adaptiven, bildgeführten Radiotherapie (IGRT) einsetzbar.

Augmented reality in conventional simulation by projection of 3-D structures into 2-D images: a comparison with virtual methods.

Background and Purpose:In this study, a new method is introduced, which allows the overlay of three-dimensional structures, that have been delineated on transverse slices, onto the fluoroscopy from conventional simulators in real time.Patients and Methods:Setup deviations between volumetric imaging and simulation were visualized, measured and corrected for 701 patient isocenters.Results:Comparing the accuracy to mere virtual simulation lacking additional X-ray imaging, a clear benefit of the new method could be shown. On average, virtual prostate simulations had to be corrected by 0.48 cm (standard deviation [SD] 0.38), and those of the breast by 0.67 cm (SD 0.66).Conclusion:The presented method provides an easy way to determine entity-specific safety margins related to patient setup errors upon registration of bony anatomy (prostate 0.9 cm for 90% of cases, breast 1.3 cm). The important role of planar X-ray imaging was clearly demonstrated. The innovation can also be applied to adaptive image-guided radiotherapy (IGRT) protocols.Hintergrund und Ziel:Es wird ein Verfahren vorgestellt, das die Einblendung von dreidimensionalen Strukturen, die zuvor z.B. auf axialen Schnittbildern segmentiert wurden, in Durchleuchtungsaufnahmen am konventionellen Simulator in Echtzeit erlaubt.Patienten und Methodik:Mit dieser Technologie wurden an 701 Patientenisozentren Lagerungsunterschiede zwischen der Schnittbildgebung und der Simulation visualisiert, vermessen und korrigiert.Ergebnisse:Im Vergleich der Genauigkeit mit der rein virtuellen Simulation, bei der auf Röntgenbildgebung verzichtet wird, zeigte sich eine deutliche Überlegenheit der neuen Methode. Im Mittel wurden virtuell simulierte Prostatabestrahlungen um 0,48 cm (Standardabweichung [SD] 0,38) und jene der Mamma um 0,67 cm (SD 0,66) korrigiert.Schlussfolgerung:Das vorgestellte Verfahren erlaubt die einfache Bestimmung entitätsspezifischer Sicherheitsränder für Lagerungsungenauigkeiten von knöchernen Strukturen (Prostatabestrahlung 0,9 cm für 90% der Fälle, Mamma 1,3 cm; Tabelle 2). Die Bedeutung von planarer kV-Bildgebung konnte gezeigt werden. Das innovative Verfahren ist auch im Rahmen von Protokollen zur adaptiven, bildgeführten Radiotherapie (IGRT) einsetzbar.

Radiotherapy for lung cancer: target splitting by asymmetric collimation enables reduction of radiation doses to normal tissues and dose escalation

PURPOSE This study was performed to develop a method of reducing the radiation doses to normal thoracic tissues, increasing the target dose, especially in the primary radiotherapy of non-small cell lung cancer (NSCLC), and to evaluate acute/subacute toxicity of dose escalation. METHODS AND MATERIALS From December 1195 to March 1998, the technique of target splitting has been applied to 58 patients. In this period, 30 patients were treated with doses > 80 Gy (ICRU-specification, mean 85.1 Gy, range 80. 1-90.2 Gy). The target volume is split into a cranial part (e.g., upper mediastinum) and a caudal part (e.g., primary tumor and middle mediastinum). Both volumes are planned and treated independently, using conformal irradiation techniques for both parts with half-collimated fields to prevent over- or underdosage in the junction plane. After fine-adjustment of the jaws, a verification film, exposed in a polymethylmethacrylate (PMMA) phantom, demonstrates the homogeneity of dose in the entire target volume. For comparison with conventional techniques, planning to identical doses is performed for 5 patients. Dose-volume histograms (DHVs) for normal lung tissue are presented for both methods. RESULTS The irradiated volume of normal tissue of the ipsilateral lung can be lowered at dose levels > or = 65, > or =45 Gy, and > or = 20 Gy to values of 37% (range 25-54%), 49% (range 46-54%), and 86% (range 55-117%), respectively. Other organs at risk, such as heart or esophagus, can also be spared significantly. Only 1 patient showed a transient grade 3 toxicity (pneumonitis), and there where no grade 4 acute/subacute side-effects. Two patients with Stage III A central tumors in close proximity to the large vessels died due to a pulmonary hemorrhage 2 and 4 months after therapy, respectively. No patient developed esophagitis. Antimycotic prophylaxis for esophagitis and posttherapeutic steroid prophylaxis for pneumonitis for several weeks were routinely used. CONCLUSION The technique of target splitting by asymmetric collimation helps to increase conformation, and thus enhances the sparing of normal tissues. It can be used whenever there is a marked difference in the shape of the planning target volume (PTV) in a cranio-caudal direction. This technique can principally be handled with 2D-planning systems, because it is coplanar. We consider target splitting as an important tool for dose escalation in the primary radiotherapy of NSCLC, that should also be used for other lung cancer patients necessitating moderate doses only.

Nonresected Non–Small-Cell Lung Cancer in Stages I Through IIIB: Accelerated, Twice-Daily, High-Dose Radiotherapy—A Prospective Phase I/II Trial With Long-Term Follow-Up

PURPOSE Our purpose was to investigate the tolerability of accelerated, twice-daily, high-dose radiotherapy. The secondary endpoints were survival and locoregional tumor control. METHODS AND MATERIALS Thirty consecutive patients with histologically/cytologically proven non-small-cell lung cancer were enrolled. Tumor Stage I, II, IIIA, and IIIB was found in 7, 3, 12, and 8 patients, respectively. We applied a median of 84.6 Gy (range, 75.6-90.0 Gy) to the primary tumors, 63.0 Gy (range, 59.4-72.0 Gy) to lymph nodes, and 45 Gy to nodes electively (within a region of about 6 cm cranial to macroscopically involved sites). Fractional doses of 1.8 Gy twice daily, with an interval of 11 hours, were given, resulting in a median treatment time of 35 days. In the majority of patients the conformal target-splitting technique was used. In 19 patients (63%) two cycles of induction chemotherapy were given. The median follow-up time of survivors is 72 months (range, 62-74 months). RESULTS We found Grade 1, 2 and 3 acute esophageal toxicity in 11 patients (37%), 2 patients (7%), and 2 patients (7%), respectively. Grade 2 acute pneumonitis was seen in 2 patients (7%). No late toxicity greater than Grade 1 was observed. The actual overall survival rates at 2 and 5 years are 63% and 23%, respectively; the median overall survival, 27.7 months. In 9 patients a local failure occurred, 7 of them presenting initially with an atelectasis without availability of 18-fluorodeoxyglucose-positron emission tomography staging at that time. In 4 patients recurrence occurred regionally. CONCLUSIONS This Phase I/II trial with long-term follow-up shows low toxicity with promising results for survival and locoregional tumor control.