ABSTRACT
PURPOSE: To compare the accuracy of the robot-assisted needle positioning with that of the conventional template-guided method with the help of a prostate model in high dose rate (HDR) brachytherapy. MATERIALS AND METHODS: A prostate model of fresh porcine abdomen and special polyvinylchloride (PVC) sheets was developed. To verify the model, deviations from 311 needle placements of real prostate implants were analyzed. Second, the accuracy of the template-guided positioning versus robot-assisted positioning was measured with 20 needle insertions in the model. For robot-assisted positioning, different velocities (2.7, 5.4, 9.8 mm/s) of needle insertion were investigated. RESULTS: The average needle positioning accuracies of manual template guidance on the model closely resembled those of real patients (approximately 3 mm). The average needle positioning accuracy for the robot-assisted method on the prostate model was 1.8 ± 0.6 mm, at a velocity of 2.7 mm/s and, in comparison to the template-guided method (2.7 ± 0.7 mm), was statistically more precise (p < 0.001). At higher robotic velocities, the measured needle positioning accuracy showed no significant difference from that of the manual insertion procedure. CONCLUSION: By employing a prostate model, we showed for the first time that robot-assisted needle placement for HDR brachy-therapy is significantly more precise than the conventional method at a velocity of 2.7 mm/s. The robot-assisted needle positioning technique improves the degree of freedom by providing additional oblique insertion channels and could be potentially exploited not only for LDR but also for HDR brachytherapy.
Subject(s)
Brachytherapy/methods , Models, Anatomic , Prostatic Neoplasms/radiotherapy , Robotics/standards , Humans , MaleABSTRACT
PURPOSE: To develop a manually movable laser system connected to the CT table for alignment of the isocenter cross of irradiation fields on the patient's skin directly after CT software simulation. MATERIAL AND METHODS: The specially designed laser system was constructed in the authors' department, and the mean focusing accuracy of isocenter translations was analyzed using Alderson phantom measurements. The mean overall accuracy from setup to treatment of the whole procedure of CT software simulation was measured by the comparison of bone structures and mamma contour of the digitally reconstructed radiograph (DRR) with the verification film. The time taken for the different setup procedure steps was evaluated for 70 breast cancer patients who were treated using tangential fields. RESULTS: The mean focusing accuracy of the manually movable laser system after defined isocenter translation was measured as 0.8 +/- 0.5 mm, the mean patient movement on the CT table as 2.0 +/- 1 mm, and the mean positioning accuracy of the first treatment after patient positioning corresponding to the skin alignments as 3.9 +/- 1.5 mm. The time periods for the different steps of the CT software simulation were measured, and the total duration was found to be 35.8 +/- 3.3 min. CONCLUSION: In general, the main advantage of well-known CT software simulation when compared to conventional simulation is the relief of the real X-ray simulator which is feasible with fast planning software (EXOMIO) and the presented movable laser system.
Subject(s)
Breast Neoplasms/diagnostic imaging , Breast Neoplasms/radiotherapy , Image Enhancement/instrumentation , Lasers , Radiographic Image Interpretation, Computer-Assisted/instrumentation , Radiotherapy Planning, Computer-Assisted/methods , Tomography, X-Ray Computed/instrumentation , Adult , Aged , Aged, 80 and over , Computer Simulation , Equipment Design , Equipment Failure Analysis , Female , Humans , Image Enhancement/methods , Imaging, Three-Dimensional/instrumentation , Imaging, Three-Dimensional/methods , Middle Aged , Motion , Radiographic Image Interpretation, Computer-Assisted/methods , Radiotherapy Dosage , Radiotherapy Planning, Computer-Assisted/instrumentation , Radiotherapy, Computer-Assisted/methods , Reproducibility of Results , Sensitivity and Specificity , Software , Tomography, X-Ray Computed/methodsABSTRACT
BACKGROUND: It is well known that precision can be achieved using radiosurgery for brain tumors. This method can be extended to treat localized lung tumors and lung metastases. MATERIAL AND METHODS: The conventional procedure of extracranial radiosurgery is contained in the following steps: adaptation of the vacuum mattress, planning CT, three-dimensional (3-D) treatment planning, CT repositioning, and irradiation. In the new procedure of continuous extracranial radiosurgery, a short treatment planning is often used for simple target shapes (spherical, rotation-symmetrical), and the irradiation follows directly after the planning procedure. During continuous extracranial radiosurgery, the patient has to lie still in the body frame from the planning CT to irradiation. Fast treatment planning is performed by using multileafs and EXOMIO (Medintec, Bochum, Germany), a software for CT simulation. The high quality of the digitally reconstructed radiographs (DRRs) of each field enables a high precision in dose application by the comparison with the verification radiograph and the DRR (Elekta iView, Hamburg, Germany). RESULTS: In five lung cancer patients the average time for the complete procedure from planning CT to irradiation was 107 min (range: 91-124 min). The mean positioning accuracy of the patient in the vacuum bed (total shift) was 3.3 mm (range: 2.9-4.7 mm). CONCLUSION: Continuous extracranial radiosurgery can be performed for small peripheral lung tumors or metastases and is optimizing the conventional procedure. It is of special interest to clinics with restricted CT capacity.
