RESUMEN
OBJECTIVE: The Gamma Knife Icon (Elekta AB, Stockholm, Sweden) allows frameless stereotactic treatment using a combination of cone beam computer tomography (CBCT), a thermoplastic mask system, and an infrared-based high-definition motion management (HDMM) camera system for patient tracking during treatment. We report on the first patient with meningioma at the left petrous bone treated with adaptive fractionated stereotactic radiotherapy (a-gkFSRT). METHODS: The first patient treated with Gamma Knife Icon at our institute received MR imaging for preplanning before treatment. For each treatment fraction, a daily CBCT was performed to verify the actual scull/tumor position. The system automatically adapted the planned shot positions to the daily position and recalculated the dose distribution (online adaptive planning). During treatment, the HDMM system recorded the intrafractional patient motion. Furthermore, the required times were recorded to define a clinical treatment slot. RESULTS: Total treatment time was around 20 min. Patient positioning needed 0.8 min, CBCT positioning plus acquisition 1.65 min, CT data processing and adaptive planning 2.66 min, and treatment 15.6 min. The differences for the five daily CBCTs compared to the reference are for rotation: -0.59 ± 0.49°/0.18 ± 0.20°/0.05 ± 0.36° and for translation: 0.94 ± 0.52 mm/-0.08 ± 0.08 mm/-1.13 ± 0.89 mm. Over all fractions, an intrafractional movement of 0.13 ± 0.04 mm was observed. CONCLUSION: The Gamma Knife Icon allows combining the accuracy of the stereotactic Gamma Knife system with the flexibility of fractionated treatment with the mask system and CBCT. Furthermore, the Icon system introduces a new online patient tracking system to the clinical routine. The interfractional accuracy of patient positioning was controlled with a thermoplastic mask and CBCT.
Asunto(s)
Tomografía Computarizada de Haz Cónico/instrumentación , Neoplasias Meníngeas/radioterapia , Meningioma/radioterapia , Radiocirugia/instrumentación , Planificación de la Radioterapia Asistida por Computador/instrumentación , Radioterapia Guiada por Imagen/instrumentación , Anciano , Tomografía Computarizada de Haz Cónico/métodos , Fraccionamiento de la Dosis de Radiación , Diseño de Equipo , Análisis de Falla de Equipo , Femenino , Humanos , Neoplasias Meníngeas/diagnóstico por imagen , Meningioma/diagnóstico por imagen , Radiocirugia/métodos , Dosificación Radioterapéutica , Planificación de la Radioterapia Asistida por Computador/métodos , Radioterapia Guiada por Imagen/métodos , Integración de Sistemas , Resultado del TratamientoRESUMEN
BACKGROUND: The use of optical surface positioning to support or replace X-ray-based image-guided radiotherapy (IGRT) may reduce patient exposure to extra dose. In specifically designed phantom tests, we analyzed the potential of a new scanning device preclinically. The system's clinical performance was evaluated in comparison to cone-beam computed tomography (CBCT) in a prospective study. MATERIALS AND METHODS: We first evaluated the scanning performance in terms of accuracy and reproducibility using phantom tests. An institutional review board (IRB)-approved clinical evaluation encompassing 224 fractions in 13 patients treated in three different regions (head and neck, thorax, pelvis) was then performed. Patients were first positioned using CBCT and then scanned with the Catalyst(TM) (C-RAD, Uppsala, Sweden) optical system to define the resulting difference vector. RESULTS: Individual system settings are necessary for different scanning conditions. Reproducibility tests with phantoms showed a mean difference of 0.25 ± 0.21 cm. Accuracy tests showed a mean difference of less than 0.52 ± 0.41 cm. Considering all patients, clinical data showed residual target position differences between Catalyst(TM) (surface-driven) and CBCT (target-driven) systems within 0.07 ± 0.28 cm/- 0.13 ± 0.40 cm/0.15 ± 0.36 cm/0.11 ± 1.57°/- 0.43 ± 1.68/- 0.10 ± 1.67° (lateral/longitudinal/vertical/rotation/roll/pitch). CONCLUSION: Scanning quality depends on the color and shape of the scanned surface. Upon prospective clinical evaluation, excellent agreement between target- and contour driven positioning was observed. Catalyst(TM) may reduce CBCT scan frequency in patients where tumor location is fixed relative to the surface.
Asunto(s)
Imagenología Tridimensional/instrumentación , Neoplasias/patología , Neoplasias/radioterapia , Posicionamiento del Paciente/instrumentación , Radioterapia Conformacional/instrumentación , Radioterapia Guiada por Imagen/instrumentación , Diseño de Equipo , Análisis de Falla de Equipo , Humanos , Posicionamiento del Paciente/métodos , Fantasmas de Imagen , Radioterapia Conformacional/métodos , Radioterapia Guiada por Imagen/métodos , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Resultado del TratamientoRESUMEN
BACKGROUND: Laser scanning-based patient surface positioning and surveillance may complement image-guided radiotherapy (IGRT) as a nonradiation-based approach. We investigated the performance of an optical system compared to standard kilovoltage cone-beam computed tomography (CBCT) and its potential to reduce the number of daily CBCTs. PATIENTS AND METHODS: We analyzed the patient positioning of 153 treatment fractions in 21 patients applied to three different treatment regions. Patients were first scanned with CBCT, shifted to the optimal isocenter position, and an optical scan was performed to verify the matching in relation to CBCT. RESULTS: For the head-and-neck region, the lateral/longitudinal/vertical/rotational/roll and pitch shift was 0.9 ± 1.8 mm/-2.7 ± 3.8 mm/-0.8 ± 3.6 mm/0.0 ± 1.1°/-0.5 ± 2.1°/0.2 ± 1.6°. For the thorax, the lateral/longitudinal/vertical/roll and pitch shift was -1.2 ± 3.6 mm/0.8 ± 5.1 mm/0.8 ± 4.3 mm/0.6 ± 1.4°/0.1 ± 0.9°/0.3 ± 1.0°. For the pelvis, the respective values were -2.5 ± 4.1 mm/4.6 ± 7.3 mm/-5.1 ± 7.4 mm/0.3 ± 1.1°/-0.5 ± 1.0°/0.3 ± 2.1°. In total, the recorded disagreement was -1.0 ± 3.6 mm/1.0 ± 6.3 mm/-1.8 ± 5.9 mm/0.3 ± 1.2°/-0.3 ± 1.5°/0.2 ± 1.7°. CONCLUSION: This analysis showed good agreement between the optical scanner approach and CBCT. The optical system holds potential to ensure precise patient positioning and reduced CBCT frequency in tumor locations with fixed relation to surface structures.
Asunto(s)
Tomografía Computarizada de Haz Cónico/instrumentación , Rayos Láser , Neoplasias/radioterapia , Posicionamiento del Paciente/instrumentación , Planificación de la Radioterapia Asistida por Computador/instrumentación , Radioterapia Guiada por Imagen/instrumentación , Diseño de Equipo , Femenino , Humanos , Masculino , Estudios Retrospectivos , Posición SupinaRESUMEN
BACKGROUND AND PURPOSE: Conventional algorithms show uncertainties in dose calculation already for three-dimensional conformal radiotherapy (3D-CRT). Intensity-modulated radiotherapy (IMRT) might even increase these. We wanted to assess differences in dose distribution for pencil beam (PB), collapsed cone (CC), and Monte Carlo (MC) algorithm for both 3D-CRT and IMRT in patients with mediastinal Hodgkin lymphoma. PATIENTS AND METHODS: Based on 20 computed tomograph (CT) datasets of patients with mediastinal Hodgkin lymphoma, we created treatment plans according to the guidelines of the German Hodgkin Study Group (GHSG) with PB and CC algorithm for 3D-CRT and with PB and MC algorithm for IMRT. Doses were compared for planning target volume (PTV) and organs at risk. RESULTS: For 3D-CRT, PB overestimated PTV(95) and V(20) of the lung by 6.9% and 3.3% and underestimated V(10) of the lung by 5.8%, compared to the CC algorithm. For IMRT, PB overestimated PTV(95), V(20) of the lung, V(25) of the heart and V(10) of the female left/right breast by 8.1%, 25.8%, 14.0% and 43.6%/189.1%, and underestimated V(10) of the lung, V(4) of the heart and V(4) of the female left/right breast by 6.3%, 6.8% and 23.2%/15.6%, compared to MC. CONCLUSION: The PB algorithm underestimates low doses to the organs at risk and overestimates dose to PTV and high doses to the organs at risk. For 3D-CRT, a well-modeled PB algorithm is clinically acceptable; for IMRT planning, however, an advanced algorithm such as CC or MC should be used at least for part of the plan optimization.