Quality Assurance for Respiratory-Gated Radiotherapy Using the Real-Time Tumor-Tracking Radiotherapy System

Abstract

Purpose: Respiratory-gated radiation therapy (RT) using the real-time tumor-tracking radiotherapy (RTRT) system is an effective technique for managing tumor motion. High dosimetric and geometric accuracy is needed; however, quality assurance (QA) for respiratory-gated RT using the RTRT system has not been reported. The purpose of this study was to perform QA for respiratorygated RT using the RTRT system. Materials and Methods: The RTRT system detected the position of the fiducial marker and radiation delivery gated to the motion of the marker was performed. The dynamic anthropomorphic thorax phantom was positioned at the isocenter using the fiducial marker in the phantom. The phantom was irradiated only when the fiducial marker was within a three-dimensional gating window of ±2 mm from the planned position. First, the absolute doses were measured using anionization chamber inserted in the phantom under the stationary, gating and non-gating state for sinusoidal (nadir-to-peak amplitude [A]: 20 -40 mm, breathing period [T]: 2 -4 s) and the basic respiratory patterns. Second, the dose profiles were measured using Gafchromic films in the phantom under the same conditions. Differences between dose profiles were calculated to evaluate the dosimetric and geometric accuracy. Finally, differences between the actual and measured position of the fiducial marker were calculated to evaluate the tracking accuracy for sinusoidal and basic respiratory patterns. We conducted QA for respiratory-gated RT using the RTRT system. The respiratory-gated RT using the RTRT system reduced the blurring effects on dose distribution with high dosimetric and geometric accuracy.

Analysis of dosimetric impact of intrafraction translation and rotation during respiratory‐gated stereotactic body radiotherapy with real‐time tumor monitoring of the lung using a novel six degrees‐of‐freedom robotic moving phantom

“…However, most phantoms can only replicate the one-dimensional (1D) or 2D motion of a target. 17,18 Our previous study reported a dynamic robotic phantom system that could reproduce 3D respiratory motion for the QA of motion management systems. 19 Recently, a 6DoF motion platform was developed to compensate for head movements during stereotactic radiosurgery, thus allowing for frameless and maskless treatment.…”

“…In addition, several researchers have developed moving phantoms to perform QA of respiratory motion management systems. However, most phantoms can only replicate the one‐dimensional (1D) or 2D motion of a target 17,18 . Our previous study reported a dynamic robotic phantom system that could reproduce 3D respiratory motion for the QA of motion management systems 19 …”

Informe del Grupo de Trabajo de la SEFM sobre Radioterapia Guiada por Superficie (SGRT): Procedimientos recomendados para la aceptación y puesta en funcionamiento

“…El método propuesto 85,137,138 consiste en emplear un maniquí móvil y un sistema de SGRT en modo gating para producir una serie de irradiaciones en la unidad de tratamiento. Con el sistema de kV se toman imágenes del proceso en modo cine (adquisición continua de imágenes).…”

Parâmetros de auxílio a tomadas de decisões clínicas e tolerâncias em testes de garantia de qualidade para gating respiratório

“…Para tratamentos radioterápicos a movimentação do tumor durante a respiração resulta em significantes incertezas dosimétricas e geométricas nas entregas de doses, principalmente em regiões de tórax e abdômen. Convencionalmente, largas margens internas são necessárias para que se cubra um alvo e considere as mudanças geométricas que ocorrem durante uma respiração livre, porém, estas podem resultar em irradiações de um volume importante de tecidos sadios (1). Em casos de Radiocirurgias (Stereotactic Body Radiation Therapy -SBRT), onde altas doses são entregues em curtas frações, estas incertezas devem ser analisadas de forma ainda mais meticulosa, já que as toxicidades desta exposição em tecidos sadios podem resultar na morte celular da região.…”

“…Algumas técnicas podem ser utilizadas para superar estas dificuldades: técnicas de manejo do movimento do tumor devido a respiração, breathhold, radioterapia com técnica de gating respiratório e técnicas 4D que auxiliem a redução das margens internas (1,2).…”