Abstract
A 3D treatment‐planning system (TPS) for stereotactic intensity‐modulated radiotherapy (IMRT) using a micro‐multileaf collimator has been made available by Radionics. In this work, we report our comprehensive quality assurance (QA) procedure for commissioning this TPS. First, the accuracy of stereotaxy established with a body frame was checked to ensure accurate determination of a target position within the planning system. Second, the CT‐to‐electron density conversion curve used in the TPS was fitted to our site‐specific measurement data to ensure the accuracy of dose calculation and measurement verification in a QA phantom. Using the QA phantom, the radiological path lengths were verified against known geometrical depths to ensure the accuracy of the ray‐tracing algorithm. We also checked inter‐ and intraleaf leakage/transmission for adequate jaw settings. Measurements for dose verification were performed in various head/neck and prostate IMRT treatment plans using the patient‐specific optimized fluence maps. Both ion chamber and film were used for point dose and isodose distribution verifications. To ensure that adjacent organs at risk receive dose within the expectation, we used the Monte Carlo method to calculate dose distributions and dose‐volume histograms (DVHs) for these organs at risk. The dosimetric accuracy satisfied the published acceptability criteria. The Monte Carlo calculations confirmed the measured dose distributions for target volumes. For organs located on the beam boundary or outside the beam, some differences in the DVHs were noticed. However, the plans calculated by both methods met our clinical criteria. We conclude that the accuracy of the XKnife™ RT2 treatment‐planning system is adequate for the clinical implementation of stereotactic IMRT.PACS numbers: 87.53.Xd, 87.53.Ly, 87.53.Wz
Highlights
The success of stereotactic radiosurgery in treating both benign and malignant tumors within the cranial region has logically led to attempts to mimic these treatments in extracranial regions
Stereotactic irradiation of extracranial targets has emerged as a new concept of treatment in clinical radiotherapy.[1,2,3,4] As a response to these attempts, a commercial treatmentplanning system (TPS), XKnifeTM RT2 (Radionics Inc., Burlington, MA), for stereotactic extracranial radiotherapy and intensity-modulated radiotherapy (IMRT) has become available
We report our comprehensive procedures to commission this system for our clinical implementation of stereotactic IMRT for extracranial radiotherapy
Summary
The success of stereotactic radiosurgery in treating both benign and malignant tumors within the cranial region has logically led to attempts to mimic these treatments in extracranial regions. It is anticipated that the development and accurate commissioning of such systems for clinical implementation will ensure the widespread use of stereotactic extracranial conformal and IMRT and facilitate dose hypofractionation/escalation for some diseases.[5,6,7,8]. The SBF can facilitate accurate patient positioning[2,10,11] as well as precise targeting of tumors based on assigned Cartesian coordinates throughout the body. With this technique, the isocenter of a target is identified based on the coordinates rather than the patient’s skin and bony landmarks. Appropriate implementation or use of this technique may result in a significant change in treatment routine compared to conventional therapy, and the technique may well facilitate CTbased image-guided radiotherapy
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