SIFT: A method to verify the IMRT fluence delivered during patient treatment using an electronic portal imaging device

Journal Article · Mon Nov 01 04:00:00 EST 2004 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2004.06.025· OSTI ID:20630952

Vieira, Sandra C ^[1]; Dirkx, Maarten L.P. ^[1]; Heijmen, Ben J.M. ^[1]

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1. Department of Radiation Oncology, Division of Clinical PhysicsErasmus MC-Daniel den Hoed Cancer Center, Rotterdam (Netherlands)

Purpose: Radiotherapy patients are increasingly treated with intensity-modulated radiotherapy (IMRT) and high tumor doses. As part of our quality control program to ensure accurate dose delivery, a new method was investigated that enables the verification of the IMRT fluence delivered during patient treatment using an electronic portal imaging device (EPID), irrespective of changes in patient geometry. Methods and materials: Each IMRT treatment field is split into a static field and a modulated field, which are delivered in sequence. Images are acquired for both fields using an EPID. The portal dose image obtained for the static field is used to determine changes in patient geometry between the planning CT scan and the time of treatment delivery. With knowledge of these changes, the delivered IMRT fluence can be verified using the portal dose image of the modulated field. This method, called split IMRT field technique (SIFT), was validated first for several phantom geometries, followed by clinical implementation for a number of patients treated with IMRT. Results: The split IMRT field technique allows for an accurate verification of the delivered IMRT fluence (generally within 1% [standard deviation]), even if large interfraction changes in patient geometry occur. For interfraction radiological path length changes of 10 cm, deliberately introduced errors in the delivered fluence could still be detected to within 1% accuracy. Application of SIFT requires only a minor increase in treatment time relative to the standard IMRT delivery. Conclusions: A new technique to verify the delivered IMRT fluence from EPID images, which is independent of changes in the patient geometry, has been developed. SIFT has been clinically implemented for daily verification of IMRT treatment delivery.

• OSTI ID: 20630952
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 3 Vol. 60; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
ACCURACY
CARCINOMAS
COMPUTERIZED TOMOGRAPHY
DOSIMETRY
EQUIPMENT
IMAGES
IN VIVO
PATIENTS
PHANTOMS
QUALITY ASSURANCE
QUALITY CONTROL
RADIATION DOSES
RADIOTHERAPY
VERIFICATION