TY  - JOUR
A1  - Sterzing, Florian
A1  - Engenhart-Cabillic, Rita
A1  - Flentje, Michael
A1  - Debus, Jürgen
T1  - Image-Guided Radiotherapy : A New Dimension in Radiation Oncology
JF  - Deutsches Ärzteblatt International
N2  - Background: 

The vital importance of imaging techniques in radiation oncology now extends beyond diagnostic evaluation and treatment planning. Recent technical advances have enabled the integration of various imaging modalities into the everyday practice of radiotherapy directly at the linear accelerator, improving the management of inter-and intrafractional variations.

Methods: 

We present the topic of image-guided radiotherapy (IGRT) on the basis of a selective review of the literature. 

Results: 

IGRT can be performed with the aid of ultrasound, 2D X-ray devices, and computed tomography. It enables instant correction for positioning deviations and thereby improves the precision of daily radiotherapy fractions. It also enables immediate adjustment for changes in the position and filling status of the internal organs. Anatomical changes that take place over the course of radiotherapy, such as weight loss, tumor shrinkage, and the opening of atelectases, can be detected as they occur and accounted for in dosimetric calculations. There have not yet been any randomized controlled trials showing that IGRT causes fewer adverse effects or improves tumor control compared to conventional radiotherapy. 

Conclusion: 

IGRT is more precise and thus potentially safer than conventional radiotherapy. It also enables the application of special radiotherapeutic techniques with narrow safety margins in the vicinity of radiosensitive organs. Proper patient selection for IGRT must take account of the goals of treatment and the planning characteristics, as well as the available technical and human resources. IGRT should be used for steep dose gradients near organs at risk, for highly conformal dose distributions in the gastrointestinal tract where adjustment for filling variations is needed, for high-precision dose escalation to avoid geographic miss, and for patients who cannot lie perfectly still because of pain or claustrophobia.
KW  - cone-beam ct
KW  - megavoltage computed-tomography
KW  - prostate-cancer
KW  - helical tomotherapy
KW  - guidance
KW  - therapy
KW  - limitations
KW  - head
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-140771
VL  - 108
IS  - 16
ER  - 
TY  - JOUR
A1  - Hardcastle, Nicholas
A1  - Tomé, Wolfgang A.
A1  - Cannon, Donald M.
A1  - Brouwer, Charlotte L.
A1  - Wittendorp, Paul W. H.
A1  - Dogan, Nesrin
A1  - Guckenberger, Matthias
A1  - Allaire, Stéphane
A1  - Mallya, Yogish
A1  - Kumar, Prashant
A1  - Oechsner, Markus
A1  - Richter, Anne
A1  - Song, Shiyu
A1  - Myers, Michael
A1  - Polat, Bülent
A1  - Bzdusek, Karl
T1  - A multi-institution evaluation of deformable image registration algorithms for automatic organ delineation in adaptive head and neck radiotherapy
JF  - Radiation Oncology
N2  - Background: Adaptive Radiotherapy aims to identify anatomical deviations during a radiotherapy course and modify the treatment plan to maintain treatment objectives. This requires regions of interest (ROIs) to be defined using the most recent imaging data. This study investigates the clinical utility of using deformable image registration (DIR) to automatically propagate ROIs. 
Methods: Target (GTV) and organ-at-risk (OAR) ROIs were non-rigidly propagated from a planning CT scan to a per-treatment CT scan for 22 patients. Propagated ROIs were quantitatively compared with expert physician-drawn ROIs on the per-treatment scan using Dice scores and mean slicewise Hausdorff distances, and center of mass distances for GTVs. The propagated ROIs were qualitatively examined by experts and scored based on their clinical utility. 
Results: Good agreement between the DIR-propagated ROIs and expert-drawn ROIs was observed based on the metrics used. 94% of all ROIs generated using DIR were scored as being clinically useful, requiring minimal or no edits. However, 27% (12/44) of the GTVs required major edits. 
Conclusion: DIR was successfully used on 22 patients to propagate target and OAR structures for ART with good anatomical agreement for OARs. It is recommended that propagated target structures be thoroughly reviewed by the treating physician.
KW  - intensity-modulated radiotherapy
KW  - megavoltage computed-tomography
KW  - cancer
KW  - variability
KW  - strategies
KW  - risk
Y1  - 2012
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-134756
VL  - 7
IS  - 90
ER  -