Universität zu Köln

Hellerbach, Alexandra, Eichner, Markus, Ruess, Daniel, Luyken, Klaus, Hoevels, Mauritius, Judge, Michael, Baues, Christian, Ruge, Maximilian, Kocher, Martin and Treuer, Harald . Impact of prescription isodose level and collimator selection on dose homogeneity and plan quality in robotic radiosurgery. Strahlenther. Onkol.. HEIDELBERG: SPRINGER HEIDELBERG. ISSN 1439-099X

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Abstract

Purpose In stereotactic radiosurgery (SRS), prescription isodoses and resulting dose homogeneities vary widely across different platforms and clinical entities. Our goal was to investigate the physical limitations of generating dose distributions with an intended level of homogeneity in robotic SRS. Methods Treatment plans for non-isocentric irradiation of 4 spherical phantom targets (volume 0.27-7.70 ml) and 4 clinical targets (volume 0.50-5.70 ml) were calculated using Sequential (phantom) or VOLOTM (clinical) optimizers (Accuray, Sunnyvale, CA, USA). Dose conformity, volume of 12 Gy isodose (V12Gy) as a measure for dose gradient, and treatment time were recorded for different prescribed isodose levels (PILs) and collimator settings. In addition, isocentric irradiation of phantom targets was examined, with dose homogeneity modified by using different collimator sizes. Results Dose conformity was generally high (nCI <= 1.25) and varied little with PIL. For all targets and collimator sets, V12Gy was highest for PIL >= 80% and lowest for PIL <= 65%. The impact of PIL on V12Gy was highest for isocentric irradiation and lowest for clinical targets (VOLOTM optimization). The variability of V12Gy as a function of collimator selection was significantly higher than that of PIL. V12Gy and treatment time were negatively correlated. Plans utilizing a single collimator with a diameter in the range of 70-80% of the target diameter were fastest, but showed the strongest dependence on PIL. Conclusion Inhomogeneous dose distributions with PIL <= 70% can be used to minimize dose to normal tissue. PIL >= 90% is associated with a marked and significant increase in off-target dose exposure. Careful selection of collimators during planning is even more important.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Hellerbach, Alexandra UNSPECIFIED UNSPECIFIED UNSPECIFIED Eichner, Markus UNSPECIFIED UNSPECIFIED UNSPECIFIED Ruess, Daniel UNSPECIFIED UNSPECIFIED UNSPECIFIED Luyken, Klaus UNSPECIFIED UNSPECIFIED UNSPECIFIED Hoevels, Mauritius UNSPECIFIED UNSPECIFIED UNSPECIFIED Judge, Michael UNSPECIFIED UNSPECIFIED UNSPECIFIED Baues, Christian UNSPECIFIED UNSPECIFIED UNSPECIFIED Ruge, Maximilian UNSPECIFIED UNSPECIFIED UNSPECIFIED Kocher, Martin UNSPECIFIED UNSPECIFIED UNSPECIFIED Treuer, Harald UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-565764
DOI:	10.1007/s00066-021-01872-4
Journal or Publication Title:	Strahlenther. Onkol.
Publisher:	SPRINGER HEIDELBERG
Place of Publication:	HEIDELBERG
ISSN:	1439-099X
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language STEREOTACTIC RADIOSURGERY; BRAIN METASTASES; MULTILEAF COLLIMATOR; OPTIMIZATION; RADIOTHERAPY; VOLUME; PREDICTOR; THERAPY; LINE Multiple languages Oncology; Radiology, Nuclear Medicine & Medical Imaging Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/56576