Assessment of patient setup errors in IGRT in combination with a six degrees of freedom couch

Schmidhalter, Daniel; Malthaner, Marco; Born, Ernst Johann; Pica, Alessia; Schmücking, Michael; Aebersold, Daniel; Fix, Michael; Manser, Peter (2014). Assessment of patient setup errors in IGRT in combination with a six degrees of freedom couch. Zeitschrift für medizinische Physik, 24(2), pp. 112-122. Elsevier, Urban & Fischer 10.1016/j.zemedi.2013.11.002

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PURPOSE The range of patient setup errors in six dimensions detected in clinical routine for cranial as well as for extracranial treatments, were analyzed while performing linear accelerator based stereotactic treatments with frameless patient setup systems. Additionally, the need for re-verification of the patient setup for situations where couch rotations are involved was analyzed for patients treated in the cranial region. METHODS AND MATERIALS A total of 2185 initial (i.e. after pre-positioning the patient with the infrared system but before image guidance) patient setup errors (1705 in the cranial and 480 in the extracranial region) obtained by using ExacTrac (BrainLAB AG, Feldkirchen, Germany) were analyzed. Additionally, the patient setup errors as a function of the couch rotation angle were obtained by analyzing 242 setup errors in the cranial region. Before the couch was rotated, the patient setup error was corrected at couch rotation angle 0° with the aid of image guidance and the six degrees of freedom (6DoF) couch. For both situations attainment rates for two different tolerances (tolerance A: ± 0.5mm, ± 0.5°; tolerance B: ± 1.0 mm, ± 1.0°) were calculated. RESULTS The mean (± one standard deviation) initial patient setup errors for the cranial cases were -0.24 ± 1.21°, -0.23 ± 0.91° and -0.03 ± 1.07° for the pitch, roll and couch rotation axes and 0.10 ± 1.17 mm, 0.10 ± 1.62 mm and 0.11 ± 1.29 mm for the lateral, longitudinal and vertical axes, respectively. Attainment rate (all six axes simultaneously) for tolerance A was 0.6% and 13.1% for tolerance B, respectively. For the extracranial cases the corresponding values were -0.21 ± 0.95°, -0.05 ± 1.08° and -0.14 ± 1.02° for the pitch, roll and couch rotation axes and 0.15 ± 1.77 mm, 0.62 ± 1.94 mm and -0.40 ± 2.15 mm for the lateral, longitudinal and vertical axes. Attainment rate (all six axes simultaneously) for tolerance A was 0.0% and 3.1% for tolerance B, respectively. After initial setup correction and rotation of the couch to treatment position a re-correction has to be performed in 77.4% of all cases to fulfill tolerance A and in 15.6% of all cases to fulfill tolerance B. CONCLUSION The analysis of the data shows that all six axes of a 6DoF couch are used extensively for patient setup in clinical routine. In order to fulfill high patient setup accuracies (e.g. for stereotactic treatments), a 6DoF couch is recommended. Moreover, re-verification of the patient setup after rotating the couch is required in clinical routine.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Department of Haematology, Oncology, Infectious Diseases, Laboratory Medicine and Hospital Pharmacy (DOLS) > Clinic of Radiation Oncology > Medical Radiation Physics
04 Faculty of Medicine > Department of Haematology, Oncology, Infectious Diseases, Laboratory Medicine and Hospital Pharmacy (DOLS) > Clinic of Radiation Oncology

UniBE Contributor:

Schmidhalter, Daniel; Malthaner, Marco; Born, Ernst Johann; Pica, Alessia; Schmücking, Michael; Aebersold, Daniel; Fix, Michael and Manser, Peter

Subjects:

600 Technology > 610 Medicine & health

ISSN:

0939-3889

Publisher:

Elsevier, Urban & Fischer

Language:

English

Submitter:

Beatrice Scheidegger

Date Deposited:

03 Mar 2015 10:36

Last Modified:

09 Nov 2015 10:04

Publisher DOI:

10.1016/j.zemedi.2013.11.002

PubMed ID:

24418323

Uncontrolled Keywords:

Patienten-Lagerungsunsicherheit, 6D-Tisch, IGRT, Stereotaktische Radiotherapie

BORIS DOI:

10.7892/boris.61626

URI:

https://boris.unibe.ch/id/eprint/61626

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