TH-AB-201-05: Determining the Direction Distribution of the Primary Radiation for a Cyberknife-M6.

Henzen, Dominik; Zanella do Amaral Campos, Pedro Paulo; Schmidhalter, Daniel; Volken, Werner; Mackeprang, Paul-Henry; Malthaner, Marco; Fix, Michael; Manser, Peter (June 2016). TH-AB-201-05: Determining the Direction Distribution of the Primary Radiation for a Cyberknife-M6. Medical physics, 43(6), p. 3850. American Association of Physicists in Medicine AAPM 10.1118/1.4958033

PURPOSE Radiation protection regulatory differentiates between primary and scatter radiation. Whereas for conventional clinical linear accelerators the solid angle for primary radiation is planar, the Cyberknife (Accuray Inc., Sunnyvale, CA) may point its beam in all spatial directions. In order to be able to judge on radiation protection calculations for a Cyberknife-M6 vault, the direction distribution for delivered plans was evaluated based on clinical experiences. METHODS The log-files of 121 delivered patient treatment plans were exported, divided into cranial and extra-cranial treatments and the delivered monitor units (MU) together with the corresponding beam directions were analyzed. This MU-weighted spatial distribution was then projected to a 9.5 × 5.9 × 3.9 m(3) vault, generating an "intensity map" using a binning of 50 × 50 cm(2) . The factor of direction (FOD) is reported as a fraction of the total applied MUs to the walls, ceiling and floor in the perspective of a patient lying in head-first-supine position on the couch. In this study, the term intFOD refers to the integral FOD and maxFOD refers to the maximal FOD for a single bin. RESULTS For all kind of treatments and collimators, intFOD and maxFOD for the wall behind the patient's head is 0.0. The intFOD for the floor varies between 0.65 and 0.74. For the ceiling, maxFOD is 0.002 and 0.0 for cranial and extra-cranial cases, respectively. The intFOD for the wall at the patient's feet, is 0.094 for cranial and 0.005 for extra-cranial cases. There is nearly no difference between the maxFOD of the right and left wall for cranial cases, whereas for extra-cranial cases these numbers differ by a factor of 1.75. CONCLUSION The varying FODs for the Cyberknife were quantified based on delivered treatment plans. These findings are helpful regarding the design of Cyberknife vaults.

Item Type:

Conference or Workshop Item (Abstract)

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
04 Faculty of Medicine > Department of Intensive Care, Emergency Medicine and Anaesthesiology (DINA) > Clinic of Intensive Care

UniBE Contributor:

Henzen, Dominik; Zanella do Amaral Campos, Pedro Paulo; Schmidhalter, Daniel; Volken, Werner; Mackeprang, Paul-Henry; Malthaner, Marco; Fix, Michael and Manser, Peter

Subjects:

600 Technology > 610 Medicine & health

ISSN:

0094-2405

Publisher:

American Association of Physicists in Medicine AAPM

Language:

English

Submitter:

Beatrice Scheidegger

Date Deposited:

27 Mar 2017 15:45

Last Modified:

27 Mar 2017 15:45

Publisher DOI:

10.1118/1.4958033

Uncontrolled Keywords:

Collimators; Linear accelerators; Radiation treatment; Spatial dimensions; Therapeutics

URI:

https://boris.unibe.ch/id/eprint/92686

Actions (login required)

Edit item Edit item
Provide Feedback