Reduced Neutron Production Through Use of a Flattening-Filter-Free Accelerator

Journal Article · Sun Jul 15 04:00:00 EDT 2007 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2007.04.002· OSTI ID:20953580

Kry, Stephen F ^[1]; Titt, Uwe ^[1]; Poenisch, Falk ^[2]; Vassiliev, Oleg N ^[1]; Salehpour, Mohammad ^[1]; Gillin, Michael ^[1]; Mohan, Radhe ^[1]

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1. Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States)
2. Medizinische Fakultaet Carl Gustav Carus, Technische Universitaet Dresden, Dresden (Germany)

Purpose: To measure and compare neutron fluence around an accelerator operating at 18 MV, both with the flattening filter present (FF mode) and absent (flattening-filter-free [FFF] mode). Methods and Materials: The neutron fluence was measured at several locations in the patient plane using gold foil activation in neutron moderators. Differences in neutron fluence between the FF and FFF mode were assessed in three frameworks: (1) measured per monitor unit of machine-on time (2) determined per dose on the central axis, and (3) determined for a complete course of prostate intensity-modulated radiotherapy. Results: Neutron fluence per monitor unit was approximately 20% lower when the accelerator was operated in the FFF mode than when it was in FF mode. The total amount of neutron fluence that would be obtained during the entire course of prostate intensity-modulate radiotherapy was 69% lower when the accelerator was operated in the FFF mode than when it was in the FF mode. This reduction in neutron fluence would correspond to a drastic reduction in the neutron dose equivalent received by the patient as a byproduct of high-energy radiotherapy. It would also correspond to a reduction in activation within the treatment vault and subsequent exposure to radiation therapists. Conclusion: When feasible, operating the accelerator without a FF will benefit both patients and radiation therapists by reducing the number of unwanted neutrons and resultant exposure. This reduces the risk of negative effects from such exposure (e.g., second cancers)

• OSTI ID: 20953580
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 4 Vol. 68; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
ACCELERATORS
DOSE EQUIVALENTS
HEALTH HAZARDS
NEOPLASMS
NEUTRON FLUENCE
PROSTATE
RADIATION DOSES
RADIOTHERAPY