A model to calculate the induced dose rate around an 18 MV ELEKTA linear accelerator.
AffiliationNorth Western Medical Physics, Christie Hospital (NHS) Trust, Wilmslow Road, Withington, Manchester, M20 4BX, UK. Bruce.Perrin@physics.cr.man.ac.uk
MetadataShow full item record
AbstractThe dose rate due to activity induced by (gamma, n) reactions around an ELEKTA Precise accelerator running at 18 MV is reported. A model to calculate the induced dose rate for a variety of working practices has been derived and compared to the measured values. From this model, the dose received by the staff using the machine can be estimated. From measured dose rates at the face of the linear accelerator for a 10 x 10 cm2 jaw setting at 18 MV an activation coefficient per MU was derived for each of the major activation products. The relative dose rates at points around the linac head, for different energy and jaw settings, were measured. Dose rates adjacent to the patient support system and portal imager were also measured. A model to calculate the dose rate at these points was derived, and compared to those measured over a typical working week. The model was then used to estimate the maximum dose to therapists for the current working schedule on this machine. Calculated dose rates at the linac face agreed to within +/- 12% of those measured over a week, with a typical dose rate of 4.5 microSv h(-1) 2 min after the beam has stopped. The estimated maximum annual whole body dose for a treatment therapist, with the machine treating at only 18 MV, for 60000 MUs per week was 2.5 mSv. This compares well with value of 2.9 mSv published for a Clinac 21EX. A model has been derived to calculate the dose from the four dominant activation products of an ELEKTA Precise 18 MV linear accelerator. This model is a useful tool to calculate the induced dose rate around the treatment head. The model can be used to estimate the dose to the staff for typical working patterns.
CitationA model to calculate the induced dose rate around an 18 MV ELEKTA linear accelerator. 2003, 48 (5):N75-81 Phys Med Biol
JournalPhysics in Medicine and Biology
- Dose to radiation therapists from activation at high-energy accelerators used for conventional and intensity-modulated radiation therapy.
- Authors: Rawlinson JA, Islam MK, Galbraith DM
- Issue date: 2002 Apr
- DOSE AND GAMMA-RAY SPECTRA FROM NEUTRON-INDUCED RADIOACTIVITY IN MEDICAL LINEAR ACCELERATORS FOLLOWING HIGH-ENERGY TOTAL BODY IRRADIATION.
- Authors: Keehan S, Taylor ML, Smith RL, Dunn L, Kron T, Franich RD
- Issue date: 2016 Dec
- Laminated primary ceiling barriers for medical accelerator rooms.
- Authors: McGinley PH, Butker EK
- Issue date: 1994 Sep
- Contribution of activation products to occupational exposure following treatment using high-energy photons in radiotherapy.
- Authors: Petrović N, Krestić-Vesović J, Stojanović D, Ciraj-Bjelac O, Lazarević D, Kovacević M
- Issue date: 2011 Jan
- Monte Carlo modeling of a 6 and 18 MV Varian Clinac medical accelerator for in-field and out-of-field dose calculations: development and validation.
- Authors: Bednarz B, Xu XG
- Issue date: 2009 Feb 21