Dosimetric verification of the Elekta motorized wedge

Mahdie Behjati--- Nuclear Science and Technology Research Institute (NSTRI) , Tehran, Iran,
Mostafa Sohrabpour--- Nuclear engineering unit, Department of Energy Engineering, Sharif University of Technology, Tehran, Iran,
Seyed Pezhman Shirmardi--- 2Nuclear Science and Technology Research Institute (NSTRI) , Tehran, Iran,
Fathollah Bouzarjomehri--- Medical Physics Unit, Department of Medical Physics and Environment Health, Shahid Sadoghi University of Medical Sciences,Yazd, Iran,
Mohammad Amin Mosleh Shirazi---



Elekta linear accelerator is equipped with a motorized wedge which produces the wedge angles of less than 60° continuously by the combination of a wedged field and an open field with appropriate proportions. The effective wedge angles for various field sizes and depths were calculated using an analytical formula and a 2-D array detector data. The validity of the effective wedge angles has been done by determining wedge angles in accordance with ICRU-24. The effect of the field size on the wedge angle and wedge factor was investigated for motorized wedge. The maximum difference between planned and measured angles was found to be about 10̊. The planned dose for different wedge angles and field sizes compared with measured doses and their differences were found to be less than 3%. The calculating wedge factor throughout linear interpolation method for all field sizes from a few selected measurements had been proved for physical wedge beforehand. This method was applied to obtain the wedge factors with field size and compared with measured data for motorized wedge. The errors were in agreement with ICRU proposed error and less than treatment planning system error. The linear relation between wedge angle and output factor and depth were investigated and the linear interpolation method was proved to calculate wedge angle for any output factor and depth. 


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Tatcher, M. "A method for varying the effective angle of wedge filters." Radiology 97.1 (1970): 132-132.

Faiz M. Khan, “Physics of Radiation”, 2010, Lippincott, Williams and Wilkins.

International Commission on Radiation Units and Measurements (ICRU). 1976, Determination of absorbed dose in a patient irradiated by beams of X or gamma rays in radiotherapy procedures. ICRU Rep; 24.

Wu, Andrew, et al. "Dosimetry characteristics of large wedges for 4‐and 6‐MV x rays." Medical physics 11.2 (1984): 186-188.

Oh, Se An, et al. "Dosimetric verification of enhanced dynamic wedges by a 2D ion chamber array." Journal of the Korean Physical Society 63.11 (2013): 2215-2219.

Varatharaj, C., et al. "Variation of beam characteristics between three different wedges from a dual-energy accelerator." Journal of Medical Physics/Association of Medical Physicists of India 36.3 (2011): 133.

Saminathan, Sathiyan, Ravikumar Manickam, and Sanjay S. Supe. "Comparison of dosimetric characteristics of physical and enhanced dynamic wedges." Reports of Practical Oncology & Radiotherapy 17.1 (2012): 4-12.

Ahamed, T. M. S. Study Of Dosimetric Characteristics Of Motorized Wedges In 6MV Photon Beam Of Linear Accelerator Used In Radiotherapy. Diss. 2014.

Sidhu, N. P. S., and Karen Breitman. "Dosimetric characteristics of wedged fields." Medical dosimetry 19.1 (2015): 35-41.

Petti, Paula L., and Robert L. Siddon. "Effective wedge angles with a universal wedge." Physics in medicine and biology 30.9 (1985): 985.

Zwicker, R. D., et al. "Effective wedge angles for 6‐MV wedges." Medical physics 12.3 (1985): 347-349.

Rajesh Kumar, D. K. (2012). Design, implementation and validation of a motorized wedge filter for a telecobalt machine. Volume 28, Issue 1 , Physica Medica: European Journal of Medical Physics , pp. 54-60.

Rajesh A. Kinhikar, S. S. ( 2007 , Jan-Mar). Characterizing and configuring motorized wedge for a new generation telecobalt machine in a treatment planning system. J Med Phys. , pp. 29–33.

Palta, Jatinder R., Inder Daftari, and N. Suntharalingam. "Field size dependence of wedge factors." Medical physics 15.4 (1988): 624-626.

Niroomand‐Rad, Azam, et al. "Wedge factor dependence on depth and field size for various beam energies using symmetric and half‐collimated asymmetric jaw settings." Medical physics 19.6 (1992): 1445-1450.

Heukelom, S., J. H. Lanson, and B. J. Mijnheer. "Wedge factor constituents of high energy photon beams: field size and depth dependence." Radiotherapy and Oncology 30.1 (1994): 66-73.

Heukelom, Stan. "Response to letter re: The effect on wedge factors of scattered radiation from the wedge." Radiotherapy and Oncology 34.2 (1995): 164.

Cozzi, A. Fogliata, L. Cozzi, and G. Garavaglia. "Wedge factors: Dependence on depth and field size." Radiotherapy and oncology 39.1 (1996): 31-34.

Popescu, Alina, et al. "Wedge factor dependence with depth, field size, and nominal distance—A general computational rule." Medical physics 26.4 (1999): 541-549.

Saffar, M. Hajizadeh, M. R. Ghavamnasiri, and H. Gholamhosseinian. "Assessment of variation of wedge factor with depth, field size and SSD for Neptun 10PC Linac in Mashhad Imam Reza Hospital." Iranian Journal of Radiation Research 2.2 (2004): 53-58.

Ahmad, Misbah, et al. "Studying wedge factors and beam profiles for physical and enhanced dynamic wedges." Journal of Medical Physics/Association of Medical Physicists of India35.1 (2010): 33.

Ilyas, Nasir, et al. "Wedge Factor Dependence on Computer Controlled Wedge System in Siemens ONCOR Linear Accelerator." Journal of Medical Physics and Biophysics 3.1 (2016): 66-72.

Memon, Sajjad Ahmed, Naeem Ahmed Laghari, and Fayaz Hussain Mangi. "Behaviour of wedges for different field sizes and depths." Journal of pakistan Society of Nuclear Medicine (2017):32-41.

Popple, Richard A., et al. "Determination of field size‐dependent wedge factors from a few selected measurements." Journal of Applied Clinical Medical Physics6.1 (2005): 51-60.

Schmidt, Ernst-Ludwig, Jiirgen Rittler, and Reiner Steurer. "A method of quality assurance of dynamic wedges." Strahlentherapie und Onkologie: Organ der Deutschen Rontgengesellschaft...[et al] 175.1 (1999): 39-41.

Andreo, Pedro, et al. "Absorbed dose determination in external beam radiotherapy: an international code of practice for dosimetry based on standards of absorbed dose to water." IAEA TRS 398 (2000).

Wu, Andrew, et al. "Dosimetry characteristics of large wedges for 4‐and 6‐MV x rays." Medical physics 11.2 (1984): 186-188.


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"Journal of Paramdedical Sciences", is a publication of "School of Paramedical Sciences, Shahid Beheshti University of Medical Sciences" and "Iranian Society of Medical Proteomics".

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EISSN: 2008-4978

PISSN: 2008-496X