Paper Information

Journal:   JOURNAL OF MEDICAL SIGNALS AND SENSORS (JMSS)   JANUARY-MARCH 2018 , Volume 8 , Number 1; Page(s) 31 To 38.
 
Paper: 

EVALUATING THE IMPACT OF VARIOUS PARAMETERS ON THE GAMMA INDEX VALUES OF 2D DIODE ARRAY IN IMRT VERIFICATION

 
DOI: 

10.4103/jmss.JMSS_15_17

 
Author(s):  JABBARI KEYVAN, PASHAEI FAKHEREH*, AY MOHAMMAD R., AMOUHEIDARI ALIREZA, TAVAKOLI MOHAMMAD B.
 
* DEPARTMENT OF MEDICAL PHYSICS, SCHOOL OF MEDICINE, ISFAHAN UNIVERSITY OF MEDICAL SCIENCES, HEZAR JARIB STREET, ISFAHAN, IRAN
 
Abstract: 

Background: MapCHECK2 is a two-dimensional diode arrays planar dosimetry verification system. Dosimetric results are evaluated with gamma index. This study aims to provide comprehensive information on the impact of various factors on the gamma index values of MapCHECK2, which is mostly used for IMRT dose verification.
Methods: Seven fields were planned for 6 and 18 MV photons. The azimuthal angle is defined as any rotation of collimators or the MapCHECK2 around the central axis, which was varied from 5 to -5o. The gantry angle was changed from -8 to 8o. Isodose sampling resolution was studied in the range of 0.5 to 4 mm. The effects of additional buildup on gamma index in three cases were also assessed. Gamma test acceptance criteria were 3%/3 mm.
Results: The change of azimuthal angle in 5o interval reduced gamma index value by about 9%. The results of putting buildups of various thicknesses on the MapCHECK2 surface showed that gamma index was generally improved in thicker buildup, especially for 18 MV. Changing the sampling resolution from 4 to 2mmresulted in an increase in gamma index by about 3.7%. The deviation of the gantry in 8° intervals in either directions changed the gamma index only by about 1.6% for 6 MV and 2.1% for 18 MV.
Conclusion: Among the studied parameters, the azimuthal angle is one of the most effective factors on gamma index value. The gantry angle deviation and sampling resolution are less effective on gamma index value reduction.

 
Keyword(s): GAMMA INDEX, INTENSITY MODULATED RADIATION THERAPY VERIFICATION, MAPCHECK2, TWO- DIMENSIONAL ARRAY
 
References: 
  • ندارد
 
  pdf-File tarjomyar Yearly Visit 34
 
Latest on Blog
Enter SID Blog