TY - JOUR
T1 - Beam spot position measurement using corotational penumbra modulation and image center shift methods
AU - Rofikoh,
AU - Rafliansyah, A.
AU - Sugiyantari,
AU - Soejoko, D. S.
N1 - Publisher Copyright:
© Published under licence by IOP Publishing Ltd.
PY - 2020/6/15
Y1 - 2020/6/15
N2 - Image and treatment quality of radiotherapy are influenced by the position of beam spot, therefore it is important to know the position of the beam spot. Beam spot position measured by the corotational penumbra modulation (CPM) and the image center shift (ICS). The CPM method uses a cylindrical ion chamber that rotate with collimator angle. The position of ion chamber, jaws, central axis are fixed to collimator angle. The signal measured to half blocked field 10x20 cm2 for every 30° collimator angle. The beam spot calculated from signal measurement results. The ICS method uses two radiopaque rings with 8.5 cm diameter. Both of rings are placed at different heights of 64.5 cm and 150 cm SSD. Image acquired by varying both collimator and couch angle for every 30° and the beam spot position calculated by measuring the shift of rings centre. Measurement also performed using ball bearing test. Beam spot shift values from the CAOR using CPM and ICS measurements are closely similar, in the range of 0.05-0.65 mm and 0-0.53 mm respectively. The measurement using CPM and ICS methods can be used for routine quality assurance (QA) to ensure that the beam spot position still in tolerance.
AB - Image and treatment quality of radiotherapy are influenced by the position of beam spot, therefore it is important to know the position of the beam spot. Beam spot position measured by the corotational penumbra modulation (CPM) and the image center shift (ICS). The CPM method uses a cylindrical ion chamber that rotate with collimator angle. The position of ion chamber, jaws, central axis are fixed to collimator angle. The signal measured to half blocked field 10x20 cm2 for every 30° collimator angle. The beam spot calculated from signal measurement results. The ICS method uses two radiopaque rings with 8.5 cm diameter. Both of rings are placed at different heights of 64.5 cm and 150 cm SSD. Image acquired by varying both collimator and couch angle for every 30° and the beam spot position calculated by measuring the shift of rings centre. Measurement also performed using ball bearing test. Beam spot shift values from the CAOR using CPM and ICS measurements are closely similar, in the range of 0.05-0.65 mm and 0-0.53 mm respectively. The measurement using CPM and ICS methods can be used for routine quality assurance (QA) to ensure that the beam spot position still in tolerance.
UR - http://www.scopus.com/inward/record.url?scp=85086800228&partnerID=8YFLogxK
U2 - 10.1088/1742-6596/1505/1/012022
DO - 10.1088/1742-6596/1505/1/012022
M3 - Conference article
AN - SCOPUS:85086800228
SN - 1742-6588
VL - 1505
JO - Journal of Physics: Conference Series
JF - Journal of Physics: Conference Series
IS - 1
M1 - 012022
T2 - 3rd Annual Scientific Meeting on Medical Physics and Biophysics, PIT-FMB in conjunction with the 17th South-East Asia Congress of Medical Physics, SEACOMP 2019
Y2 - 8 August 2019 through 10 August 2019
ER -