Absorbed dose uncertainty evaluation in proton therapy of prostate cancer by Monte Carlo method

Document Type : Conference Paper

Authors

1 Department of Physics, Isfahan University of Technology, Isfahan, Iran

2 Department of Biomedical Engineering, University of Isfahan, Isfahan, Iran

3 Department of Physics, Isfahan University of Technology, Isfahan, Iran.

Abstract

Proton therapy is one of the prostate cancer treatments. Bragg peak in proton depth-dose curve is the most important characteristic of this method. It causes the most amount deposition of energy in the tumor. Prostate is not a fixed organ and has involuntary movement in the range of 1-7mm due to bloating of the gastrointestinal tract in body, so this movement results in uncertainty in absorbed dose of particle. In this research absorbed dose are calculated regarding prostate movement using FLUKA code which works with Monte Carlo method. First, the phantom used is simulated. Regarding depth of 15cm of prostate in body the needed energy to form Bragg peak in tumor was calculated 148 MeV with 0.02% precision. Total Absorbed dose for one proton particle is 7.2 nGy when prostate was considered fixed in coordinate center .it was shown that 99.9% of total absorbed dose which is deposited in prostate and does not damage other tissues. The reason for this is the presence of Bragg Peak, which is all the energy absorbed in this area. with moving prostate for 7mm in perpendicular proton beam direction, the total dose absorbed by the prostate is reduced by 2.2%, also for moving prostate in line with proton beam, the total dose absorbed by the prostate is reduced by 6.66%.

Keywords


  1. Z. Aghaei, A. Karimian , M. H. Alamatsaz. Assessment of absorbed dose uncertainty of prostate due to tissue swelling and radioactive sources displacement in brachytherapy by Monte Carlo method. Iranian J. Physics Res. 20 (4) (2021) 599-613.
  2. X. Tong, X. chen. Intrafractional prostate motion during external beam radiotherapy monitored by a real-time target localization system. Clinical Med. Phys. 16 (2015) 8-16.
  3. M. Akbari, A. Karimian. Impact of anatomical changes on radiation absorbed dose of prostate and bladder in a potential scenario of magnetic resonance imaging (MRI)-guided carbon-ion radiotherapy (MRgCT) of prostate cancer. Measurement 171 (2021) 108772.
  4. M. J. Berger. Penetration of proton beams through water I. Depth-dose distribution, spectra and LET distributio. NIST Pub. (1993) 19-30.