Poster – 12: Radiological assessment of the secondary barrier shielding for IMRT treatments delivered through patient inhomogeneities
- Pakistan Institute of Engineering and Applied Science, Nilore, Islamabad, Pakistan, Sunnybrook Health Sciences Center, Toronto, ON, Canada & Pakistan Institute of Engineering and Applied Science, Nilore, Islamabad, Pakistan, Pakistan Institute of Engineering and Applied Science, Nilore, Islamabad (Pakistan)
Purpose: To assess the impact of radiation treatment delivery through patient inhomogeneities on the secondary barrier shielding requirements in IMRT treatments using Monte Carlo Simulations. Materials and Methods: Scatter factors were calculated at a distance of 1m from the center of a virtual phantom in Geant4.10.01. Phantom (30×30×30 cm{sup 3}) was inserted with lung (30×30×8 cm{sup 3}), stainless steel (5×5×5 cm{sup 3}) and aluminum (5×5×5 cm{sup 3}) to represent the inhomogeneities. Scatter factor was defined according to the NCRP-151 recommendations and was calculated for angles of 3° to 120° with respect to the beam’s central axis. A virtual radiation source, with energy sampled from a histogram representing 6 MV FFF beam, was used for irradiation with a field size of 15×15 cm{sup 2} and SSD of 100 cm. Results: Irradiation through the inhomogeneity affects the patient scattered dose. For high Z material inhomogeneities the scattered dose is reduced due to significant attenuation of the primary radiation. On the other hand if the inhomogeneity is a low Z material such as lung the scattered dose is higher by a maximum of 26%. The average increase in scatter factors for the lung phantom was 17% for angles between 3° and 63° compared to the homogeneous water phantom. Conclusions: In IMRT type treatments delivered through low density patient inhomogeneities (lung) the scattered dose increases significantly. Considering a large proportion of patients receiving radiation therapy for lung cancers the increase in the scattered dose should be incorporated in the shielding calculations for the secondary barriers.
- OSTI ID:
- 22689320
- Journal Information:
- Medical Physics, Journal Name: Medical Physics Journal Issue: 8 Vol. 43; ISSN 0094-2405; ISSN MPHYA6
- Country of Publication:
- United States
- Language:
- English
Similar Records
SU-E-T-643: Pure Alanine Dosimeter for Verification Dosimetry in IMRT
IMRT in a Pregnant Patient: How to Reduce the Fetal Dose?
In vivo and phantom measurements of the secondary photon and neutron doses for prostate patients undergoing 18 MV IMRT
Journal Article
·
Mon Jun 15 00:00:00 EDT 2015
· Medical Physics
·
OSTI ID:22538152
IMRT in a Pregnant Patient: How to Reduce the Fetal Dose?
Journal Article
·
Wed Dec 31 23:00:00 EST 2008
· Medical Dosimetry
·
OSTI ID:21333958
In vivo and phantom measurements of the secondary photon and neutron doses for prostate patients undergoing 18 MV IMRT
Journal Article
·
Sun Oct 15 00:00:00 EDT 2006
· Medical Physics
·
OSTI ID:20853594