Effect of the radiation field of view and angle in unconventional angiography on patient doses: a Monte Carlo simulation study using a voxelized phantom

Introduction: We aimed to investigate the effect of variation of beam angle and field of view (FOV) on organs’ and effective doses for patients undergoing interventional cardiology examinations by using Monte Carlo simulations and ICRP۱۱۰ phantom.   Materials and Methods: Simulations were done for energies obtained from experimental measurements on the left ventricle phantom of the Axiom Artis model of an angiography system by Monte Carlo N- Particle System code (MCNP). The ICRP۱۱۰ voxelized whole body model representing an average patient was employed at posterior anterior (PA) position. To guide the x-ray source, the approximate spherical coordinates were set at: ۲۷, ۲۷.۱۳۵. The collimated x-rays beam was directed toward the patient's body over ۱۶´۱۶ and ۲۵´۲۵ cm۲ field sizes for twenty alternative proposed techniques and their resulting effective doses were estimated and compared with those obtained for six relevant routine techniques of coronary angiography including LAO۴۰-CAUD۴۰, LAO۴۵, LAO۶۰-CRA۲۰, PA-CRA۴۵, RAO۲۰-CAUD۲۰ and RAO۳۰, used at a hospital. Results: Variation of the angle and FOV for the ۲۵´۲۵ cm۲ field size resulted in dose reduction for some of the proposed techniques including the LAO۲۰-CAUD۲۰, LAO۲۰-CAUD۴۵, LAO۶۰- CAUD۲۰, LAO۶۰-CAUD۴۵, LAO۳۰, LAO۶۰-CRA۳۰, RAO۱۰-CAUD۳۰, RAO۳۰-CAUD۳۰, RAO۲۰ and RAO۴۰ with an amount of ۱۲, ۱۵, ۲۷, ۷۴, ۴۰, ۵۴, ۵۰, ۵۶, ۱۳ and ۳۸ percent respectively. But, for the ۱۶´۱۶ cm۲ field size, the dose reduction was observed just for the LAO۶۰-CRA۳۰, RAO۱۰-CAUD۳۰ and RAO۳۰-CAUD۳۰ proposed techniques with an amount of ۴۱, ۱۶ and ۳۸ percent respectively. Conclusion: By appropriate variation of the beam angle and FOV, the number/volume of the critical organs exposed directly to primary x-rays can be reduced and lead to the reduction of effective dose while keeping the target organ within the radiation field.

کلیدواژه ها:

Angiography ، Monte Carlo simulation ، Patient doses ، Voxelized phantom