Dosimetric Comparison of Various Radiotherapeutic Treatment Plans Using Cobalt-60 and Linac for Prostate Cancer

Vaezzadeh, Seyed Ali; Allahverdi, Mahmood; Nedaie, Hasan; Aghili, Mahdi; Esfehani, Mahbod; Mohammadi, Ehsan

doi:10.22038/ijmp.2009.7297

Dosimetric Comparison of Various Radiotherapeutic Treatment Plans Using Cobalt-60 and Linac for Prostate Cancer

Document Type : Original Paper

Authors

Seyed Ali Vaezzadeh ¹

Mahmood Allahverdi ²

Hasan Nedaie ³

Mahdi Aghili ³

Mahbod Esfehani ⁴

Ehsan Mohammadi ⁴

¹ Ph. D. Student in Medical Physics, Tehran University of Medical Science, Tehran, Iran

² Associate Professor, Medical Physics Dept., Tehran University of Medical Science, Tehran, Iran

³ Assistant Professor, Radiotherapy Dept., Cancer Institute, Tehran University of Medical Science, Tehran, Iran

⁴ M.Sc. in Medical Physics, Radiotherapy Dept., Cancer Institute, Tehran University of Medical Science, Tehran, Iran

10.22038/ijmp.2009.7297

Abstract

Introduction: This study was designed to evaluate dosimetric parameters such as rectal dose, bladder dose, integral dose (ID), homogeneity index (HI) and conformity index (CI) in various treatment plans for prostate cancer.
Materials and Methods: Pelvic computed tomography (CT) scans of 27 patients were acquired and transferred to the RTDosePLAN treatment planning system. For each patient, 8 conventional plans (3, 4, 5 and 6 fields) were planned for the cobalt-60 photon energy. Subsequently, the same plans were performed for 6 MV and 18 MV photon energies.
Results: By increasing the energy of the beam relative to the cobalt-60 energy, the D_mean values for rectum and bladder were reduced from 3% to 4% and 4% to 6%, respectively, the dose received by the whole of the bladder volume decreased by 26% for 6 MV and by 58% for 18 MV. Increasing the photon beam energy decreased CI to 7% and 10%, ID was decreased by10% and 20% and D_max was decreased by 3% and 4%, respectively.
Discussion and Conclusion: A six-field treatment plan in comparison to the other plans offers the minimum dose to critical organs and sufficient dose to the prostate. Increasing the photon energy improves the treatment parameters of the bladder and the PTV.

Keywords

Prostate cancer

Treatment plan

Integral dose

Linac

Cobalt-60

Subjects