Dosimetric evaluation of electron total skin irradiation using gafchromic film and thermoluminescent dosimetry
Leila Falahati1, Hassan Ali Nedaie2, Mahbod Esfahani3, Nooshin Banaee4
1 Department of Medical Physics and Biomedical Engineering, Radiation Oncology Research Centre, Faculty of Medicine, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran
2 Department of Radiotherapy Oncology, Cancer Research Center, Cancer Institute; Department of Medical Physics and Biomedical Engineering, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran
3 Department of Radiotherapy Oncology, Cancer Research Center, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran
4 Department of Medical Radiation, Engineering Faculty, Central Tehran Branch, Islamic Azad University, Tehran, Iran
Dr. Hassan Ali Nedaie
Department of Radiotherapy Oncology, Cancer Research Center, Cancer Institute, Tehran University of Medical Sciences, Tehran
Source of Support: None, Conflict of Interest: None
Aim of Study: The aim of this study is to evaluate some dosimetry parameters such as uniformity, surface dose, and max depth dose with thermoluminescent dosimetry (TLD) and EBT3 film in total skin electron beam therapy (TSEBT).
Methods: Stationary and rotary methods were set on Varian linear accelerator, Clinac 2100C. To create a radiation field large enough (168 cm × 60 cm) and uniform, the source skin distance was set 400 cm. Electron beam energy was 6 MeV. The skin dose values were obtained in 21 different points on the phantom surface.
Results: The results of dose uniformity in stationary technique were obtained as 10% and 2.6% by TLDs and 6% and 2.3% by films in longitudinal axis and transverse axis, respectively. The measurements at rotational technique by TLDs at the referred conditions showed a homogeneous total field with intensity variation of 10% in the longitudinal axis and 4% at horizontal axis.
Conclusion: Based on the results of this study, stationary techniques are preferred for TSEBT. The main advantage of rotational techniques is reducing the time of treatment. The results also demonstrate that TLD should be routinely used in TSEBT treatment. Due to the high sensitivity of radiochromic films, this type of film was suitable for a wide therapeutic field. Comprehensive treatment to Rando phantom showed that the uniformity is better at the trunk than in the mobile parts of the body; the soles of the feet, perineum region, and scalp vertex should be treated in boost.