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In-Vivo Measurements for Single and Multi-Fractional TBI Using OSLDs and Ion Chamber

K Vittal

K Vittal*, S Singh , s osman , K Jassal , B Sarkar , U Giri , T Ganesh , A Munshi , B Mohanti , Fortis Memorial Research Institute, Gurgaon, Haryana


SU-I-GPD-T-312 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: To evaluate the feasibility of using optically stimulated luminescence dosimeters (OSLDs) and ion chamber for in-vivo dosimetry of patients undergoing Total Body Irradiations single and multi-fraction.

Methods: In-vivo dose measurements using OSLDs (LANDAUER, Glenwood, Illinois) and 0.6cc farmer chamber (PTW, Freiburg, Germany) were done in a total of twelve patients who received 2 Gy in single fraction and 12 Gy in 6 fractions of TBI at our institute. To provide a uniform dose to the entire patient length, the treatment was split into 2 lateral fields. In this technique, the patient is kept inside the TBI box which is filled with rice bags and irradiated using two bilateral parallel opposed beams of 40×40 cm² size with 45° collimator rotation at 333.5 cm SSD in Synergy linear accelerator (Elekta AB, Stockholm, Sweden). The beams were equally weighted at the midplane. The OSLDs (LANDAUER, Glenwood, Illinois) were placed medial and lateral sites over forehead, umbilicus, between knee, right and left neck, right and left lung, right and left abdomen and right thigh. A 0.6 cc Farmer chamber (PTW, Freiburg, Germany) was placed in between the thighs of the patient.

Results: OSLDs mean doses for medial and lateral sites 2.12±0.63 Gy and 2.16±0.84 Gy respectively. Farmer chamber mean dose was 2.17±0.86 Gy. Statistical analysis revealed that there were no significant differences between OSLDs measured and farmer chamber measured doses for single and multi-fraction TBI treatment delivery. OSLDs measured doses agreed within ± 3% of farmer chamber.

Conclusion: OSLDs and ion chamber measurements agreed well within the acceptance limits for single and multi-fraction TBI treatment delivery. Thus, OSLDs dosimetry was found to be a feasible option for dose measurements in TBI patients.

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