Purpose: The purpose of this study was to implement a novel treatment approach using manual field in field total body irradiation(MFIF-TBI) technique and their results were compared with compensator based TBI(CB-TBI).
Methods: A rice flour phantom(RFP) was placed on TBI couch with knee bent position at 385cm SSD.The separation of RFP was measured at different places.Using separations of skull, umbilicus and calf, treatment MU was calculated for the MFIF-TBI technique.Using multileaf collimator and Jaw, different field-sizes were opened according to calculated MU for different regions.The main field was opened for entire length of the patient and required MU was calculated using separation of skull. Second subfield was opened from the end of the neck to the end of the calf and remaining MU was calculated using separation of calf. Similarly, the third field was opened from the end of the neck to the end of the thigh and calculated remaining MU using separation of umbilicus.For the CB-TBI technique, treatment MU were calculated using PDD of the umbilicus region and the required compensator thickness was calculated for Perspex material.The diodes were placed on the surface of RFP to measure delivered dose and the results were compared.
Results: In MFIF-TBI technique, the deviation from the prescribed dose for umbilicus, skull, neck, thigh, knee, calf and ankle were -2.22%, -1.64%, +8.72%, -0.28%,-1.26%,-0.80%, and -0.99%. Similarly, in CB-TBI technique, the deviations for same regions were-1.86%, 1.92%,-0.50%, +0.09%, +1.26%, +1.69, and -1.32. The deviation of dose in neck region was higher in MFIF-TBI technique from the prescription dose which can be reduced with the help of compensator.
Conclusion: The results of this study showed that the MFIF technique can be implemented for TBI treatment. This study ensured that without treatment planning system and compensator, the uniform dose can be achieved within the tolerance limit using MFIF-TBI technique.
TBI, Compensators, Field Shaping
TH- External Beam- Photons: Development (new technology and techniques)