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Improving the Quality in Treatment Planning Performance of Dosimetrists Based On MUs to Dose Ratio

T Ganesh

T Ganesh1*, B Sarkar2 , K Jassal3 , S Roy4 , s Rathinamuthu5 , U Giri6 , S Singh7 , K Vittal8 , s osman9 , A Munshi10 , B Mohanthi11 , (1) KING FAHAD SPECIALIST HOSPITAL, New Delhi, ,(2) AMRI Cancer Centre, Kolkata, ,(3) Fortis Memorial Research Institute, Gurgaon, ,(4) AMRI, Kolkata, Bengal, (5) FMRI, Gurgaon, Haryana, (6) Fortis Memorial Research Institute, Gurgaon, haryana, (7) fortis memorial research institute, Gurgaon, haryana, (8) Fortis Memorial Research Institute, Gurgaon, Haryana, (9) Fortis Momerial Research Institute, Gurgaon, Haryana, (10) Fortis Memorial Research Institute, Gurgaon, Haryana, (11) Fortis Memorial Reaserch Institute, Gurgaon, Haryana


MO-L-GePD-T-4 (Monday, July 31, 2017) 1:15 PM - 1:45 PM Room: Therapy ePoster Lounge

Purpose: To improve the quality in treatment planning performance of dosimetrists through analyzing MU to dose ratio of treatment plans.

Methods: A total 1233 IMRT/VMAT treatment plans generated by 5 dosimetrists over a period of 3 years 7 months were analyzed by grouping them according to following categories: abdomen (184), brain (hypofractionated) (111), brain (conventional fractionation) (220), pelvis (188), head and neck (195), breast (175) and thorax (160). Figures within parenthesis indicate the number of plans for each category. IMRT Factor (IF), defined as the ratio of MUs to prescribed dose, was scored for every plan. Mean values achieved by each planning dosimetrist were analyzed according to plan category with the respective overall means.

Results: The overall mean IFs for abdomen, stereotactic brain, normal brain, pelvis, head and neck, breast and thorax categories were found to be 3.8±1.4, 3.1±0.9, 2.8±0.8, 4.6±0.9, 3.8±0.9, 2.8±0.7 and 3.9±1.0 respectively. For these categories, the five dosimetrists had mean scores ranging from 3.7 to 4.2, 2.6 to 3.6, 2.1 to 3.2, 4.4 to 5.6, 3.6 to 4.1, 2.8 to 3.0 and 3.7 to 4.2 respectively.

Conclusion: Although patient-to-patient dissimilarities and variations in individual dose constraints can influence IFs, the large number of cases in each category meant that, statistically they would even out and there should not be large variations between the overall institutional mean and the mean value achieved by each planner in each category. This exercise has led us to obtain the ‘most probable IF value’ for each category in our institution. These guidance values have helped the planners in identifying IF values that are significantly larger pointing to possible deficiencies in the plans they do, thus allowing appropriate corrective actions to be taken. We have gained by way of improving the quality in the institutional treatment planning process.

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