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. 2025 Jul-Sep;50(3):501-509.
doi: 10.4103/jmp.jmp_103_25. Epub 2025 Sep 29.

Validation of Treatment Planning Systems based on Dose Calculation Accuracy for Extended SSD Total Body Irradiation with and without Beam Spoiler

Jayapalan Krishnan  1 , Achuth S Nayak  1 , Nisma Farooq  1 , M Dinesh  1 , Suryanarayana Kunikullaya  1 , Muhammed Shafeeque  1
Affiliations

Validation of Treatment Planning Systems based on Dose Calculation Accuracy for Extended SSD Total Body Irradiation with and without Beam Spoiler

Jayapalan Krishnan et al. J Med Phys. 2025 Jul-Sep.

Abstract

Aims: This study aimed to confirm the accuracy of the dose calculation by commercially available treatment planning system (TPS) at the extended SSD = 350 cm with and without beam spoiler configurations.

Materials and methods: Two extended SSD plans, one without a beam spoiler and another with a beam spoiler, were created on a virtual phantom in Eclipse TPSs for 6 MV photon beam. Using dosimetry tools, percentage depth doses (PDDs) and in-line profiles of both plans were generated. Beam properties of the TPS calculated PDDs and profiles were compared with manually calculated and measured PDDs and profiles. Reference depth dose was calculated in two different phantoms and measured using an ion chamber and TLDs.

Results: At the extended SSD setup, the TPS calculated and measured PDD with and without beam spoiler were in agreement within 2%. This agreement was observed at the surface and in the buildup region as well. Flatness and symmetry of the profiles with and without beam spoiler were within ± 3%. The TPS calculated dose at a reference depth in a homogeneous and a heterogeneous phantom was agreed with measured dose using an ion-chamber and TLDs.

Conclusion: This study validated the TPS for extended SSD total body irradiation (TBI) dose calculation with and without beam spoiler. Developing computed tomography based field in field plan for homogeneous dose distribution may be feasible. This technique may allow us to treat extended SSD TBI in less time while maintaining dose calculation accuracy.

Keywords: Extended SSD percentage depth dose with beam spoiler; extended source-to-surface distance profile with beam spoiler; extended source-to-surface distance total body irradiation using treatment planning systems.

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Conflict of interest statement

There are no conflicts of interest.

Figures

Figure 1
Figure 1
Virtual water phantom without beam spoiler created using eclipse treatment planning systems
Figure 2
Figure 2
Water phantom with beam spoiler (pink color) created using Eclipse treatment planning system
Figure 3
Figure 3
Percentage depth doses and in-line profile measurement setup without beam spoiler
Figure 4
Figure 4
Percentage depth doses and In-line profile measurement setup with beam spoiler
Figure 5
Figure 5
(a) Water equivalent slab phantom (b) Slab phantom with air heterogeneity
Figure 6
Figure 6
Extended SSD (350 cm) in-line profile of the largest field size 40 cm × 40 cm collimator angle 450 with beam spoiler at dmax depth. TPS: Treatment planning systems
Figure 7
Figure 7
Shows extended SSD (350 cm) In-line profile of the largest field size 40 cm × 40 cm collimator angle 450 without beam spoiler at 10 cm depth. TPS: Treatment planning systems
Figure 8
Figure 8
Shows an extended SSD (350 cm) in-line profile of the largest field size 40 cm × 40 cm collimator angle 450 with beam spoiler at dmax depth. TPS: Treatment planning systems
Figure 9
Figure 9
Shows an extended SSD (350cm) in-line profile of the largest field size 40 cm × 40 cm collimator angle 45° with beam spoiler at 10 cm depth
Figure 10
Figure 10
Integral luminescence intensity of the irradiated TLDs in both the SSD setups
Figure 11
Figure 11
The dose distribution in a water equivalent slab phantom (a), An in-homogeneity slab phantom (b) with SSD = 100 cm with a reference field size of 10 cm × 10 cm; water equivalent slab phantom (c) and an in-homogeneity slab phantom (d) with an SSD of 350 cm and the reference field size of 10 cm × 10 cm
Figure 12
Figure 12
The luminescence curves of the irradiated TLDs in both the SSD setups
See this image and copyright information in PMC

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