ESTRO 2024 - Abstract Book

S3587

Physics - Dose prediction, optimisation and applications of photon and electron planning

ESTRO 2024

Results:

For the LN target volume, the V47.88Gy, V50.4Gy and mean dose parameters were decreased significantly using lower energies, with the average values as follows: 98.9%, 82.6 %, and 48.44 Gy for TB-10MV, 98.8 %, 81.1 %, and 48.36 Gy for TB-6FFF, 98.2 %, 79.6 %, and 48.01 Gy for H-6FFF, respectively. The differences of dose coverage parameters for the PVS target were negligible. For the PROS target, the decreases of the V66.5 Gy, V70Gy and mean dose parameters were significant only for H-6FFF cases. The dosimetric parameters of the rectum were significantly more favourable in TB-6FFF and H-6FFF plans. The dosimetric parameters of bladder did not show significant differences. The mean dose values of the BODY were 10.9 Gy, 11.41 Gy and 11.59 Gy for TB-10MV, TB 6FFF and H-6FFF plans, respectively. The V10Gy, V20Gy and V30Gy parameters of BODY have the same trend with significant differences, so the differences in low dose exposure volumes result the increase of mean dose parameters. The mean dose values for bowel bag and anus were increased, but decreased significantly for the penile bulb in TB-6FFF and H-6FFF plans. The average numbers of monitor units were 796 MU, 1088 MU and 1114 MU for TB-10MV, TB-6FFF and H-6FFF plans, respectively, so the lower energy plans require about 40 % more MUs.

Conclusion:

Decreasing the energy of the beam generally decreases the quality of the treatment plans, but the parameters remain in the clinically acceptable range. For most cases, the differences can reach the statistically significant level. The change of the treatment machine (and the type of MLC-s), but using the same energy results negligible differences. Our prostate KBTP model can be safely used for different energies and machines.

Keywords: Knowledge-based treatment planning, prostate

References:

[1] Ayuthaya IIN, Suriyapee S, Sanghangthum T. Validation of RapidPlan Knowledge-Based Model for Volumetric Modulated Arc Therapy in Prostate Cancer. J Med Phys. 2022 Jul-Sep;47(3):250-255. doi: 10.4103/jmp.jmp_138_21. Epub 2022 Nov 8. PMID: 36684695; PMCID: PMC9847006. [2] Jorgo K, Polgar C, Major T, Stelczer G, Herein A, Pocza T, Gesztesi L, Agoston P. Acute and Late Toxicity after Moderate Hypofractionation with Simultaneous Integrated Boost (SIB) Radiation Therapy for Prostate Cancer. A Single Institution, Prospective Study. Pathol Oncol Res. 2020 Apr;26(2):905-912. doi: 10.1007/s12253-019-00623 2. Epub 2019 Mar 19. PMID: 30888646; PMCID: PMC7242260.

1634

Digital Poster

Discrepancies in the absorbed dose on esophageal treatments as a result of diaphragmatic movement.

Paz Garcia-Acilu Laa 1 , Juan Garcia Ruiz-Zorrilla 1 , Ovidio Hernando 2 , Xin Chen 2 , Jaime Martí 3 , Alejandro Prado 3 , Daniel Zucca 3 , Pedro Fernandez Letón 3,1 , Carmen Rubio 3,1