ESTRO meets Asia 2024 - Abstract Book

S298

Physics - Algorithms and applications for photon and electron planning

ESTRO meets Asia 2024

245

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Impact of Bone marrow-sparing intensity-modulated radiotherapy in patients of cervical carcinoma

Shraddha Srivastava 1 , Shally Batham 1 , Jasmeet Singh Tuteja 1 , Christopher Varghese 2 , Shyamprasad S 2

1 Radiation Oncology, King George's Medical University, Lucknow, India. 2 Radiotherapy, Cancer Hospital and Research Institute, Gwalior, India

Purpose/Objective:

To study the impact of bone-marrow-sparing intensity-modulated radiotherapy (IMRT) in cervical cancer patients and compare it with IMRT plans without bone-marrow-sparing constraints.

Material/Methods:

10 patients of cervical carcinoma with the International Federation of Gynecology and Obstetrics (FIGO) staging IIB-IIIB were retrospectively studied. The planning target volume (PTV) and the organs at risk (OAR) including small bowel, bladder, rectum, femoral heads, lumbosacral spine (LS), and pelvic bone marrow (BM) were delineated on patients that were already treated with IMRT. IMRT plans generated without bone marrow sparing (WBMS) in the Monaco treatment planning system (TPS) were compared with plans where bone-marrow sparing (BMS) dose volume constraints were given. The dose-volume constraints for the pelvic bone marrow (PBM) were Dmean <32 Gy and V10< 80% and for the lumbosacral spine (LSS) were Dmean< 32 Gy and V10<85%. The constraints for bladder and rectum were Dmax<50 Gy, V50<50%, for bowel were, V40< 30% and for femoral heads were V50%< 2%. Dosimetric parameters of PTV including Dmean, Dmax and Dmin and of OAR were compared between BMS- and WBMS- IMRT plans. Dmean, Dmax and Dmin for PTV in BMS plans were 50.44±0.17 Gy, 53.91±0.38 Gy, and 39.97±1.44 Gy respectively compared to 49.72±0.84 Gy, 53.33±0.74 Gy and 39.23±2.23 Gy in WBMS plans. Dmean and V10 for PBM were 30.63±1.11 Gy and 98.08±0.81% respectively in BMS plans while 33.91±0.97 Gy and 100.14±0.23% in WBMS plans. Dmean and V10 for LSS were found to be 33.25±1.51 Gy and 87.74±8.73% respectively in BMS plans while 38.63±1.27 Gy and 98.56±0.75% in WBMS plans. For Bladder V50 and Dmax were 25.94±5.80% and 53.08±0.31 Gy respectively in BMS plans compared to 22.89±6.28% and 54.35±1.24 Gy in WBMS plans. In rectum, V50 and Dmax were 29.65±0.35% and 52.62±0.29 Gy respectively in BMS plans while 22.54±7.70 % and 52.04±0.80 Gy in WBMS plans. V50 for femoral heads was 0.06±0.03% in BMS plans and 0.05±0.03% in WBMS plans. For small bowel, V40 was 29.75±6.28 % in BMS plans and 26.2±4.61 % in WBMS plans. Results:

Conclusion:

Implementing dose-volume constraints for LSS and PBM in IMRT planning resulted in bone marrow sparing without compromising the PTV dose or exceeding the OAR tolerance doses. Therefore, BMS-IMRT could potentially yield superior dosimetric outcomes compared to WBMS plans.

Keywords: Bone Marrow, Cervical Cancer, IMRT

References: