TY - JOUR
T1 - Treatment Planning of Bulky Tumors Using Pencil Beam Scanning Proton GRID Therapy
AU - Halthore, Aditya
AU - Fellows, Zachary
AU - Tran, Anh
AU - Deville, Curtiland
AU - Wright, Jean L.
AU - Meyer, Jeffrey
AU - Li, Heng
AU - Sheikh, Khadija
N1 - Publisher Copyright:
Copyright © 2023 The Author(s)
PY - 2023
Y1 - 2023
N2 - Purpose: To compare spatially fractionated radiation therapy (GRID) treatment planning techniques using proton pencil-beam-scanning (PBS) and photon therapy. Materials and Methods: PBS and volumetric modulated arc therapy (VMAT) GRID plans were retrospectively generated for 5 patients with bulky tumors. GRID targets were arranged along the long axis of the gross tumor, spaced 2 and 3 cm apart, and treated with a prescription of 18 Gy. PBS plans used 2- to 3-beam multiple-field optimization with robustness evaluation. Dosimetric parameters including peak-to-edge ratio (PEDR), ratio of dose to 90% of the valley to dose to 10% of the peak VPDR(D90/D10), and volume of normal tissue receiving at least 5 Gy (V5) and 10 Gy (V10) were calculated. The peak-to-valley dose ratio (PVDR), VPDR(D90/D10), and organ-at-risk doses were prospectively assessed in 2 patients undergoing PBS-GRID with pretreatment quality assurance computed tomography (QACT) scans. Results: PBS and VMAT GRID plans were generated for 5 patients with bulky tumors. Gross tumor volume values ranged from 826 to 1468 cm3. Peak-to-edge ratio for PBS was higher than for VMAT for both spacing scenarios (2-cm spacing, P = .02; 3-cm spacing, P = .01). VPDR(D90/D10) for PBS was higher than for VMAT (2-cm spacing, P = .004; 3-cm spacing, P = .002). Normal tissue V5 was lower for PBS than for VMAT (2-cm spacing, P = .03; 3-cm spacing, P = .02). Normal tissue mean dose was lower with PBS than with VMAT (2-cm spacing, P = .03; 3-cm spacing, P = .02). Two patients treated using PBS GRID and assessed with pretreatment QACT scans demonstrated robust PVDR, VPDR(D90/D10), and organs-at-risk doses. Conclusions: The PEDR was significantly higher for PBS than VMAT plans, indicating lower target edge dose. Normal tissue mean dose was significantly lower with PBS than VMAT. PBS GRID may result in lower normal tissue dose compared with VMAT plans, allowing for further dose escalation in patients with bulky disease.
AB - Purpose: To compare spatially fractionated radiation therapy (GRID) treatment planning techniques using proton pencil-beam-scanning (PBS) and photon therapy. Materials and Methods: PBS and volumetric modulated arc therapy (VMAT) GRID plans were retrospectively generated for 5 patients with bulky tumors. GRID targets were arranged along the long axis of the gross tumor, spaced 2 and 3 cm apart, and treated with a prescription of 18 Gy. PBS plans used 2- to 3-beam multiple-field optimization with robustness evaluation. Dosimetric parameters including peak-to-edge ratio (PEDR), ratio of dose to 90% of the valley to dose to 10% of the peak VPDR(D90/D10), and volume of normal tissue receiving at least 5 Gy (V5) and 10 Gy (V10) were calculated. The peak-to-valley dose ratio (PVDR), VPDR(D90/D10), and organ-at-risk doses were prospectively assessed in 2 patients undergoing PBS-GRID with pretreatment quality assurance computed tomography (QACT) scans. Results: PBS and VMAT GRID plans were generated for 5 patients with bulky tumors. Gross tumor volume values ranged from 826 to 1468 cm3. Peak-to-edge ratio for PBS was higher than for VMAT for both spacing scenarios (2-cm spacing, P = .02; 3-cm spacing, P = .01). VPDR(D90/D10) for PBS was higher than for VMAT (2-cm spacing, P = .004; 3-cm spacing, P = .002). Normal tissue V5 was lower for PBS than for VMAT (2-cm spacing, P = .03; 3-cm spacing, P = .02). Normal tissue mean dose was lower with PBS than with VMAT (2-cm spacing, P = .03; 3-cm spacing, P = .02). Two patients treated using PBS GRID and assessed with pretreatment QACT scans demonstrated robust PVDR, VPDR(D90/D10), and organs-at-risk doses. Conclusions: The PEDR was significantly higher for PBS than VMAT plans, indicating lower target edge dose. Normal tissue mean dose was significantly lower with PBS than VMAT. PBS GRID may result in lower normal tissue dose compared with VMAT plans, allowing for further dose escalation in patients with bulky disease.
KW - GRID
KW - bulky tumors
KW - proton
KW - spatial fractionation
UR - http://www.scopus.com/inward/record.url?scp=85175158700&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85175158700&partnerID=8YFLogxK
U2 - 10.14338/IJPT-22-00028
DO - 10.14338/IJPT-22-00028
M3 - Article
C2 - 36721485
AN - SCOPUS:85175158700
SN - 2331-5180
VL - 9
SP - 40
EP - 49
JO - International Journal of Particle Therapy
JF - International Journal of Particle Therapy
IS - 3
ER -