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Planning and delivering high doses to targets surrounding the spinal cord at the lower neck and upper mediastinal levels: static beam-segmentation technique executed by a multileaf collimator

Abstract

The possibility to plan and deliver beam intensity modulated radiotherapy using a general purpose 3D-planning system (Sherouse`s GRATISTM) and a linear accelerator equipped with a standard multileaf collimator (MLC) was investigated in view of limiting the dose at the spinal cord below tolerance. During the planning process, dose homogenization at the target is obtained by the calculation of the weights, given to beam segments of a specific predetermined geometry. This specific geometry maximizes the area of each segment and thus reduces the number of segments. With a virtual patient in supine position, a first planning using a single isocenter, with gantry positions of -60, -30, 0, 30 and 60 degrees was performed. Medial edges of all segments were located tangential to the spinal cord. The resulting dose distribution allowed to encompass the target by an isodose surface of 66-70 Gy without exceeding spinal cord tolerance but required 42 segments distributed over 5 gantry angles. Therefore, dose-volume histogram analysis were performed for those cases where: (1) for some gantry positions, all beam segments could be omitted; (2) at the remaining gantry angles, segments could be omitted; (3) at least 2 segments could be traded off against 1 additional gantry angle. This  More>>
Authors:
Schelfhout, J; Derycke, S; Fortan, L; Van Duyse, B; Colle, C; De Wagter, C; De Neve, W [1] 
  1. Ghent Rijksuniversiteit (Belgium). Kliniek voor Radiotherapie en Kerngeneeskunde
Publication Date:
Dec 01, 1995
Product Type:
Conference
Report Number:
INIS-BE-0001; CONF-951246-
Reference Number:
SCA: 550603; PA: AIX-28:034212; EDB-97:069776; SN: 97001774980
Resource Relation:
Conference: 11. annual symposium of the Belgian Association of Hospital Physicists: conformal radiotherapy - physics, treatment planning and verification, Ghent (Belgium), 8-9 Dec 1995; Other Information: PBD: Dec 1995; Related Information: Is Part Of Conformal Radiotherapy: Physics, Treatment Planning and Verification. Proceedings book; De Wagter, C. [ed.]; PB: 273 p.
Subject:
55 BIOLOGY AND MEDICINE, BASIC STUDIES; HEAD; NEOPLASMS; NECK; RADIOTHERAPY; CONFORMAL MAPPING; SPINAL CORD; BEAM OPTICS; BIOMEDICAL RADIOGRAPHY; COLLIMATORS; DELAYED RADIATION EFFECTS; DOSIMETRY; IMAGE PROCESSING; IMAGE SCANNERS; ISODOSE CURVES; QUALITY ASSURANCE; TOMOGRAPHY
OSTI ID:
464307
Research Organizations:
Ghent Rijksuniversiteit (Belgium). Kliniek voor Radiotherapie en Kerngeneeskunde
Country of Origin:
Belgium
Language:
English
Other Identifying Numbers:
Other: ON: DE97622340; TRN: BE9700011034212
Availability:
INIS; OSTI as DE97622340
Submitting Site:
BEN
Size:
pp. 83-86
Announcement Date:

Citation Formats

Schelfhout, J, Derycke, S, Fortan, L, Van Duyse, B, Colle, C, De Wagter, C, and De Neve, W. Planning and delivering high doses to targets surrounding the spinal cord at the lower neck and upper mediastinal levels: static beam-segmentation technique executed by a multileaf collimator. Belgium: N. p., 1995. Web.
Schelfhout, J, Derycke, S, Fortan, L, Van Duyse, B, Colle, C, De Wagter, C, & De Neve, W. Planning and delivering high doses to targets surrounding the spinal cord at the lower neck and upper mediastinal levels: static beam-segmentation technique executed by a multileaf collimator. Belgium.
Schelfhout, J, Derycke, S, Fortan, L, Van Duyse, B, Colle, C, De Wagter, C, and De Neve, W. 1995. "Planning and delivering high doses to targets surrounding the spinal cord at the lower neck and upper mediastinal levels: static beam-segmentation technique executed by a multileaf collimator." Belgium.
@misc{etde_464307,
title = {Planning and delivering high doses to targets surrounding the spinal cord at the lower neck and upper mediastinal levels: static beam-segmentation technique executed by a multileaf collimator}
author = {Schelfhout, J, Derycke, S, Fortan, L, Van Duyse, B, Colle, C, De Wagter, C, and De Neve, W}
abstractNote = {The possibility to plan and deliver beam intensity modulated radiotherapy using a general purpose 3D-planning system (Sherouse`s GRATISTM) and a linear accelerator equipped with a standard multileaf collimator (MLC) was investigated in view of limiting the dose at the spinal cord below tolerance. During the planning process, dose homogenization at the target is obtained by the calculation of the weights, given to beam segments of a specific predetermined geometry. This specific geometry maximizes the area of each segment and thus reduces the number of segments. With a virtual patient in supine position, a first planning using a single isocenter, with gantry positions of -60, -30, 0, 30 and 60 degrees was performed. Medial edges of all segments were located tangential to the spinal cord. The resulting dose distribution allowed to encompass the target by an isodose surface of 66-70 Gy without exceeding spinal cord tolerance but required 42 segments distributed over 5 gantry angles. Therefore, dose-volume histogram analysis were performed for those cases where: (1) for some gantry positions, all beam segments could be omitted; (2) at the remaining gantry angles, segments could be omitted; (3) at least 2 segments could be traded off against 1 additional gantry angle. This procedure resulted in a final plan containing 22 segments spread over 8 gantry angles. Preliminary dosimetric results on a RANDO phantom support the robustness of the method. The first clinical applications have been planned. Although up to 99 beam segments can be programmed on the Philips SL25 linear accelerator, it remained impossible to use these segments synchronized with the MLC. From a clinical viewpoint, the proposed treatment for irradiating lower neck and upper mediastinal targets could be used as a standard against which other solutions might be tested.}
place = {Belgium}
year = {1995}
month = {Dec}
}