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Quality assurance of a conformal treatment technique

Abstract

For a parotid gland irradiation technique with a pair of oblique wedged photon beams the target coverage near the surface was investigated. The planning target volume extends to 5 millimetres under the skin; a minimum target dose of 95% is required when the dose at the centre is set to 100%. The treatment technique was simulated on a water phantom with a beam of 45 degree gantry angle, 55 degree wedge, 8 x 10 cm{sup 2} field size and the isocentre at 2 cm depth. Beam energies of 4, 6 and 8 MV were used. The dose distributions were measured in two orthogonal planes through the isocentre perpendicular to the water surface with p-type silicon diodes along lines through the isocentre every 45 degrees. Dose distributions were calculated in these planes with our 3-D planning system (U-Mplan, University of Michigan planning system), with model parameters are fitted to depth dose curves and profiles of open and wedged normally incident beams. The location of the 95% isodose was determined in five points near the surface. For 4, 6 and 8 MV the depths of the 95% isodose were 6.0, 10.3 and 11.0 mm, respectively. The depths of the 95% points of  More>>
Authors:
Kroes, A P.G.; Bruinvis, I A.D.; Lanson, J H; Uiterwaal, G J [1] 
  1. Nederlands Kanker Inst. `Antoni van Leeuwenhoekhuis`, Amsterdam (Netherlands)
Publication Date:
Dec 01, 1995
Product Type:
Conference
Report Number:
INIS-BE-0001; CONF-951246-
Reference Number:
SCA: 550603; PA: AIX-28:034220; EDB-97:069773; SN: 97001774988
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; ENDOCRINE GLANDS; CONFORMAL MAPPING; RADIOTHERAPY; QUALITY ASSURANCE; BEAM OPTICS; BIOMEDICAL RADIOGRAPHY; COLLIMATORS; DELAYED RADIATION EFFECTS; DOSIMETRY; IMAGE PROCESSING; IMAGE SCANNERS; IRRADIATION DEVICES; ISODOSE CURVES; NEOPLASMS; TOMOGRAPHY
OSTI ID:
466819
Research Organizations:
Ghent Rijksuniversiteit (Belgium). Kliniek voor Radiotherapie en Kerngeneeskunde
Country of Origin:
Belgium
Language:
English
Other Identifying Numbers:
Other: ON: DE97622340; TRN: BE9700019034220
Availability:
INIS; OSTI as DE97622340
Submitting Site:
BEN
Size:
pp. 9
Announcement Date:

Citation Formats

Kroes, A P.G., Bruinvis, I A.D., Lanson, J H, and Uiterwaal, G J. Quality assurance of a conformal treatment technique. Belgium: N. p., 1995. Web.
Kroes, A P.G., Bruinvis, I A.D., Lanson, J H, & Uiterwaal, G J. Quality assurance of a conformal treatment technique. Belgium.
Kroes, A P.G., Bruinvis, I A.D., Lanson, J H, and Uiterwaal, G J. 1995. "Quality assurance of a conformal treatment technique." Belgium.
@misc{etde_466819,
title = {Quality assurance of a conformal treatment technique}
author = {Kroes, A P.G., Bruinvis, I A.D., Lanson, J H, and Uiterwaal, G J}
abstractNote = {For a parotid gland irradiation technique with a pair of oblique wedged photon beams the target coverage near the surface was investigated. The planning target volume extends to 5 millimetres under the skin; a minimum target dose of 95% is required when the dose at the centre is set to 100%. The treatment technique was simulated on a water phantom with a beam of 45 degree gantry angle, 55 degree wedge, 8 x 10 cm{sup 2} field size and the isocentre at 2 cm depth. Beam energies of 4, 6 and 8 MV were used. The dose distributions were measured in two orthogonal planes through the isocentre perpendicular to the water surface with p-type silicon diodes along lines through the isocentre every 45 degrees. Dose distributions were calculated in these planes with our 3-D planning system (U-Mplan, University of Michigan planning system), with model parameters are fitted to depth dose curves and profiles of open and wedged normally incident beams. The location of the 95% isodose was determined in five points near the surface. For 4, 6 and 8 MV the depths of the 95% isodose were 6.0, 10.3 and 11.0 mm, respectively. The depths of the 95% points of single normally incident open fields were 6.0, 9.0 and 11.5 mm, respectively. The treatment planning system (TPS) calculated the 95% isodose for the parotid technique at 5.5, 7.3 and 11.5 mm depths, for 4, 6 and 8 MV, respectively. Thus for 6 MV the 95% was 3 mm deeper than calculated by the TPS; 2 mm were caused by the inaccuracy of the open field depth dose curve fit in the build-up region. The depth near the surface of the 95% isodose for this treatment technique can be estimated from single open field depth dose curves with acceptable accuracy. This result is not obvious because the effects of the wedge and oblique incidence on the dose distribution are also involved. The TPS performed well for the 4 and 8 MV beams, but for treatments with 6 MV target under dosage could have remained undetected. (Abstract Truncated)}
place = {Belgium}
year = {1995}
month = {Dec}
}