Total body irradiation with volumetric modulated arc therapy: Dosimetric data and first clinical experience

Autor: Ernst Putz, Josef Hammer, Alexandra Böhm, Roswitha Huppert, Andreas L. Petzer, Gregor Aschauer, Alexander Altenburger, Hans Geinitz, Hedwig Kasparu, C. Track, Karin Wiesauer, Karin Moser, Rainer Gruber, Ansgar Weltermann, Erwin Winkler, Andreas Springer
Rok vydání: 2015
Předmět:
Adult
Organs at Risk
Lung Neoplasms
Time Factors
Quality Assurance
Health Care
medicine.medical_treatment
Total body irradiation (TBI)
Lymphoma
T-Cell
Dose homogenising
Patient Positioning
030218 nuclear medicine & medical imaging
03 medical and health sciences
Young Adult
Organs at risk (OAR)
0302 clinical medicine
Planned Dose
Medicine
Humans
Total marrow irradiation (TMI)
Leukaemia
Radiology
Nuclear Medicine and imaging
Radiation treatment planning
Radiometry
Dose sparing
Contouring
Dosimeter
Leukemia
business.industry
Radiotherapy Planning
Computer-Assisted
Methodology
Radiotherapy Dosage
Total body irradiation
Middle Aged
Volumetric modulated arc therapy
Radiation therapy
Volumetric modulated arc therapy (VMAT)
Oncology
Radiology Nuclear Medicine and imaging
030220 oncology & carcinogenesis
Radiotherapy
Intensity-Modulated
business
Nuclear medicine
Tomography
X-Ray Computed
Quality assurance
Software
Whole-Body Irradiation
Stem Cell Transplantation
Zdroj: Radiation Oncology (London, England)
ISSN: 1748-717X
Popis: Background To implement total body irradiation (TBI) using volumetric modulated arc therapy (VMAT). We applied the Varian RapidArc™ software to calculate and optimize the dose distribution. Emphasis was placed on applying a homogenous dose to the PTV and on reducing the dose to the lungs. Methods From July 2013 to July 2014 seven patients with leukaemia were planned and treated with a VMAT-based TBI-technique with photon energy of 6 MV. The overall planning target volume (PTV), comprising the whole body, had to be split into 8 segments with a subsequent multi-isocentric planning. In a first step a dose optimization of each single segment was performed. In a second step all these elements were calculated in one overall dose-plan, considering particular constraints and weighting factors, to achieve the final total body dose distribution. The quality assurance comprised the verification of the irradiation plans via ArcCheck™ (Sun Nuclear), followed by in vivo dosimetry via dosimeters (MOSFETs) on the patient. Results The time requirements for treatment planning were high: contouring took 5–6 h, optimization and dose calculation 25–30 h and quality assurance 6–8 h. The couch-time per fraction was 2 h on day one, decreasing to around 1.5 h for the following fractions, including patient information, time for arc positioning, patient positioning verification, mounting of the MOSFETs and irradiation. The mean lung dose was decreased to at least 80 % of the planned total body dose and in the central parts to 50 %. In two cases we additionally pursued a dose reduction of 30 to 50 % in a pre-irradiated brain and in renal insufficiency. All high dose areas were outside the lungs and other OARs. The planned dose was in line with the measured dose via MOSFETs: in the axilla the mean difference between calculated and measured dose was 3.6 % (range 1.1–6.8 %), and for the wrist/hip-inguinal region it was 4.3 % (range 1.1–8.1 %). Conclusion TBI with VMAT provides the benefit of satisfactory dose distribution within the PTV, while selectively reducing the dose to the lungs and, if necessary, in other organs. Planning time, however, is extensive.
Databáze: OpenAIRE
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