Inverse-planned modulated-arc total-body irradiation

Neil Kirby, Mareike Held, Olivier Morin, Shannon Fogh, Jean Pouliot

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

Purpose: To develop a simple and robust method for inverse-planned total-body irradiation (TBI) that is more comfortable and has better dose homogeneity than the conventional forward-planned techniques and that can be delivered in a standard-sized treatment vault. Methods: Modulated-arc TBI (MATBI) utilizes an arc of static open-field beams to irradiate patients as they lay on a stationary couch beneath the gantry, with cerrobend blocks suspended over organs at risk to provide shielding. Prior to treatment, full-body computed tomography (CT) images are acquired of each patient and imported into the PINNACLE3 planning system, which modulates the monitor units for the open-field beams to optimize the body dose uniformity. The volume of the body within 10 of the prescription dose, V(±10), is used as a metric to evaluate the dose uniformity. For comparison to MATBI, the dose distribution of a conventional forward-planned treatment is also calculated. Quality assurance measurements are acquired before treatment by delivering the plans to a phantom and during treatment with an ionization chamber inside a buildup block, placed between the patient's ankles. Results: For MATBI, the achieved values of V(±10) were 75.8%, 90.2%, 84.6%, and 79.8% compared to 60.3%, 77.4%, 65.6%, and 68.5% for the conventional TBI technique, respectively. The pretreatment ion chamber measurements in the phantom had an average error of 1.2%. Those acquired during treatment had larger errors, with most points being within 3% of predictions. Conclusions: MATBI provides better dose uniformity and comfort than the conventional forward-planned TBI techniques. In addition, the technique can be implemented on most linacs, in standard-sized vaults, without the use of a translating couch.

Original languageEnglish (US)
Pages (from-to)2761-2764
Number of pages4
JournalMedical physics
Volume39
Issue number5
DOIs
StatePublished - May 2012

Keywords

  • gantry motion
  • hematopoietic stem cell transplant
  • inverse planning
  • patient comfort
  • total-body irradiation

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging

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