Radiation treatment planning with an integrated positron emission and computer tomography (PET/CT): a feasibility study

Int J Radiat Oncol Biol Phys. 2003 Nov 1;57(3):853-63. doi: 10.1016/s0360-3016(03)00346-8.


Purpose: To investigate the usefulness of hardware coregistered PET/CT images for target volume definition.

Methods and materials: Thirty-nine patients presenting with various solid tumors were investigated. CT and a FDG-PET were obtained in treatment position in an integrated PET/CT scanner, and coregistered images were used for treatment planning. First, volume delineation was performed on the CT data. In a second step, the corresponding PET data were used as an overlay to the CT data to define the target volume. Delineation was done independently by two investigators.

Results: Coregistered PET/CT showed good fusion accuracy. The GTV increased by 25% or more because of PET in 17% of cases with head-and-neck (2/12) and lung cancer (1/6), and in 33% (7/21) in cancer of the pelvis. The GTV was reduced > or =25% in 33% of patients with head-and-neck cancer (4/12), in 67% with lung cancer (4/6), and 19% with cancer of the pelvis (4/21). Overall, in 56% (22/39) of cases, GTV delineation was changed significantly if information from metabolic imaging was used in the planning process. The modification of the GTV translated into altered PTV changes exceeding >20% in 46% (18/39) of cases. With PET, volume delineation variability between two independent oncologists decreased from a mean volume difference of 25.7 cm(3) to 9.2 cm(3) associated with a reduction of the standard deviation from 38.3 cm(3) to 13.3 cm(3) (p = 0.02). In 16% of cases, PET/CT revealed distant metastasies, changing the treatment strategy from curative to palliative.

Conclusion: Integrated PET/CT for treatment planning for three-dimensional conformal radiation therapy improves the standardization of volume delineation compared with that of CT alone. PET/CT has the potential for reducing the risk for geographic misses, to minimize the dose of ionizing radiation applied to non-target organs, and to change the current practice to three-dimensional conformal radiation therapy planning by taking into account the metabolic and biologic features of cancer. The impact on treatment outcome remains to be demonstrated.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Feasibility Studies
  • Female
  • Genital Neoplasms, Female / diagnostic imaging
  • Genital Neoplasms, Female / radiotherapy
  • Head and Neck Neoplasms / diagnostic imaging
  • Head and Neck Neoplasms / radiotherapy
  • Humans
  • Lung Neoplasms / diagnostic imaging
  • Lung Neoplasms / radiotherapy
  • Male
  • Middle Aged
  • Neoplasms / diagnostic imaging*
  • Neoplasms / radiotherapy
  • Observer Variation
  • Radiotherapy Planning, Computer-Assisted / methods*
  • Rectal Neoplasms / diagnostic imaging
  • Rectal Neoplasms / radiotherapy
  • Tomography, Emission-Computed / methods*
  • Tomography, X-Ray Computed / methods*