CNS treatment planningIntensity modulation with photons for benign intracranial tumours: A planning comparison of volumetric single arc, helical arc and fixed gantry techniques
Section snippets
Materials and methods
Twelve patients with small “benign” brain tumours were randomly selected from the database of treated patients for comparative planning as described in [4]: five meningiomas, five acoustic neurinomas and two pituitary adenomas. Anatomical data were acquired on computed tomography (CT) with adjacent slices 3 mm thick. The mean volume for PTV was 4.22 cm3, median 2.37 cm3, minimum 0.49 cm3and maximum 14.32 cm3. Volumes of organs at risk (OAR: brain stem, chiasm, ipsi-lateral optic nerve and eye) were
Results
In Fig. 1, isodose distributions on axial and sagittal views are presented for all the techniques for a neurinoma and a meningioma case to provide a qualitative overview. Two medium-low isodoses are shown (30% and 60%) to illustrate also the differences present in healthy tissue irradiation among the techniques.
Fig. 2 shows, for an example case, the variation of Dose Rate and of Gantry Speed as a function of the Gantry Angular position during rotation. It can be seen, as intuitively apparent,
Discussion
Tumours of the base of skull are particularly complex to treat because of their proximity to organs at risk like brain stem, eyes, optic chiasm and optic nerves. In addition, ‘benign’ types like meningiomas, neurinomas or adenomas, leading to a long life expectancy for affected patients, require additional care in preserving structures at risk. Advanced solutions based on sophisticated photon delivery methods are becoming widely available, and have significant potential to benefit large numbers
Conclusion
For the class of tumours investigated in this report, coplanar modulated arc solutions as RapidArc or Helical Tomotherapy and non-coplanar fixed beam IMRT showed similar degrees of target coverage and sparing of organs at risk. Concerning conformity and sparing of healthy brain tissue, some differences were found to be statistically significant. Planning for the newly developed RapidArc technique on linacs showed promising results for this class of very small, benign indications, but further
Disclosure
Dr. L. Cozzi acts as Scientific Advisor to Varian Medical Systems managing the European Varian Science Circles and as Head of Research and Technological Development to Oncology Institute of Southern Switzerland, Bellinzona.
Acknowledgements
This study was conducted in strict cooperation with many persons at Varian Medical systems involved in the development of this novel technology. Among them we are particularly in debt for support and assistance to Martin Sabel and Yves Archambault for planning and to Jiri Bocanek for delivery issues.
References (26)
- et al.
A comparison of dose distributions of proton and photon beams in stereotactic conformal radiotherapy of brain lesions
Int J Radiat Oncol Biol Phys
(2001) - et al.
TomoTherapy: implications on daily workload and scheduling patients
Radiother Oncol
(2008) - et al.
Radiotherapy of small intracranial tumours with different advanced techniques using photon and proton beams: a treatment planning study
Radiother Oncol
(2003) - et al.
A comparison of three stereotactical radiotherapy techniques; arc vs. noncoplanar fixed fields vs. intensity modulation
Int J Radiat Oncol Biol Phys
(1998) - et al.
Comparison of plan quality provided by intensity modulated arc therapy and helical tomotherapy
Int J Radiat Oncol Biol Phys
(2007) - et al.
Clinical implementation of intensity modulated arc therapy (IMAT) for rectal cancer
Int J Radiat Oncol Biol Phys
(2004) - et al.
Whole abdominal radiotherapy (WAPRT) using intensity modulated arc therapy (IMAT): first clinical experience
Int J Radiat Oncol Biol Phys
(2003) - et al.
Tolerance of normal tissue to therapeutic irradiation
Int J Radiat Oncol Biol Phys
(1991) - et al.
Tomotherapy and other innovative IMRT systems
Sem Rad Oncol
(2006) - et al.
Potential clinical efficacy of intensity modulated conformal therapy
Int J Radiat Oncol Biol Phys
(1998)
Comparison of radiosurgery treatment modalities based on complication and control probabilities
Int J Radiat Oncol Biol Phys
Tomotherapy planning of small brain tumours
Radiother Oncol
Clinical implementation of intensity-modulated arc therapy
Int J Radiat Oncol Biol Phys
Cited by (173)
First experimental demonstration of VMAT combined with MLC tracking for single and multi fraction lung SBRT on an MR-linac
2022, Radiotherapy and OncologyAn empirical method for splitting arcs in VMAT
2021, Physica MedicaCitation Excerpt :This method accurately shapes the radiation dose to the target while reducing the dose to the normal tissues surrounding the tumor. Several studies have shown that additional degrees of freedom offered by VMAT leads to improved plan quality and reduced treatment delivery time compared to conventional Intensity Modulated Radiation Therapy (IMRT) techniques [1–9]. The main advantage of VMAT is that it delivers the prescribed dose in significantly lesser time (in few minutes), which potentially leads to a reduction in patient motion induced errors [10–11].
Lower doses to hippocampi and other brain structures for skull-base meningiomas with intensity modulated proton therapy compared to photon therapy
2020, Radiotherapy and OncologyCitation Excerpt :With regard to the data analysis one might argue about the dose rescaling performed for the comparison, but in order to give relative meaning to any observed differences between the techniques we considered this a necessary step. In other studies published in literature, a similar approach was used [15,16,34,35]. Obviously there are inherent differences between treatment planning for photons and protons, as the IMRT and VMAT plans are generated using a CTV-PTV margin, while for IMPT a mini-max robust optimization was used.
A systematic review and meta-analysis of radiotherapy planning studies comparing multi leaf collimator designs
2018, Physics and Imaging in Radiation OncologySingle-Isocenter Multitarget Stereotactic Radiosurgery Is Safe and Effective in the Treatment of Multiple Brain Metastases
2020, Advances in Radiation Oncology