Radiosurgery is a non-invasive option in early lung cancer. High
dose precise radiosurgery has immense potential. Early data from phase II
studies have shown excellent loco-regional control and survival function.
CyberKnife Radiosurgery in lung cancer has
following advantages:
1.
Cyberknife has the unique technology of ‘see and shoot’. In
this technology before each treatment field matching of the target and
‘intra-fraction motion correction’ is done, hence minimal normal lung comes
in the radiation field.
2.
Cyberknife has sub-millimeter treatment accuracy. Margin
(planning target volume) required (where normal lung comes) is minimal around
the target. High dose region volume is minimal with Cyberknife and lung
toxicity is expected to be lower compared with conventional treatment.
3.
Cyberknife has the multiple isocentric technique with
non-coplanar field arrangement, hence have unmatched conformity index
(uniform dose is delivered). Cyberknife use ‘pencil beam’ with multiple small
beamlets delivered from various angles (maximum 1200 different position)
hence ‘penumbra’ margin is less.
4.
As dosimetry is favorable and total dose delivered with
Cyberknife is not higher compared with conventional fraction (usual dose
delivered with Cyberknife 60 Gy/3 fr/ 1 week) there is no expected increase
in lung toxicity with Cyberknife. Phase II prospective studies with
Cyberknife have not shown any increase in radiation induced pneumonitis.
5.
‘STAR trial’ is a multicentric randomized study initiated by
MD Anderson Cancer Centre may provide answer to impact of Cyberknife on lung
toxicity. There are other few ongoing clinical studies with hypofractionated
radiation therapy on lung cancer that will provide useful information in near
future
For more information of successful treatments using cyberknife you may please blog your comments or write to lakshmipriya_b@apollohospitals.com
Radiosurgery in brain tumours
|
Short course radiation
therapy is the one of the most talked about subject in recent years and
also a fascinating research zone. Hypofractionated radiation therapy is an
old concept, but only in recent years with tremendous improvement in
radiation therapy delivery technologies there is a significant visible
surge in it’s applicability in clinical practice. Modern radiation therapy
technology is capable of delivering high dose to the target while sparing
majority of the adjacent critical structures. Hence, it is possible to
deliver short course of treatment regimen with higher dose per fraction
without increasing in toxicity. In brain tumours, radiosurgery with
gamma-knife is considered standard of care in many of the clinical
indications such as small meningiomas, acaustic schwannomas, residual low
grade gliomas, AVMs and solitary/ oligo brain metastasis. Gamma-knife
radiosurgery is in clinical practice for more than five decades.
There are several prospective and randomized studies (level I evidence)
with long-term follow up data supporting the use of radiosurgery in these
clinical indications. Other indications of radiosurgery are pituitary
tumour, craniopharyngiomas, glomus tumours, chordomas and others. Robotic
radiosurgery (CyberKnife®) is precision radiosurgery delivery system and an
extension of gamma-knife system. CyberKnife uses the principle of
gamma-knife, but with linear accelerator source instead of multiple cobalt
sources. CyberKnife is capable to treating all tumours indicated for
gamma-knife with similar accuracy.
This modern tool has some additional advantages from gamma-knife, such as
1) CyberKnife can use fractionated treatment, hence relatively larger
tumours can be treated, 2) require only thermoplastic mask, no need for
invasive frame, 3) has inverse planning system, can spare critical
structure, 4) there is a ‘intra-fraction’ correction technology with
imaging, 5) there is no need to change the source, hence may be more cost
effective and 6) can be used to treat extra-cranial tumours also.
CyberKnife has a linear accelerator attached with a robot and is capable of
treatment from various coplanar and non-coplanar field arrangements.
CyberKnife has sub-millimeter accuracy and unmatched dose distribution.
The advanced technology behind CyberKnife uses image guidance technology
and computer-controlled robotics to deliver and extremely precise dose of
radiation to targets, avoiding the surrounding healthy tissue, and
adjusting for patient and tumor movement during treatment. In conclusion, CyberKnife
is an extension of gammaknife radiosurgery delivery system. This machine
has immense promise to treat with short course regimens with high dose and
improve local control without increasing toxicities.
|
|
