Hypofractionated stereotactic radiotherapy
see also Single-fraction stereotactic radiosurgery.
Fractionated Stereotactic Radiotherapy also refers to a method of cancer treatment with radiotherapy. When the total dose of radiation is divided into several, smaller doses over a period of several days, there are fewer toxic effects on healthy cells. This maximizes the effect of radiation on cancer and minimizes the negative side effects. Typical fractionation schemes divide the dose into 30 units delivered every weekday over 6 weeks, though current research is considering the benefits of accelerated fractionation (2 deliveries per day and/or deliveries on weekends as well). Hypofractionation is a treatment regimen that delivers higher doses of radiation in fewer visits. The logic behind this treatment is that applying greater amounts of radiation works to lower the effects of accelerated tumor growth that typically occurs during the later stages of radiotherapy.
Many tumors in the brain and in other parts of the body are not suitable for treatment by surgery.
Features that determine this include:
Site (including proximity to important brain structures such as the optic chiasm and the brain stem)
Involvement of the spinal cord
Previous treatment
Patient preference for non-surgical treatment
Types of brain tumours suitable for Fractionated Stereotactic Radiotherapy include: Benign:
Malignant:
Meningiomas
Gliomas
Fractionated Stereotactic Radiotherapy for Glioblastoma recurrence
Pituitary tumours
Medulloblastomas
see Fractionated stereotactic radiotherapy for vestibular schwannoma
Chordomas
Craniopharyngiomas
Haemangiomas
Stereotactic radiation treatment relies upon precisely locating the lesion in the brain with exact co-ordinates (as with latitude and longitude).
Fractionated Stereotactic Radiotherapy (FSRT) is delivered over a number of fractions for a specific number of days. The number of treatments is determined by the size and type of the tumour and proximity to adjacent tissues. FSRT can be delivered as 'multiple fixed beams' using the MMLC (Mini-Multi Leaf Collimator), or IMRT (Intensity Modulated Radiotherapy). This department was the first in the world to treat any patient with stereotactic IMRT. IMRT is used to treat tumours of irregular shape. This technique enables the specialist to shape the beam to better treat the tumour and minimise the dose to normal tissue. Consultation for FSRT with the Specialist
Not all patients are suitable for FSRT. The proximity of the tumour(s) to critical brain structures determines whether the radiotherapy should be given in small doses over a number of fractions each day, ranging from 5-30Gy, and for a number of days or weeks.
Scans are evaluated at the time of consultation with your doctor and discussion regarding the benefits and possible side effects of the treatment will also be discussed. Treatment sessions average from fifteen to twenty minutes daily with little to no acute side effects, however over the course of the treatment there may fatigue, alopecia (hair loss) and sometimes mouth discomfort associated with using the dental plate (this generally settles quickly after treatment is concluded).
At consultation a Stereotactic Radiotherapy Brochure will be given to you. If the decision is made to have treatment you will be contacted by the Planning Co-ordinator confirming the date and time of your planning session.
Planning Sessions
Planning sessions are usually organised 1-2 weeks prior to commencement of radiotherapy treatment and take approximately half a day. This includes:
Impression of your upper palate and the back of the head (occipital region)
Head frame fitting
Attachment of impression moulds to the base head ring.
CT scan
MRI
It is important that all dental work is avoided during the period of the head frame fitting, planning and during the course of treatment. Also, any changes of hair style may affect the accuracy and stability of the 'head frame set' during treatment.
The head frame fitting session is usually attended in the morning. Once the fitting is done there is a free 1-2 hour break (this allows time for the impression to set, to have lunch and familiarise yourself with the department and our resources available). When the impression is set you will have a CT scan with the head frame fitted in the afternoon. An MRI is also needed to complete your plan for your treatment and is usually arranged during your planning session.
Radiation Treatment
Treatment usually commences approximately one week after planning. When arriving the first day for treatment, please notify the radiation reception staff of your arrival and you will be escorted to the Treatment Area. When the radiotherapists are ready you will be called into the treatment room where the head frame is fitted daily prior to each treatment. At the conclusion of each treatment the following day's treatment time will be confirmed with you (this occasionally may change). Weekly Reviews
Review with your clinician is weekly either before or after treatment. This allows time to discuss any concerns you may have and informs the clinician how treatment is progressing.
In the final week of treatment at clinic review your clinician will organise a follow-up appointment 4-6 weeks post treatment. A follow-up scan may also be organised at this time.
Fractionated Stereotactic Radiotherapy for skull base meningioma
Fractionated Stereotactic Radiotherapy for skull base meningioma.
The current treatment for patients with relapsed malignant glioma (MG) remains unsatisfactory. Utilization of hypofractionated stereotactic radiotherapy (HFSRT) for recurrent malignant glioma has shown some encouraging results and may be a proper option.
Hu et al., performed a systematic review and meta-analysis of publications which investigated the use of HFSRT for recurrent MG. Relevant studies were obtained through searching PubMed, EMBASE, and Cochrane Library. Data about treatment regimens, median overall survival, radiation necrosis, as well as other major neurological complications were extracted. They performed a descriptive analysis of the median overall survival and meta-analysis of the reported rates of radiation necrosis and other major neurologic complications (MNC).
A total of 26 studies were included in our study, containing 861 patients. Median overall survival ranged from 8.6 to 18 months. A total of 19 studies were included to perform a meta-analysis of radiation necrosis rate and the pooled radiation necrosis rate was 5% (0-64%). The pooled rate of other major neurological complications was 3% (0-14%), calculated from 20 studies.
Based on the present evidence, it suggests that HFSRT is an efficacious and safe treatment approach to treat patients with recurrent MG. However, retrospective and observational nature of the studies included in our systematic review and meta-analysis restricted formation of more solid conclusions. Thus, well-designed prospective controlled trials are warranted to further define the therapeutic role of HFSRT for recurrent MG 1).