Radiosurgery from the brain to the spine: 20 years experience

Clinical Evaluation of the Accuracy of an Invasive Frame Designed for Stereotactic Intracranial Radiosurgery Treatment with Helical Tomotherapy

Aims and background

The study focused on the evaluation of the accuracy of intracranial stereotactic radiosurgery treatments delivered with helical tomotherapy by means of the InterFix™ Radiosurgery kit.

Methods and study design

Twenty-two patients received stereotactic radiosurgery treatments with single fraction dose ranging from 13 to 20 Gy depending on diagnosis. Megavoltage computed tomography scans performed prior the treatments were analyzed in order to determine the position accuracy. For 8 selected cases, they were also performed at the end of the treatment to evaluate the intra-fraction motion.

Results

Mean setup errors and standard deviations were −1.6 ± 2.2 mm, −0.2 ± 1.2 mm, 0.4 ± 1.3 mm, 0.2 ± 0.5° for the lateral (IEC-x), longitudinal (IEC-y), vertical (IEC-z) directions and rotational variation (roll), respectively. Setup error was found to be greater than 3 mm-PTV expansion in 36% of the cases. Mean intra-fraction motion was 0.5 ± 0.7 mm, −0.3 ± 0.4 mm, 0.1 ± 0.5 mm and 0.1 ± 0.2° for the IEC-x, IEC-y, IEC-z and roll, respectively.

Conclusions

Observed intra-fraction movements of less than 1 mm suggested the use of the tested fixation device for stereotactic radiosurgery treatment on helical tomotherapy providing that the image-guidance procedure is always performed prior to treatment.

Optimal technique of linear accelerator-based stereotactic radiosurgery for tumors adjacent to brainstem

Stereotactic radiosurgery (SRS) is a well-established technique that is replacing whole-brain irradiation in the treatment of intracranial lesions, which leads to better preservation of brain functions, and therefore a better quality of life for the patient. There are several available forms of linear accelerator (LINAC)-based SRS, and the goal of the present study is to identify which of these techniques is best (as evaluated by dosimetric outcomes statistically) when the target is located adjacent to brainstem. We collected the records of 17 patients with lesions close to the brainstem who had previously been treated with single-fraction radiosurgery. In all, 5 different lesion catalogs were collected, and the patients were divided into 2 distance groups-1 consisting of 7 patients with a target-to-brainstem distance of less than 0.5cm, and the other of 10 patients with a target-to-brainstem distance of ≥ 0.5 and < 1cm. Comparison was then made among the following 3 types of LINAC-based radiosurgery: dynamic conformal arcs (DCA), intensity-modulated radiosurgery (IMRS), and volumetric modulated arc radiotherapy (VMAT). All techniques included multiple noncoplanar beams or arcs with or without intensity-modulated delivery. The volume of gross tumor volume (GTV) ranged from 0.2cm(3) to 21.9cm(3). Regarding the dose homogeneity index (HIICRU) and conformity index (CIICRU) were without significant difference between techniques statistically. However, the average CIICRU = 1.09 ± 0.56 achieved by VMAT was the best of the 3 techniques. Moreover, notable improvement in gradient index (GI) was observed when VMAT was used (0.74 ± 0.13), and this result was significantly better than those achieved by the 2 other techniques (p < 0.05). For V4Gy of brainstem, both VMAT (2.5%) and IMRS (2.7%) were significantly lower than DCA (4.9%), both at the p < 0.05 level. Regarding V2Gy of normal brain, VMAT plans had attained 6.4 ± 5%; this was significantly better (p < 0.05) than either DCA or IMRS plans, at 9.2 ± 7% and 8.2 ± 6%, respectively. Owing to the multiple arc or beam planning designs of IMRS and VMAT, both of these techniques required higher MU delivery than DCA, with the averages being twice as high (p < 0.05). If linear accelerator is only 1 modality can to establish for SRS treatment. Based on statistical evidence retrospectively, we recommend VMAT as the optimal technique for delivering treatment to tumors adjacent to brainstem.

Glossopharyngeal neuralgia

In this review, the clinical characteristics, differentiating features from other forms of neuralgia, etiology and treatment options of glossopharyngeal neuralgia will be discussed.

Analgesic efficacy and safety of medical therapy alone vs combined medical therapy and extraoral glossopharyngeal nerve block in glossopharyngeal neuralgia

OBJECTIVE

The aim of this study is to compare medical therapy alone and medical therapy with add on extraoral glossopharyngeal nerve block in terms of analgesic efficacy and hemodynamic safety in patients with glossopharyngeal neuralgia (GPN). As GPN is a rare disease, our secondary targets were to review the demographic profile of the disease, clinical profile, and any associations with the disease.

DESIGN

This was a randomized, prospective, active-controlled, parallel group study conducted from 2007 to 2009 to determine the safety and efficacy of extraoral glossopharyngeal nerve block in GPN and compare it with pharmacological intervention. After institutional ethics committee approval and patient's consent, GPN patients were randomly allocated into two groups. Group A (N = 15) received standard medical therapy (gabapentin 300 mg, tramadol 50 mg TDS, methylcobalamin 500 μgm PO) and group B (N = 15) patients received extraoral glossopharyngeal nerve block together with standard medical therapy. Patients were analyzed for analgesic outcome using numerical pain scale (NPS) and brief pain inventory (BPI) assessing both analgesic effect and degree of interference in quality of life (QOL) during 3-month follow-up. They were also evaluated for any significant hemodynamic alterations.

RESULTS

Over the follow-up of 90 days, the mean NPS in group A decreased from 6 ± 2 to 3 ± 2 and in group B from 5 ± 1 to 2 ± 2. From the mean NPS scores, it can be interpreted that both the modalities were effective clinically in treating GPN. However, NPS scores were statistically similar by the end of 90 days. Improvement from baseline in BPI measurement of QOL (mood, interpersonal relationship, and emotion) was earlier in group B (1, 2, and 1 months, respectively) compared with group A (2, 3, and 2 months, respectively). However, there were no significant hemodynamic adverse outcomes after administration of the block.

CONCLUSION

This study found that patients in both the groups had significantly lower pain intensities, improved pain relief, and reduced pain interference with QOL, which was especially evident on fourth visit (2 months) after the initiation of treatment regimen. Both were safe and well tolerated. The study advocates rational polypharmacy approach (oral and block) in difficult to treat painful conditions. Further controlled trials are warranted to further define the impact of such a combination therapy.

Stereotactic radiosurgery for movement disorders

Initially designed for the treatment of functional brain targets, stereotactic radiosurgery (SRS) has achieved an important role in the management of a wide range of neurosurgical pathologies. The interest in the application of the technique for the treatment of pain, and psychiatric and movement disorders has returned in the beginning of the 1990s, stimulated by the advances in neuroimaging, computerized dosimetry, treatment planning software systems, and the outstanding results of radiosurgery in other brain diseases. Since SRS is a neuroimaging-guided procedure, without the possibility of neurophysiological confirmation of the target, deep brain stimulation (DBS) and radiofrequency procedures are considered the best treatment options for movement-related disorders. Therefore, SRS is an option for patients who are not suitable for an open neurosurgical procedure. SRS thalamotomy provided results in tremor control, comparable to radiofrequency and DBS. The occurrence of unpredictable larger lesions than expected with permanent neurological deficits is a limitation of the procedure. Improvements in SRS technique with dose reduction, use of a single isocenter, and smaller collimators were made to reduce the incidence of this serious complication. Pallidotomies performed with radiosurgery did not achieve the same good results. Even though the development of DBS has supplanted lesioning as the first alternative in movement disorder surgery; SRS might still be the only treatment option for selected patients.

Single fraction radiosurgery using Rapid Arc for treatment of intracranial targets

Background

Stereotactic-Radio-Surgery (SRS) using Conformal-Arc-Therapy (CAT) is a well established irradiation technique for treatment of intracranial targets. Although small safety margins are required because of very high accuracy of patient positioning and exact online localisation, there are still disadvantages like long treatment time, high number of monitor units (MU) and covering of noncircular targets. This planning study analysed whether Rapid Arc (RA) with stereotactic localisation for single-fraction SRS can solve these problems.

Methods

Ten consecutive patients were treated with Linac-based SRS. Eight patients had one or more brain metastases. The other patients presented a symptomatic vestibularis schwannoma and an atypic meningeoma. For all patients, two plans (CAT/RA) were calculated and analysed.

Results

Conformity was higher for RA with additional larger low-dose areas. Furthermore, RA reduced the number of MU and the treatment time for all patients. Dose to organs at risk were equal or slightly higher using RA in comparison to CAT.

Conclusions

RA provides a new alternative for single-fraction SRS irradiation combining advantages of short treatment time with lower number of MU and better conformity in addition to accuracy of stereotactic localisation in selected cases with uncomplicated clinical realization.