Vaneerat Ratanatharathorn

Relative roles of microsurgery and stereotactic radiosurgery for the treatment of patients with cranial meningiomas: a single-surgeon 4-year integrated experience with both modalities

OBJECT The authors sought to assess the respective roles of microsurgery and gamma knife surgery (GKS) in the treatment of patients with meningiomas. METHODS The authors culled from a 4-year prospective database data on 74 cases of meningiomas. Thirty-eight were treated with GKS and 35 with microsurgery. Simpson Grade 1 or 2 resection was achieved in 86.1% of patients who underwent microsurgery. Patients who underwent GKS received a mean margin dose of 16.4 Gy (range 14-20 Gy). The mean tumor coverage was 94.7%, and the mean conformity index was 1.76. Significant differences between the two treatment groups (GKS compared with microsurgery) included age (mean 60 compared with 50.7 years), volume (mean 7.85 cm3 compared with 44.4 cm3), treatment history (55.3% compared with 14.3%), and tumor location (cavernous sinus/petroclival, 14 compared with three). The median follow up was 21.5 months (range 1.5-50 months). In patients with benign meningiomas GKS tumor control was 96.8% with one recurrence at the margin. The recurrence rate was zero of 27 for Simpson Grade 1 or 2 resection and three of four for higher grades in those patients who underwent microsurgery. There was no procedure-related mortality or permanent major neurological morbidity. The mean Karnofsky Performance Scale score was maintained for both forms of treatment. Symptoms improved in 48.4% of patients undergoing microsurgery and 16.7% of those who underwent GKS. Transient and permanent cranial nerve morbidity was 7.9 compared with 2.9%, and 5.3 compared with 8.5% for GKS and microsurgery, respectively. In a patient satisfaction survey 93.1% of microsurgery patients and 91.2% of GKS patients were highly satisfied. CONCLUSIONS Both GKS and microsurgery serve important roles in the overall management of patients with meningiomas. Both are safe and effective and provide high degrees of satisfaction when used for differentially selected patients.

A prospective cohort study of microvascular decompression and Gamma Knife surgery in patients with trigeminal neuralgia

OBJECT The aim of this study was to analyze 1 surgeons 4-year experience with microvascular decompression ([MVD], 36 patients) and Gamma Knife surgery ([GKS], 44 patients) in 80 consecutive patients with trigeminal neuralgia (TN). METHODS The authors conducted a prospective cohort study from March 1999 to December 2003 with an independent clinical assessment of the results and serial patient satisfaction surveys. All patients completed a 2004 patient satisfaction survey (0.5-5 years postoperative), and 70% of surviving patients completed the same survey in 2007 (3.9-8.5 years postoperative). Follow-up was undertaken in 100% of the patients (mean 3.4 +/- 2.14 years, range 0.17-8.5 years). RESULTS Respective initial and latest follow-up raw pain-free rates were 100 and 80.6% for MVD and 77.3 and 45.5% for GKS. The median time to the maximal benefit after GKS was 4 weeks (range 1 week-6 months). Respective initial, 2-, and 5-year actuarial pain-free rates were 100, 88, and 80% for MVD and 78, 50, and 33% for GKS (p = 0.0002). The relative risk of losing a pain-free status by 5 years posttreatment was 3.35 for patients in the GKS group compared with the MVD group. Initial and 5-year actuarial rates for >or= 50% pain relief after GKS were 100 and 80%, respectively. The respective rates of permanent mild and severe sensory loss were 5.6 and 0% for patients in the MVD group, as opposed to 6.8 and 2.3% for patients in the GKS group. Anesthesia dolorosa did not occur during the study. Both procedures enjoyed a high degree of early patient satisfaction (95-100%). Microvascular decompression maintained the same rate of patient satisfaction, but satisfaction with GKS decreased to 75% as pain control waned. Twenty-three patients (29%) died of causes unrelated to the TN or the surgical intervention during the follow-up, and their pain status was known at the time of death. Statistically significant intergroup differences for the MVD versus GKS cohorts were age (median 54 years, range 36-70 years vs median 74 years, range 48-92 years, respectively), preoperative symptom duration (median 2.58 years, range 0.33-15 years vs median 7.5, range 0.6-40 years, respectively), and the presence of major comorbidities (2.8 vs 58.3%, respectively). CONCLUSIONS In this nonrandomized prospective cohort trial of selected patients with potentially relevant intergroup differences, MVD was significantly superior to GKS in achieving and maintaining a pain-free status in those with TN and provided similar early and superior longer-term patient satisfaction rates compared with those for GKS. The complications of wound cerebrospinal fluid leakage, hearing loss, and persistent diplopia (1 case each in the MVD group) were not seen after GKS.

Eye metastasis from carcinoma of the breast: diagnosis, radiation treatment and results

The experience at the Gershenson Radiation Oncology Center of 32 cases of metastases to the eye or orbit from breast cancer are presented with a review of the literature. The 32 patients were referred for radiation therapy in the period of 1980-1991. Eighteen patients had metastasis to the choroid, 2 patients had involvement of other parts of the eye (anterior chamber +/- choroid), and 11 patients had orbital metastasis. In one patient, the diffuse nature of the disease prevents subsite assignment. Ten of the patients with eye metastases also had brain or meningeal metastases (8 patients concurrent with eye metastases). Four of the 32 patients had bilateral choroidal metastases. A complete course of radiation therapy was delivered to 28 patients, one patient was not treated and 3 patients received only partial treatment because of general deterioration due to other widespread metastases from breast cancer. Of 21 evaluable patients, 15 had definite improvement. There was no progression of the eye metastases in the other 6 patients. The rest (7 patients) were lost to detailed follow-up of the response of the eye metastases. Four patients are still alive without any severe long-term side-effects. The diagnosis, treatment and outcome is presented with a review of the literature. The importance of emergency treatment for rapidly progressing lesions is stressed as well as the need for detailed treatment planning, careful delivery of daily treatments with a high degree of reproducibility and precision to prevent possible damage to sensitive normal structures.

Pediatric Craniospinal Axis Irradiation With Helical Tomotherapy: Patient Outcome and Lack of Acute Pulmonary Toxicity

PURPOSE To present the patient outcomes and risk of symptomatic acute radiation pneumonitis (ARP) in 18 pediatric patients treated with helical tomotherapy to their craniospinal axis for a variety of neoplasms. METHODS AND MATERIALS A total of 18 patients received craniospinal axis irradiation with helical tomotherapy. The median age was 12 years (range, 2.5-21). The follow-up range was 3-48 months (median, 16.5). Of the 18 patients, 15 received chemotherapy in the neoadjuvant, adjuvant, or concomitant setting. Chemotherapy was tailored to the particular histologic diagnosis; 10 of 18 patients underwent surgical removal of the gross primary tumor. The patients were followed and evaluated for ARP starting at 3-6 months after completion of craniospinal axis irradiation. ARP was graded using the Common Toxicity Criteria, version 3. RESULTS At the last follow-up visit, 14, 2, and 2 patients were alive without disease, alive with disease, and dead of disease, respectively. The cause-specific survival rate was 89% (16 of 18), disease-free survival rate was 78% (14 of 18), and overall survival rate was 89% (16 of 18). No patient had treatment failure at the cribriform plate. No patient developed symptoms of ARP. CONCLUSION Craniospinal axis irradiation using helical tomotherapy yielded encouraging patient outcomes and acute toxicity profiles. Although large volumes of the lung received low radiation doses, no patient developed symptoms of ARP during the follow-up period.

Modeling of carbon fiber couch attenuation properties with a commercial treatment planning system

The purpose of this work is to evaluate the modeling of carbon fiber couch attenuation properties with a commercial treatment planning system (TPS, Pinnacle3, v8.0d). A carbon fiber couch (Brain-Lab) was incorporated into the TPS by automatic contouring of all transverse CT slices. The couch shape and dimensions were set according to the vendor specifications. The couch composition was realized by assigning appropriate densities to the delineated contours. The couch modeling by the TPS was validated by absolute dosimetric measurements. A phantom consisting of several solid water slabs was CT scanned, the CT data set was imported into the TPS, and the carbon fiber couch was auto-contoured. Open (unblocked) field plans for different gantry angles and field sizes were generated. The doses to a point at 3 cm depth, placed at the linac isocenter, were computed. The phantom was irradiated according to the dose calculation setup and doses were measured with an ion chamber. In addition, percent depth dose (PDD) curves were computed as well as measured with radiographic film. The calculated and measured doses, transmissions, and PDDs were cross-compared. Doses for several posterior fields (0 degree, 30 degrees, 50 degrees, 75 degrees, 83 degrees) were calculated for 6 and 18 MV photon beams. For model validation a nominal field size of 10 x 10 cm2 was chosen and 100 MU were delivered for each portal. The largest difference between computed and measured doses for those posterior fields was within 1.7%. A comparison between computed and measured transmissions for the aforementioned fields was performed and the results were found to agree within 1.1%. The differences between computed and measured doses for different field sizes, ranging from 5 x 5 cm2 to 25 x 25 cm2 in 5 cm increments, were within 2%. Measured and computed PDD curves with and without the couch agree from the surface up to 30 cm depth. The PDDs indicate a surface dose increase resulting from the carbon fiber couch field modification. The carbon fiber couch attenuation for individual posterior oblique fields (75 degrees) can be in excess of 8% depending on the beam energy and field size. When the couch is contoured in Pinnacle3 its attenuation properties are modeled to within 1.7% with respect to measurements. These results demonstrate that appropriate contouring together with relevant density information for the contours is sufficient for adequate modeling of carbon fiber supporting devices by modern commercial treatment planning systems.

Dosimetric comparison of Helical Tomotherapy and Gamma Knife Stereotactic Radiosurgery for single brain metastasis

BackgroundHelical Tomotherapy (HT) integrates linear accelerator and computerized tomography (CT) technology to deliver IMRT. Targets are localized (i.e. outlined as gross tumor volume [GTV] and planning target volume [PTV]) on the planning kVCT study while daily MVCT is used for correction of patients set-up and assessment of inter-fraction anatomy changes. Based on dosimetric comparisons, this study aims to find dosimetric equivalency between single fraction HT and Gamma Knife® stereotactic radiosurgery (GKSRS) for the treatment of single brain metastasis.MethodsThe targeting MRI data set from the GKSRS were used for tomotherapy planning. Five patients with single brain metastasis treated with GKSRS were re-planned in the HT planning station using the same prescribed doses. There was no expansion of the GTV to create the PTV. Sub-volumes were created within the PTV and prescribed to the maximum dose seen in the GKSRS plans to imitate the hot spot normally seen in GKSRS. The PTV objective was set as a region at risk in HT planning using the same prescribed dose to the PTV periphery as seen in the corresponding GKSRS plan. The tumor volumes ranged from 437–1840 mm3.ResultsConformality indices are inconsistent between HT and GKSRS. HT generally shows larger lower isodose line volumes, has longer treatment time than GKSRS and can treat a much larger lesion than GKSRS. Both HT and GKSRS single fraction dose-volume toxicity may be prohibitive in treating single or multiple lesions depending on the number and the sizes of the lesions.ConclusionBased on the trend for larger lower dose volumes and more constricted higher dose volumes in HT as compared to GKSRS, dosimetric equivalency was not reached between HT and GKSRS.

Evaluation of Spatially Fractionated Radiotherapy (GRID) and Definitive Chemoradiotherapy With Curative Intent for Locally Advanced Squamous Cell Carcinoma of the Head and Neck: Initial Response Rates and Toxicity

PURPOSE To present results and acute toxicity in 14 patients with bulky (>or=6 cm) tumors from locally advanced squamous cell carcinoma of the head and neck who received spatially fractionated radiotherapy (GRID) therapy to the bulky mass followed by concomitant chemoradiotherapy using simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT). METHODS AND MATERIALS GRID therapy to the GTV was delivered by creating one treatment field with a checkerboard pattern composed of open-closed areas using a multileaf collimator. The GRID prescription was 20 Gy in one fraction. Chemotherapy started the day of GRID therapy and continued throughout the course of SIB-IMRT. The SIB-IMRT prescription was 66, 60, and 54 Gy to the planning target volume (PTV), intermediate-risk PTV, and low-risk PTV, respectively, in 30 fractions. RESULTS With a median follow-up of 19.5 months (range, 2-38 months), the overall control rate of the GRID gross tumor volume was 79% (11 of 14). The most common acute skin and mucosal toxicities were Grade 3 and 2, respectively. CONCLUSION For the treatment of locally advanced neck squamous cell carcinoma of the head and neck, GRID followed by chemotherapy and SIB-IMRT is well tolerated and yields encouraging clinical and pathologic responses, with similar acute toxicity profiles as in patients receiving chemoradiotherapy without GRID.

Evaluation of Integral Dose in Cranio-spinal Axis (CSA) Irradiation with Conventional and Helical Delivery:

In cranio-spinal axis (CSA) irradiation, patients are usually treated in the prone position with junctions between cranial and spinal fields. Collimator angle and pedestal rotations are introduced to obtain coplanar alignment of the matched junction. Furthermore, daily moving junctions are commonly used to feather out the junctional dose as additional safe-guards to avoid radiation myelopathy. Helical tomotherapy integrates linear accelerator and CT technology capable of delivering CSA treatment without geometric matches or feathering of junctions. The patient is treated with helical beams in the supine position. Since CSA is used mainly in the pediatric population, the potential increase in integral dose to structures or the whole body from linac- or tomotherapy-based IMRT raises concerns of increased rates of secondary malignancies. In this study, we will present an integral dose comparison between conventional CSA (3D) and helical delivery to the CSA (TOMO) utilizing the Tomotherapy Hi-ART system for three pediatric patients. Integral dose was calculated for organ at risk (OAR), two targets (PTV-BRAIN and PTV-SPINE), entire planning CT data set and to the healthy tissue (entire CT-DATA SET minus the PTV). Overall integral dose was 8% higher in the TOMO plans for Patients #1 and #3, but 2% lower in Patient #2. DVH analysis shows that TOMO plans give lower doses to larger volumes and higher doses to smaller volumes of tissue in all three cases. The advantages of the TOMO plans are minimization of matched junctions and better sparing of most OARs. With increased computational and memory power in the tomotherapy planning station, the excess integral dose to the healthy tissue can be re-distributed within the patient and in turn the total integral dose can be same or lower than in conventional delivery. The impact of a small increase in overall integral dose and the associated risks of secondary malignancies are unknown. Long-term follow-up is needed to answer this question.

Clinical feasibility of TBI with helical tomotherapy.

Our purpose was to present the clinical feasibility of TBI with helical tomotherapy (HT) in four patients with AML. Treatment planning, delivery, dose verification and summation, toxicity and patient outcomes for each patient are presented. TBI prescription was set in such a manner that 80% of the clinical target volume received 12 Gy in six fractions, at two fractions per day. Dose reconstruction was carried out by recontouring the regions of interest in the daily pretreatment megavoltage computed tomography of each individual fraction and calculating its corresponding dose. A deformable registration model was used for dose summation of all individual fractions. Differences between planned and delivered doses were calculated. Average planned and delivered doses to the regions of interest differed by up to 2.7%. TBI toxicity was limited to radiotherapy oncology group grade 1 dermatitis in all patients and grade 1 headache in one patient. Two patients are alive with no evidence of disease and no GVHD. Two patients died of GVHD, but there was no evidence of disease at the time of death. We conclude that HT simplifies the process of TBI. Dose verification is possible with HT showing small differences between plan and delivered doses.

Retrospective Evaluation of Pediatric Cranio-Spinal Axis Irradiation Plans with the Hi-ART Tomotherapy System

Helical tomotherapy (HT) can be used for the delivery of cranio-spinal axis irradiation (CSAI) without the need for beam matching of conventional linac-based external beam irradiation. The aim of this study is to retrospectively evaluate HT plans used for treatment in nine patients treated with CSAI. Helical tomotherapy cranio-spinal axis irradiation (HT-CSAI) plans were created for each patient. Average length along the cranio-spinal axis of the PTV was 65.6 cm with a range between 53 and 74 cm. Treatment planning optimization and plan evaluation parameters were obtained from the HT planning station for each of the nine patients. PTV coverage by the 95% isodose surface ranged between 98.0 to 100.0% for all nine patients. The clinically acceptable dose variation within the PTV or tolerance range was between 0.7 and 2.5% for all nine patients. Doses to the organs at risk were clinically acceptable. An increasing length along the longitudinal axis of the PTV did not consistently increase the beam-on time indicating that using a larger jaw width had a greater impact on treatment time. With a larger jaw width it is possible to substantially reduce the normalized beam-on treatment time without compromising plan quality and sparing of organs at risk. By using a larger jaw width or lower modulation factor or both, normalized beam-on times were decreased by up to 61% as compared to the other evaluated treatment plans. From the nine cases reported in this study the minimum beam-on time was achieved with a jaw width of 5.0 cm, pitch of 0.287 and a modulation factor of 2.0. Large and long cylindrical volumes can be effectively treated with helical tomotherapy with both clinically acceptable dose distribution and beam-on time.