- Email: [email protected]
945 poster GAS ELECTRON MULTIPLIERS (GEM) DETECTOR – A NOVEL RADIOTHERAPY IMAGING DEVICE: GEM VERSUS AMORPHOUS SILICON PANELS
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cases 53% were male patients vs. 47% females and 68% were treated with radical intent compaared to 32 % of patients treated with palliative intent in their first visit. Common tumour sites included Breast, Prostate, Skin and palliative bone metsastasis. Frequent tumour sites included rectal cancers, uterine cervical and endometrial tumours, primary brain tumours, testicular seminoma, and palliative brain and spine metastasis, and palliative primary lung cancers. broad spectrum of less frequent cases were found to rpresent cases seen at a frequency of less than 20 per year. Conclusions: The Infrastructure, treatment planning and delivery equipment, staffing, and access to other specialty services and educational resources were found to meet the minimum criteria defined for radiotherapy training in europe. The workload and case mix allows trainees to fulfill the required standards. more organisd protected learning time on weekly basis is required in addition to more structured training format to increase exposure to rare cases through the three years of training is required. Continuous development in education and training need to go hand-in-hand with the technology development that took place in the fields of planning and delivery of Radiotherpy over the last three decades. 942 poster GAMMA KNIFE RADIOSURGERY (GKRS) IN THE MANAGEMENT OF PARKINSON’S DISEASE AND ESSENTIAL TREMOR : LONG-TERM FOLLOW-UP REPORT OF 196 CASES R. Mojica1 , R. Mark1 , H. Smith1 , R. Akins1 , M. Nair1 1
J OE A RRINGTON C ANCER AND R ESEARCH C ENTER, Department of Radiation Oncology, Lubbock, USA Purpose: Management options for tremors secondary to Parkinson’s Disease (PD) and Essential Tremor (ET), include medications, Deep Brain Stimulation (DBS), Radiofrequency (RF), and Gamma Knife Radiosurgery (GKRS). Results with GKRS have compared favorably to DBS and RF with respect to tremor relief and complications. We report our updated long-term results with GKRS in the treatment of tremors. Materials: Between 1991 and 2010, 196 patients underwent MRI Scan targeted GKRS thalamotomy for medically refractory tremors secondary to PD (n = 120) and ET (n = 76). The target was the Ventralis Inter-Medius (VIM) nucleus. The target received between 140 Gy in a single shot prescribed to Dm using the 4 mm collimator. Treatment planning was accomplished thru the Leksell Treatment Planning System. Pre-operative and post-operative blinded assessments were performed by a team of independent examiners. The Unified Parkinson’s Disease Rating Scale and Clinical Rating Scale for Tremors was used to score tremors. Results: With a median follow-up of 7 years (range 2-19 years), 82.6% (161/196) of patients had significant, or complete resolution of tremors. In patients with PD, 81.7% (98/120) had near or complete tremor resolution, vs. 82.9% (63/76) with ET. There was no statistically significant difference by the Fisher’s Test (p = 1.0). Five patients experienced MRI proven edema and transient hemiparesis and speech difficulty. In four patients, the deficits were resolved on high dose steroids. The 4th patient required high dose steroids and hyperbaric oxygen for resolution of deficits and edema. There were no cases of hemorrhage, infection, or death. Conclusions: GKRS thalamotomy to the VIM nucleus provides favorable results, both in tremor relief and complications, for patients with medically refractory tremors secondary to PD or ET. Furthermore, these results compare favorably to DBS and RF, with regard to tremor relief, complications and cost. In view of these long-term tremor resolution results, low complication risks, and cost savings, GKRS should be considered as a primary initial treatment option in medically refractory tremors. The optimal dose with minimal complications, is 140 Gy. 943 poster GAMMA KNIFE RADIOSURGERY (GKRS) IN THE MANAGEMENT OF TRIGEMINAL NEURALGIA (TN) : MEDIAN 10 YEAR FOLLOW-UP OF 545 PATIENTS K. Thompson1 , R. Mark2 , R. Akins3 , M. Nair4
1 J OE A RRINGTON C ANCER AND R ESEARCH C ENTER, Department of Radiation Oncology and Image-applied Therapy, Lubbock, Texas, USA 2 J OE A RRINGTON C ANCER AND R ESEARCH C ENTER, Department of Radiation Oncology, Lubbock, USA 3 J OE A RRINGTON C ANCER AND R ESEARCH C ENTER, Department of Radiation Oncology Molecular Radiation Sciences, Lubbock, Texas, USA 4 J OE A RRINGTON C ANCER AND R ESEARCH C ENTER, Lubbock, Texas, USA
Purpose: Gamma Knife Radiosurgery (GKRS) has been used successfully in the treatment of Trigeminal Neuralgia (TN). Results have compared favorably to surgical procedures with respect to pain relief and complications. We report our updated long-term results with GKRS in the treatment of TN. Materials: Between 1991 and 2010, 545 patients with medically refractory typical TN were treated with GKRS, and have not been lost to follow-up. Prior neurosurgical intervention had been performed in 30.3% of the patients (165/545), with a total of 374 procedures. All patients had typical TN. GKRS
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was given to the cranial nerve V entry root zone into the brainstem. Targeting was defined by CT and MRI Scans, and inversion recovery MRI, utilizing axial, coronal and sagittal images. Treatment planning was accomplished thru the Leksell Treatment Planning System. The prescribed doses ranged from 70 to 90 Gy prescribed to Dm, in one shot using the 4 mm collimator, with the 20% Isodose line just touching the brainstem. Response to treatment was defined as excellent (no pain, off analgesics), good (no pain, with analgesics), and poor (continued pain despite analgesics). Response to treatment was recorded in interviews conducted by a Gamma Knife Nurse. Results: With a median follow-up of 10 years (range 5-19 years), 53.9% (294/545) of patients reported an excellent result, and 22.9% (125/545) a good result after GKRS. There was a dose response, with 55.7% (68/122) of patients reporting an excellent or good response after 70 Gy, compared to 80.8% (207/256) at 80 Gy, and 86.2% (144/167) at 90 Gy (p <0.01). Temporary ipsilateral facial numbness occurred in 18.7% (102/545), and permanent facial numbness in 5.3% (29/545). Loss of corneal reflex occurred in 1.7% (9/545), and painful dysesthesias in 2.9% (16/545). There have been three cases of anesthesia dolorosa. There was a dose response in facial numbness, with temporary numbness occurring in 6.5% (8/122) at 70 Gy, 17.6% (45/256) at 80 Gy, and 29.3% (49/167) at 90 Gy (p<0.01). Permanent numbness occurred in 2.5% (3/122) at 70 Gy, 4.3% (11/256) at 80 Gy, and 9.0% (15/167) at 90 Gy (p<0.01). Conclusions: GKRS offers favorable results, both in pain relief and complications, compared to surgery in the management of medically refractory TN. In view of these long-term good pain relief and low complication risks, GKRS should be considered as a primary initial treatment option in medically refractory TN. The optimal dose with maximum pain relief and minimal complications, appears to be 80 Gy. 944 poster GAMMA KNIFE RADIOSURGERY FOR THE TREATMENT OF NON-SURGICAL CYSTIC CEREBRAL METASTASES P. Goetz1 , S. Lwu1 , M. Aryaee1 , E. Monsalves1 , J. Ebinu1 , N. Laperriere2 , C. Menard2 , M. Bernstein3 , G. Zadeh4 1 TORONTO W ESTERN H OSPITAL - U NIVERSITY H EALTH N ETWORK, Division of Neurosurgery, Toronto, Canada 2 P RINCESS M ARGARET H OSPITAL, Department of Radiation Oncology, Toronto, Canada 3 P RINCESS M ARGARET H OSPITAL AND U NIVERSITY OF TORONTO, Division of Neurosurgery, Toronto, Canada 4 U NIVERSITY H EALTH N ETWORK, Toronto, Canada Purpose: Treatment options for cystic cerebral metastases include surgical aspiration/resection, whole-brain radiation therapy (WBRT), and stereotactic radiosurgery (SRS). Larger cystic lesions are regarded as unsuitable for SRS: higher radiation doses required carry an associated risk of radiation toxicity and the non-cellular component may not respond to radiation. Such lesions often require surgery. We aimed to assess the role of Gamma Knife Radiosurgery (GKRS) in the treatment of non-surgical cystic brain metastases. Materials: We reviewed a prospectively maintained database of brain metastases patients treated at our institution between February 2006 and July 2009. 223 consecutive patients with brain metastases underwent GKS. Lesions with a greater and less than 50% cystic component were identified. Clinical, radiological and dosimetry parameters were reviewed to establish the response to SRS and identify potential predictive factors of response Results: 57 lesions in 40 patients were analyzed. The primary cancer was lung, breast and other in 47%, 16% and 37% respectively. 52% of the patients were RPA Class I, the remainder class II. Mean tumour volume was 4.4 ml (range 0.1123.18 ml). Mean prescription dose was 20.1 Gy (range 15-24 Gy). Mean follow-up was 12.5 months (range 1.8-56). Mean conformality index was 1.6 (range 0.83-3.2). Local control rates were 94, 87, 72 and 51% at 3, 6, 12, and 18 months respectively; they were superior in lung compared to non-lung subtypes and unaffected by percentage of cystic component. Conclusions: These results support the use of GKRS in the management of non-surgical cystic metastases despite a perceived poorer response in the reported literature. Our local control rates are comparable to a matched cohort of non-cystic brain metastases. Tumour subtype was as predictor of response. 945 poster GAS ELECTRON MULTIPLIERS (GEM) DETECTOR - A NOVEL RADIOTHERAPY IMAGING DEVICE: GEM VERSUS AMORPHOUS SILICON PANELS B. Mitterlechner1 , S. Huber2 , M. Mooslechner2 , F. Sedlmayer1 2 , H. Deutschmann2 1 1 U NIVERSITY C LINIC S ALZBURG, University Clinic for Radiotherapy and Radio-Oncology, Salzburg, Austria 2 PARACELSUS M EDIZINISCHE P RIVATUNIVERSITÄT, Institute for Research and Development on Advanced Radiation Technologies, Salzburg, Austria Purpose: Todays standard in electronic portal imaging devices (EPID) as
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used for kV and MV imaging applications in radiotherapy is amorphous silicon (aSi:H) flat panel technology. While new aSi:H panels provide relatively good MV images, the quality and dosimetrical usefulness of devices suffers significantly from radiation damages under normal clinical use. After average life spans of 18 months, detectors have to be replaced. A novel flat panel imaging technology, based on gas electron multipliers (GEMs), is promising unlimited life span due to increased radiation hardness. Materials: A new GEM detector was installed on a clinical linear accelerator (retro-fit), and integrated in our software open-radART (a record and verify system with fast image feedback loops to enable robotic applications in adaptive IGRT on conventional linacs). In several test plans, we compare images from the GEM detector with the aSi:H flat panel devices. Focus is set on exact specification of framerate, digital quantum efficiency, linearity of response to doserate, spatial resolution (MTF), temperature behaviour, ghosting (image lag) and aging / radiation hardness. Besides phantom studies, first clinical images of the GEM detector are captured. Results: The clinical test environment was successfully implemented and all test cases were performed in this setting. At a first glance, 16 bit image quality is comparable to that of aSi:H imaging devices with the advantage of higher possible framerates of the GEM panel (20 Hz vs. 2 Hz). Ghosting effects have not been seen with GEM (intrinsic: no trapped charges), digital quantum efficiency (SNR at lower doses per frame) is significantly increased compared to aSi:H. Although pixel size and active area are comparable, depending on adjustable high voltage settings on the GEMs, the spatial resolution (MTF) can be slightly lower compared to aSi:H technology. The GEM system appears to be stable, and re-calibration intervals are reasonable. However, long term follow up data of radiation hardness in a typical clinical setting is not yet available. Conclusions: Relating to the measurement results, the GEM detector has proven its potential to be a suitable imaging device in radiotherapy. However, further investigations need to be done to gain more expertise on tuning of the new detector’s properties and to quantify aging effects due to radiation damages. 946 poster GLIOBLASTOMA IN ELDERLY: IS ADJUVANT RADIOCHEMOTHERAPY EFFECTIVE AND FEASIBLE? A. Fiorentino1 , C. Chiumento1 , A. M. Mileo1 , V. Fusco1 1 IRCCS/CROB, Department of Radiation Oncology, Rionero in Vulture, Italy Purpose: Glioblastoma (GBM) is frequent among elderly patients (>65yars). The Purpose of this retrospective study was to evaluate the feasibility and the effective of Standard Radiochemotherapy (RTCHT) in GBM elderly patients. Materials: Patients (pts) >65 yrs old with histological proven GBM (WHO grade IV); were retrospectively evaluated. Patients received a surgical resection or biopsy and standard RTCHT with TMZ. The Clinical Target Volume was defined as surgical bed + residual tumor + oedema + 0.5 cm and the Planning Target Volume was defined as CTV + 0.7 cm. RTOG scale was used to define acute toxicity. Results: From March 2005 to June 2010, 27 GBM patients (pts) >65 yrs were treated in our Institution (21 pts > 70 yrs). Fourteen are female and 13 male. Eight pts (29.6%) received a complete resection. After a median follow-up of 27 (range 3-65) months, median progression-free survival (PFS) was 7 months (mts) and median Overall Survival (OS) was 12 months. Extent of resection (p:0.03) and RPA class (p:0.05) correlated with OS. At multivariate analysis only the extent of resection was a significant prognostic factor (p:0.032).During RTCHT toxicity was mild, thrombocytopenia G3-4 occurred in 3 pts and Neurological toxicity G3-4 in 2 pts. Conclusions: In conclusion, our data suggest that the association of RT with TMZ could be considered as a safe and effective strategy to treat GBM in elderly pts. 947 poster HAS COMBINED MODALITY TREATMENT OF GLIOBLASTOMA MULTIFORME CHANGED THE PATTERNS OF PROGRESSION? G. Ryan1 , A. Gunjur2 , Y. Taouk3
to analyse the pattern of progression of GBM in our institution, to guide us in future research and treatment protocols. Materials: Patients with GBM treated as per Stupp protocol between October 2004 and August 2009 at the Peter MacCallum Cancer Centre in Melbourne were reviewed retrospectively. Sixty-eight eligible patients with complete follow-up were identified, of whom 54 were found to have progressed following treatment. MRI scans at progression and original radiotherapy plans were available for 47 patients, and were fused in the radiotherapy planning system and analysed for site(s) of progression. Results: There was an over-representation of males and patients over 60 years in our patient group (66% and 38% respectively) compared to the Stupp study population. Coverage of site(s) of progression by the radiotherapy planning target volume was defined as: central >95% coverage, in-field >80-95%, marginal 20-80%, and out-offield <20%. In our patient group 77% of progressions were central, 15% in-field, 6% marginal and 2% out-of-field. Given the small number of out-of-field recurrences, no temporal trends could be identified. Overall survival for the cohort was 11.6 months, with the 1 and 2 year survival rates 50% and 18%. Conclusions: There is no evidence of an increase in out-of-field progressions in our patient group. The relatively unfavourable demographics of the group may have contributed to this negative result. Further patient data will be collected prospectively to address potential biases, and will be correlated with MGMT methylation status and newer imaging modalities. 948 poster HDR BRACHYTHERAPY IN SKIN CANCERS: TARGET DETERMINATION AND OUTCOME VERSUS CONVENTIONAL RADIOTHERAPY F. Piro1 , R. Siciliano2 , D. Cosentino1 , P. Indrieri1 , L. Ziccarelli1 , P. Ziccarelli1 , L. Marafioti1 1 O SPEDALE M ARIANO S ANTO, Department of Radiotherapy, Cosenza, Italy 2 O SPEDALE M ARIANO S ANTO, Fisica Sanitaria, Cosenza, Italy Purpose: Brachitherapy in skin cancers is a interesting alternative to conventional radiotherapy because offers personalized treatment (also in multisite cancers) and due to new fractionation used in our Center the treatment time is shorter than conventional RT. Otherwise the leterature data for these treatment are few. So we performed this rewiew to evaluate outcome, toxicity and or target missing in patients treated with high dose rate brachytherapy, and with minimum follow up of 60 months. Materials: From August 1999 to September 2010, 118 consecutive pts. with skin cancer (20% squamous cell) (5% with cancer larger >4 cm) were enrolled in this perspective study: HDR treatment consisting of twice-daily fractionation of 350 cGy each, 6 hour apart final dose delivered 49 Gy as esclusive modality or as postoperative treatment for positive margins; as postoperative treatment for squamous cell with clear margins the final dose delivered was 42 Gy. To provide the maximum coverage of the tumor the implants were performed with afterloading spaced (at least 1 cm) catheters embedded in personalized surface molds or interstitial implant both planned with a semi-3-D technique aided by simulator. Radiopaque markers for target definition around the cancer were obbligatory (minimum space 5 mm maximum 10 mm). So implant dosimetry was performed as 100% of prescription at each skin marker. The follow up consisted in clinical examination of each cancer site. We studied the pts. with a minimum follow up of 5 years. For failure cases a rewiew of dosimetry was performed. Results: The eligible pts. were 93, the median follow up 84 months (range 60-96). The cosmetics results were poor in 6% of cases; the only important toxicity was a telangectasia of the skin. The local relapse were 10% (9 cases) especially for bulky cases (6), for 3 of these cases a full-dose reirradiation was performed after the dosimetry rewiew without severe toxicity. The cases of missing target 3% (3 cases). Conclusions: According the letterature this treatment schedule is effective and can be used in skin cancers with a good compliance of the treated pts. (seven days of treatment). HDR brachytherapy is a tecnique with a good learning curve that offers personalized treatments without radiation damage to OAR ( as eye ) in alternative to conventional radiotherapy. Actually this schedule is the standard for skin cancer in our Center. 949 poster
1
P ETER M AC C ALLUM C ANCER C ENTRE, Radiation Oncology, Melbourne, Australia 2 P ETER M AC C ALLUM C ANCER C ENTRE, Medical Student, Melbourne, Australia 3 P ETER M AC C ALLUM C ANCER C ENTRE, Biostatistics and Clinical Trials, Melbourne, Australia Purpose: More than 90% of patients with glioblastoma multiforme (GBM) treated with adjuvant radiotherapy alone post-surgery progress within 2cm of the enhancing tumour/surgical cavity, and this information is currently used in defining radiotherapy field margins. With the introduction of combined modality adjuvant treatment incorporating temozolomide chemotherapy (the "Stupp Protocol"), there is emerging literature suggesting that the risk of progression beyond these margins is substantially increased. This study therefore aims
HIGH DOSE RATE BRACHYTHERAPY BOOST FOR RESIDUAL MALIGNANT GLIOMA: CLINICAL RESULTS FROM SINGLE INSTITUTION M. H. Elnaggar1 , H. El Bakry1 , A. Fakhr2 , A. Hassouna1 , M. El-Sayed1 1
E GYPTIAN N ATIONAL C ANCER I NSTITUTE , C AIRO U NIVERSITY, Radiation Oncology Department, Cairo, Egypt 2 FACULTY OF M EDICINE , A IN S HAMS U NIVERSITY, Neurosurgery, Cairo, Egypt Purpose: Investigate the role of additional brachytherapy boost in malignant glioma patients having residual lesion after conventional radiotherapy treatment. Materials: After initial surgical intervention and external beam radiotherapy
cases 53% were male patients vs. 47% females and 68% were treated with radical intent compaared to 32 % of patients treated with palliative intent in their first visit. Common tumour sites included Breast, Prostate, Skin and palliative bone metsastasis. Frequent tumour sites included rectal cancers, uterine cervical and endometrial tumours, primary brain tumours, testicular seminoma, and palliative brain and spine metastasis, and palliative primary lung cancers. broad spectrum of less frequent cases were found to rpresent cases seen at a frequency of less than 20 per year. Conclusions: The Infrastructure, treatment planning and delivery equipment, staffing, and access to other specialty services and educational resources were found to meet the minimum criteria defined for radiotherapy training in europe. The workload and case mix allows trainees to fulfill the required standards. more organisd protected learning time on weekly basis is required in addition to more structured training format to increase exposure to rare cases through the three years of training is required. Continuous development in education and training need to go hand-in-hand with the technology development that took place in the fields of planning and delivery of Radiotherpy over the last three decades. 942 poster GAMMA KNIFE RADIOSURGERY (GKRS) IN THE MANAGEMENT OF PARKINSON’S DISEASE AND ESSENTIAL TREMOR : LONG-TERM FOLLOW-UP REPORT OF 196 CASES R. Mojica1 , R. Mark1 , H. Smith1 , R. Akins1 , M. Nair1 1
J OE A RRINGTON C ANCER AND R ESEARCH C ENTER, Department of Radiation Oncology, Lubbock, USA Purpose: Management options for tremors secondary to Parkinson’s Disease (PD) and Essential Tremor (ET), include medications, Deep Brain Stimulation (DBS), Radiofrequency (RF), and Gamma Knife Radiosurgery (GKRS). Results with GKRS have compared favorably to DBS and RF with respect to tremor relief and complications. We report our updated long-term results with GKRS in the treatment of tremors. Materials: Between 1991 and 2010, 196 patients underwent MRI Scan targeted GKRS thalamotomy for medically refractory tremors secondary to PD (n = 120) and ET (n = 76). The target was the Ventralis Inter-Medius (VIM) nucleus. The target received between 140 Gy in a single shot prescribed to Dm using the 4 mm collimator. Treatment planning was accomplished thru the Leksell Treatment Planning System. Pre-operative and post-operative blinded assessments were performed by a team of independent examiners. The Unified Parkinson’s Disease Rating Scale and Clinical Rating Scale for Tremors was used to score tremors. Results: With a median follow-up of 7 years (range 2-19 years), 82.6% (161/196) of patients had significant, or complete resolution of tremors. In patients with PD, 81.7% (98/120) had near or complete tremor resolution, vs. 82.9% (63/76) with ET. There was no statistically significant difference by the Fisher’s Test (p = 1.0). Five patients experienced MRI proven edema and transient hemiparesis and speech difficulty. In four patients, the deficits were resolved on high dose steroids. The 4th patient required high dose steroids and hyperbaric oxygen for resolution of deficits and edema. There were no cases of hemorrhage, infection, or death. Conclusions: GKRS thalamotomy to the VIM nucleus provides favorable results, both in tremor relief and complications, for patients with medically refractory tremors secondary to PD or ET. Furthermore, these results compare favorably to DBS and RF, with regard to tremor relief, complications and cost. In view of these long-term tremor resolution results, low complication risks, and cost savings, GKRS should be considered as a primary initial treatment option in medically refractory tremors. The optimal dose with minimal complications, is 140 Gy. 943 poster GAMMA KNIFE RADIOSURGERY (GKRS) IN THE MANAGEMENT OF TRIGEMINAL NEURALGIA (TN) : MEDIAN 10 YEAR FOLLOW-UP OF 545 PATIENTS K. Thompson1 , R. Mark2 , R. Akins3 , M. Nair4
1 J OE A RRINGTON C ANCER AND R ESEARCH C ENTER, Department of Radiation Oncology and Image-applied Therapy, Lubbock, Texas, USA 2 J OE A RRINGTON C ANCER AND R ESEARCH C ENTER, Department of Radiation Oncology, Lubbock, USA 3 J OE A RRINGTON C ANCER AND R ESEARCH C ENTER, Department of Radiation Oncology Molecular Radiation Sciences, Lubbock, Texas, USA 4 J OE A RRINGTON C ANCER AND R ESEARCH C ENTER, Lubbock, Texas, USA
Purpose: Gamma Knife Radiosurgery (GKRS) has been used successfully in the treatment of Trigeminal Neuralgia (TN). Results have compared favorably to surgical procedures with respect to pain relief and complications. We report our updated long-term results with GKRS in the treatment of TN. Materials: Between 1991 and 2010, 545 patients with medically refractory typical TN were treated with GKRS, and have not been lost to follow-up. Prior neurosurgical intervention had been performed in 30.3% of the patients (165/545), with a total of 374 procedures. All patients had typical TN. GKRS
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was given to the cranial nerve V entry root zone into the brainstem. Targeting was defined by CT and MRI Scans, and inversion recovery MRI, utilizing axial, coronal and sagittal images. Treatment planning was accomplished thru the Leksell Treatment Planning System. The prescribed doses ranged from 70 to 90 Gy prescribed to Dm, in one shot using the 4 mm collimator, with the 20% Isodose line just touching the brainstem. Response to treatment was defined as excellent (no pain, off analgesics), good (no pain, with analgesics), and poor (continued pain despite analgesics). Response to treatment was recorded in interviews conducted by a Gamma Knife Nurse. Results: With a median follow-up of 10 years (range 5-19 years), 53.9% (294/545) of patients reported an excellent result, and 22.9% (125/545) a good result after GKRS. There was a dose response, with 55.7% (68/122) of patients reporting an excellent or good response after 70 Gy, compared to 80.8% (207/256) at 80 Gy, and 86.2% (144/167) at 90 Gy (p <0.01). Temporary ipsilateral facial numbness occurred in 18.7% (102/545), and permanent facial numbness in 5.3% (29/545). Loss of corneal reflex occurred in 1.7% (9/545), and painful dysesthesias in 2.9% (16/545). There have been three cases of anesthesia dolorosa. There was a dose response in facial numbness, with temporary numbness occurring in 6.5% (8/122) at 70 Gy, 17.6% (45/256) at 80 Gy, and 29.3% (49/167) at 90 Gy (p<0.01). Permanent numbness occurred in 2.5% (3/122) at 70 Gy, 4.3% (11/256) at 80 Gy, and 9.0% (15/167) at 90 Gy (p<0.01). Conclusions: GKRS offers favorable results, both in pain relief and complications, compared to surgery in the management of medically refractory TN. In view of these long-term good pain relief and low complication risks, GKRS should be considered as a primary initial treatment option in medically refractory TN. The optimal dose with maximum pain relief and minimal complications, appears to be 80 Gy. 944 poster GAMMA KNIFE RADIOSURGERY FOR THE TREATMENT OF NON-SURGICAL CYSTIC CEREBRAL METASTASES P. Goetz1 , S. Lwu1 , M. Aryaee1 , E. Monsalves1 , J. Ebinu1 , N. Laperriere2 , C. Menard2 , M. Bernstein3 , G. Zadeh4 1 TORONTO W ESTERN H OSPITAL - U NIVERSITY H EALTH N ETWORK, Division of Neurosurgery, Toronto, Canada 2 P RINCESS M ARGARET H OSPITAL, Department of Radiation Oncology, Toronto, Canada 3 P RINCESS M ARGARET H OSPITAL AND U NIVERSITY OF TORONTO, Division of Neurosurgery, Toronto, Canada 4 U NIVERSITY H EALTH N ETWORK, Toronto, Canada Purpose: Treatment options for cystic cerebral metastases include surgical aspiration/resection, whole-brain radiation therapy (WBRT), and stereotactic radiosurgery (SRS). Larger cystic lesions are regarded as unsuitable for SRS: higher radiation doses required carry an associated risk of radiation toxicity and the non-cellular component may not respond to radiation. Such lesions often require surgery. We aimed to assess the role of Gamma Knife Radiosurgery (GKRS) in the treatment of non-surgical cystic brain metastases. Materials: We reviewed a prospectively maintained database of brain metastases patients treated at our institution between February 2006 and July 2009. 223 consecutive patients with brain metastases underwent GKS. Lesions with a greater and less than 50% cystic component were identified. Clinical, radiological and dosimetry parameters were reviewed to establish the response to SRS and identify potential predictive factors of response Results: 57 lesions in 40 patients were analyzed. The primary cancer was lung, breast and other in 47%, 16% and 37% respectively. 52% of the patients were RPA Class I, the remainder class II. Mean tumour volume was 4.4 ml (range 0.1123.18 ml). Mean prescription dose was 20.1 Gy (range 15-24 Gy). Mean follow-up was 12.5 months (range 1.8-56). Mean conformality index was 1.6 (range 0.83-3.2). Local control rates were 94, 87, 72 and 51% at 3, 6, 12, and 18 months respectively; they were superior in lung compared to non-lung subtypes and unaffected by percentage of cystic component. Conclusions: These results support the use of GKRS in the management of non-surgical cystic metastases despite a perceived poorer response in the reported literature. Our local control rates are comparable to a matched cohort of non-cystic brain metastases. Tumour subtype was as predictor of response. 945 poster GAS ELECTRON MULTIPLIERS (GEM) DETECTOR - A NOVEL RADIOTHERAPY IMAGING DEVICE: GEM VERSUS AMORPHOUS SILICON PANELS B. Mitterlechner1 , S. Huber2 , M. Mooslechner2 , F. Sedlmayer1 2 , H. Deutschmann2 1 1 U NIVERSITY C LINIC S ALZBURG, University Clinic for Radiotherapy and Radio-Oncology, Salzburg, Austria 2 PARACELSUS M EDIZINISCHE P RIVATUNIVERSITÄT, Institute for Research and Development on Advanced Radiation Technologies, Salzburg, Austria Purpose: Todays standard in electronic portal imaging devices (EPID) as
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used for kV and MV imaging applications in radiotherapy is amorphous silicon (aSi:H) flat panel technology. While new aSi:H panels provide relatively good MV images, the quality and dosimetrical usefulness of devices suffers significantly from radiation damages under normal clinical use. After average life spans of 18 months, detectors have to be replaced. A novel flat panel imaging technology, based on gas electron multipliers (GEMs), is promising unlimited life span due to increased radiation hardness. Materials: A new GEM detector was installed on a clinical linear accelerator (retro-fit), and integrated in our software open-radART (a record and verify system with fast image feedback loops to enable robotic applications in adaptive IGRT on conventional linacs). In several test plans, we compare images from the GEM detector with the aSi:H flat panel devices. Focus is set on exact specification of framerate, digital quantum efficiency, linearity of response to doserate, spatial resolution (MTF), temperature behaviour, ghosting (image lag) and aging / radiation hardness. Besides phantom studies, first clinical images of the GEM detector are captured. Results: The clinical test environment was successfully implemented and all test cases were performed in this setting. At a first glance, 16 bit image quality is comparable to that of aSi:H imaging devices with the advantage of higher possible framerates of the GEM panel (20 Hz vs. 2 Hz). Ghosting effects have not been seen with GEM (intrinsic: no trapped charges), digital quantum efficiency (SNR at lower doses per frame) is significantly increased compared to aSi:H. Although pixel size and active area are comparable, depending on adjustable high voltage settings on the GEMs, the spatial resolution (MTF) can be slightly lower compared to aSi:H technology. The GEM system appears to be stable, and re-calibration intervals are reasonable. However, long term follow up data of radiation hardness in a typical clinical setting is not yet available. Conclusions: Relating to the measurement results, the GEM detector has proven its potential to be a suitable imaging device in radiotherapy. However, further investigations need to be done to gain more expertise on tuning of the new detector’s properties and to quantify aging effects due to radiation damages. 946 poster GLIOBLASTOMA IN ELDERLY: IS ADJUVANT RADIOCHEMOTHERAPY EFFECTIVE AND FEASIBLE? A. Fiorentino1 , C. Chiumento1 , A. M. Mileo1 , V. Fusco1 1 IRCCS/CROB, Department of Radiation Oncology, Rionero in Vulture, Italy Purpose: Glioblastoma (GBM) is frequent among elderly patients (>65yars). The Purpose of this retrospective study was to evaluate the feasibility and the effective of Standard Radiochemotherapy (RTCHT) in GBM elderly patients. Materials: Patients (pts) >65 yrs old with histological proven GBM (WHO grade IV); were retrospectively evaluated. Patients received a surgical resection or biopsy and standard RTCHT with TMZ. The Clinical Target Volume was defined as surgical bed + residual tumor + oedema + 0.5 cm and the Planning Target Volume was defined as CTV + 0.7 cm. RTOG scale was used to define acute toxicity. Results: From March 2005 to June 2010, 27 GBM patients (pts) >65 yrs were treated in our Institution (21 pts > 70 yrs). Fourteen are female and 13 male. Eight pts (29.6%) received a complete resection. After a median follow-up of 27 (range 3-65) months, median progression-free survival (PFS) was 7 months (mts) and median Overall Survival (OS) was 12 months. Extent of resection (p:0.03) and RPA class (p:0.05) correlated with OS. At multivariate analysis only the extent of resection was a significant prognostic factor (p:0.032).During RTCHT toxicity was mild, thrombocytopenia G3-4 occurred in 3 pts and Neurological toxicity G3-4 in 2 pts. Conclusions: In conclusion, our data suggest that the association of RT with TMZ could be considered as a safe and effective strategy to treat GBM in elderly pts. 947 poster HAS COMBINED MODALITY TREATMENT OF GLIOBLASTOMA MULTIFORME CHANGED THE PATTERNS OF PROGRESSION? G. Ryan1 , A. Gunjur2 , Y. Taouk3
to analyse the pattern of progression of GBM in our institution, to guide us in future research and treatment protocols. Materials: Patients with GBM treated as per Stupp protocol between October 2004 and August 2009 at the Peter MacCallum Cancer Centre in Melbourne were reviewed retrospectively. Sixty-eight eligible patients with complete follow-up were identified, of whom 54 were found to have progressed following treatment. MRI scans at progression and original radiotherapy plans were available for 47 patients, and were fused in the radiotherapy planning system and analysed for site(s) of progression. Results: There was an over-representation of males and patients over 60 years in our patient group (66% and 38% respectively) compared to the Stupp study population. Coverage of site(s) of progression by the radiotherapy planning target volume was defined as: central >95% coverage, in-field >80-95%, marginal 20-80%, and out-offield <20%. In our patient group 77% of progressions were central, 15% in-field, 6% marginal and 2% out-of-field. Given the small number of out-of-field recurrences, no temporal trends could be identified. Overall survival for the cohort was 11.6 months, with the 1 and 2 year survival rates 50% and 18%. Conclusions: There is no evidence of an increase in out-of-field progressions in our patient group. The relatively unfavourable demographics of the group may have contributed to this negative result. Further patient data will be collected prospectively to address potential biases, and will be correlated with MGMT methylation status and newer imaging modalities. 948 poster HDR BRACHYTHERAPY IN SKIN CANCERS: TARGET DETERMINATION AND OUTCOME VERSUS CONVENTIONAL RADIOTHERAPY F. Piro1 , R. Siciliano2 , D. Cosentino1 , P. Indrieri1 , L. Ziccarelli1 , P. Ziccarelli1 , L. Marafioti1 1 O SPEDALE M ARIANO S ANTO, Department of Radiotherapy, Cosenza, Italy 2 O SPEDALE M ARIANO S ANTO, Fisica Sanitaria, Cosenza, Italy Purpose: Brachitherapy in skin cancers is a interesting alternative to conventional radiotherapy because offers personalized treatment (also in multisite cancers) and due to new fractionation used in our Center the treatment time is shorter than conventional RT. Otherwise the leterature data for these treatment are few. So we performed this rewiew to evaluate outcome, toxicity and or target missing in patients treated with high dose rate brachytherapy, and with minimum follow up of 60 months. Materials: From August 1999 to September 2010, 118 consecutive pts. with skin cancer (20% squamous cell) (5% with cancer larger >4 cm) were enrolled in this perspective study: HDR treatment consisting of twice-daily fractionation of 350 cGy each, 6 hour apart final dose delivered 49 Gy as esclusive modality or as postoperative treatment for positive margins; as postoperative treatment for squamous cell with clear margins the final dose delivered was 42 Gy. To provide the maximum coverage of the tumor the implants were performed with afterloading spaced (at least 1 cm) catheters embedded in personalized surface molds or interstitial implant both planned with a semi-3-D technique aided by simulator. Radiopaque markers for target definition around the cancer were obbligatory (minimum space 5 mm maximum 10 mm). So implant dosimetry was performed as 100% of prescription at each skin marker. The follow up consisted in clinical examination of each cancer site. We studied the pts. with a minimum follow up of 5 years. For failure cases a rewiew of dosimetry was performed. Results: The eligible pts. were 93, the median follow up 84 months (range 60-96). The cosmetics results were poor in 6% of cases; the only important toxicity was a telangectasia of the skin. The local relapse were 10% (9 cases) especially for bulky cases (6), for 3 of these cases a full-dose reirradiation was performed after the dosimetry rewiew without severe toxicity. The cases of missing target 3% (3 cases). Conclusions: According the letterature this treatment schedule is effective and can be used in skin cancers with a good compliance of the treated pts. (seven days of treatment). HDR brachytherapy is a tecnique with a good learning curve that offers personalized treatments without radiation damage to OAR ( as eye ) in alternative to conventional radiotherapy. Actually this schedule is the standard for skin cancer in our Center. 949 poster
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P ETER M AC C ALLUM C ANCER C ENTRE, Radiation Oncology, Melbourne, Australia 2 P ETER M AC C ALLUM C ANCER C ENTRE, Medical Student, Melbourne, Australia 3 P ETER M AC C ALLUM C ANCER C ENTRE, Biostatistics and Clinical Trials, Melbourne, Australia Purpose: More than 90% of patients with glioblastoma multiforme (GBM) treated with adjuvant radiotherapy alone post-surgery progress within 2cm of the enhancing tumour/surgical cavity, and this information is currently used in defining radiotherapy field margins. With the introduction of combined modality adjuvant treatment incorporating temozolomide chemotherapy (the "Stupp Protocol"), there is emerging literature suggesting that the risk of progression beyond these margins is substantially increased. This study therefore aims
HIGH DOSE RATE BRACHYTHERAPY BOOST FOR RESIDUAL MALIGNANT GLIOMA: CLINICAL RESULTS FROM SINGLE INSTITUTION M. H. Elnaggar1 , H. El Bakry1 , A. Fakhr2 , A. Hassouna1 , M. El-Sayed1 1
E GYPTIAN N ATIONAL C ANCER I NSTITUTE , C AIRO U NIVERSITY, Radiation Oncology Department, Cairo, Egypt 2 FACULTY OF M EDICINE , A IN S HAMS U NIVERSITY, Neurosurgery, Cairo, Egypt Purpose: Investigate the role of additional brachytherapy boost in malignant glioma patients having residual lesion after conventional radiotherapy treatment. Materials: After initial surgical intervention and external beam radiotherapy