24 research outputs found
Patient reported upper gastro-intestinal symptoms associated with fractionated image-guided conformal radiotherapy for metastatic spinal cord compression
Background and purpose
Palliative radiotherapy is given to sustain or improve quality of life for patients with advanced cancer. Radiotherapy may however result in symptomatic side effects, which may affect the patient negatively. This prospective longitudinal study of 30 patients aimed at investigating the incidence and severity of early toxicity, particularly focusing on dysphagia, esophagitis and mucositis, following fractionated radiotherapy for cervical and thoracic metastatic spinal cord compression (MSCC), as well as determining the relationship between esophageal dose and early upper gastro-intestinal symptoms.
Materials and methods
Thirty patients receiving radiotherapy of 3Gyx10 for MSCC were included in the study. Patients were assessed for a total of 7âŻweeks from onset of radiotherapy using the Edmonton Symptom Assessment System (ESAS) questionnaire. Upper gastro-intestinal symptoms and severity were assessed from the tenth and eleventh question section of the ESAS questionnaire of âother problemsâ and how much this affected them. The relationships between the mean and maximum esophageal doses and incidence of dysphagia, esophagitis or mucositis were estimated and dose response curves determined.
Results
Eleven patients reported esophageal symptoms (average duration eleven days, range 1â18âŻdays). Incidence of esophageal toxicity in patients treated at Th8 or above was 79 percent, while no patients treated below Th8 reported any symptoms (pâŻ<âŻ0.001). Furthermore, 2 out of 3 patients irradiated at the cervical region reported substantial changes in taste sensation.
Risk of symptoms correlated with both mean and maximum esophageal dose and may be a useful tool in planning radiotherapy for MSCC, potentially reducing early upper gastro-intestinal toxicity
Predicting Visual Acuity Deterioration and Radiation-Induced Toxicities after Brachytherapy for Choroidal Melanomas
Ruthenium-106 (Ru-106) brachytherapy is an established modality for eye-preserving treatment of choroidal melanoma. To achieve optimal treatment outcomes, there should be a balance between tumour control and the risk of healthy tissue toxicity. In this retrospective study, we examined normal tissue complication probability (NTCP) for visual acuity deterioration and late complications to aid the understanding of dose-dependence after Ru-106 treatments. We considered consecutive patients diagnosed with choroidal melanoma and primarily treated at a single institution from 2005â2014. Treatment plans were retrospectively recreated using dedicated software and image guidance to contour the tumour and determine the actual plaque position. Dose distributions were extracted from each plan for all relevant anatomical structures. We considered visual acuity deterioration and late complications (maculopathy, optic neuropathy, ocular hypertension, vascular obliteration, cataract and retinal detachment). Lasso statistics were used to select the most important variables for each analysis. Outcomes were related to dose and clinical characteristics using multivariate Cox regressions analysis. In total, 227 patients were considered and 226 of those were eligible for analysis. Median potential follow-up time was 5.0 years (95% CI: 4.5â6.0). Visual acuity deterioration was related to optic disc-tumour distance and dose metrics from the retina and the macula, with retina V10Gy showing the strongest correlation. Macula V10Gy was the only dose metric impacting risk of maculopathy, while optic disc-tumour distance also proved important. Optic disc V50Gy had the largest impact on optic neuropathy along with optic disc-tumour distance. Optic disc V20Gy was the only variable associated with vascular obliteration. Lens D2% had the largest impact on the risk of cataract along with older age and the largest base dimension. We found no variables associated with the risk of ocular hypertension and retinal detachment. Visual acuity deterioration and most late complications demonstrated dependence on dose delivered to healthy structures in the eye after Ru-106 brachytherapy for choroidal mela
Isolating the effects of precipitation, soil conditions, and litter quality on leaf litter decomposition in lowland tropical forests
A dosimetric phantom study of dose accuracy and build-up effects using IMRT and RapidArc in stereotactic irradiation of lung tumours
3D imageâguided treatment planning for Rutheniumâ106 brachytherapy of choroidal melanomas
Background
Current standard treatment procedures for Rutheniumâ106 (Ruâ106) brachytherapy for choroidal melanomas do not use 3D imageâguided treatment planning. We evaluated the potential impact of introducing 3D treatment planning and quantified the theoretical clinical benefits in terms of tumour control probability (TCP) and normal tissue complication probability (NTCP).
Materials and methods
Treatment plans for thirtyâtwo patients were optimized using 3D imageâguided treatment planning and compared to the original 2D clinical plans. Optimization of plans was done in an imageâbased treatment planning system by optimizing the plaque position and treatment time such that the entire tumour received the prescribed dose of 100 Gy. TCP and NTCP for 2D clinical plans and optimized 3D imageâguided plans were estimated from published outcome prediction models and compared within patients using Wilcoxon signedârank test.
Results
The median minimum tumour dose (D99%) for 2D clinical plans was 93 Gy (range: 23â158 Gy), corresponding to 5âyear TCP of 75% (IQR 61â86%), while median tumour D99% for optimized 3D imageâguided plans was 115 Gy (range 103â141 Gy), corresponding to TCP of 82% (IQR 80â84%). This was a statistically significant increase in estimated TCP (median increase in TCP 8% (IQR: â5â23, p = 0.006). While the dose to normal tissue increased somewhat, there was no significant change in NTCP.
Conclusion
3D treatment planning theoretically allows for improved tumour dose delivery for Ruâ106 brachytherapy of choroidal melanomas, resulting in a significant increase in expected tumour control compared to traditional approaches using 2D calculations. The deliverability of optimized plans, and potential increased risk of late complications, will have to be confirmed in future clinical studies
Tumour control probability after Ruthenium-106 brachytherapy for choroidal melanomas
Purpose: Ruthenium-106 (Ru-106) brachytherapy is a common eye-preserving treatment for choroidal melanomas. However, a dose-response model describing the relationship between the actual delivered tumour dose and tumour control has, to the best of our knowledge, not previously been quantified for Ru-106 brachytherapy; we aimed to rectify this.
Material and methods: We considered consecutive patients with primary choroidal melanomas, treated with Ru-106 brachytherapy (2005â2014). Dosimetric plans were retrospectively recreated using 3D image-guided planning software. Pre-treatment fundus photographies were used to contour the tumour; post-treatment photographies to determine the accurate plaque position. Patient and tumour characteristics, treatment details, dose volume histograms, and clinical outcomes were extracted. Median follow-up was 5.0âyears. The relationship between tumour dose and risk of local recurrence was examined using multivariate Cox regression modelling, with minimum physical tumour dose (D99%) as primary dose metric.
Results: We included 227 patients with median tumour height and largest base dimension of 4âmm (range 1â12, IQR 3â6) and 11âmm (range 4â23, IQR 9â13). The estimated 3 year local control was 82% (95% CI 77â88). Median D99% was 105âGy (range 6â783, IQR 65â138); this was the most significant factor associated with recurrence (pâ<â.0001), although tumour height, combined TTT and Ru-106 brachytherapy, and sex were also significant. The hazard ratio (HR) for a 10âGy increase in D99% was 0.87 (95% CI 0.82â0.93). Using biological effective dose in the model resulted in no substantial difference in dose dependence estimates. Robustness cheques with D1â99% showed D99% to be the most significant dose metric for local recurrence.
Conclusion: The minimum tumour dose correlated strongly with risk of tumour recurrence, with 100âGy needed to ensure at least 84% local control at 3 years
A step and shoot intensity modulated technique for total body irradiation.
INTRODUCTION: Total body irradiation (TBI) is a part of the conditioning regimen for bone marrow transplant.At the Royal Marsden (Sutton, UK) and Rigshospitalet (Copenhagen, Denmark), we introduced a step and shoot IMRT (SS IMRT) technique for TBI. This technique requires no equipment other than that used to deliver other external beam radiation. In this paper, we describe this technique and report on data from the two clinics. MATERIALS AND METHODS: The patients were positioned supine, supported by vacuum bag(s). The entire body of the patients were CT scanned with 5âŻmm slices. Multiple multi-leaf collimator (MLC) defined fields were used.In-vivo dosimetry was performed at the Royal Marsden for 113 patients.Calculated doses for 18 adult and 4 paediatric patients from Rigshospitalet were extracted. RESULTS: The in-vivo data from the Royal Marsden showed that the mean TLD measured dose difference was -1.9% with a standard deviation of 4.5%.SS IMRT plans for 22 patients from Rigshospitalet resulted in mean doses to the brain, lungs and kidneys all within the range of 11.1-11.8âŻGy, while the V(12âŻGy) was below 5% for the brain, 2% for the lungs and 0% for the kidneys. DISCUSSION: SS IMRT is feasible for TBI and can deliver targeted doses to the organs at risk
Ultrasonic mirror image from ruthenium plaque facilitates calculation of uveal melanoma treatment dose
Background/aims To present a new method to determine dose depth and the distance from the concave side of the plaque to the tumour base in patients with uveal melanoma treated with ruthenium-106 based on ultrasonic mirror image. Methods We used the mirror image associated with ultrasound during plaque brachytherapy to determine intraobserver reproducibility and interobserver agreement between two surgeons. 230 eyes with primary uveal melanoma were included in a retrospective analysis to determine the distance from the plaque to the tumour base using ultrasound. A phantom study was used to illustrate the effects on radiation dose to apex of the tumour when the dose depth was incorrectly determined. Doses to apex of the tumour were determined using Plaque Simulator. Results The intraobserver variation in dose depth measurement with plaque was significantly lower than for measures without plaque (p<0.001). Agreement between the surgeons was better with a plaque in place. Distances from the plaque to the tumour base were distributed with mean=0.99 (median: 1, range: 0.1â2.9â
mm). From the phantom study, it was clear that the tumour did not receive the prescribed 100â
Gy if the dose depth was incorrectly determined. Conclusions The dose depth in patients with uveal melanoma must be measured accurately for correct calculation of the radiation dose to the apex of the tumour. Repeated in vivo and in vitro ultrasound measurements of dose depth showed higher variance than measurements using the mirror image produced from a ruthenium plaque. Using the mirror image thus help to improve the dose calculation