Risk of breast fibrosis following irradiation using a breast-specific SBRT system compared with conventional APBI.

2011 ◽  
Vol 29 (27_suppl) ◽  
pp. 116-116
Author(s):  
Z. A. Husain ◽  
S. J. Feigenberg ◽  
E. Nichols ◽  
J. Zhang ◽  
C. Yu ◽  
...  
Keyword(s):  
Normal Tissue Complication Probability ◽  
Tumor Location ◽  
Imaging Studies ◽  
Ipsilateral Breast ◽  
Treatment Plans ◽  
Prescription Dose ◽  
Irradiation Unit ◽  
Immobilization Device ◽  
Biologically Equivalent Dose ◽  
Breast Dosimetry

116 Background: To determine the dosimetric characteristics and risk of breast fibrosis using a normal tissue complication probability (NTCP) model in conjunction with a novel preoperative stereotactic radiotherapy system called the GammaPod. Results are compared with linac based post-lumpectomy APBI plans for the same cohort. Methods: The GammaPod breast SBRT system consists of a Co-60 irradiation unit in combination with an immobilization device with embedded fiducials. Eight patients were enrolled in an IRB-approved protocol and underwent CT scans in the prone position with breast immobilization. A preoperative target (GTV) was synthesized to match the tumor location and volume reported in imaging studies obtained prior to surgery (0.3-2.4 cc). The GTV was expanded by 1.5 cm to create a CTV, and a PTV was created using an additional 0.3 cm margin. The PTV was prescribed 25.5 Gy in 3 fx, which is radiobiologically equivalent to conventional APBI doses of 38.5 Gy in 10 fx. Following the radioablative experience in NSCLC, we also planned to deliver 60.0 Gy to the GTV+0.3 cm as a simultaneous boost in conjunction with the 25.5 Gy PTV prescription dose. For comparison, linac-based treatment plans were created for the same cohort following NSABP B-39 guidelines. Whole breast dosimetry was analyzed in terms of biologically equivalent dose (BED) and Lyman NTCP analysis was performed. Results: The volume of ipsilateral breast receiving 10, 20, 50, and 100% of the prescribed dose was substantially smaller in GammaPod vs. APBI plans, with cohort averages of 19.3, 13.0, 7.1 and 4.0% vs. 75.8, 67.3, 48.1 and 27.6% respectively (p<0.001). Even though the PTV equivalent uniform BED (EUD) was substantially higher in GammaPod plans (87.9 Gy vs. 57.3 Gy), the ipsilateral breast EUD was still smaller in these plans, 18.9 ± 5.0 Gy vs. 47.2 ± 3.2 Gy (p<0.001). Corresponding NTCP predictions for breast fibrosis rates following GammaPod and APBI treatments were 0.2 ± 0.1% vs. 2.8 ± 0.8% (p<0.001), respectively. Conclusions: The GammaPod system improves upon traditional post-lumpectomy linac-based APBI by decreasing dose to the ipsilateral breast as well as the predicted rates of breast fibrosis.

Clinical introduction of Monte Carlo treatment planning: A different prescription dose for non-small cell lung cancer according to tumor location and size

2010 ◽  
Vol 96 (1) ◽  
pp. 55-60 ◽  
Author(s):  
Noëlle C. van der Voort van Zyp ◽  
Mischa S. Hoogeman ◽  
Steven van de Water ◽  
Peter C. Levendag ◽  
Bronno van der Holt ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Monte Carlo ◽  
Small Cell Lung Cancer ◽  
Treatment Planning ◽  
Cell Lung Cancer ◽  
Tumor Location ◽  
Small Cell ◽  
Small Cell Lung ◽  
Prescription Dose

scholarly journals Gamma Knife Radiosurgery for Trigeminal Neuralgia: A Comparison of Dose Protocols

2019 ◽  
Vol 9 (6) ◽  
pp. 134 ◽  
Author(s):  
Warren Boling ◽  
Minwoo Song ◽  
Wendy Shih ◽  
Bengt Karlsson
Keyword(s):  
Patient Satisfaction ◽  
Pain Relief ◽  
Trigeminal Neuralgia ◽  
Gamma Knife Radiosurgery ◽  
Sensory Disturbance ◽  
Kaplan Meier ◽  
Facial Numbness ◽  
Satisfaction With Treatment ◽  
Treatment Plans ◽  
Prescription Dose

Purpose: A variety of treatment plans including an array of prescription doses have been used in radiosurgery treatment of trigeminal neuralgia (TN). However, despite a considerable experience in the radiosurgical treatment of TN, an ideal prescription dose that balances facial dysesthesia risk with pain relief durability has not been determined. Methods and Materials: This retrospective study of patients treated with radiosurgery for typical TN evaluates two treatment doses in relation to outcomes of pain freedom, bothersome facial numbness, and patient satisfaction with treatment. All patients were treated with radiosurgery for intractable and disabling TN. A treatment dose protocol change from 80 to 85 Gy provided an opportunity to compare two prescription doses. The variables evaluated were pain relief, treatment side-effect profile, and patient satisfaction. Results: Typical TN was treated with 80 Gy in 26 patients, and 85 Gy in 37 patients. A new face sensory disturbance was reported after 80 Gy in 16% and after 85 Gy in 27% (p = 0.4). Thirteen failed an 80 Gy dose whereas seven failed an 85 Gy dose. Kaplan–Meier analysis found that at 29 months 50% failed an 80 Gy treatment compared with 79% who had durable pain relief after 85 Gy treatment (p = 0.04). Conclusion: The 85 Gy dose for TN provided a more durable pain relief compared to the 80 Gy one without a significantly elevated occurrence of facial sensory disturbance.

scholarly journals PS1 - 189 A Universal Predictive Model for Dose Fall-Off in MLC-Based Stereotactic Brain Radiosurgery

2016 ◽  
Vol 43 (S4) ◽  
pp. S8-S8
Author(s):  
M. Ruschin ◽  
A. Sahgal ◽  
H. Soliman ◽  
B. Chugh ◽  
S. Myrehaug ◽  
...  
Keyword(s):  
Clinical Decision Making ◽  
Treatment Plan ◽  
Clinical Decision ◽  
Target Volume ◽  
Adjustment Factor ◽  
Ongoing Work ◽  
Toxicity Risk ◽  
Treatment Plans ◽  
Prescription Dose ◽  
Prediction Band

Predictive modeling of dose fall-off in radiosurgery could assist in clinical decision-making when prescribing a treatment plan with minimized toxicity risk. The purpose of this study is to develop a predictive dose fall-off model. Materials/Methods: We retrospectively reviewed treatment plans from 257 patients (365 lesions) with total doses ranging from 20 to 35Gy in 5 fractions. For each plan, we measured both total volume of the external contour (EXT) and BrainMinusPTV (BMP) receiving P=20% to P=80% of the prescription dose. The model has form y=Fa(PTV)b+/-delta. y=volume of EXT or BMP (cc’s); a and b are curve-fitting coefficients; PTV=total planning target volume (cc’s); F is an adjustment factor (>1) to account for number of targets; delta is the 95% prediction band. F, a, b, and delta were modeled such that dose-fall can be forecast for any PTV and dose level. Results: The model coefficients were as follows: Coefficient EXT BMP a 19927(100×P)exp(-2) 17122(100×P)exp(-2) b 0.42(100×P)exp(0.17) 0.63 F -0.0156×(100×P)+2.5517 delta 384467×(100×P)exp(-2.3159) The table can be used to determine the model for any P from 20% to 80%. Example: the EXT receiving 50%, P=0.5, a=8.0, b=0.82, F=1.8, delta=45. Thus, EXT-50=8(PTV0.82) or 1.8×8(PTV0.82) for 1-3 or >3 targets, respectively,+/-45cc’s. The model was verified against published values of dose fall-off from linacs. Conclusion: A predictive dose fall-off model was generated for linac-based radiosurgery. The model can be used for quality assurance or for inter-institutional comparisons. Ongoing work is being conducted to extend the model to a SRS cones system.

scholarly journals Impact of respiratory motion on breast tangential radiotherapy using the field-in-field technique compared to irradiation using physical wedges

2014 ◽  
Vol 48 (1) ◽  
pp. 94-98 ◽  
Author(s):  
Hidekazu Tanaka ◽  
Shinya Hayashi ◽  
Kazuhiro Ohtakara ◽  
Hiroaki Hoshi
Keyword(s):  
Respiratory Motion ◽  
Early Stage ◽  
Free Breathing ◽  
Ct Images ◽  
Data Set ◽  
Acceptable Range ◽  
Treatment Plans ◽  
Prescription Dose ◽  
Ct Data ◽  
The Impact

Abstract Background. This study aimed to evaluate whether the field-in-field (FIF) technique was more vulnerable to the impact of respiratory motion than irradiation using physical wedges (PWs). Patients and methods. Ten patients with early stage breast cancer were enrolled. Computed tomography (CT) was performed during free breathing (FB). After the FB-CT data set acquisition, 2 additional CT scans were obtained during a held breath after light inhalation (IN) and light exhalation (EX). Based on the FB-CT images, 2 different treatment plans were created for the entire breast for each patient and copied to the IN-CT and EX-CT images. The amount of change in the volume of the target receiving 107%, 95%, and 90% of the prescription dose (V107%, V95%, and V90%, respectively), on the IN-plan and EX-plan compared with the FB-plan were evaluated. Results. The V107%, V95%, and V90% were significantly larger for the IN-plan than for the FB-plan in both the FIF technique and PW technique. While the amount of change in the V107% was significantly smaller in the FIF than in the PW plan, the amount of change in the V95% and V90% was significantly larger in the FIF plan. Thus, the increase in the V107% was smaller while the increases in the V95% and V90% were larger in the FIF than in the PW plan. Conclusions. During respiratory motion, the dose parameters stay within acceptable range irrespective of irradiation technique used although the amount of change in dose parameters was smaller with FIF technique.

scholarly journals Options for Combining Altered Fractionation with IMRT

2008 ◽  
Vol 7 (6) ◽  
pp. 457-461 ◽  
Author(s):  
Aaron M. Allen ◽  
Luciant Wolfsberger ◽  
Roy B. Tishler ◽  
Laurence E. Court
Keyword(s):  
Hot Spots ◽  
Imrt Plan ◽  
Planning Time ◽  
Once Daily ◽  
Integral Dose ◽  
Altered Fractionation ◽  
Time To Completion ◽  
Concomitant Boost ◽  
Treatment Plans ◽  
Prescription Dose

We set out to investigate IMRT-based concomitant boost. Eight patients with stage III/IV squamous cell carcinoma of the head and neck treated with once daily with chemoradiotherapy at the Dana-Farber/Brigham and Women's Hospital had their treatment plans reviewed with IRB approval. Each case was replanned for treatment with a a concomitant boost regimen. Plans delivered 1.9 Gy in 30 fractions to 57 Gy with a boost of 1.5 Gy in 10 fractions for a total dose of 72 Gy. The boost was planned with both IMRT and 3-D conformal, to compare the two techniques. For each patient, both plans (IMRT-IMRT and IMRT-3DCRT) were evaluated for target and avoidance coverage, monitor units and integral dose. Finally, we evaluated the plans for time to completion. The IMRT-IMRT and IMRT-3-DCRT techniques were equivalent for target coverage. 100% coverage of the GTV and PTV was achieved with 97% of the prescription dose. Hot spots were seen 104% to 108% with IMRT-IMRT plan and from 102–111% with the IMRT-3DCRT plans. The IMRT-IMRT boost had double the monitor units as the 3-DCRT boosts. When the total monitor units from both the initial and boost portions of the plans were e combined there was not a significant differnce. There was a slight increase in integral dose with the IMRT-IMRT plans of mean 3.8%. Planning time was increased for the 3-DCRT boost as opposed to the IMRT boost (mean 3.5 hours vs. 1.5 hours). More time was needed for quality assurance of the IMRT-IMRT plans (3.0 hours vs. 1.5 hours for IMRT-3-DCRT). We found that both IMRT-based concomitant-boost strategies are achievable and produce good dosimetric results.

scholarly journals RADI-15. CLUSTERING AND GROUPING OF BRAIN METS IN RADIOSURGERY TREATMENTS

2019 ◽  
Vol 1 (Supplement_1) ◽  
pp. i24-i24
Author(s):  
Khaled Salah ◽  
John Mckenna ◽  
Gabor Jozsef ◽  
Jonathan Knisely
Keyword(s):  
Maximum Dose ◽  
Treatment Plan ◽  
Normal Brain ◽  
Dose Distributions ◽  
Treatment Plans ◽  
Prescription Dose ◽  
Clustering Approach ◽  
Centers Of Mass ◽  
Dose Volumes ◽  
Single Isocenter

Abstract INTRODUCTION: Radiosurgical treatment of numerous lesions in the brain with ‘single-isocenter’ radiosurgery on a linac often requires using multiple isocenters. With our TPS (Elements, Brainlab) multiple plans need to be generated for each set of lesions, and a sum plan calculated. We investigated how to distribute multiple lesions into two groups for two isocenters to achieve a good summed dose distribution. METHODS: The DICOM RS file is exported and the PTV data is extracted by a MATLAB program that calculates the convex hulls, estimated radii, and the centers of mass for each PTV. Two approaches were tried: (1) Lesions close to each other (closer than a certain limit) are put in different groups and (2) Create clusters by kMeans clustering, which allows close lesions but the groups are distant from each other. MATLAB programs were written for all approaches. Treatment plans were generated for three patients (20, 13, 15 lesions) using each method and compared with the actual treatment plan used to treat the patient based on the intuitive grouping of lesions by the planners. Dose maximums outside the lesions, and volumes in the normal tissue exceeding 75, 50 and 25% of the prescription dose were evaluated. RESULTS AND DISCUSSION: The coverage of all lesions for all plans were 95% of the prescription dose. The first approach allowed lowering the maximum dose between lesions, but with summing dose distributions this advantage disappeared. The maximum dose and the 75, 50 and 25% dose volumes were also all worse than in plans generated by experienced planners and higher normal brain doses are delivered if closely spaced lesions are separated into different isocenters for treatment. However, the clustering approach resulted in the same or better values of these same parameters, i.e. improved dose distributions over the dosimetrist’s intuitively chosen separation.

Using FFF beams to improve the therapeutic ratio of lung SBRT

2020 ◽  
pp. 1-7
Author(s):  
Oleg N. Vassiliev ◽  
Christine B. Peterson ◽  
Joe Y. Chang ◽  
Radhe Mohan
Keyword(s):  
At Risk ◽  
Early Stage ◽  
Organs At Risk ◽  
Normal Tissue Complication Probability ◽  
Planning System ◽  
Treatment Planning System ◽  
Early Stage Lung Cancer ◽  
Therapeutic Ratio ◽  
Treatment Plans ◽  
Flattening Filter

Abstract Aim: The aim of this study was to investigate the extent to which lung stereotactic body radiotherapy (SBRT) treatment plans can be improved by replacing conventional flattening filter (FF) beams with flattening filter-free (FFF) beams. Materials and methods: We selected 15 patients who had received SBRT with conventional 6-MV photon beams for early-stage lung cancer. We imported the patients’ treatment plans into the Eclipse 13·6 treatment planning system, in which we configured the AAA dose calculation model using representative beam data for a TrueBeam accelerator operated in 6-MV FFF mode. We then created new treatment plans by replacing the conventional FF beams in the original plans with FFF beams. Results: The FFF plans had better target coverage than the original FF plans did. For the planning target volume, FFF plans significantly improved the D98, D95, D90, homogeneity index and uncomplicated tumour control probability. In most cases, the doses to organs at risk were lower in FFF plans. FFF plans significantly reduced the mean lung dose, V10, V20, V30, and normal tissue complication probability for the total lung and improved the dosimetric indices for the ipsilateral lung. For most patients, FFF beams achieved lower maximum doses to the oesophagus, heart and the spinal cord, and a lower chest wall V30. Conclusions: Compared with FF beams, FFF beams achieved lower doses to organs at risk, especially the lung, without compromising tumour coverage; in fact, FFF beams improved coverage in most cases. Thus, replacing FF beams with FFF beams can achieve a better therapeutic ratio.

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