Comparison of volumetric modulated arc therapy and intensity-modulated radiotherapy for left-sided whole-breast irradiation using automated planning.

BACKGROUND: Published treatment technique comparisons for postoperative left-sided whole breast irradiation (WBI) with deep-inspiration breath-hold (DIBH) are scarce, small, and inconclusive. In this study, fully automated multi-criterial plan optimization, generating a single high-quality, Pareto-optimal plan per patient and treatment technique, was used to compare for a large patient cohort 1) intensity modulated radiotherapy (IMRT) with two tangential fields and 2) volumetric modulated arc therapy (VMAT) with two small tangential subarcs. MATERIALS AND METHODS: Forty-eight randomly selected patients recently treated with DIBH and 16â€¯× 2.66 Gy were included. The optimizer was configured for the clinical planning protocol. Comparisons between IMRT and VMAT included dosimetric plan parameters, estimated excess relative risks (ERR) for toxicities, delivery times, MUs, and deliverability accuracy at a linac. RESULTS: The automatically generated IMRT and VMAT plans applied in this study were similar or higher in quality than the manually generated clinical plans. For equal PTVin V95% (98.4 ± 0.9%), VMAT had significant advantages compared to IMRT regarding breast dose homogeneity and doses in heart and ipsilateral lung, at the cost of some minor deteriorations for contralateral breast (few cases with larger deteriorations) and lung. Conformality improved from 1.38 to 1.18 (p < 0.001). With VMAT, ERR for major coronary events and ipsilateral lung tumors were reduced by 3% (range: -1-12%) and 16% (range: -3-38%), respectively. MUs and delivery times were higher for VMAT. There were no statistical differences in γ passing rates. CONCLUSION: For WBI in conservative therapy of left-sided breast patients treated with DIBH, VMAT with two tangential subarcs was generally dosimetrically superior to IMRT with two tangential static fields. Results need confirmation by robustness analyses.

A semi-automatic planning technique for whole breast irradiation with tangential IMRT fields.

PURPOSE: To implement a semi-automatic planning technique for whole breast irradiation with two tangential IMRT fields and to test the produced dose distribution against clinical 3DCRT plans, for introducing the technique in clinical practice. METHODS: The Auto-Planning module of the Pinnacle3 (Philips) treatment planning system was used for generating a Treatment Technique on left-sided breast cancer patients treated in free breathing or in deep inspiration breath hold (DIBH) and to right-sided breast cancer patients. The technique was evaluated against 3DCRT clinical plans in terms of dosimetric plan parameters. Plan robustness toward patient displacements was assessed on a subset of patients by inducing shifts to the isocenter. RESULTS: A statistically significant improvement in target coverage and dose homogeneity was observed for autoIMRT. No statistically significant differences were observed for ipsilateral organs, except for the ipsilateral lung in left DIBH, where slightly lower Dmean and V18% are registered for autoIMRT. Slightly higher Dmean doses (although far below the constraints) to contralateral organs were observed for autoIMRT plans. AutoIMRT plans were shown to be as robust as 3DCRT plans toward isocenter shifts, with a maximum decrease in CTV coverage of -2.2% and -2.1% for autoIMRT and 3DCRT, respectively. Average planning times were 40 min for 3DCRT and 6 min for IMRT plans. CONCLUSIONS: The developed autoIMRT technique was proven to be advantageous for target coverage and homogeneity and sufficiently robust towards isocenter displacements. The use of automated planning consistently reduces the planning workload with improvements in plan quality.

End-to-end test for lung SBRT: An Italian multicentric pilot experience.

PURPOSE: Set up a lung SBRT end-to-end (e2e) test and perform a multicentre validation. MATERIAL AND METHODS: A group of medical physicists from four hospitals and the Italian Institute of Ionizing Radiation Metrology designed the present e2e test. One sub-group set up the test, while another tested its feasibility and ease of use. A satisfaction questionnaire was used to collect user feedback. Each participating centre (PC) received the ADAM breathing phantom, a microDiamond detector and radiochromic films. Following the e2e protocol, each PC performed its standard internal procedure for simulating, planning, and irradiating the phantom. Each PC uploaded its planning and treatment delivery data in a shared Google Drive. A single centre analyzed all the data. RESULTS: The e2e test was successfully performed by all PCs. Participants' comments indicated that ADAM was well suited to the purpose and the protocol well described. All PCs performed the test in static and dynamic modes. The ratio between measured and planned point dose obtained by PC1, PC2, PC3, PC4 was: 0.99, 0.96, 1.01 and 1.01 (static track) and 0.99, 1.02, 1.01 and 0.94 (dynamic track). The gamma passing rates (3 % global, 3 mm) between planned and measured dose maps were 98.5 %, 94.0 %, 99.1 % and 94.0 % (static track) and 99.5 %, 96.5 %, 86.0 % and 94.5 % (dynamic track) for PC1, PC2, PC3 and PC4, respectively. CONCLUSIONS: An e2e test for lung SBRT has been proposed and tested in a multicentre framework. The results and user feedback prove the validity of the proposed e2e test.

Concomitant adjuvant chemo-radiation therapy with anthracycline-based regimens in breast cancer: a single centre experience.

PURPOSE: This study was done to evaluate the toxicity related to concurrent radiotherapy and anthracycline (AC)-based chemotherapy in the adjuvant treatment of early breast cancer and to investigate the impact of treatment interruptions and the feasibility of this uncommon therapeutic approach. MATERIALS AND METHODS: From September 2002 to December 2007, 60 patients were treated at our Centre. The mean age at presentation was 48.5 (range 38-64) years. All patients underwent conservative surgery, and radiotherapy to the entire breast (mean dose 50 Gy; range 46-52 Gy). AC-based regimens consisted of four cycles of AC (doxorubicin plus cyclophosphamide) or four cycles of epirubicin (EPI) followed by four courses of cyclophosphamide, methotrexate and 5-fluorouracil (CMF). RESULTS: Concomitant treatment caused acute skin G3 toxicity in 8.9% of patients and one case of G4 toxicity (1.7%). Concerning cardiac assessment, six of the 56 evaluable patients (10.7%) developed an asymptomatic decline of left ventricular ejection fraction >10% and <20% of the baseline value. Radiotherapy was temporarily stopped in 21.3% and chemotherapy in 57.1% of patients. CONCLUSIONS: In our experience, concomitant chemotherapy did not emerge as a significant factor in radiotherapy interruption. Moreover, no severe cardiac events were recorded.

In phantom evaluation of targeting accuracy in MRI-based brain radiosurgery.

PURPOSE: To determine the targeting accuracy of brain radiosurgery when planning procedures employing different MRI and MRI + CT combinations are adopted. MATERIALS AND METHOD: A new phantom, the BrainTool, has been designed and realized to test image co-registration and targeting accuracy in a realistic anatomical situation. The phantom was created with a 3D printer and materials that mimic realistic brain MRI and CT contrast using a model extracted from a synthetic MRI study of a human brain. Eight markers distributed within the BrainTool provide for assessment of the accuracy of image registrations while two cavities that host an ionization chamber are used to perform targeting accuracy measurements with an iterative cross-scan method. Two procedures employing 1.5 T MRI-only or a combination of MRI (taken with 1.5 T or 3 T scanners) and CT to carry out Gamma Knife treatments were investigated. As distortions can impact targeting accuracy, MR images were preliminary evaluated to assess image deformation extent using GammaTool phantom. RESULTS: MR images taken with both scanners showed average and maximum distortion of 0.3 mm and 1 mm respectively. The marker distances in co-registered images resulted below 0.5 mm for both MRI scans. The targeting mismatches obtained were 0.8 mm, 1.0 mm and 1.2 mm for MRI-only and MRI + CT (1,5T and 3 T), respectively. CONCLUSIONS: Procedures using a combination of MR and CT images provide targeting accuracies comparable to those of MRI-only procedures. The BrainTool proved to be a suitable tool for carrying out co-registration and targeting accuracy of Gamma Knife brain radiosurgery treatments.

Automatic VMAT technique to treat glioblastoma: A two years' experience.

PURPOSE: The present work aims to guide the physicist in order to start automated planning for the VMAT treatment of glioblastoma multiforme (GBM) by giving a recipe that was set up and tested during a long-term (two years) evaluation. METHODS: An automatic technique in AutoPlanning module of the Pinnacle3 (Philips Medical Systems, Fitchburg, WI) treatment planning system was created and validated by comparing dose distributions of automatic plans (APs) and manual plans (MPs) and by performing a blind AP-MP comparison on a cohort of 20 patients. Automatic technique was then applied to 145 patients and failures were recorded i.e. the number of times for which dose distributions produced by the automatic module were not suitable for treatment. RESULTS: Each of the 20 APs considered in the validation step was clinically acceptable and proved to be better (15 cases) or equal (5 cases) respect to MPs. A statistically significant improvement in brain stem, optic pathways, cochleae, pituitary gland and scalp sparing was observed for APs, while no statistically significant differences were recorded in target coverage or plan parameters. For only 5 cases out of the 145 plans the operator intervention was needed in order to obtain a clinical acceptable plan, while for the remaining 140 plans the automatic created solution was suitable. CONCLUSIONS: A straightforward automatic procedure has been created and tested in our clinic. The AutoPlanning technique proposed represents a reliable tool to improve treatment planning efficiency and the recipe, here presented, could be simply imported to every radiotherapy center.

TomoTherapy treatments of multiple brain lesions: an in-phantom accuracy evaluation.

Aim of the present study was to evaluate the accuracy which can be obtained with helical TomoTherapy® (HT, Accuray) systems in the case of multiple intracranial targets treatments. Set-up accuracy was measured, for different registration options and MegaVoltage CT (MVCT) slice thickness, by applying known misalignments to an ad-hoc developed phantom. End-to-end (E2E) tests were performed to assess the delivery accuracy in phantoms containing multiple targets by using radiochromic films: measured dose distribution centroids were compared with physical and calculated target positions on axial and coronal planes. A Gamma index analysis was carried out on planned and measured planar dose maps. The bone and tissue algorithm with the fine MVCT reconstruction grid gave the best results among the automatic options. The most accurate registration modality resulted to be the manual one with a sub-voxel accuracy shifts and a capability in the detection of rotations within 0.3°. For the E2E along the coronal plane (six targets), a mean deviation between measured dose distribution centroids and physical barycenters of 0.6 mm (range 0.1 mm-1.3 mm) was observed. Along the axial plane (five targets), a mean deviation of 1.2 mm (range 0.7 mm-2.1 mm) was found for the centroids shifts. Gamma index (5%, 1 mm, local) passing rates higher than 87.5% between planned and delivered dose distributions were measured. These results demonstrate that multiple brain lesion HT treatments are feasible with an accuracy at least comparable to frameless linac-based delivery, when a set-up capable to assure angular corrections and a reliable patient immobilization is employed.

An intercomparison between film dosimetry and diode matrix for IMRT quality assurance.

The evaluation of the agreement between measured and calculated dose plays an essential role in the quality assurance (QA) procedures for intensity modulated radiation therapy (IMRT). Film dosimetry has been widely adopted for this purpose due to excellent film characteristics in terms of spatial resolution; unfortunately, it is a time-consuming procedure and requires great care if film has to be used as an absolute dosimeter. If this is not the case, then an independent ionimetric measurement is mandatory to assess the absolute dose agreement. Arrays of detectors are now replacing films for routine IMRT QA, since they permit very simple verification procedures. They show excellent characteristics in terms of linearity, repeatability, and independence of the response from the dose rate, but at the same time present a poor spatial resolution, due to the limited number of detectors available. In our institution, a diode matrix (MapCHECK, provided by Sun Nuclear) is adopted for routine QA. The aim of this work is to compare the performances of absolute film dosimetry with this matrix in QA procedures and to investigate the origin of possible discrepancies between the two methods. The results we present show a very good agreement between the two detectors when used to assess the mean dose deviation between calculated and measured doses (in both cases 0.2%). If the y matrix method is adopted, MapCHECK response shows a slightly better agreement with computed dose distribution than film dosimetry (mean percentage of points satisfying the constraint y < or = 1: 96% versus 94%). This difference is shown not to depend on the different field sampling, but on the detectors' capabilities. Moreover, we show that the diode matrix is able to identify eventual delivery errors as well as film. Our conclusion is that the diode matrix may effectively replace both film dosimetry and ionimetric measurements in routine IMRT QA.

Role of radiotherapy boost in women with ductal carcinoma in situ: a single-center experience in a series of 389 patients.

BACKGROUND: The use of adjuvant radiotherapy in ductal carcinoma in situ is accepted by most radiation oncologists worldwide; the role of a boost on the tumor bed is however more controversial. MATERIALS AND METHODS: We reviewed our Institute experience in DCIS treatment, focusing on main prognostic factors and impact of radiation boost on local relapse. A total of 389 patients treated between 1990 and 2007 were retrospectively analyzed. All patients received adjuvant radiotherapy after breast-conserving surgery for a median dose of 50 Gy; 190 patients (48.8%) received and additional radiation boost on the tumor bed. RESULTS: At a mean follow up of 7.7 years, we recorded 26 local recurrence (6.7%). Concerning local relapse-free survival, at Cox regression univariate analyses <1 mm surgical margins (p < 0.0001) and young age (p = 0.01) emerged as significant unfavorable prognostic factors. At multivariate analysis Cox regression model, surgical margins (p < 0.001) and radiation boost (p = 0.014) resulted as the significant independent predictors of recurrence. CONCLUSIONS: Our experience showed the negative prognostic impact of surgical margins <1 mm and the protective role of radiation boost on LR rate. Anyway, results from ongoing prospective Phase III studies are strongly necessary to better identify high-risk DCIS patients.

The impact of young age on breast cancer outcome.

AIMS: We conducted a retrospective analysis in order to evaluate the impact of age on women aged less than 35 years affected by breast cancer. MATERIALS AND METHODS: Between January 1972 and December 2006, 346 patients aged less than 35 years underwent adjuvant treatment at Florence University. The mean age of the patient population was 32 years (range 22-35): 76 patients were under 30 years old, the remaining were above 30 years old. RESULTS: In our series, 215 patients received adjuvant radiotherapy to whole breast after conservative surgery, 131 patients underwent mastectomy without subsequent radiation therapy and 323 patients had lymphadenectomy; 191 patients received adjuvant chemotherapy, 73 with anthracycline-containing regimen. With a median time of 2.5 years (range 6 months to 27.6 years) local relapses were observed in 67 cases (19.4%). At the multivariate analysis of local disease-free survival, ductal and ductal plus lobular histotypes, having more than 3 positive nodes, and age emerged as independent significant relapse predictors (p=0.018, p=0.0005, p=0.003 and p=0.024, respectively). For the DSS analysis, the median follow-up was 6.8 years (range 0.6-36.7 years). At the multivariate analysis, age (p=0.0038), positive nodes (p=0.0035) and distant metastases (p<0.0001) resulted to be independent death predictors. Patients younger than 30 had a worse prognosis. At the univariate analysis also local relapse resulted to be statistically significant (p=0.0004). CONCLUSIONS: Anthracycline-based chemotherapy seems to improve the outcome of these patients. However, there is an urgent need for tailored treatment investigations within the framework of randomized, controlled clinical trials.

The impact of young age on breast cancer outcome.

AIMS: We conducted a retrospective analysis in order to evaluate the impact of age on women aged less than 35 years affected by breast cancer. MATERIALS AND METHODS: Between January 1972 and December 2006, 346 patients aged less than 35 years underwent adjuvant treatment at Florence University. The mean age of the patient population was 32 years (range 22-35): 76 patients were under 30 years old, the remaining were above 30 years old. RESULTS: In our series, 215 patients received adjuvant radiotherapy to whole breast after conservative surgery, 131 patients underwent mastectomy without subsequent radiation therapy and 323 patients had lymphadenectomy; 191 patients received adjuvant chemotherapy, 73 with anthracycline-containing regimen. With a median time of 2.5 years (range 6 months to 27.6 years) local relapses were observed in 67 cases (19.4%). At the multivariate analysis of local disease-free survival, ductal and ductal plus lobular histotypes, having more than 3 positive nodes, and age emerged as independent significant relapse predictors (p = 0.018, p = 0.0005, p = 0.003 and p = 0.024, respectively). For the DSS analysis, the median follow-up was 6.8 years (range 0.6-36.7 years). At the multivariate analysis, age (p = 0.0038), positive nodes (p = 0.0035) and distant metastases (p < 0.0001) resulted to be independent death predictors. Patients younger than 30 had a worse prognosis. At the univariate analysis also local relapse resulted to be statistically significant (p = 0.0004). CONCLUSIONS: Anthracycline-based chemotherapy seems to improve the outcome of these patients. However, there is an urgent need for tailored treatment investigations within the framework of randomized, controlled clinical trials.