Safe reirradiation relies on assessment of cumulative doses to organs at risk (OARs) across multiple treatments. Different clinical pathways can result in inconsistent estimates. Here, we quantified the consistency of cumulative dose to OARs across multi-centre clinical pathways. We provided DICOM planning CT, structures and doses for two reirradiation cases: head & neck (HN) and lung. Participants followed their standard pathway to assess the cumulative physical and EQD2 doses (with provided α/β values), and submitted DVH metrics and a description of their pathways. Participants could also submit physical dose distributions from Course 1 mapped onto the CT of Course 2 using their best available tools. To assess isolated impact of image registrations, a single observer accumulated each submitted spatially mapped physical dose for every participating centre. Cumulative dose assessment was performed by 24 participants. Pathways included rigid (n = 15), or deformable (n = 5) image registration-based 3D dose summation, visual inspection of isodose line contours (n = 1), or summation of dose metrics extracted from each course (n = 3). Largest variations were observed in near-maximum cumulative doses (25.4 - 41.8 Gy for HN, 2.4 - 33.8 Gy for lung OARs), with lower variations in volume/dose metrics to large organs. A standardised process involving spatial mapping of the first course dose to the second course CT followed by summation improved consistency for most near-maximum dose metrics in both cases. Large variations highlight the uncertainty in reporting cumulative doses in reirradiation scenarios, with implications for outcome analysis and understanding of published doses. Using a standardised workflow potentially including spatially mapped doses improves consistency in determination of accumulated dose in reirradiation scenarios.

Our aim was to improve dose distribution to the left breast and to determine the dose received by the ipsilateral lung, heart, contralateral lung and contralateral breast during primary left-sided breast irradiation by using intensity modulated radiotherapy (IMRT) techniques compared to conventional tangential techniques (CTT). At the same time, different beams of IMRT plans were compared to each other in respect to CI, HI and organs at risk (OAR) dose. Conventional early breast cancer treatment consists of lumpectomy followed by whole breast radiation therapy. CTT is a traditional method used for whole breast radiotherapy and includes standard wedged tangents (two opposed wedged tangential photon beams). The IMRT technique has been widely used for many treatment sites, allowing both improved sparing of normal tissues and more conformal dose distributions. IMRT is a new technique for whole breast radiotherapy. IMRT is used to improve conformity and homogeneity and used to reduce OAR doses. Thirty patients with left-sided breast carcinoma were treated between 2005 and 2008 using 6, 18 or mixed 6/18 MV photons for primary breast irradiation following breast conserving surgery (BCS). The clinical target volume [CTV] was contoured as a target volume and the contralateral breast, ipsilateral lung, contralateral lung and heart tissues as organs at risk (OAR). IMRT with seven beams (IMRT7), nine beams (IMRT9) and 11 beams (IMRT11) plans were developed and compared with CTT and among each other. The conformity index (CI), homogeneity index (HI), and doses to OAR were compared to each other. ALL OF IMRT PLANS SIGNIFICANTLY IMPROVED CI (CTT: 0.76; IMRT7: 0.84; IMRT9: 0.84; IMRT11: 0.85), HI (CTT: 1.16; IMRT7: 1.12; IMRT9: 1.11; IMRT11: 1.11), volume of the ipsilateral lung receiving more than 20 Gy (>V20 Gy) (CTT: 14.6; IMRT7: 9.08; IMRT9: 8.10; IMRT11: 8.60), and volume of the heart receiving more than 30 Gy (>V30 Gy) (CTT: 6.7; IMRT7: 4.04; IMRT9: 2.80; IMRT11: 2.98) compared to CTT. All IMRT plans were found to significantly decrease >V20 Gy and >V30 Gy volumes compared to conformal plans. But IMRT plans increased the volume of OAR receiving low dose radiotherapy: volume of contralateral lung receiving 5 and 10 Gy (CTT: 0.0-0.0; IMRT7: 19.0-0.7; IMRT9: 17.2-0.66; IMRT11: 18.7-0.58, respectively) and volume of contralateral breast receiving 10 Gy (CTT: 0.03; IMRT7: 0.38; IMRT9: 0.60; IMRT11: 0.68). The differences among IMRT plans with increased number of beams were not statistically significant. IMRT significantly improved conformity and homogeneity index for plans. Heart and lung volumes receiving high doses were decreased, but OAR receiving low doses was increased.

The aim of our study was the dosimetric and physical evaluation of the CK and IMRT treatment plans for 16 patients with localized prostate cancer. Intensity modulated radiation therapy (IMRT) is one of the recent technical advances in radiotherapy. The prostate is a well suited site to be treated with IMRT. The challenge of accurately delivering the IMRT needs to be supported by new advances such as image-guidance and four-dimensional computed conformal radiation therapy (4DCRT) tomography. CyberKnife (CK) provides real time orthogonal X-ray imaging of the patient during treatment course to follow gold fiducials installed into the prostate and to achieve motion correlation between online acquired X-ray imaging and digital reconstructed radiographs (DRRs) which are obtained from planning computed tomography images by translating and rotating the treatment table in five directions. Sixteen IMRT and CK plans were performed to be compared in terms of conformity (CI), heterogeneity indices (HI), percentage doses of 100% (V100), 66% (V66), 50% (V50), 33% (V33) and 10% (V10) volumes of the bladder and rectum. Dose-volume histograms for target and critical organs, (CI) and indices (HI) and isodose lines were analyzed to evaluate the treatment plans. Statistically significant differences in the percentage rectal doses delivered to V10, V33, and V50 of the rectum were detected in favor of the CK plans (p values; <0.001, <0.001 and 0.019, respectively). The percentage doses for V66 and V100 of the rectum were larger in CK plans (13%, 2% in IMRT and 21%, 3% in CK plans, respectively). Percentage bladder doses for V10 and V33 were significantly lower in CK plans [96% in IMRT vs 48% in CK (p < 0.001) and 34% in IMRT vs 24% in CK (p = 0.047)]. Lower percentage doses were observed for V50, V66 of the bladder for the IMRT. They were 5.4% and 3.45% for IMRT and 13.4% and 8.05% for CK, respectively. Median CI of planning target volume (PTV) for IMRT and CK plans were 0.94 and 1.23, respectively (p < 0.001). Both systems have a very good ability to create highly conformal volumetric dose distributions. Median HI of PTV for IMRT and CK plans were 1.08 and 1.33, respectively (p < 0.001).

Background: We evaluated the efficacy, toxicity, and dose responses of re-irradiation with stereotactic body radiotherapy (SBRT) in patients with recurrent non- small cell lung cancer (NSCLC) after previous irradiation. Patients and Methods: 28 patients were included. Previous median radiation doses were 54 and 66 Gy. The median interval time between previous radiotherapy and SBRT was 14 months. The median follow-up time after SBRT was 9 months (range 3-93 months). To evaluate the effectiveness of SBRT, local control, overall survival, and treatment-related toxicity were reported. Results: SBRT doses and fractionation ranged from 60 to 30 Gy and from 3 to 8, respectively, according to previous doses, location of the recurrence, and interval time. 65% of tumor recurrences overlapped with previous treatment, while 35% of tumors recurred outside of the previous treatment. 4 patients had local progression after SBRT at their first follow-up. The Kaplan-Meier estimates of the 1- and 2-year actuarial overall survival were 71 and 42%, respectively. The mean survival following SBRT was 32.8 months, and the median survival was 21 months. No grade 3 or higher toxicities were observed. Conclusion: Robotic SBRT is a tolerable treatment option with manageable toxicity which can be used with radical or palliative intent in carefully selected patients with locally recurrent tumors after previous irradiation.

Organization [WHO] grade IV) were studied in Anadolu Medical Center, Department of Radiation Oncology, between January 2006 and July 2015. The diagnosis was established by pathology in all cases. The median age was 59 years (range, 19–86 years). The median tumor diameter was 45 mm, and the rate of the multicentric tumors was 16.3%. The location of the tumor was temporal in 33.7%, parietal in 14.1%, frontal in 23.9%, occipital in 9.8%, and others in 18.5%. The gross total and subtotal resection were performed in 60.9% of the patients, partial resection in 26.1%, and only stereotactic biopsy in 13.0% of the patients. RESULTS: The median overall survival (OS) was 33.01 ± 4.76 months (95% confidence interval 25.64–40.38 months). 1, 2, and 5 years OS was 74.3%, 44.3%, and 31.8%, respectively. The median progression-free survival (PFS) was 27.36 ± 3.87 months (95% confidence interval 19.82–34.89 months). 1, 2, and 5 years PFS was 62.7%, 32.6%, and 27.2%, respectively. On univariate analysis, gender, extent of surgery, tumor size, Karnofsky performance status, and tumor suppressor gene (P53) were significant predictors of OS and PFS. On multivariate analysis, gender (PFS: P = 0.006, OS: P = 0.003), extent of surgery (PFS: P = 0.004, OS: P = 0.012), P53 (PFS: P = 0.003, OS: P = 0.021), and size of tumor (PFS: P = 0.005, OS: 0.012) remained significantly associated with PFS and OS. There is no statistically significant in OS and PFS between female and male (OS: log-rank: 0.79 P = 0.375, PFS: log-rank: 0.54 P = 0.465). PSF and OS were not significantly significant with total/near total resection compared with partial resection (PSF: P = 0.46 log-rank = 0.54, OS: P = 0.340 log-rank = 0.91). Patients with P53 50% value were compared and results were not found statistically significant (PSF: P = 0.917 log-rank = 0.01, OS: P = 0.892 log-rank = 0.02). For patients with tumor size <0 mm, small tumor size did not improve the PSF and OS (PSF: P = 0.291 log-rank = 1.11, OS: P = 0.288 log-rank = 1.13). CONCLUSION: Ninety-two previously treated patients with high-grade glioma (WHO Grade IV) were evaluated with multivariate analysis. Gender, extent of surgery, P53, and tumor size were found as prognostic factors affecting on survival....

Karaman K, et al. Korean J Radiol. 2015 May-Jun;16(3):626-631. http://dx.doi.org/10.3348/kjr.2015.16.3.626