Practical Radiation Oncology

Evaluation of predictive variables in locally advanced pancreatic adenocarcinoma patients receiving definitive chemoradiation

2011-08-04

Abstract: Purpose: To analyze a single-center experience with locally advanced pancreatic cancer (LAPC) patients treated with chemoradiation (CRT) and to evaluate predictive variables of outcome.Methods and Materials: LAPC patients at our institution between 1997 and 2009 were identified (n = 109). Progression-free survival (PFS) and overall survival (OS) were assessed using Kaplan-Meier analysis. Cox proportional hazard models were used to evaluate predictive factors for survival. Patterns of failure were characterized, and associations between local progression and distant metastasis were explored.Results: Median OS was 12.1 months (2.5-34.7 months) and median PFS was 6.7 months (1.1-34.7 months). Poor prognostic factors for OS include Karnofsky performance status ≤80 (P = .0062), treatment interruption (P = .0474), and locally progressive disease at time of first post-therapy imaging (P = .0078). Karnofsky performance status ≤80 (P = .0128), pretreatment CA19-9 >1000 U/mL (P = .0224), and treatment interruption (P = .0009) were poor prognostic factors for PFS. Both local progression (36%) and distant failure (62%) were common. Local progression was associated with a higher incidence of metastasis (P < .0001) and decreased time to metastasis (P < .0001).Conclusions: LAPC patients who suffer local progression following definitive CRT may experience inferior OS and increased risk of metastasis, warranting efforts to improve control of local disease. However, patients with poor pretreatment performance status, elevated CA19-9 levels, and treatment interruptions may experience poor outcomes despite aggressive management with CRT, and may optimally be treated with induction chemotherapy or supportive care. Novel therapies aimed at controlling both local and systemic progression are needed for patients with LAPC.

Six sigma tools for a patient safety-oriented, quality-checklist driven radiation medicine department

Ajay Kapur, Louis Potters — 2011-08-08

Abstract: Introduction: The purpose of this work was to develop and implement six sigma practices toward the enhancement of patient safety in an electronic, quality checklist-driven, multicenter, paperless radiation medicine department.Methods and Materials: A quality checklist process map (QPM), stratified into consultation through treatment-completion stages was incorporated into an oncology information systems platform. A cross-functional quality management team conducted quality-function-deployment and define-measure-analyze-improve-control (DMAIC) six sigma exercises with a focus on patient safety. QPM procedures were Pareto-sorted in order of decreasing patient safety risk with failure mode and effects analysis (FMEA). Quantitative metrics for a grouped set of highest risk procedures were established. These included procedural delays, associated standard deviations and six sigma Z scores. Baseline performance of the QPM was established over the previous year of usage. Data-driven analysis led to simplification, standardization, and refinement of the QPM with standard deviation, slip-day reduction, and Z-score enhancement goals. A no-fly policy (NFP) for patient safety was introduced at the improve-control DMAIC phase, with a process map interlock imposed on treatment initiation in the event of FMEA-identified high-risk tasks being delayed or not completed. The NFP was introduced in a pilot phase with specific stopping rules and the same metrics used for performance assessments. A custom root-cause analysis database was deployed to monitor patient safety events.Results: Relative to the baseline period, average slip days and standard deviations for the risk-enhanced QPM procedures improved by over threefold factors in the NFP period. The Z scores improved by approximately 20%. A trend for proactive delays instead of reactive hard stops was observed with no adverse effects of the NFP. The number of computed potential no-fly delays per month dropped from 60 to 20 over a total of 520 cases. The fraction of computed potential no-fly cases that were delayed in NFP compliance rose from 28% to 45%. Proactive delays rose to 80% of all delayed cases. For potential no-fly cases, event reporting rose from 18% to 50%, while for actually delayed cases, event reporting rose from 65% to 100%.Conclusions: With complex technologies, resource-compromised staff, and pressures to hasten treatment initiation, the use of the six sigma driven process interlocks may mitigate potential patient safety risks as demonstrated in this study.

Video surface image guidance for external beam partial breast irradiation

2011-08-01

Abstract: Objective: Accelerated partial breast irradiation is an emerging treatment option for early stage breast cancer. With accelerated partial breast irradiation, patient setup, and target registration accuracy is vital. The current study compared various methods for isocenter placement accuracy.Methods and Materials: Twenty-three patients treated on an institutional-approved partial breast irradiation protocol were monitored at each treatment fraction. All patients included in this study underwent clip placement at the time of surgery. Patients underwent computed tomographic simulation and surface contours were used to reconstruct a reference surface map. At the treatment machine, patients were initially positioned by laser alignment to tattoos. Orthogonal kilovoltage imaging of the chest wall, followed by video surface mapping of the breast, was performed. This video surface map was matched to the reference surface map to adjust the couch position. Verification orthogonal chest wall imaging and video surface mapping was again performed. The accuracy of setup by laser, orthogonal imaging of the chest wall, and surface alignment was retrospectively compared using the centroid clip position as the reference standard. The impact of setup error by surface alignment and by orthogonal kilovoltage imaging on planning target volume coverage was then calculated.Results: Laser-based positioning resulted in a residual setup error of 3.9 ± 3.7 mm, 4.6 ± 3.9 mm, and 4.3 ± 4.5 mm in the posterior-anterior (P-A), inferior-superior (I-S), and left-right (L-R) directions, respectively, using clips as the reference standard. Setup based on bony anatomy with orthogonal imaging resulted in residual setup error of 3.2 ± 2.9 (P-A), 4.2 ± 3.5 (I-S), and 4.7 ± 5.3 mm (L-R). Setup with video surface mapping resulted in a residual setup error of 1.9 ± 2.2, 1.8 ± 1.9, and 1.8 ± 2.1 mm in the P-A, I-S, and L-R directions, respectively. Vector spatial deviation was 8.8 ± 4.2, 8.3 ± 3.8, and 4.0 ± 2.3 mm with laser, chest wall on board imaging, and video surface mapping based setup, respectively. Setup by video surface mapping resulted in improved dosimetric coverage of the planning target volume when compared with orthogonal imaging of the chest wall (V100 96.0% ± 0.1% vs 89.3% ± 0.2%; V95 99.7% ± 0.01% vs 98.6% ± 0.01%, P < .05).Conclusions: Video surface mapping of the breast is a more accurate method for isocenter placement in comparison to conventional laser-based alignment or orthogonal kilovoltage imaging of the chest wall.

Postmastectomy chest wall radiotherapy with single low-energy electron beam: An assessment of outcome and prognostic factors

2011-08-26

Abstract: Purpose: This study aimed to evaluate the outcome of patients who had received postmastectomy chest wall radiotherapy using a single electron beam, and to identify the relevant factors that influenced prognosis.Methods: The medical records of patients with breast cancer treated with postmastectomy radiotherapy from January 2000 to December 2004 were retrospectively analyzed (n = 328). Two hundred seventy-one (82.6%) patients were staged as (tumor-nodes-metastasis [TNM]) T3-4, any N, M0; or T1-2, N2-3, M0, and 57 (17.4%) patients were staged as T1-2, N1, M0. All patients received chest wall radiation with a 6-10 MeV electron beam. In addition, 327 patients (99.7%) received supraclavicular node radiation, 67 (20.4%) axillary radiation, and 35 (10.7%) internal mammary chain (IMC) radiation. Chemotherapy with anthracycline and taxane was given to 323 patients (98.5%). Of patients with positive hormone receptor, 183 (82.8%) received hormone therapy and 8 patients with negative and 3 patients with unknown hormone receptor received hormone therapy. Locoregional recurrence (LRR), distant metastasis (DM), and overall survival (OS) were calculated using the Kaplan-Meier method, and the differences assessed by log-rank test.Results: The median follow-up time was 78 months (range, 5-123 months) for patients who remained alive. The 5-year LRR, DM, disease-free survival and OS rates were 5.9%, 26.2%, 72.5%, and 83.1%, respectively. LRR occurred in 1 or more sites in 21 patients. The 5-year recurrence rates in the chest wall, supraclavicular node, axilla, and internal mammary chain were 1.9%, 2.3%, 2.9%, and 0%, respectively. In multivariate analysis, hormone therapy was the only independent favorable prognostic factor for LRR (P = .017). LRR was significantly associated with DM and OS. The 5-year DM rate was 82.9% and 22.7% (P < .0001) and the 5-year OS rate was 52.8% and 84.7% (P < .0001) for patients with or without LRR. The treatment-related toxicity was low, with the incidence of symptomatic pneumonitis being 0.3%.Conclusions: Breast cancer patients can be treated with postmastectomy single electron beam radiotherapy with excellent local control and low toxicity.

Evaluation of variability in seroma delineation between clinical specialist radiation therapist and radiation oncologist for adjuvant breast irradiation

2011-09-21

Abstract: Purpose: Breast cancer is managed by a multidisciplinary team with a goal for the timely provision of high quality care. Given radiation oncologist (RO) time constraints, an opportunity arises for task delegation of breast seroma target delineation to an advanced practice clinical specialist radiation therapist (CSRT) with clinical and technical expertise to facilitate treatment planning. To explore this further, we quantitatively evaluated the variability in post-surgical seroma delineation between the CSRT and ROs.Methods: Specialized site specific training was provided to the CSRT, who, with 7 ROs, independently contoured the seroma and graded its clarity, using the cavity visualization score (CVS), for 20 patients with clinical stage Tis-2N0 breast tumors. The conformity indices were analyzed for all possible pairs of delineations. The estimated “true” seroma contour was derived from the RO contours using the simultaneous truth and performance level estimation algorithm. Generalized kappa coefficient and center of mass metrics were used to examine the performance level of the CSRT in seroma delineations.Results: The CVS of the CSRT correlated well with the mean RO-group CVS, (Spearman ρ = 0.87, P < .05). The mean seroma conformity index for the RO group was 0.61 and 0.65 for the CSRT; a strong correlation was observed between the RO and CSRT conformity indices (Spearman ρ = 0.95, P < .05). Almost perfect agreement levels were observed between the CSRT contours and the STAPLE RO consensus contours, with an overall kappa statistic of 0.81 (P < .0001). The average center of mass shift between the CSRT and RO consensus contour was 1.69 ± 1.13 mm.Conclusions: Following specialized education and training, the CSRT delineated seroma targets clinically comparable with those of the radiation oncologists in women with early breast tumors suitable for accelerated partial breast or whole breast radiotherapy following lumpectomy. This study provides support for potential task delegation of breast seroma delineation to the CSRT in our current multidisciplinary environment. Further study is needed to assess the impact of this role expansion on radiotherapy system efficiency.

Dosimetric evaluation of a “virtual” image-guidance alternative to explicit 6 degree of freedom robotic couch correction

2011-09-26

Abstract: Purpose: Clinical evaluation of a “virtual” methodology for providing 6 degrees of freedom (6DOF) patient set-up corrections and comparison to corrections facilitated by a 6DOF robotic couch.Methods: A total of 55 weekly in-room image-guidance computed tomographic (CT) scans were acquired using a CT-on-rails for 11 pelvic and head and neck cancer patients treated at our facility. Fusion of the CT-of-the-day to the simulation CT allowed prototype virtual 6DOF correction software to calculate the translations, single couch yaw, and beam-specific gantry and collimator rotations necessary to effectively reproduce the same corrections as a 6DOF robotic couch. These corrections were then used to modify the original treatment plan beam geometry and this modified plan geometry was applied to the CT-of-the-day to evaluate the dosimetric effects of the virtual correction method. This virtual correction dosimetry was compared with calculated geometric and dosimetric results for an explicit 6DOF robotic couch correction methodology.Results: A (2%, 2mm) gamma analysis comparing dose distributions created using the virtual corrections to those from explicit corrections showed that an average of 95.1% of all points had a gamma of 1 or less, with a standard deviation of 3.4%. For a total of 470 dosimetric metrics (ie, maximum and mean dose statistics for all relevant structures) compared for all 55 image-guidance sessions, the average dose difference for these metrics between the plans employing the virtual corrections and the explicit corrections was −0.12% with a standard deviation of 0.82%; 97.9% of all metrics were within 2%.Conclusions: Results showed that the virtual corrections yielded dosimetric distributions that were essentially equivalent to those obtained when 6DOF robotic corrections were used, and that always outperformed the most commonly employed clinical approach of 3 translations only. This suggests that for the patient datasets studied here, highly effective image-guidance corrections can be made without the use of a robotic couch.

Efficacy of fiducial marker-based image-guided radiation therapy in prostate tomotherapy and potential dose coverage improvement using a patient positioning optimization method

Ning J. Yue, Akshar N. Patel, Bruce G. Haffty, Sung Kim — 2011-08-29

Abstract: Purpose: To evaluate the dose coverage efficacy of fiducial marker-based prostate tomotherapy and a positioning correction optimization technique for the improvement of suboptimal dose distributions.Methods: Three gold fiducial markers were implanted in prostate glands for patients who were to receive prostate tomotherapy. TomoTherapy megavoltage computed tomographies (MVCTs; TomoTherapy, Madison, WI) were routinely acquired at treatment and were registered to corresponding planning CTs based on the markers to correct for interfractional positioning deviations using translational table movements. The prostate glands and seminal vesicles were delineated on the MVCTs acquired for 10 patients at different treatment fractions and the treatment dose coverage was computed with the marker-based correction taken into account. The treatment dose coverage was compared with the corresponding plan to evaluate the efficacy of the marker-based image-guided radiation therapy (IGRT) approach. Separately, a hill-climbing optimization algorithm was used to optimize the positioning by maximizing a dose-based objective function. During the optimization, the dose was constantly recomputed with the translational correction until an optimized dose coverage was reached. This optimized dose coverage was compared with the marker-based dose coverage to evaluate dosimetric improvement for treatments in which suboptimal dose distributions were observed after the marker-based corrections.Results: Suboptimal dose coverage of prostate glands and seminal vesicles were observed in about 8 and 6 of a total 75 fractions, respectively, after the marker-based IGRT positioning corrections. Six of the 10 patients experienced 1 or more factions of suboptimal prostate gland coverage and 2 of the 10 patients experienced 1 or more fractions of suboptimal seminal vesicle dose coverage. Utilization of the proposed positioning correction optimization method led to satisfactory dose coverage of both prostate glands and seminal vesicles for all 10 patients.Conclusions: Given the planning target volume margin size specified in the current study, the fiducial marker-based IGRT approach may not be completely adequate to achieve desired dose coverage of the target volumes at every fraction. Due to relatively poor image quality of MVCTs, additional investigations may be required to confirm the finding. The proposed positioning correction optimization method is shown to effectively improve the observed suboptimal dose coverage of the target volumes.

Continuous localization technologies for radiotherapy delivery: Report of the American Society for Radiation Oncology Emerging Technology Committee

2011-11-21

An active arena for technological advancement in radiation oncology treatment delivery has focused on the motion inherent in target structures and normal organs. With the advances over the last decade (and more so within the last few years), in intensity modulated radiation therapy (IMRT), stereotactic radiosurgery (SRS)/radiotherapy and stereotactic body radiotherapy (SBRT), and image-guided radiation therapy, it has become critical to position patients in the treatment positions precisely and reproducibly. To address these localization issues, devices have been developed that may be implanted in the organ or volume of interest and tracked during and between treatments

Radiation-induced sarcoma following radiation prophylaxis of heterotopic ossification

2011-07-22

Heterotopic ossification (HO) is defined as the abnormal formation of mature, lamellar bone in soft tissues, often containing bone marrow. Heterotopic ossification was first identified in 1883 by Riedel, a German physician. It was later described as “paraosteoarthropathy” by French physicians Dejerine and Ceillier based on their observations of patients with traumatic paraplegia in World War I.

In regard to Vargo et al: "Early Clinical Outcomes for 3 Radiation Techniques for Brain Metastases: Focal Versus Whole-Brain"

Glenn Bauman, George Rodrigues, Frank Lagerwaard — 2012-04-01

We read with interest the report by Vargo et al comparing the results with whole brain radiotherapy with simultaneous integrated boost (SIB), focal stereotactic intensity modulated radiotherapy, and conventional whole brain radiotherapy. The authors noted a trend toward improved intracranial control with the SIB technique and in the discussion raise the possibility that their focal lesion boost (median 45 Gy over 10-15 fractions) may have been too low. They also cite a lack of dosing guidelines for the SIB approach.

Editorial Board

2012-04-01