Feasibility of patient-specific quality assurance (PSQA) for real-time robotic stereotactic body radiotherapy (SBRT) based on tumor motion traces.

PURPOSE: To design a patient specific quality assurance (PSQA) process for the CyberKnife Synchrony system and quantify its dosimetric accuracy using a motion platform driven by patient tumor traces with rotation. METHODS: The CyberKnife Synchrony system was evaluated using a motion platform (MODUSQA) and a SRS MapCHECK phantom. The platform was programed to move in the superior-inferior (SI) direction based on tumor traces. The detector array housed by the StereoPhan was placed on the platform. Extra rotational angles in pitch (head down, 4.0° ± 0.15° or 1.2° ± 0.1°) were added to the moving phantom to examine robot capability of angle correction during delivery. A total of 15 Synchrony patients were performed SBRT PSQA on the moving phantom. All the results were benchmarked by the PSQA results based on static phantom. RESULTS: For smaller pitch angles, the mean gamma passing rates were 99.75% ± 0.87%, 98.63% ± 2.05%, and 93.11% ± 5.52%, for 3%/1 mm, 2%/1 mm, and 1%/1 mm, respectively. Large discrepancy in the passing rates was observed for different pitch angles due to limited angle correction by the robot. For larger pitch angles, the corresponding mean passing rates were dropped to 93.00% ± 10.91%, 88.05% ± 14.93%, and 80.38% ± 17.40%. When comparing with the static phantom, no significant statistic difference was observed for smaller pitch angles (p = 0.1 for 3%/1 mm), whereas a larger statistic difference was observed for larger pitch angles (p < 0.02 for all criteria). All the gamma passing rates were improved, if applying shift and rotation correction. CONCLUSIONS: The significance of this work is that it is the first study to benchmark PSQA for the CyberKnife Synchrony system using realistically moving phantoms with rotation. With reasonable delivery time, we found it may be feasible to perform PSQA for Synchrony patients with a realistic breathing pattern.

Implementing and evaluating a high-resolution diode array for patient-specific quality assurance of robotic brain stereotactic radiosurgery/radiotherapy.

The purpose of the study was to introduce and evaluate a high-resolution diode array for patient-specific quality assurance (PSQA) of CyberKnife brain stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT). Thirty-three intracranial plans were retrospectively delivered on the SRS MapCHECK using fixed cone, Iris, and multileaf collimator (MLC). The plans were selected to cover a range of sites from large tumor bed, single/multiple small brain metastases (METs) to trigeminal neuralgia. Fiducial tracking using the four fiducials embedded around the detector plane was used as image guidance. Results were analyzed before and after registration based on absolute dose gamma criterion of 1 mm distance-to-agreement and 0.5%-3% dose-difference. Overall, the gamma passing rates (1 mm and 3% criterion) before registration for all the patients were above 90% for all three treatment modalities (96.8 ± 3.5%, the lowest passing rate of 90.4%), and were improved after registration (99.3 ± 1.5%). When tighter criteria (1 mm and 2%) were applied, the gamma passing rates after registration for all the cases dropped to 97.3 ± 3.2%. For trigeminal neuralgia cases, we applied 1 mm and 0.5% criterion and the passing rates dropped from 100 ± 0.0% to 98.5 ± 2.0%. The mean delivery time was 33.4 ± 11.7 min, 24.0 ± 4.9 min, and 17.1 ± 2.6 min for the fixed cone, Iris, and MLC, respectively. With superior gamma passing rates and reasonable quality assurance (QA) time, we believe the SRS MapCHECK could be a good option for routine PSQA for CyberKnife SRS/SRT.

Evaluating the impact of prescription isodose line on plan quality using Gamma Knife inverse planning.

The impact of selection of prescription isodose line (IDL) on plan quality has not been well evaluated during inverse planning (IP). In this study, a total of 180 IP plans at five levels of IDL were generated for 30 brain metastases (BMs). For each BM, one round of IP was performed with typical IP settings, followed by a quick fine-tuning to ensure the same target coverage and comparable conformality index. The impact of the IDL on the quality metrics (selectivity, gradient index [GI], and treatment time) was evaluated. The decrease of selectivity and increase of GI meant inferior target dose conformality and more dose spillage. Additionally, a metric directly correlated to the treatment time was proposed. For all cases, the mean GI decreased monotonically as IDL decreased from 70% to 30%, and the decreasing rate was significantly different based on tumor size. The mean selectivity and number of shots decreased monotonically as IDL decreased for all the tumors. From 70% to 30% IDL, the decreasing rate of the mean selectivity was 2.8% (p = 0.020), 7.7% (p = 0.005), and 15.4% (p = 0.020) and that of the number of shots was 75.4% (p = 0.001), 73.2% (p = 0.001), and 50.7% (p = 0.009), for the large, medium, and small tumors, respectively. For the medium and small tumor groups, the mean treatment time increased monotonically when IDLs decreased (increasing rate was 80.0% [p = 0.002] for medium tumors [p = 0.001] and 130.8% [p = 0.001] for small tumors from 70% to 30%). For the large tumors, the mean treatment time was the shortest at 50% IDL (59.0 min) and higher at 70% (65.9 min) and 30% (71.9 min). Overall, the GammaPlan chose smaller sectors for plans with lower IDLs except for the large size group.

Oral Cavity Squamous Cell Carcinoma: Review of Pathology, Diagnosis, and Management.

Squamous cell carcinoma of the oral cavity presents a significant global health burden, primarily due to risk factors such as tobacco smoking, smokeless tobacco use, heavy alcohol consumption, and betel quid chewing. Common clinical manifestations of oral cavity cancer include visible lesions and sores, often accompanied by pain in advanced stages. Diagnosis relies on a comprehensive assessment involving detailed history, physical examination, and biopsy. Ancillary imaging studies and functional evaluations aid in accurate staging and facilitate treatment planning. Prognostic information is obtained from histopathological factors, such as tumor grade, depth of invasion, lymphovascular invasion, and perineural invasion. Notably, lymph node metastasis, found in approximately half of the patients, carries significant prognostic implications. Effective management necessitates a multidisciplinary approach to optimize patient outcomes. Surgical resection is the backbone of treatment, aimed at complete tumor removal while preserving functional outcomes. Adjuvant therapies, including radiation and chemotherapy, are tailored according to pathological factors. Further work in risk stratification and treatment is necessary to optimize outcomes in squamous cell carcinoma of the oral cavity.

Validation of daily 0.35 T diffusion-weighted MRI for MRI-guided glioblastoma radiotherapy.

BACKGROUND: MRI-Linac systems enable daily diffusion-weighed imaging (DWI) MRI scans for assessing glioblastoma tumor changes with radiotherapy treatment. PURPOSE: Our study assessed the image quality of echoplanar imaging (EPI)-DWI scans compared with turbo spin echo (TSE)-DWI scans at 0.35 Tesla (T) and compared the apparent diffusion coefficient (ADC) values and distortion of EPI-DWI on 0.35 T MRI-Linac compared to high-field diagnostic MRI scanners. METHODS: The calibrated National Institute of Standards and Technology (NIST)/Quantitative Imaging Biomarkers Alliance (QIBA) Diffusion Phantom was scanned on a 0.35 T MRI-Linac, and 1.5 T and 3 T MRI with EPI-DWI. Five patients were scanned on a 0.35 T MRI-Linac with a TSE-DWI sequence, and five other patients were scanned with EPI-DWI on a 0.35 T MRI-Linac and a 3 T MRI. The quality of images was compared between the TSE-DWI and EPI-DWI on the 0.35 T MRI-Linac assessing signal-to-noise ratios and presence of artifacts. EPI-DWI ADC values and distortion magnitude were measured and compared between 0.35 T MRI-Linac and high-field MRI for both phantom and patient studies. RESULTS: The average ADC differences between EPI-DWI acquired on the 0.35 T MRI-Linac, 1.5 T and 3 T MRI scanners and published references in the phantom study were 1.7%, 0.4% and 1.0%, respectively. Comparing the ADC values based on EPI-DWI in glioblastoma tumors, there was a 3.36% difference between 0.35 and 3 T measurements. Susceptibility-induced distortions in the EPI-DWI phantoms were 0.46 ± 1.51 mm for 0.35 MRI-Linac, 0.98 ± 0.51 mm for 1.5 T MRI and 1.14 ± 1.88 mm for 3 T MRI; for patients -0.47 ± 0.78 mm for 0.35 T and 1.73 ± 2.11 mm for 3 T MRIs. The mean deformable registration distortion for a phantom was 1.1 ± 0.22 mm, 3.5 ± 0.39 mm and 4.7 ± 0.37 mm for the 0.35 T MRI-Linac, 1.5 T MRI, and 3 T MRI scanners, respectively; for patients this distortion was -0.46 ± 0.57 mm for 0.35 T and 4.2 ± 0.41 mm for 3 T. EPI-DWI 0.35 T MRI-Linac images showed higher SNR and lack of artifacts compared with TSE-DWI, especially at higher b-values up to 1000 s/mm2. CONCLUSION: EPI-DWI on a 0.35 T MRI-Linac showed superior image quality compared with TSE-DWI, minor and less distortions than high-field diagnostic scanners, and comparable ADC values in phantoms and glioblastoma tumors. EPI-DWI should be investigated on the 0.35 T MRI-Linac for prediction of early response in patients with glioblastoma.

Socioeconomic Influence on Speech Rehabilitation After Total Laryngectomy.

OBJECTIVE: Speech rehabilitation following a total laryngectomy significantly impacts the quality of life. Indwelling prosthetic voice restoration provides optimal outcomes; however, the long-term maintenance of these devices carries considerable financial costs, which are not universally covered by insurance. This investigation aimed to analyze associations between socioeconomic factors and outcomes in postlaryngectomy speech rehabilitation. STUDY DESIGN: Retrospective cohort analysis. SETTING: Academic tertiary-care center from May 2014 to September 2021. METHODS: In patients undergoing total laryngectomy, the incidence of tracheoesophageal puncture with indwelling vocal prostheses (TEP-VP) placement within the first postoperative year was compared among household income, demographic factors, and disease characteristics. Functional and maintenance outcomes served as secondary endpoints. RESULTS: Seventy-seven patients were included. Forty-five (58%) underwent indwelling TEP-VP (41 primaries). Eighty-nine percent of patients with annual incomes greater than $50k underwent TEP-VP compared to only 35% with incomes less than $50k/year. TEP-VP was performed in 85% of patients with commercial insurance, 70% with Medicare, 42% with Medicaid, and 0% with no insurance. On multivariate analysis, annual household incomes greater than $50k were predicted for TEP-VP placement (odds ratio: 12.7 [2.45-65.8], p = .002). The utilization of postoperative speech therapy and functional communication outcomes were similar among socioeconomic groups. Twelve patients were unable to afford supplies within the first year, with differences noted among insurance (p = .015) and income status (p = .003). CONCLUSION: Disparities in vocal and speech rehabilitation following laryngectomy may disproportionally affect underserved patients.

Stereotactic Radiosurgery for Brain Metastases in Patients With Small Cell Lung Cancer.

Purpose: Treatment of small cell lung cancer (SCLC) with brain metastatic disease has traditionally involved whole brain radiation therapy (WBRT). The role of stereotactic radiosurgery (SRS) is unclear. Methods and Materials: Our study was a retrospective review of an SRS database evaluating patients with SCLC who received SRS. A total of 70 patients and 337 treated brain metastases (BM) were analyzed. Forty-five patients had previous WBRT. The median number of treated BM was 4 (range, 1-29). Results: Median survival was 4.9 months (range, 0.70-23.9). The number of treated BM was correlated with survival; patients with fewer BM had improved overall survival (P < .021). The number of treated BM was associated with different brain failure rates; 1-year central nervous system control rates were 39.2% for 1 to 2 BM, 27.6% for 3 to 5 BM, and 0% for >5 treated BM. Patients with previous WBRT had worse brain failure rates (P < .040). For patients without previous WBRT, the 1-year distant brain failure rate was 48%, and median time to distant failure was 15.3 months. Conclusions: SRS for SCLC in patients with <5 BM appears to offer acceptable control rates. Patients with >5 BM have high rates of subsequent brain failure and are not ideal candidates for SRS.

Management of non-small cell lung cancer with oligometastasis.

Patients with oligometastatic Non-Small Cell Lung Cancer (NSCLC) present a potential opportunity for curative therapy; however, the challenge remains the definitive treatment of their localized disease and ablation of their limited overt metastatic sites of disease. In selecting patients with oligometastatic NSCLC for definitive therapy, proper staging through radiographic studies, including PET and brain MRI, and the pathologic staging of the mediastinal lymph nodes and potential sites of metastatic disease, are critical. With that in mind, the available literature suggests that in highly selected patients with solitary metastases to the brain, adrenals and other organs, long term survival may be achieved with combined definitive therapy of both the primary lung tumor and the solitary metastatic site.

The Effect of Race in the Palliative Treatment of Bone Metastases.

PURPOSE: Prior studies demonstrated that single and multiple-fraction radiation therapy (RT) provide comparable pain relief in palliative-care patients. In addition, unconscious racial biases may affect practice patterns in oncology. In this study, we examined the effect of race on the duration of RT for palliative treatment of bone metastases. METHODS AND MATERIALS: This is a retrospective study of 707 patients treated for bone metastases between 2013 and 2020 (1348 treatments). Patient race, demographics, RT dose, number of fractions, use of stereotactic radiosurgery (SRS), and performance score were collected. A short-course was defined as a single fraction, whereas a long-course was defined as more than one fraction. SRS cases were analyzed separately. RESULTS: Of all nonradiosurgery RT treatments delivered, 28.9% were single fraction and 71.1% were multiple fraction. In total, 76% of the patients were White and 24% were non-White. With regard to race, the number of White patients receiving short- and long-course RT was 256 (27.9%) and 663 (72.1%), respectively. The number of non-White patients receiving short- and long-course RT was 97 (31.9%) and 207 (68.1%), respectively. There was no difference in treatment duration based on patient race (P = .20). The use of SRS did not vary based on race (P = .79). There was no statistically significant difference in Karnofsky Performance Status Scale score between White and non-White patients (P = .44). CONCLUSIONS: Analysis of patient and physician characteristics revealed that race did not influence treatment decisions such as duration of palliative RT regimen or use of SRS. Although palliative-care regimens must be individualized for each patient, such investigations can identify potential biases in treatment decisions.

Outcomes of curative treatment for head and neck squamous cell carcinoma in very elderly adults ≥80 years old.

BACKGROUND: Head and neck cancer treatment can be difficult and advancing age is associated with greater frailty. It is unclear if curative treatment for very elderly patients is beneficial. This study compared outcomes to curative treatment in patients ≥80 aged with HNSCC to patients aged 70-79. METHODS: Retrospective study of 114 patients diagnosed with HNSCC. Overall survival (OS), Disease-Free Survival (DFS), and local-regional control (LRC) were compared and adjusted for confounders. RESULTS: Patients aged 70-79 had a higher median OS (35 months [95% CI, 19.58-50.42]) compared with patients aged ≥80 (19 months [11.72-26.28]; p = 0.008) but similar DFS and LRC. KPS < 90 was the stand-alone independent prognostic factor for OS (HR = 2.14 [1.05-4.38]). CONCLUSION: Very elderly HNSCC patients (aged ≥80) can have favorable outcomes with curative therapy and advanced chronological age alone should not prohibit patients from receiving treatment. Performance status may be a greater predictor of survival outcome than age alone. LEVEL OF EVIDENCE: Level III.

Stereotactic Body Radiotherapy and Systemic Dose Chemotherapy for Locally Advanced Lung Cancer: Single Arm Phase 2 Study.

PURPOSE: This is a single arm phase 2 study (Clinical trials.gov NCT02568033) to examine the role of stereotactic body radiotherapy (SBRT) along with full dose systemic chemotherapy in the treatment of unresectable stage 2 and stage 3 nonsmall cell lung cancer. Primary endpoints are disease free survival and toxicity. MATERIALS: Patients were treated with SBRT to all sites of gross disease. Dosing consisted of 60 Gy in 3 fractions for peripheral lung tumors, 50 Gy in 5 fractions for central lung tumors, and 40 to 50 Gy in 5 fractions for hilar and mediastinal lymph nodes. Chemotherapy consisted of 4 cycles of pemetrexed and cisplatin or carboplatin and paclitaxel for nonsquamous histology and cisplatin and docetaxel or cisplatin and paclitaxel for squamous histology. SBRT was given in between the chemotherapy cycles. There was a 7 days break between chemotherapy and SBRT. Quality of life was measured using functional assessment of cancer therapy-lung. RESULTS: Twenty two patients were enrolled and analyzed. Seventeen (77%) were stage III and 19 (86%) had lymph node involvement. Median follow-up for all patients was 23.1 months. Median overall survival is 27.2 months. Overall survival at 1 year was 82% and overall survival at 2 years was 53%. Median disease free survival is 16.0 months with a 2-year regional failure rate of 19% and 2-year distant failure rate of 47.2%. There were 6 grade 3 acute toxicities and 2 late grade 3 or higher toxicities including 1 grade 5 hemoptysis. Quality of life scores were unchanged compared with baseline. CONCLUSION: A combination of SBRT and full dose chemotherapy appears to be a safe and effective treatment for locally advanced NSCLC and warrants further investigation.

Preoperative Stereotactic Body Radiation Therapy for Soft-Tissue Sarcoma: Results of Phase 2 Study.

Purpose: Preoperative radiation followed by surgical resection is a standard treatment for soft-tissue sarcomas (STS). We report on 2 consecutive, phase 2, single-arm studies evaluating 5 fraction stereotactic body radiation therapy (SBRT) treatments followed by surgical resection for STS (clinical trails.gov NCT02706171). Methods and Materials: A total of 16 patients were treated with preoperative SBRT. Tumor size in the greatest dimension was a median 6.7 cm (maximum: 14 cm) and the majority of STS were in the extremities. SBRT consisted of 35 to 40 Gy in 5 fractions every other day. Results: Median follow-up time was 1719 days (4.7 years). Grade ≥3 acute toxicity occurred in 1 patient (grade 3 skin changes). Fifteen patients proceeded with surgical resection. Three patients had a wound complication after surgery, 1 patient had grade ≥3 late toxicity (grade 4 requiring surgical intervention). There was 1 local recurrence and 5 distant recurrences. Conclusions: Long-term follow-up on SBRT for STS found acceptable control and toxicity rates, and warrants further evaluation.

Transthoracic placement of fiducials with ultrasound or electronic navigational bronchoscopy needle guidance by the interventional pulmonologist: A case series.

Stereotactic body radiotherapy (SBRT) has become one of the main options for treatment of thoracic malignancies, leading to the need for more fiducial marker placement. We report cases where these fiducials were placed transthoracically by interventional pulmonologists using ultrasound (US) and electronic navigational bronchoscopy (ENB) needle guidance. Six cases were identified in the Cooper University Hospital medical records where such procedures were performed, alone or in combination with other interventions. All six patients underwent successful placement of fiducials. Concomitant bronchoscopic procedures were performed in four cases. All patients proceeded to SBRT without the need for further interventions. The overall retention rate of fiducials was 80%. No complications were noted. Fiducials' placement by interventional pulmonologists using US or ENB needle guidance is safe and effective, and may be combined with other procedures in a single setting.

Osteoradionecrosis of the hyoid presenting as acute airway compromise.

BACKGROUND: Osteoradionecrosis (ORN) of the mandible is a well-known complication of radiation therapy for head and neck cancer. However, few reports have described hyoid bone ORN and its clinical implications. METHODS: We describe a retrospective case series of previously irradiated patients who were seen with sudden airway compromise, found to have underlying pathological hyoid fractures secondary to osteoradionecrosis. RESULTS: Six patients within postchemoradiation period (3-9 months) for oropharyngeal squamous cell carcinoma were seen with acute-onset dyspnea. Computed topography (CT) imaging was remarkable for severe airway luminal narrowing and pathological hyoid fractures. All six patients required urgent intervention with direct laryngoscopy and tracheostomy. Intraoperatively, five patients were seen with exposed necrotic hyoid bones. CONCLUSION: The hyoid and its associated musculature strongly influence upper airway patency. ORN may compromise its physiological function and leads to acute airway compromise. Hyoid ORN may hold significant and imperative clinical implications in head and neck cancer post-treatment surveillance.

Cancer Stem Cells in Tumor Modeling: Challenges and Future Directions.

Microfluidic tumors-on-chips models have revolutionized anticancer therapeutic research by creating an ideal microenvironment for cancer cells. The tumor microenvironment (TME) includes various cell types and cancer stem cells (CSCs), which are postulated to regulate the growth, invasion, and migratory behavior of tumor cells. In this review, the biological niches of the TME and cancer cell behavior focusing on the behavior of CSCs are summarized. Conventional cancer models such as three-dimensional cultures and organoid models are reviewed. Opportunities for the incorporation of CSCs with tumors-on-chips are then discussed for creating tumor invasion models. Such models will represent a paradigm shift in the cancer community by allowing oncologists and clinicians to predict better which cancer patients will benefit from chemotherapy treatments.

A Statewide Multi-Institutional Study of Asymptomatic Pretreatment Testing of Radiation Therapy Patients for SARS-CoV-2 in a High-Incidence Region of the United States.

PURPOSE: Our purpose was to establish the prevalence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in asymptomatic patients scheduled to receive radiation therapy and its effect on management decisions. METHODS AND MATERIALS: Between April 2020 and July 2020, patients without influenza-like illness symptoms at four radiation oncology departments (two academic university hospitals and two community hospitals) underwent polymerase chain reaction testing for SARS-CoV-2 before the initiation of treatment. Patients were tested either before radiation therapy simulation or after simulation but before treatment initiation. Patients tested for indications of influenza-like illness symptoms were excluded from this analysis. Management of SARS-CoV-2-positive patients was individualized based on disease site and acuity. RESULTS: Over a 3-month period, a total of 385 tests were performed in 336 asymptomatic patients either before simulation (n = 75), post-simulation, before treatment (n = 230), or on-treatment (n = 49). A total of five patients tested positive for SARS-CoV-2, for a pretreatment prevalence of 1.3% (2.6% in north/central New Jersey and 0.4% in southern New Jersey/southeast Pennsylvania). The median age of positive patients was 58 years (range, 38-78 years). All positive patients were white and were relatively equally distributed with regard to sex (2 male, 3 female) and ethnicity (2 Hispanic and 3 non-Hispanic). The median Charlson comorbidity score among positive patients was five. All five patients were treated for different primary tumor sites, the large majority had advanced disease (80%), and all were treated for curative intent. The majority of positive patients were being treated with either sequential or concurrent immunosuppressive systemic therapy (80%). Initiation of treatment was delayed for 14 days with the addition of retesting for four patients, and one patient was treated without delay but with additional infectious-disease precautions. CONCLUSIONS: Broad-based pretreatment asymptomatic testing of radiation oncology patients for SARS-CoV-2 is of limited value, even in a high-incidence region. Future strategies may include focused risk-stratified asymptomatic testing.

Neuro-oncology Multidisciplinary Clinic and Improvements in Patient Outcome.

BACKGROUND: Neuro-oncology care is becoming increasingly complex and patients often see multiple specialists. Multidisciplinary clinic (MDC) is a patient-centric option to allow multiple specialists to be involved where patients see multiple providers on the same day. OBJECTIVE: The objective of this study was to evaluate the role of a neuro-oncology MDC on patient outcomes. MATERIALS AND METHODS: Retrospective study was performed on consecutive patients who received radiosurgery for central nervous system (CNS) disease. We evaluated patients 2 years before and 2 years after the implementation of a MDC. RESULTS: A total of 351 patients were analyzed, 163 patients before MDC and 188 after implementation of MDC. Before MDC the median follow-up was dependent on which department ordered follow-up radiographic imaging. This discrepancy decreased after the MDC. Overall survival for patients with CNS metastatic disease improved in the MDC cohort (median survival of 248 before MDC and 315 d after, P<0.027). CONCLUSION: We found that neuro-oncology MDC improved follow-up across disciplines and improved overall survival for patients with CNS metastatic disease.

Dosimetric comparison of inverse and forward planning for Gamma Knife stereotactic radiosurgery of brain metastases.

The Leksell GammaPlan (LGP) with an inverse planning (IP) tool has been upgraded to version 11.1 since its launch in 2010. We evaluated its IP planning performance by re-planning 16 targets that had been planned using forward planning (FP). The FP and IP plans were compared. A planning guideline for IP process was developed aiming for an unbiased comparison. Sixteen brain metastases (BMs) without nearby critical structures were included in the study (size > 1 cm for all targets). All prior FP were re-planned in the LGP using IP and maintaining the same beam-on time and coverage. The dose to all the targets was scaled to 20 Gy in a single fraction at 50% isodose line (IDL) for FP and IP comparison purpose. The coverage and beam-on time were nearly the same for both the FP and IP plans. For all the IP plans, the mean selectivity was 0.85 ± 0.04 (vs 0.83 ± 0.04 in FP plans, p = 0.02), the mean GI was 2.92 ± 0.21 (vs 3.18 ± 0.60 in FP plans, p = 0.047), the mean V12Gy was 8.18 ± 8.57 cc (vs 9.09 ± 9.08 cc in FP plans, p = 0.001), the mean V8Gy was 14.63 ± 15.14 cc (vs 16.34 ± 16.17 cc in FP plans, p = 0.001), and the mean V5Gy was 29.01 ± 28.77 cc (vs 32.77 ± 31.41 cc in FP plans, p = 0.001). The number of shots was higher in IP plans (means of 16.69 ± 8.11 vs 10.81 ± 6.87 in FP plans, p = 0.001). We retrospectively re-planned 16 FP plans using the IP tool while meeting the quality limiting factors for the FP plans. The dosimetry parameters from the IP plans outperformed the treated FP plans and the IP tool should be preferred for tumors with size > 1 cm.

Tuning-Target-Guided Inverse Planning of Brain Tumors With Abutting Organs at Risk During Gamma Knife Stereotactic Radiosurgery.

Purpose We proposed a planning strategy that utilized tuning targets to guide GammaKnife (GK) Inverse Planning (IP) to deliver higher dose to the tumor, while keeping acceptable dose to the abutting organ at risk (OAR). Methods Ten patients with a large portion of brain tumor abutting the OAR previously treated with GK stereotactic radiosurgery (SRS) were selected. For each patient, multiple tuning targets were created by cropping the target contour from three-dimensional (3D) expansions of the OAR. The number of the tuning targets depended on the complexity of the planning process. To demonstrate dose sparing effect, an IP plan was generated for each tuning target after one round of optimization without shot fine-tuning. In the dose enhancement study, a more aggressive target dose was prescribed to the tuning target with a larger margin and one to two shots were filled in the region with missing dose. The resulting plans were compared to the previously approved clinical plans. Results For all 10 patients, a dose sparing effect was observed, i.e. both target coverage and dose to the OARs decreased when the margins of 3D expansion increased. For one patient, a margin of 6 mm was needed to decrease the maximum dose to the optical chiasm and optical nerve by 44.3% and 28.4%, respectively. For the other nine patients, the mean dropping rate of V12Gyto brain stem were 28.2% and 59.5% for tuning targets of 1 and 2 mm margins, respectively. In the dose enhancement study, the tuning-target-guided plans were hotter than the approved treatment plans, while keeping similar dose to the OARs. The mean of the treatment and enhancement dose was 15.6 ± 2.2 Gy and 18.5 ± 3.2 Gy, respectively. The mean coverage of the target by prescription dose was slightly higher in the enhancement plans (96.9 ± 2.6% vs 96.3 ± 3.6%), whereas the mean coverage of the enhancement dose was 20.1% higher in the enhancement plans (89.6 ± 9.0% vs 74.6 ± 19.9%). Conclusions We demonstrated that an inverse planning strategy could facilitate target dose enhancement for challenging GK cases while keeping acceptable OAR dose.

Importance of treatment institution in head and neck cancer radiotherapy.

OBJECTIVE: The treatment for head and neck cancer (HNC) often involves radiotherapy. Many HNC patients are treated at the academic center (AC) where the initial surgery or diagnosis was made. Because of the lengthy time course for radiotherapy, some patients are treated at community radiation facilities (non-AC) rather than the AC despite potential AC advantages in terms of experience and technology. Our goal is to determine if these potential AC advantages correspond to a difference in treatment outcome. STUDY DESIGN: Historical cohort study. SETTING: University of Kansas Medical Center, Kansas City, Kansas. SUBJECTS AND METHODS: Review of records of patients with HNC cancers evaluated at the otolaryngology (ENT) department of an AC. Each patient's information and treatment characteristics were recorded, including radiotherapy treatment venue and treatment outcome. RESULTS: Three hundred seventy-four patients were analyzed, 263 were treated at an AC and 101 at a non-AC. Patients treated at a non-AC were more likely to present with earlier stage tumors, be treated with radiation alone rather than chemoradiotherapy, and be treated with adjuvant rather than primary radiotherapy. There was no difference in overall survival or recurrence rates between AC and non-AC. CONCLUSION: Patients treated at an AC are more likely to have advanced stage tumors and receive chemoradiotherapy as their primary treatment. In analyses of matching patient subsets, there was no significant difference in patient outcomes. Patients can be treated at a non-AC without affecting outcome compared with treatment at an AC.