Heavy metal in radiation therapy: A simple method to differentiate hip prosthesis materials.

BACKGROUND: In recent years, the number of hip replacement patients receiving radiation therapy has steadily increased. In parallel, strategies have been developed to reduce metal artifacts in computed tomography (CT) images and improve the accuracy of dose calculation algorithms. However, in certain situations, knowledge of the type of prosthesis material is required to accurately determine the dose distribution. PURPOSE: This study aims to identify physical materials in hip prostheses to correctly assign them in the treatment planning system and improve dose calculation accuracy. METHODS: We first verified the validity of the extended CT mass density calibration curve measured on titanium (Ti) and stainless steel (SS) metal inserts of two different diameters. Then using dedicated reference objects of various circular diameters, we developed a method based on interpolation functions to differentiate between Ti and SS material groups. Forty data sets from 18 patients were used to validate our method on two different reconstruction kernels: a standard Br44f and the electron DirectDensity (Sd40f) kernels from Siemens. RESULTS: Hounsfield units (HU) of Ti and SS inserts were found to vary widely depending on insert diameter, CT spectrum, and reconstruction kernels due to cupping artifacts. The largest HU difference (-79%) was obtained for SS at 70 kV with Br44f when the diameter increased from 8 to 30 mm. Therefore, under these conditions, the extended CT-density calibration curve is not recommended for heavy metal density determination. Using our interpolation-based method, we achieved excellent detection (100%) and material differentiation (100%) results for stems in both reconstruction kernels. At CT energies between 110 and 140 kV, the detection and material differentiation rates were 93.3% and 92.9% for the heads and 93.3% and 92.9% for the acetabular cups, respectively, with the Br44f. Similarly, the use of Sd40f resulted in detection and differentiation rates of 94.7% and 100% for the heads and 100% and 95.0% for the acetabular cups, respectively. CONCLUSION: This method makes it possible to differentiate between hip prosthesis materials and correctly assign them to the Ti or SS group without prior knowledge of the prosthesis type, regardless of the reconstruction kernels. In combination with the Acuros XB (Varian) or Monte Carlo dose algorithms, excellent dosimetric accuracy can be achieved even in the vicinity of hip prostheses. By performing basic measurements, the method can be adapted to other CT units and reconstruction kernels, replacing the use of an extended CT-density calibration curve.

Post-mastectomy radiotherapy: Impact of bolus thickness and irradiation technique on skin dose.

PURPOSE: To determine 10 MV IMRT and VMAT based protocols with a daily bolus targeting a skin dose of 45 Gy in order to replace the 6 MV tangential fields with a 5 mm thick bolus on alternate days method for post-mastectomy radiotherapy. METHOD: We measured the mean surface dose along the chest wall PTV as a function of different bolus thicknesses for sliding window IMRT and VMAT plans. We analyzed surface dose profiles and dose homogeneities and compared them to our standard 6 MV strategy. All measurements were performed on a thorax phantom with Gafchromic films while dosimetric plans were computed using the Acuros XB algorithm (Varian). RESULTS: We obtained the best compromise between measured surface dose (mean dose and homogeneity) and skin toxicity threshold obtained from the literature using a daily 3 mm thick bolus. Mean surface doses were 91.4 ±â€¯2.8% [85.7% - 95.4%] and 92.2 ±â€¯2.3% [85.6% - 95.2%] of the prescribed dose with IMRT and VMAT techniques, respectively. Our standard 6 MV alternate days 5 mm thick bolus leads to 89.0 ±â€¯3.7% [83.6% - 95.5%]. Mean dose differences between measured and TPS results were < 3.2% for depths as low as 2 mm depth. CONCLUSION: 10 MV IMRT-based protocols with a daily 3 mm thick bolus produce a surface dose comparable to the standard 6 MV 5 mm thick bolus on alternate days method but with an improved surface dose homogeneity. This allows for a better control of skin toxicity and target volume coverage.

Adjuvant radio-chemotherapy for extrahepatic biliary tract cancers.

BACKGROUND: Extrahepatic biliary duct cancers (EBDC) are uncommon malignancies characterized by a poor prognosis with high rate of loco-regional recurrence. The purpose of the present study is to assess the feasibility and the potential impact of adjuvant radiotherapy (RT) in a series of patients treated in one institution. METHODS: Twenty three patients with non-metastatic bile duct cancer treated surgically with curative intent (4 gallbladder, 7 ampullary and 12 cholangiocarcinoma) received 3D conformal external beam RT to a median total dose of 50.4 Gy. Concurrent chemotherapy based on 5-FU was delivered to 21 patients (91%). Surgical margins were negative in 11 patients (48%), narrow in 2 (9%), and microscopically involved in 8 (35%). Eleven patients (55%) had metastatic nodal involvement. The average follow-up time for all patients was 30 months (ranging from 3-98). RESULTS: Acute gastrointestinal grade 2 toxicity (RTOG scale) was recorded in 2 patients (9%). Nausea or vomiting grade 1 and 2 was observed in 8 (35%) and 2 patients (9%) respectively. Only one patient developed a major late radiation-induced toxicity. The main pattern of recurrence was both loco-regional and distant (liver, peritoneum and/or lung). No difference was observed in loco-regional control according to the tumor location. The 5-year actuarial loco-regional control rate was 48.3% (67% and 30% for patients operated on with negative and positive/narrow/unknown margins respectively, p=0.04). The 5-year actuarial overall survival was of 35.9% for the entire group (61.4% in case of negative margins and 16.7% in case of positive/narrow/unknown margins, p=0.07). CONCLUSIONS: Postoperative RT with 50-60 Gy is feasible with acceptable acute and late toxicities. The potential benefit observed in our series may support the use of adjuvant RT in patients with locally advanced disease. Prospective randomized trials are warranted to confirm definitively the role of RT in this tumor location.

Impact of Early Prophylactic Cranial Irradiation With Hippocampal Avoidance on Neurocognitive Function in Patients With Limited Disease Small Cell Lung Cancer. A Multicenter Phase 2 Trial (SAKK 15/12).

PURPOSE: Our purpose was to evaluate neurocognitive function (NCF) and clinical outcomes after early hippocampal avoidance (HA) prophylactic cranial irradiation (PCI) in limited disease (LD) small cell lung cancer (SCLC). METHODS AND MATERIALS: In a phase 2 trial, patients with LD SCLC received HA-PCI concomitant with the second cycle of chemotherapy and thoracic radiation therapy. All patients underwent objective NCF testing at baseline, 6 weeks, and 6 and 12 months after HA-PCI. NCF tests included Hopkins Verbal Learning Test Revised, Controlled Oral Word Association, and Trail Making Tests A and B. The primary endpoint was NCF decline at 6 months after HA-PCI. We assumed ≤30% of patients with no NCF decline to be unpromising. Secondary endpoints included brain metastases-free survival (BMFS), overall survival (OS), and safety of the concomitant treatment. RESULTS: Among the 44 patients enrolled in the trial, 38 had evaluable NCF assessment at 6 months after HA-PCI. The proportion of evaluable patients showing no NCF decline at 6 and 12 months was 34.2% (90% confidence interval [CI], 21.6-48.8) and 48.5% (95% CI, 30.8-66.5), respectively. Median follow-up was 13.2 months (95% CI, 12.6-14.1). At 12 months, BMFS was 84.2% and OS was 87.7% (95% CI, 73.0-94.7). Four patients died of SCLC, 1 of respiratory failure, 1 of hemorrhage, and 1 for unknown reason. The most frequently reported grade ≥3 acute adverse events were anemia (21.4%), febrile neutropenia (19.1%), and fatigue (14.3%). CONCLUSIONS: The proportion of patients showing no NCF decline 6 and 12 months after early HA-PCI does not appear to be better than, but rather similar to, that observed in patients receiving sequential PCI without HA. Early HA-PCI in LD SCLC is feasible, with observation of promising BMFS and OS in this selected population.

Improved long-term outcome of surgery for advanced colorectal liver metastases: reasons and implications for management on the basis of a severity score.

BACKGROUND: The outcome of liver resection for colorectal liver metastases (CRLM) appears to be improving despite the fact that surgery is offered to patients with more-severe disease. To quantify this assumption and to understand its causes we analyzed a series of patients on the basis of a standardized severity score and changes in management occurring over the years. METHODS: Patients' characteristics, operative data, chemotherapies and follow-up were recorded. CRLM severity was quantified according to Fong's clinical risk score (CRS), modified to take into account the presence of bilateral liver metastases. Three periods were analyzed, in which different indications, surgical strategies and uses of chemotherapy were applied: 1984-1992, 1993-1998, and 1999-2005. RESULTS: Between January 1984 and December 2005, 210 liver resections were performed in 180 patients (1984-1992, 43 patients; 1993-1998, 42 patients; 1999-2005, 95 patients). CRLM severity increased throughout the time periods, as did the use of neoadjuvant chemotherapies, repeat resections, and multistep procedures. While the disease-free survival did not improve over time, the 1-, 3- and 5-year overall survival rate increased from 85%, 30%, and 23% in the first period, to 88%, 60%, and 34% in the second period, and to 94%, 69%, and 46% in the third period. CONCLUSIONS: Analysis according to the CRS showed that despite the fact that patients had more severe disease, the overall survival improved over the years, mainly thanks to more aggressive treatment of recurrent disease. Management of advanced CRLM should, from the start, take into account the likelihood of secondary procedures.

Imaging of the larynx and hypopharynx.

The purpose of this article is to review currently used imaging protocols for the evaluation of pathologic conditions of the larynx and hypopharynx, to describe key anatomic structures in the larynx and hypopharynx that are relevant to tumor spread and to discuss the clinical role of Computed Tomography (CT), Magnetic Resonance Imaging (MRI) and PET CT in the pretherapeutic workup and posttherapeutic follow-up of patients with squamous cell carcinoma of this region. A detailed discussion of the characteristic neoplastic submucosal invasion patterns, including extension to the preepiglottic space, paraglottic space and laryngeal cartilages and the implications of imaging for tumor staging and treatment planning is provided. The present article also reviews less common tumors of this region, such as chondrosarcoma, lymphoma, minor salivary gland tumors and lipoma. As the majority of non-neoplastic conditions do not require imaging the role of CT and MRI is discussed in some particular situations, such as to delineate cysts and laryngoceles, abscess formation in inflammatory conditions, to evaluate laryngeal and hypopharyngeal involvement in granulomatous and autoimmune diseases, and to evaluate the extent of laryngeal fractures due to severe blunt trauma.

TransitQA - A new method for transit dosimetry of Tomotherapy patients.

PURPOSE: TransitQA is an innovative method for Tomotherapy transit dosimetry using the on-board detector (OBD). Our previously published model for Tomotherapy treatment plan verification (AirQA) has been enhanced to take into account patient and couch transmission. AirQA estimates the OBD signal during irradiation with nothing in the beam path from the leaf control sinogram, allowing us to check whether the planned treatment is correctly delivered by the machine. TransitQA allows us to check the treatment delivery with the patient on the couch, potentially showing the effects of changes in the patient anatomy and delivery errors. METHODS: Patient and couch transmission have been added to the model using the OBD projections of pretreatment megavoltage computed tomography (MVCT). The difference in the energy spectra between the imaging and treatment beams has been corrected by an exponent from the MVCT projections consisting of the ratio of the mass attenuation coefficients. This exponent has been found to not vary significantly with the atomic number Z, allowing us to apply this procedure to heterogeneous media, such as patients. The attenuated OBD projections acquired during the treatment are compared to the model via a signed global γ-index analysis. The dose criterion was 5% of the 95th percentile of the dose distribution, and the distance to agreement (DTA) was 4 mm. RESULTS: Our method has been applied to a heterogeneous phantom with 98.1% of the points passing the γ-evaluation test, showing that the model can predict the attenuated OBD projection. The method has been applied to two representative patients throughout the whole treatment, highlighting variations in the signal transmission and γ-index. CONCLUSION: This paper establishes the proof-of-concept of transit dosimetry for all patients treated by Tomotherapy. Moreover, this method can be used as a surrogate for in vivo dosimetry.

Pancreatic Cancer: Feasibility and Outcome After Radiochemotherapy with High Dose External Radiotherapy for Non-resected and R1 Resected Patients.

Background Non-resected locally advanced and microscopic positive-margin resected (R1) pancreatic adenocarcinoma are associated with a dismal prognosis. The combination of high dose radiotherapy and concomitant chemotherapy is among the strategies that are used to improve the outcome. The aims of this study were to evaluate the acute and late toxicities and patients' outcome in a retrospective study from a single center. Material and methods From 2009 to 2015, 24 patients, with non-resected locally advanced or R1 resected pancreatic adenocarcinoma, have been treated with concomitant radiochemotherapy, with a median dose of 60 Gy and gemcitabine (50 mg/m2 administered bi-weekly). The acute and late toxicities were evaluated during and after the treatment. Results The actuarial overall survival rates were 39% at 24 months and 8.6% at 36 months. The disease-free survival rates were 32.5% at 24 months and 12.2% at 36 months. Acute toxicities were mainly grade 1 (G1) to grade 2 (G2) except for one patient who presented with severe digestive bleeding potentially linked to the treatment. Late toxicities consisted mainly of G1 digestive toxicities. Conclusion This study confirms the feasibility of high dose radiotherapy combined with gemcitabine-based chemotherapy in patients with locally advanced pancreatic adenocarcinoma. While the outcome remains unsatisfactory, some patients seem to have benefited from this aggressive therapy, which merits to be investigated further.

Correction: Pancreatic Cancer: Feasibility and Outcome After Radiochemotherapy with High Dose External Radiotherapy for Non-resected and R1 Resected Patients.

[This corrects the article DOI: 10.7759/cureus.2713.].

Value of ezrin, maspin and nm23-H1 protein expressions in predicting outcome of patients with head and neck squamous-cell carcinoma treated with radical radiotherapy.

BACKGROUND: Prognostic factors in predicting outcomes in patients with head and neck squamous-cell carcinoma (HNSCC) are limited to the clinical-pathological parameters, including lymph node metastasis, location, grade and stage of the disease. AIM: To determine whether the expression of these proteins has a value in predicting patient outcome. METHODS: Ezrin, maspin and nm23-H1 immunohistochemistry in tissue samples of 120 patients with HNSCC were evaluated using the microarray technique. RESULTS: In determining the association among each of the three proteins and the clinical-pathological parameters, low maspin expression was the only one found to be significantly associated with high tumour grade (p = 0.007); all others showed no significant associations. In univariate analysis, patients with tumours expressing high ezrin had a shorter disease-free survival (DFS) of 51% than those with low ezrin expression (DFS 84%; p = 0.08). In multivariate analysis, tumours with the combination of loss of maspin and low histological grade had longer DFS (83%) compared with those with high maspin and high histological grade (DFS 42%; p = 0.08). CONCLUSION: Our study is the first to determine the value of ezrin and maspin in HNSCC in a large series of patients with long follow-up. Ezrin and maspin seem to have a potential prognostic value in patients with HNSCC but results should be confirmed with further studies.