Radiotherapy of large target volumes in Hodgkin's lymphoma: normal tissue sparing capability of forward IMRT versus conventional techniques

<p>Abstract</p> <p>Background</p> <p>This paper analyses normal tissue sparing capability of radiation treatment techniques in Hodgkin's lymphoma with large treatment volume.</p> <p>Methods</p> <p>10 patients with supradiaphragmatic Hodgkin's lymphoma and planning target volume (PTV) larger than 900 cm³were evaluated. Two plans were simulated for each patient using 6 MV X-rays: a conventional multi-leaf (MLC) parallel-opposed (AP-PA) plan, and the same plan with additional MLC shaped segments (forward planned intensity modulated radiation therapy, FPIMRT). In order to compare plans, dose-volume histograms (DVHs) of PTV, lungs, heart, spinal cord, breast, and thyroid were analyzed. The Inhomogeneity Coefficient (IC), the PTV receiving 95% of the prescription dose (V95), the normal tissue complication probability (NTCP) and dose-volume parameters for the OARs were determined.</p> <p>Results</p> <p>the PTV coverage was improved (mean V95_AP-PA= 95.9 and IC_AP-PA= 0.4 vs. V95_FPIMRT= 96.8 and IC_FPIMRT= 0.31, <it>p </it>≤ 0.05) by the FPIMRT technique compared to the conventional one. At the same time, NTCPs of lung, spinal cord and thyroid, and the volume of lung and thyroid receiving ≥ 30 Gy resulted significantly reduced when using the FPIMRT technique.</p> <p>Conclusions</p> <p>The FPIMRT technique can represent a very useful and, at the same time, simple method for improving PTV conformity while saving critical organs when large fields are needed as in Hodgkin's lymphoma.</p

Radiation therapy in primary orbital lymphoma: a single institution retrospective analysis

<p>Abstract</p> <p>Background</p> <p>Primary orbital lymphoma is a rare disease that accounts for 10% of all orbital tumors. Radiotherapy on the orbital cavity is the treatment of choice for this unusual presentation of localized non-Hodgkin's lymphoma (NHL). The aim of this study is to retrospectively evaluate the effectiveness and the toxicity of radiation treatment in patients with primary orbital lymphoma.</p> <p>Methods</p> <p>Forty-seven consecutive patients having primary orbital lymphoma treated in our department between May 1983 and September 2006 were investigated in a retrospective study. Either ⁶⁰Co γ rays or 6 MV X rays were used to deliver daily fractions of 1.8 or 2.0 Gy, 5 times/week, with total doses ranging from 34.2 to 50 Gy. Forty-three patients had stage IE, three had stage II and one stage IV disease. Thirty-eight patients had marginal zone B-cell lymphoma, 5 diffuse large B cell lymphoma, 3 mantle cell lymphoma and 1 Burkitt lymphoma. Local control (LC), disease free survival (DFS), overall survival (OS) and late side effects were evaluated in all patients.</p> <p>Results</p> <p>With a median follow up of 45 months, LC was obtained in 100% of patients. The estimated 5- and 7-year DFS rates were 75.8% and 55.3%, and the 5- and 7-year OS rates were 88.7% and 79.9% respectively. Acute toxicity was minimal. Late toxicity such as cataract, keratitis, retinopathy and xerophthalmia occurred respectively in 12 (25.5%), 5 (10.6%), 1 (2.1%), and 9 (19.1%) patients.</p> <p>Conclusion</p> <p>Radiotherapy is an effective and at the same time well tolerated treatment for primary orbital lymphoma.</p

Range margin reduction in carbon ion therapy: potential benefits of using radioactive ion beams

Radiotherapy with heavy ions, in particular, 12C beams, is one of the most advanced forms of cancer treatment. Sharp dose gradients and high biological effectiveness in the target region make them an ideal tool to treat deep-seated and radioresistant tumors, however, at the same time, sensitive to small errors in the range prediction. Safety margins are added to the tumor volume to mitigate these uncertainties and ensure its uniform coverage, but during the irradiation they lead to unavoidable damage to the surrounding healthy tissue. To fully exploit the benefits of a sharp Bragg peak, a large effort is put into establishing precise range verification methods for the so-called image-guided radiotherapy. Despite positron emission tomography being widely in use for this purpose in 12C ion therapy, the low count rates, biological washout, and broad shape of the activity distribution still limit its precision to a few millimeters. Instead, radioactive beams used directly for treatment would yield an improved signal and a closer match with the dose fall-off, potentially enabling precise in vivo beam range monitoring. We have performed a treatment planning study to estimate the possible impact of the reduced range uncertainties, enabled by radioactive 11C beams treatments, on sparing critical organs in the tumor proximity. We demonstrate that (i) annihilation maps for 11C ions can in principle reflect even millimeter shifts in dose distributions in the patient, (ii) outcomes of treatment planning with 11C beams are significantly improved in terms of meeting the constraints for the organs at risk compared to 12C plans, and (iii) less severe toxicities for serial and parallel critical organs can be expected following 11C treatment with reduced range uncertainties, compared to 12C treatments

A djuvant treatment in patients at high risk of recurrence of thymoma: Efficacy and safety of a three-dimensional conformal radiation therapy regimen

The clinical benefits of postoperative radiation therapy (PORT) for patients with thymoma are still controversial. In the absence of defined guidelines, prognostic factors such as stage, status of surgical margins, and histology are often considered to guide the choice of adjuvant treatment (radiotherapy and/or chemotherapy). In this study, we describe our single-institution experience of three-dimensional conformal PORT administered as adjuvant treatment to patients with thymoma. METHODS: Twenty-two consecutive thymoma patients (eleven male and eleven female) with a median age of 52 years and treated at our institution by PORT were analyzed. The patients were considered at high risk of recurrence, having at least one of the following features: stage IIB or III, involved resection margins, or thymic carcinoma histology. Three-dimensional conformal PORT with a median total dose on clinical target volume of 50 (range 44-60) Gy was delivered to the tumor bed by 6-20 MV X-ray of the linear accelerator. Follow-up after radiotherapy was done by computed tomography scan every 6 months for 2 years and yearly thereafter. RESULTS: Two of the 22 patients developed local recurrence and four developed distant metastases. Median overall survival was 100 months, and the 3-year and 5-year survival rates were 83% and 74%, respectively. Median disease-free survival was 90 months, and the 5-year recurrence rate was 32%. On univariate analysis, pathologic stage III and presence of positive surgical margins had a significant impact on patient prognosis. Radiation toxicity was mild in most patients and no severe toxicity was registered. CONCLUSION: Adjuvant radiotherapy achieved good local control and showed an acceptable toxicity profile in patients with high-risk thymoma

Delineazione automatica di strutture cerebrali in pazienti sottoposti a radioterapia per tumori primitivi encefalici: dall'atlante all'istogramma dose-volume

Scopo: Implementare e validare una procedura automatizzata di segmentazione basata su atlanti effettuata su immagini di risonanza magnetica (MRI-ABAS) intesa per la definizione di formazioni grigie corticali e sottocorticali, e utilizzabile per valutazioni dosimetriche in pazienti affetti da tumori encefalici e sottoposti a radioterapia. Pazienti e Metodi: Sono state utilizzate immagini di risonanza magnetica acquisite per dieci pazienti affetti da tumore cerebrale prima dell'inizio della RT. MRI ABAS consiste di due momenti fondamentali: la procedura di classificazione della sostanza grigia e la definizione delle regioni di interesse basata sull'utilizzo di atlanti. L'algoritmo Simultaneous Truth and Performance Level Estimation (STAPLE) è stato applicato alle strutture delineate manualmente da quattro diversi operatori con lo scopo di generare uno standard di riferimento. Per la valutazione della efficienza di MRI-ABAS sono state utilizzate cinque misure geometriche (incluso il coefficiente di similarità di Dice, DSC) e tre diversi parametri dosimetrici. Risultati: Confrontato con la delineazione manuale, MRI-ABAS ha mostrato un'eccellente riproducibilità [valori mediani di DSCMRI-ABAS= 1 (95% CI, 0.97-1.0) vs. DSCMANUALE= 0.90 (0.73-0.98)], un'accuratezza accettabile [DSCMRI-ABAS= 0.81 (0.68-0.94) vs. DSCMANUALE= 0.90 (0.76-0.98)] e una riduzione dei tempi di delineazione di circa il 90%. I parametri dosimetrici ottenuti dall'analisi degli istogrammi dose-volume per MRI ABAS sono risultati comparabili a quelli ottenuti con la metodica manuale. Conclusioni: Le caratteristiche di rapidità, riproducibilità e robustezza fanno della procedura MRI-ABAS un utile strumento per la valutazione degli effetti legati all'irradiazione in strutture encefaliche "non-target". Inoltre, della procedura automatizzata proposta va sottolineato il vantaggio legato alla possibilità di ottenere numerosi dati in maniera standardizzata con tempi di elaborazione ridotti