The Impact of Radiation Energy on Dose Homogeneity and Organ Dose in the Göttingen Minipig Total-Body Irradiation Model.

Animal models of total-body irradiation (TBI) are used to elucidate normal tissue damage and evaluate the efficacy of medical countermeasures (MCM). The accuracy of these TBI models depends on the reproducibility of the radiation dose-response relationship for lethality, which in turn is highly dependent on robust radiation physics and dosimetry. However, the precise levels of radiation each organ absorbs can change dramatically when different photon beam qualities are used, due to the interplay between their penetration and the natural variation of animal sizes and geometries. In this study, we evaluate the effect of varying the radiation energy, namely cobalt-60 (Co-60); of similar penetration to a 4-MV polyenergetic beam), 6 MV and 15 MV, in the absorbed dose delivered by TBI to individual organs of eight Göttingen minipigs of varying weights (10.3-24.1 kg) and dimensions (17.5-25 cm width). The main organs, i.e. heart, lungs, esophagus, stomach, bowels, liver, kidneys and bladder, were contoured by an experienced radiation oncologist, and the volumetric radiation dose distribution was calculated using a commercial treatment planning system commissioned and validated for Co-60, 6-MV and 15-MV teletherapy units. The dose is normalized to the intended prescription at midline in the abdomen. For each animal and each energy, the body and organ dose volume histograms (DVHs) were computed. The results show that more penetrating photon energies produce dose distributions that are systematically and consistently more homogeneous and more uniform, both within individual organs and between different organs, across all animals. Thoracic organs (lungs, heart) received higher dose than prescribed while pelvic organs (bowel, bladder) received less dose than prescribed, due to smaller and wider separations, respectively. While these trends were slightly more pronounced in the smallest animals (10.3 kg, 19 cm abdominal width) and largest animals (>20 kg, ∼25 cm abdominal width), they were observed in all animals, including those in the 9-15 kg range typically used in MCM models. Some organs received an average absorbed dose representing <80% of prescribed dose when Co-60 was used, whereas all organs received average doses of >87% and >93% when 6 and 15 MV were used, respectively. Similarly, average dose to the thoracic organs reached as high as 125% of the intended dose with Co-60, compared to 115% for 15 MV. These results indicate that Co-60 consistently produces less uniform dose distributions in the Göttingen minipig compared to 6 and 15 MV. Moreover, heterogeneity of dose distributions for Co-60 is accentuated by anatomical and geometrical variations across various animals, leading to different absorbed dose delivered to organs for different animals. This difference in absorbed radiation organ doses, likely caused by the lower penetration of Co-60 and 6 MV compared to 15 MV, could potentially lead to different biological outcomes. While the link between the dose distribution and variation of biological outcome in the Göttingen minipig has never been explicitly studied, more pronounced dose heterogeneity within and between organs treated with Co-60 teletherapy units represents an additional confounding factor which can be easily mitigated by using a more penetrating energy.

Cuidados de enfermagem oncológica em radioterapia / Care of oncological nursing in radiotherapy

Objetivo: identificar os cuidados de Enfermagem Oncológica em Radioterapia. Método: trata-se de um estudo qualitativo, descritivo, realizado em um centro de tratamento oncológico referência com três enfermeiras. Coletaram-se os dados mediante entrevistas semiestruturadas por meio de um roteiro e analisados a partir da técnica de Análise de Conteúdo. Resultados: extraíram-se as expressões-chave e ideias centrais, emergiram três categorias que desenharam a atuação do enfermeiro: a) Equipe multidisciplinar envolvida na radioterapia; b) O processo de trabalho das enfermeiras em radioterapia; e, c) As práticas para amenizar os efeitos colaterais da radioterapia Conclusão: ressaltam-se que os cuidados oncológicos em radioterapia consistem em ações individualizadas que, auxiliam diretamente na prevenção, minimização e/ou tratamento das reações adversas causadas pelo tratamento, articulados promovem melhor qualidade de vida do paciente oncológico.(AU)

Objective: to identify the care of Oncology Nursing in Radiotherapy. Method: this is a qualitative, descriptive study performed at a referral center for cancer treatment with three nurses. The data were collected through semi-structured interviews through a script and analyzed using the Content Analysis technique. Results: key expressions and central ideas were extracted, three categories emerged that designed the nurse's performance: a) Multidisciplinary team involved in radiotherapy; b) The work process of the nurses in radiotherapy; and c) Practices to mitigate the side effects of radiotherapy Conclusion: it is emphasized that oncological care in radiotherapy consists of individualized actions that directly aid in the prevention, minimization and / or treatment of the adverse reactions caused by the treatment, articulations promote better quality of life of cancer patients.(AU)

Objetivo: identificar los cuidados de Enfermería Oncológica en Radioterapia. Método: se trata de un estudio cualitativo, descriptivo, realizado en un centro de tratamiento oncológico referencia con tres enfermeras. Se recolectaron los datos mediante entrevistas semiestructuradas por medio de un guion y analizados a partir de la técnica de Análisis de Contenido. Resultados: se extrajeron las expresiones clave e ideas centrales, surgieron tres categorías que diseñaron la actuación del enfermero: a) Equipo multidisciplinario involucrado en la radioterapia; b) el proceso de trabajo de las enfermeras en radioterapia; y c) las prácticas para amenizar los efectos colaterales de la radioterapia Conclusión: se resalta que los cuidados oncológicos en radioterapia consisten en acciones individualizadas que, auxilian directamente en la prevención, minimización y / o tratamiento de las reacciones adversas causadas por el tratamiento, articulados promueven mejor calidad de vida del paciente oncológico.(AU)

Animal models of radiation retinopathy - From teletherapy to brachytherapy.

Radiation retinopathy is a serious vision-impairing complication of radiation therapy used to treat ocular tumors. Characterized by retinal vasculopathy and subsequent retinal damage, the first sign of radiation retinopathy is the preferential loss of vascular endothelial cells. Ensuing ischemia leads to retinal degradation and late stage neovascularization. Despite the established disease progression, the pathophysiology and cellular mechanisms contributing to radiation retinopathy remain unclear. Clinical experience and basic research for other retinal vasculopathies, such as diabetic retinopathy and retinopathy of prematurity, can inform our understanding of radiation retinopathy; however, the literature investigating the fundamental mechanisms in radiation retinopathy is limited. Treatment trials have shown modest success but, ultimately, fail to address the cellular events that initiate radiation retinopathy. Animal models of radiation retinopathy could provide means to identify effective therapies. Here, we review the literature for all animal models of radiation retinopathy, summarize anatomical highlights pertaining to animal models, identify additional physiological factors to consider when investigating radiation retinopathy, and explore the use of clinically relevant tests for studying in vivo models of radiation retinopathy. We encourage further investigation into the mechanistic characterization of radiation retinopathy in the hope of discovering novel treatments.

Incidence of second tumours in high risk prostate cancer patients according to the primary treatment applied. / Incidencia de segundos tumores en pacientes con cáncer de próstata de alto riesgo según el tratamiento primario aplicado.

INTRODUCTION AND OBJECTIVES: The onset of second primary tumours should be considered in high-risk prostate cancer patients in the natural course of the disease. Our aim was to evaluate the influence of primary treatment with curative intent for these patients on the development of second primary tumours. MATERIAL AND METHODS: A retrospective study of 286 patients diagnosed between 1996 and 2008, treated by radical prostatectomy (n=145) or radiotherapy and androgen blockade (n=141). The homogeneity of both series was analysed using the Chi-squared test for the qualitative variables, and the Student's t-test for the quantitative variables. A multivariate Cox regression analysis was performed to assess whether the type of primary treatment influenced the development of second tumours. RESULTS: The median age was 66 years, and the median follow-up was 117.5 months. At the end of follow-up, 60 patients (21%) had developed a second primary tumour. In the prostatectomy group it was located in the pelvis in 13 (9%) cases, and those treated with radiotherapy and hormonotherapy in 8 (5.7%) cases (P=.29). The most common organ sites were: colo-rectal in 17 (28.3%) patients, the lung in 11 (18.3%), and the bladder in 6 (10%) patients. In the multivariable analysis, the risk of a second tumour doubled for those treated with radiotherapy and hormonotherapy (HR=2.41, 95%CI: 1.31-4.34, P=.005) compared to the patients treated by prostatectomy. Age and rescue radiotherapy did not behave as independent predictive factors. CONCLUSIONS: The onset of a second primary tumour was related with the primary treatment given; thus the risk for those treated with radiotherapy and androgen deprivation therapy more than doubled.

Capacitive hyperthermia as an alternative to brachytherapy in DNA damages of human prostate cancer cell line (DU-145).

PURPOSE: The aim of this study was the evaluation of induced DNA damages of human prostate cancer cells, DU-145, treated with a combination of radiofrequency capacitive hyperthermia (HT) and teletherapy (EBRT) compared to a combination of teletherapy with high-dose rate brachytherapy (BR). MATERIALS AND METHODS: DU-145 cells were cultured as spheroids in 300 micron diameter. Then the following treatments were conducted: (a) EBRT at doses of either 2 Gy or 4 Gy of photon 15 MV, (b) HT for 0, 30, 60, and 90 minutes duration at 43 °C from a 13.56 MHz radiofrequency capacitive heating device (Celsius TCS), (c) BR with Ir-192 seed at doses of either 2 Gy or 5.5 Gy, (d) The mentioned HT followed by EBRT (HT + EBRT) and (e) EBRT followed by BR (EBRT + BR). Alkaline comet assay was performed to measure tail moment. RESULTS: The induced DNA damages of DU-145 cells treated by adding HT to EBRT compared with EBRT alone, showed a significant enhancement; 3.28 and 5.14 times respectively for 30 and 60 minutes HT. By plotting dose-response curves, we could find a range of doses, which create radiobiological iso-effect in HT + EBRT and EBRT + BR treatments. CONCLUSIONS: This study suggests that about DNA damages of DU-145 cells, HT + EBRT could partly be considered as an alternative to EBRT + BR.

Dosimetric and bremsstrahlung performance of a single convergent beam for teletherapy device.

The present work investigates preliminary feasibility and characteristics of a new type of radiation therapy modality based on a single convergent beam of photons. The proposal consists of the design of a device capable of generating convergent X-ray beams useful for radiotherapy. The main goal is to achieve high concentrated dose delivery. The first step is an analytical approach in order to characterize the dosimetric performance of the hypothetical convergent photon beam. Then, the validated FLUKA Monte Carlo main code is used to perform complete radiation transport to account also for scattering effects. The proposed method for producing convergent X-rays is mainly based on the bremsstrahlung effect. Hence the operating principle of the proposed device is described in terms of bremsstrahlung production. The work is mainly devoted characterizing the effect on the bremsstrahlung yield due to accessories present in the device, like anode material and geometry, filtration and collimation systems among others. The results obtained for in-depth dose distributions, by means of analytical and stochastic approaches, confirm the presence of a high dose concentration around the irradiated target, as expected. Moreover, it is shown how this spot of high dose concentration depends upon the relevant physical properties of the produced convergent photon beam. In summary, the proposed design for producing single convergent X-rays attained satisfactory performance for achieving high dose concentration around small targets depending on beam spot size that may be used for some applications in radiotherapy, like radiosurgery.

Assessment of national dosimetry quality audits results for teletherapy machines from 1989 to 2015.

The purpose of this study was to ensure accuracy in radiation dose delivery, external dosimetry quality audit has an equal importance with routine dosimetry performed at clinics. To do so, dosimetry quality audit was organized by the Secondary Standard Dosimetry Laboratory (SSDL) of Pakistan Institute of Nuclear Science and Technology (PINSTECH) at the national level to investigate and minimize uncertainties involved in the measurement of absorbed dose, and to improve the accuracy of dose measurement at different radiotherapy hospitals. A total of 181 dosimetry quality audits (i.e., 102 of Co-60 and 79 of linear accelerators) for teletherapy units installed at 22 different sites were performed from 1989 to 2015. The percent deviation between users' calculated/stated dose and evaluated dose (in the result of on-site dosimetry visits) were calculated and the results were analyzed with respect to the limits of ± 2.5% (ICRU "optimal model") ± 3.0% (IAEA on-site dosimetry visits limit) and ± 5.0% (ICRU minimal or "lowest acceptable" model). The results showed that out of 181 total on-site dosimetry visits, 20.44%, 16.02%, and 4.42% were out of acceptable limits of ± 2.5% ± 3.0%, and ± 5.0%, respectively. The importance of a proper ongoing quality assurance program, recommendations of the followed protocols, and properly calibrated thermometers, pressure gauges, and humidity meters at radiotherapy hospitals are essential in maintaining consistency and uniformity of absorbed dose measurements for precision in dose delivery.

A treatment planning comparison between modulated tri-cobalt-60 teletherapy and linear accelerator-based stereotactic body radiotherapy for central early-stage non-small cell lung cancer.

We evaluated the feasibility of planning stereotactic body radiotherapy (SBRT) for large central early-stage non-small cell lung cancer with a tri-cobalt-60 (tri-(60)Co) system equipped with real-time magnetic resonance imaging (MRI) guidance, as compared to linear accelerator (LINAC)-based SBRT. In all, 20 patients with large central early-stage non-small cell lung cancer who were treated between 2010 and 2015 with LINAC-based SBRT were replanned using a tri-(60)Co system for a prescription dose of 50Gy in 4 fractions. Doses to organs at risk were evaluated based on established MD Anderson constraints for central lung SBRT. R100 values were calculated as the total tissue volume receiving 100% of the dose (V100) divided by the planning target volume and compared to assess dose conformity. Dosimetric comparisons between LINAC-based and tri-(60)Co SBRT plans were performed using Student׳s t-test and Wilcoxon Ranks test. Blinded reviews by radiation oncologists were performed to assess the suitability of both plans for clinical delivery. The mean planning target volume was 48.3cc (range: 12.1 to 139.4cc). Of the tri-(60)Co SBRT plans, a mean 97.4% of dosimetric parameters per patient met MD Anderson dose constraints, whereas a mean 98.8% of dosimetric parameters per patient were met with LINAC-based SBRT planning (p = 0.056). R100 values were similar between both plans (1.20 vs 1.21, p = 0.79). Upon blinded review by 4 radiation oncologists, an average of 90% of the tri-(60)Co SBRT plans were considered acceptable for clinical delivery compared with 100% of the corresponding LINAC-based SBRT plans (p = 0.17). SBRT planning using the tri-(60)Co system with built-in MRI is feasible and achieves clinically acceptable plans for most central lung patients, with similar target dose conformity and organ at risk dosimetry. The added benefit of real-time MRI-guided therapy may further optimize tumor targeting while improving normal tissue sparing, which warrants further investigation in a prospective feasibility clinical trial.

Assessment of dose error due to nylon mesh of treatment couch.

PURPOSE: This study aims at the assessment of dose error in patients undergoing radiotherapy due to treatment couch of Co-60 teletherapy unit. MATERIALS AND METHODS: In this study beam attenuation due to treatment couch of Co-60 unit was measured in air for different gantry angles and field sizes. Polymethylmethacrylate (PMMA) phantom was used to estimate the effect of depth on attenuation. Impact of couch on surface dose was also evaluated. RESULTS: Beam attenuation due to couch was in the range of 0.5-28% for different gantry angles with standard field size of 10 × 10 cm(2) with optimum position of metallic cranks. Maximum attenuation (29%) was observed with smallest field size i.e. 5 × 5 cm(2). Beam attenuation has been found higher in phantom as compared to that in air However, no particular trend of attenuation has been noted with varying depth of phantom. A 6% increase in surface dose has also been observed due to couch insertion for normal beam incidence. Maximum error of 80% is also note-worthy for most unfavorable situation of irradiation at 180 degree through the metallic cranks. CONCLUSION: It has been determined that ignoring the treatment couch and its accessories can result in dose error of 0.5-80%, depending on gantry angle, field size and position of couch accessories. Therefore, consideration of dose error due to couch during treatment planning is recommended.

Physical characterization of single convergent beam device for teletherapy: theoretical and Monte Carlo approach.

The main purpose of this work is to determine the feasibility and physical characteristics of a new teletherapy device of radiation therapy based on the application of a convergent x-ray beam of energies like those used in radiotherapy providing highly concentrated dose delivery to the target. We have denominated it Convergent Beam Radio Therapy (CBRT). Analytical methods are developed first in order to determine the dosimetry characteristic of an ideal convergent photon beam in a hypothetical water phantom. Then, using the PENELOPE Monte Carlo code, a similar convergent beam that is applied to the water phantom is compared with that of the analytical method. The CBRT device (Converay(®)) is designed to adapt to the head of LINACs. The converging beam photon effect is achieved thanks to the perpendicular impact of LINAC electrons on a large thin spherical cap target where Bremsstrahlung is generated (high-energy x-rays). This way, the electrons impact upon various points of the cap (CBRT condition), aimed at the focal point. With the X radiation (Bremsstrahlung) directed forward, a system of movable collimators emits many beams from the output that make a virtually definitive convergent beam. Other Monte Carlo simulations are performed using realistic conditions. The simulations are performed for a thin target in the shape of a large, thin, spherical cap, with an r radius of around 10-30 cm and a curvature radius of approximately 70 to 100 cm, and a cubed water phantom centered in the focal point of the cap. All the interaction mechanisms of the Bremsstrahlung radiation with the phantom are taken into consideration for different energies and cap thicknesses. Also, the magnitudes of the electric and/or magnetic fields, which are necessary to divert clinical-use electron beams (0.1 to 20 MeV), are determined using electromagnetism equations with relativistic corrections. This way the above-mentioned beam is manipulated and guided for its perpendicular impact upon the spherical cap. The first results that were achieved show in-depth dose peaks, having shapes qualitatively similar to those from hadrontherapy techniques. The obtained results demonstrate that in-depth dose peaks are generated at the focus point or isocenter. These results are consistent with those obtained with Monte Carlo codes. The peak-focus is independent of the energy of the photon beam, though its intensity is not. The realistic results achieved with the Monte Carlo code show that the Bremsstrahlung generated on the thin cap is mainly directed towards the focus point. The aperture angle at each impact point depends primarily on the energy beam, the atomic number Z and the thickness of the target. There is also a poly-collimator coaxial to the cap or ring with many holes, permitting a clean convergent-exit x-ray beam with a dose distribution that is similar to the ideal case. The electric and magnetic fields needed to control the deflection of the electron beams in the CBRT geometry are highly feasible using specially designed electric and/or magnetic devices that, respectively, have voltage and current values that are technically achievable. However, it was found that magnetic devices represent a more suitable option for electron beam control, especially at high energies. The main conclusion is that the development of such a device is feasible. Due to its features, this technology might be considered a powerful new tool for external radiotherapy with photons.

Can c-myc amplification reliably discriminate postradiation from primary angiosarcoma of the breast?

PURPOSE: Breast angiosarcomas are rare vascular malignancies that arise secondary to irradiation or de novo as primary tumours. The aim of this study is to know whether c-myc amplification can reliably discriminate these two entities. MATERIEL AND METHODS: Forty-seven patients treated for breast angiosarcomas were studied. Thirty-two patients were diagnosed with postradiation angiosarcomas after breast cancer treatment and 15 patients with primary angiosarcomas. Interphase fluorescence in situ hybridization (FISH) was performed by hybridization of probes covering C-MYC (chromosome 8q24.21) and CEP8 on tissue sections. RESULTS: Amplification (5- to 20-fold) of the c-myc oncogene was found in all breast radiation-induced angiosarcomas (32 tumours) but in none of the 15 primary angiosarcomas except one (7%). CONCLUSION: This study reinforces that there are true pathogenetic differences between the two types of breast angiosarcomas which are morphologically indistinguishable. These data point the pathways preferentially involved in the pathogenesis of post radiation angiosarcomas of the breast and may provide the basis for an additional targeted therapy.

Experimental dosimetry in conformal breast teletherapy compared with the planning system.

The objective of this study was to compare and analyse the absorbed dose profiles from the conformal radiotherapy planning and experimental dosimetry taken in a breast anthropomorphic and anthropometric phantom. Conformal radiotherapy planning was elaborated in the Treatment Planning System (TPS). EBT2 Gafchromic radiochromic films were applied as dosimeters, positioned internally and superficially in the breast phantom. The standard radiation protocol was applied in the breast phantom. The films were digitalised, and their responses were analysed in RGB. The optical densities were processed, reproducing the spatial dose distribution.

[Myxoid liposarcoma of the anterior mediastinum. A case report and bibliography review]. / Liposarcoma mixoide de mediastino anterior. Reporte de caso y revisión de la bibliografía.

UNLABELLED: Five cases per year. Of those cases 50% are located in the extremities and 40% are located in the trunk and retroperitoneum. Primary mediastinal liposarcomas represent less than 1% of mediastinal tumors. CLINICAL CASE: A 53 year old female, native and resident of Tabasco, with a history of anterior mediastinal tumor was treated with resection at the National Institute of Cancerology about 16 years ago with histopathological diagnosis of pleomorphic liposarcoma. She started her condition with chest pain, cough and hyaline expectoration, managed as pneumonia in her unit. Other symptoms occurred, moderate exertion dyspnea and edema of lower limbs, chest computed tomography prompted for documenting mediastinal tumor measured to be 9 × 9 cm and sent to our unit which is managed with resection.

Antecedentes: la incidencia de sarcomas de tejidos blandos es de 1.8 a 5 casos por año; 50% aparecen en las extremidades, 40% en el tronco y retroperitoneo. Los liposarcomas primarios de mediastino representan menos de 1% de los tumores mediastinales. Caso clínico: paciente femenina de 53 años de edad, originaria y residente de Tabasco, con antecedente de liposarcoma pleomórfico de mediastino anterior (durante su tercer embarazo) 16 años antes de su ingreso actual; fue tratada en el Instituto Nacional de Cancerología con resección y radioterapia. Acudió a su unidad de adscripción por dolor torácico, tos y expectoración hialina, la trataron como neumonía. Después se agregó disnea de medianos esfuerzos, y edema de miembros pélvicos; con la tomografía computada de tórax se diagnosticó un tumor mediastinal delimitado de 9 × 9 cm; la enviaron a nuestra unidad para su resección. Conclusiones: los liposarcomas representan menos de 1% de los tumores del mediastino, y requieren seguimiento a largo plazo por su alta recidiva después de un largo periodo libre de enfermedad.

Secondary radiation dose during high-energy total body irradiation.

AIM: The goal of this work was to assess the additional dose from secondary neutrons and γ-rays generated during total body irradiation (TBI) using a medical linac X-ray beam. BACKGROUND: Nuclear reactions that occur in the accelerator construction during emission of high-energy beams in teleradiotherapy are the source of secondary radiation. Induced activity is dependent on the half-lives of the generated radionuclides, whereas neutron flux accompanies the treatment process only. MATERIALS AND METHODS: The TBI procedure using a 18 MV beam (Clinac 2100) was considered. Lateral and anterior-posterior/posterior-anterior fractions were investigated during delivery of 2 Gy of therapeutic dose. Neutron and photon flux densities were measured using neutron activation analysis (NAA) and semiconductor spectrometry. The secondary dose was estimated applying the fluence-to-dose conversion coefficients. RESULTS: The main contribution to the secondary dose is associated with fast neutrons. The main sources of γ-radiation are the following: (56)Mn in the stainless steel and (187)W of the collimation system as well as positron emitters, activated via (n,γ) and (γ,n) processes, respectively. In addition to 12 Gy of therapeutic dose, the patient could receive 57.43 mSv in the studied conditions, including 4.63 µSv from activated radionuclides. CONCLUSION: Neutron dose is mainly influenced by the time of beam emission. However, it is moderated by long source-surface distances (SSD) and application of plexiglass plates covering the patient body during treatment. Secondary radiation gives the whole body a dose, which should be taken into consideration especially when one fraction of irradiation does not cover the whole body at once.

Using fiducial markers in the prostate bed in postprostatectomy external beam radiation therapy improves accuracy over surgical clips.

BACKGROUND AND PURPOSE: The purpose of this work was to assess the stability of fiducial markers in the prostate bed and compared their use to surgical clips. PATIENTS AND METHODS: In this study, 3-4 gold fiducial markers were transrectally implanted in the prostate bed of 14 patients. The stability of the fiducial markers position (fiducial markers fixity) over an EBRT course was assessed. Furthermore, the advantages of the fiducial markers compared to the surgical clips were assessed and the interobserver variation between the two technologies was compared. RESULTS: The mean fiducial marker migration during a course of EBRT was small with 1.2 mm (SD ± 0.8 mm). Compared to fiducial markers, the matches with surgical clips were mismatched ≥ 2 mm in 68% of treatments. This discrepancy of > 2 mm was on average 3.7 ± 1.3 mm. There was less interobserver variability for matching of fiducial markers (0.8 ± 0.7 mm) than for surgical clips (2.0 ± 1.6 mm). CONCLUSION: Fiducial markers showed less interobserver variability in matching and less variation in position than surgical clips. Fiducial markers could ultimately help in reducing treatment margins.

Dose measurement of cobalt-60 radiotherapy beams in treatment fields.

BACKGROUND: Radiation-therapy is a complex process with multiple steps, each of which has an impact on the quality of treatment. Accurate dosimetry is a critical step during the radiotherapy of cancer patients.The aim of the present study was to measure and evaluate the doses of two cobalt- 60 (60Co) teletherapy units GWXJ80 of NPIC China and Theratron 780 of AECL Canada at various points within fields for different field sizes. METHODS: This cross-sectional descriptive study was done to measure the 60Co doses in the treatment fields.The dose measurements were done in air and 30x30x30 cm3 Phantom at 80 cm SSD by using calibrated NE 2570 Farmer Electrometer & NE 2571 Farmer Ionization Chamber and percentage of doses were calculated. RESULTS: The results showed that 60% central area of all fields ranging from 100-98.79% and 100-96.12% for GWXJ80 in the air and phantom, whereas for Theratron 780, they were ranging from 100-98.50% and 100-96.45% in air and phantom respectively. The percentages of doses at the edges for GWXJ80 and Theratron 780 in the air were 75.39-38.66% & 85.65-46.47% respectively and they were 82.22-40.39% & 49.05-24.55% respectively in phantom. CONCLUSIONS: The doses within 60% central area of fields in air were higher than phantom for both teletherapy units. The doses at field edges in air were lower in GWXJ80 than Theratron 780 whereas in phantom they were vice versa. But all were in the acceptable range as recommended by International Commission on Radiation Units and Measurements.

[Localized primary bone lymphoma: about four cases]. / Lymphome osseux primitif localisé : à propos de quatre cas.

PURPOSE: To study epidemiological, clinical, pathological anatomy and therapeutic results of localized primary bone lymphoma. PATIENTS AND METHODS: Between February 1993 and February 2013, four patients were treated for localized primary bone lymphoma in Sfax's hospitals (Tunisia). Treatment was decided regarding to the age of the patient, his performance status, stage of the disease, lactate dehydrogenase (LDH) and socio-economical conditions of the patient. The therapeutic evaluation was done after chemotherapy and after radiotherapy. There was a clinical, biological and radiological follow-up. RESULTS: The mean age was 59.5 years. The sex-ratio was 3. Bone localizations were clavicula, femur, humerus and mandibula. All patients had stage I large cell B lymphoma. In 3 cases, imaging showed osteolytic lesions with cortical destruction and extension to soft tissues. One patient had a fracture of the humerus. The treatment consisted in chemotherapy followed by radiotherapy. Three patients were alive with complete remission after a mean follow-up of 76 months. CONCLUSION: The treatment of primary bone lymphoma is based on a combination of chemotherapy (with or without anti-CD20) and radiotherapy. The prognosis is excellent when it is localized.

[The importance of pathology in the German prostate cancer study PREFERE]. / Die Bedeutung der Pathologie in der deutschen Prostatakrebsstudie PREFERE.

Prostate cancer is the most common carcinoma of elderly males and holds the third place in the ranking of cancer-specific mortality. However, total mortality rate of 3 % is low and half of the patients die from other diseases, which is for the most part due to significantly improved diagnostic methods and the increasing use of prostate-specific antigen (PSA) screening. This has led to a stage migration towards early tumor stages that are prognostically heterogeneous and require differentiated treatment. The German and European guidelines recommend four therapy options (i.e. radical prostatectomy, percutaneous irradiation, permanent seed implantation and active surveillance) for localized prostate cancer and from contemporary study data it is unclear which therapy is most beneficial. This will be the subject of the PREFERE trial, a prospective randomized multicentre trial which plans to recruit 7,600 patients and to observe them over a period of up to 17 years. The histopathological diagnosis of the primary biopsy plays a crucial role in the inclusion criteria, as this article outlines in detail.