Application of PET-LINAC in Biology-guided Radiotherapy / 中国医疗器械杂志

Biology-guided radiotherapy (BgRT) is a novel technique of external beam radiotherapy, combining positron emission tomography-computed tomography (PET-CT) with a linear accelerator (LINAC). The key innovation is to utilize PET signals from tracers in tumor tissues for real-time tracking and guiding beamlets. Compared with a traditional LINAC system, a BgRT system is more complex in hardware design, software algorithm, system integration and clinical workflow. RefleXion Medical has developed the world's first BgRT system. Nevertheless, its actively advertised function, PET-guided radiotherapy, is still in the research and development phase. In this review study, we presented a number of issues related to BgRT, including its technical advantages and potential challenges.

Uso de PET-CT en el delineado de volumen en la planificación del tratamiento con radiación / Use of PET-CT in the one delineated of volume in the planning of the one radiant treatment

El tratamiento con radioterapia, consiste en irradiar de forma homogénea el tumor, evitando irradiar los órganos cercanos. El desarrollo de la tecnología en el campo de la medicina, ha permitido que se cumpla este principio, con buenos resultados de respuesta objetiva, que se traduce en el control de la enfermedad de los pacientes con cáncer. La Tomografía axial computarizada por emisión de positrones (PET-CT) consigue una mayor precisión en el delineado del volumen blanco o tumoral. El propósito de este estudio fue analizar la influencia del uso del PET-CT en el delineado de volúmenes a tratar en la planificación del tratamiento con radiaciones.Se diseñó un estudio piloto con dos pacientes preparados para radioterapia por neoplasias malignas, a los cuáles se les realizó un TAC simple y un PET-CT y observadores independientes realizaron la delimitación del tumor. Se examinó la consistencia entre los observadores y las mediciones en las imágenes.El uso del PET-CT favoreció la delimitación del volumen a irradiar lo que disminuye el riesgo para los órganos vecinos.

The treatment with radiotherapy consists on irradiating in a homogeneous way the tumor, avoiding to irradiate the near organs. The development of the technology in the field of the medicine, it has allowed that this principle is completed, with good results of objective answer what allows the control of the illness of the patients with cancer. The computerized axial tomography by positrons emission (PET-CT) it gets a bigger precision in the one delineated of the white volume or tumoral. The purpose of this study was to analyze the influence of the use of the PET-CT in the one delineated of volumes to try in the planning of the treatment with radiations.A study pilot was designed with two prepared patients for radiotherapy for malignant diseases, to those which they were carried out a simple TAC and a PET-CT and independent observers carried out the delimitation of the tumor. The consistency was examined between the observers and the mensuration in the images.The use of the PET-CT favors the delimitation of the volume to irradiate what diminishes the risk for the neighboring organs.

Braquiterapia adaptativa guiada por resonancia magnética para el cáncer cervical localmente avanzado: experiencia del Hospital Carlos Van Buren / MRI-guided adaptive brachytherapy for locally advanced cervical cancer: experience at Carlos Van Buren Hospital

Introducción y objetivos: El tratamiento estándar para pacientes con cáncer cervical localmente avanzado (CCLA) se basa en radioterapia externa y quimioterapia concomitante seguida de braquiterapia adaptativa guiada por imágenes (BTAGI). El objetivo de este estudio fue describir los resultados del protocolo de BTAGI de resonancia magnética del Servicio de Oncología del Hospital Carlos Van Buren. Métodos: En pacientes con CCLA tratadas con Radioquimioterapia concomitante seguida de BTAGI de resonancia magnética se evaluó la reducción tumoral, parámetros dosimétricos y la toxicidad aguda. Resultados: Se evaluó la reducción tumoral entre el diagnóstico y el momento de la braquiterapia en 34 pacientes. Todas las pacientes completaron el tratamiento de radioterapia externa. Veinticuatro pacientes recibieron 3 sesiones de braquiterapia. Dosis equivalentes totales > 80 Gy se logro en todos los pacientes. Doce pacientes presentaron reducción del volumen tumoral mayor al 70%. La mediana de las dosis equivalentes totales prescritas al D2cc de vejiga fue 73.9 Gy, al recto 65.6 Gy y al intestino fue de 69.1 Gy. Una paciente presento toxicidad gastrointestinal grado ≥ 3. No hubo diferencias estadísticamente significativas al comparar pacientes que recibieron dosis equivalentes totales desde los 85 Gy con las que recibieron menor dosis respecto a toxicidad gastrointestinal (p=0.33) y genitourinaria (p=0.97). Conclusión: La braquiterapia adaptativa guiada por resonancia magnética se puede realizar en el sistema público de salud y cumplir con las recomendaciones internacionales requeridas para el tratamiento estándar del CCLA.

Introduction and purpose: External beam radiation therapy with concomitant chemotherapy followed by adaptive image-guided brachytherapy (IGABT) is the standard of care for patients with locally advanced cervical cancer (LACC). The purpose of this study was to describe the local outcomes of the magnetic resonance IGABT protocol at the radiation oncology department of the Carlos Van Buren Hospital. Methods: Tumor reduction, dosimetric parameters and acute toxicity were evaluated in patients with LACC treated with concomitant radiochemotherapy followed by magnetic resonance IGABT. Results: Tumor reduction between diagnosis and brachytherapy was evaluated in 34 patients. All patients completed external radiation therapy treatment. Twenty-four patients received 3 sessions of brachytherapy. All patients received a total equivalent dose > 80 Gy. Twelve patients showed a tumor volume reduction greater than 70%. The median total equivalent dose prescribed to the bladder D2cc was 73.9 Gy, the rectum 65.6 Gy, and the intestine 69.1 Gy. One patient presented grade ≥ 3 gastrointestinal toxicity. No statistically significant differences were found when comparing patients who received total equivalent doses larger than 85 Gy with those who received lower doses regarding gastrointestinal (p = 0.33) and genitourinary (p = 0.97) toxicity. Conclusion: MRI-guided adaptive brachytherapy can be performed in the public health system and achieve the international recommendations required as standard of care treatment of LACC.

Image-Guided BrachyAblation (IGBA) en hepatocarcinoma: descripción de la técnica y reporte del primer caso en Chile / Image-guided brachyablation for hepatocarcinoma: report of one case

Eighty percent of hepatocarcinomas are inoperable at the moment of diagnosis. Liver transplantation is the treatment of choice in these cases, but local therapies are another alternative. Among these, Image-Guided BrachyAblation is a safe choice. We report a 76-year-old male with a hepatocarcinoma, who was considered inoperable due to the high surgical risk of the patient. A local treatment with Image-Guided BrachyAblation was decided. A brachytherapy needle was placed in the tumor under computed tomography guidance and a 15 Gy single dose was delivered from an Iridium-192 source. The patient had no immediate complications and at one month of follow up he continued without incidents.

Spine radiosurgery for the local treatment of spine metastases: Intensity-modulated radiotherapy, image guidance, clinical aspects and future directions

Many cancer patients will develop spinal metastases. Local control is important for preventing neurologic compromise and to relieve pain. Stereotactic body radiotherapy or spinal radiosurgery is a new radiation therapy technique for spinal metastasis that can deliver a high dose of radiation to a tumor while minimizing the radiation delivered to healthy, neighboring tissues. This treatment is based on intensity-modulated radiotherapy, image guidance and rigid immobilization. Spinal radiosurgery is an increasingly utilized treatment method that improves local control and pain relief after delivering ablative doses of radiation. Here, we present a review highlighting the use of spinal radiosurgery for the treatment of metastatic tumors of the spine. The data used in the review were collected from both published studies and ongoing trials. We found that spinal radiosurgery is safe and provides excellent tumor control (up to 94% local control) and pain relief (up to 96%), independent of histology. Extensive data regarding clinical outcomes are available; however, this information has primarily been generated from retrospective and nonrandomized prospective series. Currently, two randomized trials are enrolling patients to study clinical applications of fractionation schedules spinal Radiosurgery. Additionally, a phase I clinical trial is being conducted to assess the safety of concurrent stereotactic body radiotherapy and ipilimumab for spinal metastases. Clinical trials to refine clinical indications and dose fractionation are ongoing. The concomitant use of targeted agents may produce better outcomes in the future.

Effect of sugarcane biopolymer in vocal fold of rabbits. Comparative study with calcium hydroxyapatite

PURPOSE: To compare the inflammatory reaction caused by the injection of a sugarcane biopolymer (SCB) into the vocal fold of rabbits with that caused by calcium hydroxyapatite (CaH). METHODS: CaH (Radiesse(r)) and SCB gel were injected respectively into the right and left vocal cords of thirty rabbits. The rabbits were distributed into two equal groups and sacrificed at three and twelve weeks after injection. We then evaluated the intensity of the inflammatory reaction, plus levels of neovascularization, fibrogenesis and inflammatory changes in the vocal mucosa. RESULTS: The vocal cords injected with CaH had a stronger inflammatory reaction by giant cells in both study periods. The SCB group had a more intense inflammatory involvement of polymorphonuclear cells three weeks after injection. SCB caused a higher level of neovascularization compared with CaH three weeks after the procedure. CONCLUSION: Whereas calcium hydroxyapatite triggers a more intense and lasting inflammatory reaction mediated by giant cells, sugarcane biopolymer causes a greater response from polymorphonuclear leukocytes, as well as higher levels of vneoascularization three weeks after injection. .

Stereotactic Body Radiation Therapy for Low- to Intermediate-risk Prostate Adenocarcinoma

The aim of the present study was to evaluate the efficacy and toxicity of stereotactic body radiation therapy (SBRT) for low- to intermediate-risk prostate adenocarcinoma. Thirty-nine patients were retrospectively reviewed. The SBRT was delivered using the CyberKnife with the fiducial tracking method combined with In-tempo imaging. The gross target volume, which included the prostate only, was delineated on the fused CT/MRI scans. The prescription dose was delivered every other day as 5 fractions of 7.5 Gy. Venous blood was obtained before and after SBRT to assess the prostate-specific antigen (PSA) level. Toxicity was evaluated using the CTCAE, v4.03. The median follow-up time was 30.0 months. The median initial PSA level was 7.7 ng/mL. PSA levels decreased in all patients treated with SBRT, and after 5 months, the median PSA was less than 2 ng/mL. The rate of overall 3-yr actuarial biochemical failure free survival was 93.9%. Acute side effects were generally comparable with those of previous studies. The PSA change and toxicity after SBRT for low- to intermediate-risk prostate adenocarcinoma indicates favorable biochemical responses and tolerable levels of toxicity. Additionally short course treatment may produce cost benefit and convenience to patients.

Lipiodol as a Fiducial Marker for Image-Guided Radiation Therapy for Bladder Cancer

Purpose To evaluate Lipiodol as a liquid, radio-opaque fiducial marker for image-guided radiation therapy (IGRT) for bladder cancer.Materials and Methods Between 2011 and 2012, 5 clinical T2a-T3b N0 M0 stage II-III bladder cancer patients were treated with maximal transurethral resection of a bladder tumor (TURBT) and image-guided radiation therapy (IGRT) to 64.8 Gy in 36 fractions ± concurrent weekly cisplatin-based or gemcitabine chemotherapy. Ten to 15mL Lipiodol, using 0.5mL per injection, was injected into bladder submucosa circumferentially around the entire periphery of the tumor bed immediately following maximal TURBT. The authors looked at inter-observer variability regarding the size and location of the tumor bed (CTVboost) on computed tomography scans with versus without Lipiodol.Results Median follow-up was 18 months. Lipiodol was visible on every orthogonal two-dimensional kV portal image throughout the entire, 7-week course of IGRT. There was a trend towards improved inter-observer agreement on the CTVboost with Lipiodol (p = 0.06). In 2 of 5 patients, the tumor bed based upon Lipiodol extended outside a planning target volume that would have been treated with a radiation boost based upon a cystoscopy report and an enhanced computed tomography (CT) scan for staging. There was no toxicity attributable to Lipiodol.Conclusions Lipiodol constitutes a safe and effective fiducial marker that an urologist can use to demarcate a tumor bed immediately following maximal TURBT. Lipiodol decreases inter-observer variability in the definition of the extent and location of a tumor bed on a treatment planning CT scan for a radiation boost.