Cecília Maria Kalil Haddad

ROLE OF INTRA- OR PERIPROSTATIC CALCIFICATIONS IN IMAGE-GUIDED RADIOTHERAPY FOR PROSTATE CANCER

PURPOSE Image-guided radiotherapy (IGRT) allows more precise localization of the prostate, thus minimizing errors resulting from organ motion and set-up during treatment of prostate cancer. Using megavoltage cone-beam computed tomography (MVCBCT), references such as bones, the prostate itself or implanted fiducial markers can be used as surrogates to correct patient positioning immediately before each treatment fraction. However, the use of fiducials requires an invasive procedure and may increase costs. We aimed to assess whether intra- or periprostatic calcifications (IPC) could be used as natural fiducials. METHODS AND MATERIALS Data on patients treated with IGRT for prostate cancer with clearly visible IPC and implanted fiducials in both planning CT and MVCBCT images were reviewed. IPC were classified as central when inside the prostate and peripheral when within the planning target volume. Daily deviations in lateral, longitudinal, and vertical directions from baseline positioning using fiducials and using IPC were compared. RESULTS A total of 287 MVCBCT images were obtained and analyzed from 10 patients. The mean ± standard deviation daily deviation (mm) in the lateral, longitudinal, and vertical coordinates were 0.55 ± 3.11, 0.58 ± 3.45, and -0.54 ± 4.03, respectively, for fiducials, and 0.72 ± 3.22, 0.63 ± 3.58, and -0.69 ± 4.26, for IPC. The p values for comparisons (fiducials vs. IPC) were 0.003, 0.653, and 0.078 for lateral, longitudinal, and vertical coordinates, respectively. When cases with central IPC were analyzed (n = 7), no significant difference was found in such comparisons. Central IPC and fiducials exhibited a similar pattern of displacement during treatment, with equal values for daily displacements in the three directions for more than 90% of measurements. CONCLUSIONS Our data suggest that centrally located IPC may be used as natural fiducials for treatment positioning during IGRT for prostate cancer, with potential reductions in the risks and costs associated with fiducial implantation.

Outcomes of high-dose intensity-modulated radiotherapy alone with 1 cm planning target volume posterior margin for localized prostate cancer.

BackgroundClinically localized prostate cancer may be treated by different approaches of radiation therapy. The aim of this study was to report the results of disease control and toxicity in patients with clinically localized prostate cancer treated with high dose IMRT alone with 1 cm PTV posterior margin.MethodsFrom September 2001 to April 2008, 140 patients with localized prostate cancer were treated with definitive IMRT (dose ≥ 74 Gy) without hormone therapy. Outcomes were measured from the conclusion of radiotherapy. Biochemical failure was defined as PSA nadir + 2.0 ng/dL. Toxicities were assessed using the NCI-CTCAE-version 3.0. Median follow-up was 58 months.ResultsBiochemical failure occurred in 13.6% of patients. Actuarial 5-year biochemical control rates were 91.7%, 82.5% and 85.9% for low-, intermediate-, and high-risk patients, respectively. Stage T2 patients presented a risk of biochemical failure almost three times higher than stage T1 (RR = 2.91; 95% CI: 1.04; 8.17). Distant metastases occurred in 3 (2%) patients. Five-year metastasis-free and overall survivals were 96% and 97.5%, respectively. Late grade 3 genitourinary and gastrointestinal toxicity rates were, respectively, 1.6% and 3%.ConclusionHigh-dose IMRT alone with 1 cm posterior PTV margin was effective and safe for patients with localized prostate cancer.

The value of positron-emission tomography/computed tomography for radiotherapy treatment planning: a single institutional series

BackgroundThis study aimed to compare the clinical target volumes (CTV) delineated by computed tomography (CT) and positron emission tomography (PET)/CT using fluoro-deoxy-glucose to assess the impact of using PET information for radiotherapy (RT) planning. MethodsWe retrospectively reviewed data on patients with tumors from different sites who had indications for RT and had undergone RT treatment planning with PET/CT at our institution between July 2003 and July 2009. Statistical analysis included the comparison of CTV planned for treatment only by CT (CTVCT) with that by PET/CT (CTVPET) using the Wilcoxon test for paired samples. ResultsOf 105 patients eligible for analysis, 56.2% were men. The most common diagnoses were head and neck cancer (28.6%), lung cancer (21.9%), lymphoma (11.4%), upper gastrointestinal (10.5%), and others (14.3%). Comparison of CTVCT and CTVPET revealed that RT planning has changed in 77% of cases because of PET/CT additional information, with impact on treatment volume varying according to diagnosis. Despite the absolute difference observed between median CTVs, there was no significant difference between CTVCT and CTVPET (114 vs. 90.4 ml, respectively; P=0.1266), considering all patients. Nonetheless, a significant difference between CTVs delineated by CT and PET/CT was found when only head and neck, lung and lymphoma cases – representing more than 60% of the sample – were examined (112.5 and 80.7 ml, respectively; P=0.0053). ConclusionWe have shown that PET/CT use promotes significant changes in the CTV delineated for treatment of different tumors, modifying RT planning. Our data suggest that PET/CT has a good potential for optimizing RT treatment planning, especially in head and neck, lung, and lymphoma tumors.

Radiation dose distribution in the teeth, maxilla, and mandible of patients with oropharyngeal and nasopharyngeal tumors who were treated with intensity-modulated radiotherapy.

The purpose of this study was to evaluate the distribution of the intensity‐modulated radiotherapy (IMRT) dose delivered to the teeth, maxilla, and mandible.

Biochemical control of prostate cancer with iodine-125 brachytherapy alone: experience from a single institution

AimBrachytherapy is an adequate option as monotherapy for localised prostate cancer. The objective of this study was to evaluate and compare biochemical failure free survival (BFFS) after low-dose-rate brachytherapy (LDRB) alone for patients with prostate cancer using ASTRO and Phoenix criteria, and detect prognostic factors.MethodsData on 220 patients treated between 1998 and 2002 with LDRB were retrospectively analysed. Neoadjuvant hormone therapy was used in 74 (33.6%) patients.ResultsMedian follow-up was 53.5 months (24–116). Five year BFFS was 83.0% and 83.7% using, respectively, the ASTRO and Phoenix criteria. Low -and intermediate-risk patients presented, respectively, 86.7% and 77.8% 5-year BFFS using the ASTRO definition (p=0.069), and 88.5% and 78.6% considering the Phoenix criteria (p=0.016). Bounce was observed in 66 (30%) patients. Multivariate analysis detected PSA at diagnosis <10 ng/ml and less than 50% positive biopsy fragments as favourable prognostic factors, regarding BF using both criteria. For the Phoenix criteria, also Gleason score <7 and low-risk group were identified as independent favourable prognostic factors.ConclusionsLDRB alone should be considered mostly for low-risk patients. PSA level was a strong independent prognostic factor. We support the use of the Phoenix criteria for detection of BF in patients submitted to LDRB alone.

Micose fungoide: relato de caso tratado com radioterapia

Mycosis fungoides is a rare type of non-Hodgkins lymphoma of T cells that primarily affects the skin. It is characterized by the presence of erythematous plaques that evolve into ulcerated lesions, tumors throughout the skin or even bone marrow infiltration in advanced stages. Chemotherapy and topical steroids, phototherapy and radiotherapy are treatment options for early cases. This study reports the case of patient with multiple tumor lesions in the skin already biopsied with diagnosis of mycosis fungoides. The patient was refractory to both treatments with topical chemotherapy and phototherapy. It was then indicated total skin irradiation with electrons

Educación a Distancia (EaD) en Física Médica

A formacao inicial e continuada de profissionais de fisica medica possui caracteristicas peculiares por ser uma area interdisciplinar, de evolucao tecnologica constante. Em paises como o Brasil, existem barreiras como: pequeno numero de profissionais, geograficamente mal distribuidos, baixos recursos financeiros, e poucas opcoes em termos de acesso a informacao, dificultando a incorporacao e disseminacao de novas tecnicas que impactam na qualidade do atendimento em saude. Esta revisao da literatura se propos a avaliar o papel da EaD na educacao de fisicos medicos, retratando sua aplicabilidade mediante a identificacao de experiencias relevantes. Os trabalhos mostram que a EaD tem caracteristicas interessantes para a area, tais como alta efetividade pedagogica e eficiencia economica, possibilitando o uso massivo de recursos multimidia, com grande abrangencia geografica e de forma gerenciavel. Portanto tem potencial para superar as barreiras e suprir carencias da area.

Stereotactic Body Radiation Therapy for Biopsy-Proven Primary Non–Small-Cell Lung Cancer: Experience of Patients With Inoperable Cancer at a Single Brazilian Institution

Purpose Stereotactic body radiation therapy (SBRT) has emerged as a treatment option for patients with non–small-cell lung cancer (NSCLC). We report the clinical outcomes and toxicity for patients with inoperable primary NSCLC treated with SBRT. Methods Between 2007 and 2015, 102 consecutive lung lesions were treated with SBRT at our center, of which 59 primary NSCLC lesions (from 54 patients with inoperable disease) were retrospectively reviewed (43 lesions were excluded because of metastases or because there was no biopsy specimen). We report infield local control (LC) per SBRT target, regional or distant failure-free survival, and overall survival (OS) per patient, using Kaplan-Meier estimates. Serious toxicity was retrospectively scored using Common Terminology Criteria for Adverse Events, version 4. Results Most of the 54 patients were men (n = 41; 76%), median age was 75 years; stage IA (n = 36; 66%) and adenocarcinoma (n = 43; 80%) were the most common stage and histologic diagnosis, respectively. Five patients had two lung lesions. A median of three fractions (range, 3 to 5 fractions) and a total median dose of 54 Gy (range, 45 to 60 Gy) per lesion were prescribed. The median follow-up was 17.8 months (range, 4 to 56.4 months). The 2-year rates of LC, regional or distant failure-free survival, and OS were 89.1% (95% CI, 72.2% to 96%), 79% (95% CI, 59.8% to 89.8%), and 80% (95% CI, 64% to 89.8%), respectively. Grade 3 to 4 toxicities were observed in two patients (3%): grade 3 pneumonitis (n = 1) and grade 4 skin toxicity (n = 1). Conclusion SBRT results in high rates of 2-year LC, regional or distant failure-free survival, and OS with low rates of severe toxicity in patients with inoperable primary NSCLC disease.

Determination of the Uncertainty in the Cross-calibration of an Ionization Chamber Used in Radiation Therapy

It was performed an analysis of the uncertainties involved in a cross-calibration procedure of an ionization chamber used in Sirio-Libanes Hospital, according to the methodology proposed in IAEA-TECDOC-1585, based on ISO GUM. The overall uncertainty obtained was 2,55% (coverage factor k = 2), which meant an increase of 0,04% compared to the reference ionization chamber uncertainty reported by the dosimetry laboratory of LCI-GMR-IPEN/CNEN-SP.

Feasibility study of using epitaxial silicon diodes for clinical electron and photon beams dosimetry

In this work the feasibility of using epitaxial (EPI) silicon diodes for clinical dosimetry was studied with a Siemens Primus Linear Accelerator from Sírio-Libanês Hospital. Three samples of EPI diodes were investigated, concerning the influence of pre-irradiation on their response as on-line clinical photon and electron beam dosimeter. All measurements were performed with the diodes unbiased, operating in the direct current mode and inserted into a PMMA phantom. The dynamic current responses of the diodes under irradiation with electron beams in the energy range of 6 MeV-21 MeV and photon beams of the 6 and 18 MV were measured at different dose-rates. The dose-response curves of the diodes are quite linear in the range of zero up to 29.54 kGy for electrons and evaluated from 63 cGy up to 370 cGy for photon beams. The percentage depth dose profile (PDD) and transversal dose profile (TDP) for both electron and photon beams were also measured in PMMA with the EPI diodes. The results were in excellent agreement with those calculated with Monte Carlo code using the Oncentra MasterPlan® Treatment Planning System (TPS). The TDP was also evaluated with a commercialized array of 2D pixel ionization chambers MatriXX from IBA Dosimetry®.