José Carlos Cruz

RADIOSURGERY FOR BRAIN METASTASES: WHO MAY NOT BENEFIT?

PURPOSE To select a group of patients with brain metastases for whom stereotactic radiosurgery (SRS) may not be beneficial. PATIENTS, MATERIALS, AND METHODS Actuarial survival of 87 patients with brain metastases treated with SRS between July 1993 and May 1999 was retrospectively analyzed under stratification by the Score Index for Stereotactic Radiosurgery for Brain Metastases (SIR). To identify the group of patients most likely to survive less than 6 months after SRS, Cox model survival curves were calculated for all SIR values, and Kaplan-Meier survival curves were calculated for two SIR subsets (0-5 and 6-10) and were compared by log-rank test. RESULTS Overall median survival after SRS was 6.88 months. The stratification of patients into two SIR subsets (0-5 and 6-10) sustained statistical significance regarding survival with p = 0.0001. The median survival time for the group of patients with SIR between 0 and 5 was 4.52 months (95% confidence interval of 2.82 to 5.84 months). Survival probability at 6 months for this group of patients with poor prognosis was 35.6%. CONCLUSION Patients with brain metastases and SIR of 5 or lower have an expected median survival of less than 6 months after treatment with radiosurgery. Thus, radiosurgery may not be beneficial for this group of patients.

Intensity modulated radiotherapy for localized prostate cancer: rigid compliance to dose-volume constraints as a warranty of acceptable toxicity?

BackgroundTo report the toxicity after intensity modulated radiotherapy (IMRT) for patients with localized prostate cancer, as a sole treatment or after radical prostatectomy.MethodsBetween August 2001 and December 2003, 132 patients with prostate cancer were treated with IMRT and 125 were evaluable to acute and late toxicity analysis, after a minimum follow-up time of one year. Clinical and treatment data, including normal tissue dose-volume histogram (DVH) constraints, were reviewed. Gastro-intestinal (GI) and genito-urinary (GU) signs and symptoms were evaluated according to the Radiation Therapy Oncology Group (RTOG) toxicity scales. Median prescribed dose was 76 Gy. Median follow-up time was of 26.1 months.ResultsFrom the 125 patients, 73 (58.4%) presented acute Grade 1 or Grade 2 GI and 97 (77.2%) presented acute Grade 1 or Grade 2 GU toxicity. Grade 3 GI acute toxicity occurred in only 2 patients (1.6%) and Grade 3 GU acute toxicity in only 3 patients (2.4%). Regarding Grade 1 and 2 late toxicity, 26 patients (20.8%) and 21 patients (16.8%) presented GI and GU toxicity, respectively. Grade 2 GI late toxicity occurred in 6 patients (4.8%) and Grade 2 GU late toxicity in 4 patients (3.2%). None patient presented any Grade 3 or higher late toxicity. Non-conformity to DVH constraints occurred in only 11.2% of treatment plans. On univariate analysis, no significant risk factor was identified for Grade 2 GI late toxicity, but mean dose delivered to the PTV was associated to higher Grade 2 GU late toxicity (p = 0.042).ConclusionIMRT is a well tolerable technique for routine treatment of localized prostate cancer, with short and medium-term acceptable toxicity profiles. According to the data presented here, rigid compliance to DHV constraints might prevent higher incidences of normal tissue complication.

Comparison of conformal and intensity modulated radiation therapy techniques for treatment of pelvic tumors. Analysis of acute toxicity

BackgroundThis retrospective analysis reports on the comparative outcome of acute gastrointestinal (GI) and genitourinary (GU) toxicities between conformal radiation therapy (CRT) and intensity modulated radiation therapy (IMRT) techniques in the treatment of patients with pelvic tumors.MethodsFrom January 2002 to December 2008, 69 patients with pelvic tumors underwent whole pelvic CRT and 65 underwent whole pelvic IMRT to treat pelvic lymph nodes and primary tumor regions. Total dose to the whole pelvis ranged from 50 to 50.4 Gy in 25 to 28 daily fractions. Chemotherapy (CT) regimen, when employed, was based upon primary tumor. Acute GI and GU toxicities were graded by RTOG/EORTC acute radiation morbidity criteria.ResultsAbsence of GI symptoms during radiotherapy (grade 0) was more frequently observed in the IMRT group (43.1% versus 8.7; p < 0.001) and medication for diarrhea (Grade 2) was more frequently used in the CRT group (65.2% versus 38.5%; p = 0.002). Acute GI grade 1 and 3 side effects incidence was similar in both groups (18.5% versus 18.8%; p = 0.95 and 0% versus 7.2%; p = 0.058, respectively). Incidence of GU toxicity was similar in both groups (grade 0: 61.5% versus 66.6%, p = 0.54; grade 1: 20% versus 8.7%, p = 0.06; grade 2: 18.5% versus 23.5%, p = 0.50 and grade 3: 0% versus 1.5%, p > 0.99).ConclusionsThis comparative case series shows less grade 2 acute GI toxicity in patients treated with whole pelvic IMRT in comparison with those treated with CRT. Incidence of acute GU toxicity was similar in both groups.

Radioterapia em adenocarcinoma de pâncreas

BACKGROUND: The pancreatic adenocarcinoma is an aggressive disease for which cure is only possible in less than 20% of the best cases. Adjuvant radiotherapy and chemotherapy so far have improved symptoms with little, but significant, increase in survival rates.METHODS: Retrospective assessment of 40 patients admitted at Department of Radiation Oncology of the Hospital Israelita Albert Einstein between April 1993 and August 1999 was done. Radical surgery with tumor resection was previously performed in 25 and palliative procedures or nothing in 15.RESULTS: Overall actuarial median survival was 14.8 months; and actuarial survival rates at 12 and 24 months were 70% and 22.2% respectively. Actuarial median survival for the group of patients with resected tumor was 21.4 and for the group of patients with non-resected tumor was 16.1 months. Expected survival rates at 12 and 24 months were 76% and 32% for the former group and 60% and 0% for the latter.CONCLUSIONS: Results were similar to other published series. Better drugs and more frequent intraoperative radiotherapy are necessary.

Intracoronary brachytherapy in the treatment of in-stent restenosis. Initial experience in Brazil

Intracoronary brachytherapy using beta or gamma radiation is currently the most efficient type of therapy for preventing the recurrence of coronary in-stent restenosis. Its implementation depends on the interaction among interventionists, radiotherapists, and physicists to assure the safety and quality of the method. The authors report the pioneering experience in Brazil of the treatment of 2 patients with coronary in-stent restenosis, in whom beta radiation was used as part of the international multicenter randomized PREVENT study (Proliferation REduction with Vascular ENergy Trial). The procedures were performed rapidly and did not require significant modifications in the traditional techniques used for conventional angioplasty. Alteration in the radiological protection devices of the hemodynamic laboratory were also not required, showing that intracoronary brachytherapy using beta radiation can be incorporated into the interventional tools of cardiology in our environment.

TL and OSL dose response of LiF:Mg,Ti and Al2O3:C dosimeters using a PMMA phantom for IMRT technique quality assurance.

The principle of IMRT is to treat a patient from a number of different directions (or continuous arcs) with beams of nonuniform fluences, which have been optimized to deliver a high dose to the target volume and an acceptably low dose to the surrounding normal structures (Khan, 2010). This study intends to provide information to the physicist regarding the application of different dosimeters type, phantoms and analysis technique for Intensity Modulated Radiation Therapy (IMRT) dose distributions evaluation. The measures were performed using dosimeters of LiF:Mg,Ti and Al2O3:C evaluated by techniques of thermoluminescent (TL) and Optically Stimulated Luminescence (OSL). A polymethylmethacrylate (PMMA) phantom with five cavities, two principal target volumes considered like tumours to be treated and other three cavities to measure the scattered radiation dose was developed to carried out the measures.

Development and characterization tests of a homemade ionization chamber with silver collecting electrode for use in electron beams

Ionization chambers are special detectors for radiation beam dosimetry in hospitals. In this work, a PMMA parallel-plate ionization chamber with air sensitive volume was designed and built for use in electron beams of linear accelerators. This ionization chamber has a PMMA collecting electrode covered with silver paint. Several characterization tests were undertaken following international recommendations. The ionization chamber showed good performance in the characterization tests of its electrical properties and in most of the tests performed in the linear accelerator beams.

OSL and TL response characterization of LiF:MG,Ti microdosimeters to be applied to VMAT quality assurance

This paper aims to evaluate the feasibility of applying LiF:Mg,Ti microdosimeters as a new method of dosimetry to volumetric-modulated arc therapy (VMAT) RapidArc. The response of microdosimeters presented a maximum variation of ±3.18% and ±0.510% using optically stimulated luminescence (OSL) and thermoluminescence (TL) techniques, respectively. Although studies were conducted on LiF:Mg,Ti microdosimeters previously, the microdosimeters in this study showed precision and high potential of application in VMAT dosimetry and in the verification of treatment planning using the VMAT technique.

Dose-response and intrinsic efficiency of thermoluminescent dosimeters in a 15 MV clinical photon beam in a liquid water phantom.

This paper compares the performance of CaSO4:Dy and LiF dosimeters irradiated with a 15 MV photon beam of a clinical linear accelerator to 0.1-10 Gy in a liquid water. The dose-response curves are linear up to 5 Gy. The average TL sensitivity of CaSO4:Dy is 26 and 287 times higher than the sensitivities of LiF:Mg,Ti and microLiF:Mg,Ti, respectively. CaSO4:Dy has an intrinsic efficiency 71% and 94% higher than the intrinsic efficiencies of LiF:Mg,Ti and microLiF:Mg,Ti, respectively.

Avaliação de variações anatômicas em neoplasias pélvicas utilizando CBCT

Avaliar as variacoes dos orgaos de risco (OR) reto e bexiga, movimentacao dos volumes alvo de prostata ou leito prostatico (CTV), e alteracao da anatomia externa usando a ferramenta de localizacao guiada por imagens (IGRT) com Cone beam CT (CBCT) em pacientes pelvicos. Foram desenhados os OR em 90 CBCTs e o CTV em 41. Foram avaliados a media +σ da variacao dos ORs e regiao de interseccao do volume de planejamento (PTV) e os OR (Ov_reto e Ov_bexiga) em relacao aos volumes originais. Foi contabilizado o numero de CBCTs onde o CTV ultrapassou o PTV. Analisou-se tambem a variacao da anatomia externa dos pacientes atraves da medida da dimensao latero-lateral (DLL) e antero-posterior (DAP) nos CBCTs em relacao ao CT de referencia. Em media foram adquiridos 3,9 (1-9) CBCTs por paciente. Os OR bexiga e reto estavam em media -52%±30% e -12%±40% inferiores ao volume original. Os volumes de interseccao entre o PTV e os orgaos de risco Ov_reto e Ov_bexiga, estiveram em media 9%±14% e 5%±17%. A diferenca media, em modulo, do DAP e DLL foi 0,4±0,3cm (maximo 1,2 cm) e -0,3±0,4cm (maximo 1,7 cm). Em 8 imagens analisadas os CTVs ultrapassaram os limites do PTV.