Medicina nuclear y radioterapia

Purpose: Deformable image registration is widely used in radiation therapy applications. There are several different algorithms for deformable image registration. The purpose of this study was to evaluate the optimal similarity measures needed to obtain accurate deformable image registration by using a phantom.

Methods: To evaluate the optimal similarity measures for the deformable image registration, we compared several similarity measures, including the normalized correlation coefficient, the mutual information, the dice similarity coefficient, and the Tanimoto coefficient. In this study, the mutual information was normalized to have a value of 1 when there is complete correspondence between the images in order to compare it with other similarity measures. First, a reference image was acquired with the phantom located in the center of the field of view of a computed tomography. The phantom consisted of two sections a Teflon sphere and four samples of various electron density values. Then, to acquire the moving images, the phantom was scanned for various displacement values as it was moved to the left (range: 1.00-30.0 mm). Second, images for various Teflon sphere diameters (range: 0–25.4 mm) were acquired with the CT scanner. The image similarity for each condition was compared with the reference image by using several similarity measures.

Results: In the moved phantom study, although the normalized correlation coefficient, dice similarity coefficient, and Tanimoto coefficient showed the same tendency of sensitivity for measuring image similarity, the mutual information showed significant sensitivity for both of the two distinct sections of the phantom. In the study in which the phantom sphere diameter was varied, the mutual information also showed the best performance among the tested similarity measures.

Conclusions: Mutual information appears to have an advantage over other similarity measures for accurate deformable image registration.

Because of the many controversies concerning the consumption of antioxidants during the treatment of cancer, herein we decided to ascertain whether the supplementation of Beta vulgaris (strong antioxidant) in irradiated head and neck cancer patients would influence parameters which describe oxidative stress/DNA damage and the clinical effects of therapy. Forty one patients with head and neck cancer (T3-4 N1 M0) were divided into two subgroups: I/supplementation chips from beetroot (n=19) and II/control group (n=22). All the patients were eligible for radiotherapy; acute reactions were measured using the Dische scale. Total survival times were assessed together with oxidative DNA damage on the level of the whole organism and whether the biomarkers of the damage such as 8-oxo-dG and its modified base (8-oxo-Gua) were present in urine and DNA. Results of the present work suggest that with irradiated patients supplementation of Beta vulgaris does not worsen survival times, intensification of acute radiation reactions is reduced, and the level markers of oxidative stress/DNA damage are also not influenced. Results also suggest that supplementation of Beta vulgaris in irradiated patients is the safe method for assisting therapy.

Background: It is well documented that low dose ionizing radiation induces migration of glioma cells, but the mechanisms are still poorly understood. The aim of the current study was to elucidate the intracellular signal transduction pathways of radiation induced migration in human glioma cells.

Methods: Migration was assessed via a wound healing assay. In addition, tumor cell proliferation was evaluated with a MTT colorimeritric assay using 3 glioma cell lines (LN18, LN229, LNZ308). The cells were treated with increasing doses of irradiation (2Gy, 5Gy, 8Gy) in the presence or absence of EGF or inhibitors of the EGFR or downstream pathways (AG1478, LY294002, PD98059). Biochemical activation of EGFR, Akt/PKB and MAPK/ERK was examined by Western blot analysis.

Results: Irradiation induced a dose dependant intense increase of migrating cells and a decrease of proliferation. The inhibition of PI3K by LY294002 (50 µmol/L) reduced the radiation-induced migration (LN18: p<0.001, LN229: p=0.16, LNZ308: p=0.13), the blockade of MEK1 by PD98059 (50 µmol/L) was also effective (LN18: p=0.036, LN229: p=0.021, LNZ308: p=0.021). After irradiation, no effect on EGFR or the downstream pathways was observed in Western blot analysis.

Conclusion: Our results demonstrate that the downstream pathways of EGFR are involved in radiation induced migration of glioma cells.

Purpose of review: To summarize the current role of alpha particles in cancer treatment including both clinical and pre-clinical data.

Recent findings: Though discovered more than hundred years ago, no targeted alpha emitters have yet to be approved as a systemic approach to cancer therapy. Until recently, most approaches to target alpha particle emitters utilized conjugation with antibodies through chelators. Limited clinical data are available using this approach; most alpha emitters have been studied in pre-clinical models though 213bismuth has been studied in leukemic patients. The novel alpha emitter 223radium has been studied more extensively than other agents in this class and a recent large randomized phase III trial data with 223radium demonstrates overall survival benefit in castrate resistant prostate cancer patients with skeletal metastasis.

Summary: The alpha emitter 223radium is expected to play a significant future role in therapy for bone-metastatic disease and a variety of novel alpha emitters offer the potential for targeted therapy via conjugation with specific antibodies or targeted nanoparticles.

Nowadays, 18-fluorodeoxyglucose positron emission tomography (18-FDG/PET) and computed tomography (CT) are frequently used in the diagnosis and staging of lung cancer. Usually, FDG-PET/CT images are taken from cranium or skull base to the groin, which covers most of the potential locations of metastasis. We describe three cases of stage IIIB NSCLC with unexpected stage-changing solitary bone metastasis outside the usual range of FDG PET/CT. We discuss whether a total body PET/CT should be performed on a regular basis. In addition, we propose a practical solution that is applicable in each clinic, to assess the whole body “on demand”, without compromising the logistics in a busy PET/CT clinic.

To assess the role of Radiation Therapy (RT), in the treatment of optic glioma analyzing 11 retrospective trials during the latest twenty-five years.

In a 25-year-old woman, referred to our centre because of right optic glioma, fractionated stereotactic radiation therapy (FSRT) was the treatment of choice using a commercial linear accelerator Elekta Synergy beam modulator with an integrated Cone Beam Computed Tomography (CBCT) system. In order to evaluate volumetric changes of the right optic nerve lesion a co-registration of pre-RT Magnetic Resonance Imaging (MRI) and CT planning scan was performed and compared with the co-registration of CT planning scan and MRI performed 3 years after the end of the treatment. A noticeable shrinkage in Clinical Target Volume was found and the patient experienced a complete recovery of the right eye visual deficit.

Successful Progression Free Survival and Overall Survival at 10 years can be obtained using a dose between 52 and 60 Gy. FSRT is advantageous compared to conventional RT because of sparing of normal tissues within the high dose volume. Modern linear accelerators with an integrated Cone Beam system improve treatment set-up and dose delivery