Medicina nuclear y radioterapia

Purpose: Whole breast irradiation is part of breast conservative management for early breast cancer; addition of boost dose to tumor bed improves local recurrence rates and is currently the standard of care. Randomized trials reported low a/b ratio for breast cancer that predict a radiobiological advantage for hypofractionation. Simultaneous boost radiation as a method of hypofractionation proved safe and effective for head and neck tumors. In this study we attempt to compare and analyze the dosimetric aspects of adding Simultaneous Integrated Boost (SIB) over Sequential Boost (SB) to a hypofractionated treatment schedule in breast cancer patients after BCS.

Materials and methods: CT simulation data sets for 23 patients were selected for this planning study; Targets and OAR were delineated as per RTOG guidelines. Multiple dynamic field IMRT plans were generated for each patient. The prescribed dose was 40 Gy/15 fractions to whole breast (2.67 Gy/fraction) and 48 Gy/15fractions to lumpectomy cavity (3.2 Gy/fraction) for SIB, and 40 Gy/15 fractions followed by 10Gy/5 fractions for SB. Generated Treatment plans were evaluated by experienced radiation oncologist, and the best plan was selected for the dosimetric analysis.

Results: The pre specified target coverage criteria were met for the lumpectomy cavity as well as whole breast in all plans. All quality indices for PTV coverage showed to be significantly improved with SIB for both whole breast and tumor bed volumes. SB technique showed more dose spillage outside the boost volume. SIB-IMRT was better in sparing OAR ,the volume of the ipsilateral lung V20 Gy was 19.8 % compared to 22.8 % (p = 0.04), maximum dose to LAD was 17.6 Gy Vs. 21.6 (p= 0.01) and contralateral breast mean dose was 0.36 Gy Vs. 1.27 Gy (p = 0.01) for SIB and SB respectively.

Conclusions: Hypofractionated breast SIB is feasible with better PTV coverage and OAR. Along with further reduction of the overall period which may increase patient convenience and resource utilization benefit.

The Daily intrinsic flood uniformity test of a gamma camera is required to be performed before using the gamma camera to acquire patient images. It is meant to detect changes in the performance of a gamma camera system that may affect the interpretation of clinical studies adversely.

5-aminolevulinic acid heptyl ester (heptyl 5-aminolevulinate), a potential prodrug for fluorescence diagnosis and Photodynamic Therapy (PDT), was investigated in human adenocarcinoma WiDr cells and in healthy skin of athymic nude mice in comparison with 5-aminolevulinic acid (ALA). Incubation of WiDr cells with ALA and ALA heptyl ester resulted in the production of Protoporphyrin IX (PpIX). Concentrations higher than 0.01 mM for ALA heptyl ester and 1 mM for ALA were cytotoxic. Similar amounts of PpIX production and same photobleaching rate were observed in WiDr cells, although a 100 times lower concentration of ALA heptyl ester was needed in comparison with ALA. In contrast to cells culture, topical application of 2% of ALA and ALA heptyl ester gave similar fluorescence of PpIX and PpIX photobleaching in mouse model. But a faster PpIX pbotobleaching was observed in vivo compared to in vitro.

The primitive Small Cell Neuroendocrine Carcinoma (SCNC) is a rare subtype of neuroendocrine laryngeal tumors which are the second most common laryngeal neoplasm after squamous cell carcinoma. We report a case of SCNC of the larynx occurring in a 35-year-old man, who smokes and drinks alcohol, who presented with dysphonia and dyspnea. On clinical examination there were painless, mobile cervical lymph nodes in addition to gynecomastia. On endoscopy, the lesion was exophytic and involved the whole of the right vocal cord. SCNC diagnosis was based on morphologic and immune-histochemical criteria. Treatment was non-surgical based on sequential chemoradiation therapy. An isolated local relapse was, unexpectedly, the first post therapeutic event, occurring at the end of the first year of follow up and managed by salvage surgery. Metastatic-free survival was 28 months.

Purpose: In this prospective study, we have aimed to analyze the levels of doses and toxicities of critical normal structures in the treatment of non-small cell lung cancer (NSCLC) with 3-D Conformal Radiotherapy.

Material and Method: We have evaluated 24 patients with biopsy proven inoperable NSCLC stages III, treated with Conformal Radiotherapy. After CT- simulation, GTV, CTV, PTV and critical normal structures (lungs, esophagus, heart, and spinal cord) were contoured by the physician and radiologist and then dose volumes were calculated. Chemoradiotherapy was used in these patients after induction treatment. Induction chemotherapy was administrated: Docetaxe l75 mg/m² + Cisplatin 75 mg/m² from day 1 for each 21 days, total 3 cycles. After induction therapy concomitant Docetaxel 25 mg/m² + Cisplatin 25 mg/m² were administrated weekly for 5 to 6 weeks and radiotherapy was delivered with linear accelerator, 64 – 66 Gy/32 – 33 fr/200 cGy/d. The study endpoints were critical normal structures doses, early and late toxicities, and local control.

Results: DVH: Lungs V20 is 32%. Heart Dmean doses are 1892 cGy (Dmin 22 cGy - Dmax. 4084 cGy). Esophagus Dmean doses are 2700 cGy (Dmin. 912 cGy - Dmax. 4513 cGy) and Spinal cord Dmean is 1201 cGy (Dmin. 115 cGy - Dmax. 2139 cGy). Acute toxicities; 18 patients (75%) have grade I-II esophagitis, 6 patients (25%) have grade III esohagitis, 7 patients (29%) have grade III-IV pneumonia and 4 patients (16,6 %) have grade I-II pneumonia. No late toxicity has been observed in esophagus, heart and even lungs. Median follow-up was 13 months and local control rate was 41.6%.

Conclusion: This study confirms that 3-D Conformal Radiotherapy is an effective treatment with NSCLC. But patients in the study have large tumors or tumors near critical locations, so critical normal structures doses were high compared with literature.