Radiation therapy, in conjunction with surgical implant fixation, is a common combined treatment in cases of bone metastases. However, metal implants generally used in orthopedic implants perturb radiation dose distributions. Carbon‐Fiber Reinforced Polyetheretherketone (CFR‐PEEK) material has been recently introduced for production of intramedullary nails and plates. The purpose of this work was to investigate the perturbation effects of the new CFR‐PEEK screws on radiotherapy dose distributions and to evaluate these effects in comparison with traditional titanium screws. The investigation was performed by means of Monte Carlo (MC) simulations for a 6 MV photon beam. The project consisted of two main stages. First, a comparison of measured and MC calculated doses was performed to verify the validity of the MC simulation results for different materials. For this purpose, stainless steel, titanium, and CFR‐PEEK plates of various thicknesses were used for attenuation and backscatter measurements in a solid water phantom. For the same setup, MC dose calculations were performed. Next, MC dose calculations for titanium, CFR‐PEEK screws, and CFR‐PEEK screws with ultrathin titanium coating were performed. For the plates, the results of our MC calculations for all materials were found to be in good agreement with the measurements. This indicates that the MC model can be used for calculation of dose perturbation effects caused by the screws. For the CFR‐PEEK screws, the maximum dose perturbation was less than 5%, compared to more than 30% perturbation for the titanium screws. Ultrathin titanium coating had a negligible effect on the dose distribution. CFR‐PEEK implants have good prospects for use in radiotherapy because of minimal dose alteration and the potential for more accurate treatment planning. This could favorably influence treatment efficiency and decrease possible over‐ and underdose of adjacent tissues. The use of such implants has potential clinical advantages in the treatment of bone metastases.

The following is a report on the clinical experience of an Israeli referral center for iodine-131 metaiodobenzylguanidine (131-MIBG) therapy for malignant pheochromocytoma (MPCC) and malignant paraganglioma (MPGG). The charts of 10 patients with MPCC (n = 7) and MPGG (n = 3) treated between 2000 and 2008 were reviewed. Response to 131-MIBG therapy was evaluated by tumor, hormone, and symptomatic relief criteria. The median follow-up was 18 months (2-48 months). The number of 131-MIBG treatments ranged from 1 to 4 (mean: 2.1). The average single dose of 131-MIBG was 5.4 +/- 0.2 GBq (145 +/- 5.0 mCi). The average cumulative dose was 11.6 +/- 1.6 GBq (310 +/- 44.0 mCi). There were no complete responses. Three patients (30%) had partial tumor response, 5 (50%) had stable disease, and 2 (20%) progressed after therapy. Five patients (50%) experienced symptomatic response. Hormone response was noted in 5 patients (50%). Progression-free survival was 17.5 months (2-47 months). One patient (10%) had thrombocytopenia and 2 patients (20%) developed subclinical hypothyroidism. Hormonal and symptomatic relief can be achieved with 131-MIBG therapy in patients with MPCC and MPGG with minor side effects.

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The purpose of this study was to evaluate the feasibility of hippocampal‐sparing whole‐brain radiotherapy (HS WBRT) using the Elekta Infinity linear accelerator and Monaco treatment planning system (TPS). Ten treatment plans were created for HS‐WBRT to a dose of 30 Gy (10 fractions). RTOG 0933 recommendations were applied for treatment planning. Intensity‐modulated radiotherapy (IMRT) plans for the Elekta Infinity linear accelerator were created using Monaco 3.1 TPS‐based on a nine‐field arrangement and step‐and‐shoot delivery method. Plan evaluation was performed using D2% and D98% for the whole‐brain PTV (defined as whole brain excluding hippocampus avoidance region), D100% and maximum dose to the hippocampus, and maximum dose to optic nerves and chiasm. Homogeneity index (HI) defined as false(D2normal%−D98normal%false)/normalDmedian was used to quantify dose homogeneity in the PTV. The whole‐brain PTV D2% mean value was 37.28 Gy (range 36.95–37.49 Gy), and D98% mean value was 25.37 Gy (range 25.40–25.89 Gy). The hippocampus D100% mean value was 8.37 Gy (range 7.48–8.97 Gy) and the hippocampus maximum dose mean value was 14.35 Gy (range 13.48–15.40 Gy). The maximum dose to optic nerves and optic chiasm for all patients did not exceed 37.50 Gy. HI mean value was 0.36 (range 0.34–0.37). Mean number of segments was 105 (range 88–122) and mean number of monitor units was 1724 (range 1622–1914). Gamma evaluation showed that all plans passed 3%, 3 mm criteria with more than 99% of the measured points. These results indicate that Elekta equipment (Elekta Infinity linac and Monaco TPS) can be used for HS WBRT planning according to compliance criteria defined by the RTOG 0933 protocol.PACS numbers: 87.55D, 87.55 –v, 87.55 de

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