Introduction
Aim of this analysis was to report toxicity and clinical outcomes in oligorecurrent prostate cancer (PCa) patients treated with single fraction stereotactic radiosurgery (SRS) for bone ...metastases.
Methods
We separately analyzed clinical data of PCa patients with bone oligometastases enrolled in a prospective phase I trial (DESTROY-2). DESTROY-2 was based on SRS delivered using volumetric modulated arc therapy in patients with primary or metastatic tumors in several extra-cranial body sites. Acute and late toxicity, biochemical tumor response, local control (LC), distant metastases-free (DPFS), progression-free (PFS), time to next-line systemic treatment-free (NEST-FS), and overall survival (OS) were calculated.
Results
Data on 37 PCa patients, carrying out 50 bone metastases, candidates for curative-intent treatment and treated with SRS at our Institution were collected. SRS dose ranged between 12 and 24 Gy. One grade 1 acute skin toxicity in one patient treated on the hip (24 Gy) and one grade 1 late skin toxicity in a patient with a scapular lesion (24 Gy) were recorded. No cases of bone fracture were registered in the treated population. With a median follow-up of 25 months (range 3–72 months) 2-year actuarial LC, DPFS, PFS, and OS were 96.7%, 58.1%, 58.1%, and 95.8%, respectively. Median and 2-year NEST-FS were 30 months (range 1–69 months) and 51.2%, respectively.
Conclusions
Data analysis showed few toxicity events, high local control rate and prolonged NEST-FS after linear accelerator-based radiosurgery of bone oligometastases from PCa. The possibility of postponing systemic treatments in patients with oligometastatic PCa by means of SRS should be taken into account. Further prospective studies on larger series are needed to confirm the reported results.
•24 centres performed an autoplanning validation for whole breast radiotherapy.•Centers had large variations in case complexity and clinical practices.•A single autoplanning configuration was used ...for all patients and all centres.•Autoplanning was favorable compared to manual, but with large inter-centre variations.•Autoplanning configuration adaptation in some centres may enhance clinician satisfaction.
To present the results of the first multi-centre real-world validation of autoplanning for whole breast irradiation after breast-sparing surgery, encompassing high complexity cases (e.g. with a boost or regional lymph nodes) and a wide range of clinical practices.
The 24 participating centers each included 10 IMRT/VMAT/Tomotherapy patients, previously treated with a manually generated plan (‘manplan’). There were no restrictions regarding case complexity, planning aims, plan evaluation parameters and criteria, fractionation, treatment planning system or treatment machine/technique. In addition to dosimetric comparisons of autoplans with manplans, blinded plan scoring/ranking was conducted by a clinician from the treating center. Autoplanning was performed using a single configuration for all patients in all centres. Deliverability was verified through measurements at delivery units.
Target dosimetry showed comparability, while reductions in OAR dose parameters were 21.4 % for heart Dmean, 16.7 % for ipsilateral lung Dmean, and 101.9 %, 45.5 %, and 35.7 % for contralateral breast D0.03cc, D5% and Dmean, respectively (all p < 0.001). Among the 240 patients included, the clinicians preferred the autoplan for 119 patients, with manplans preferred for 96 cases (p = 0.01). Per centre there were on average 5.0 ± 2.9 (1SD) patients with a preferred autoplan (range 0–10), compared to 4.0 ± 2.7 with a preferred manplan (0,9). No differences were observed regarding deliverability.
The automation significantly reduced the hands-on planning workload compared to manual planning, while also achieving an overall superiority. However, fine-tuning of the autoplanning configuration prior to clinical implementation may be necessary in some centres to enhance clinicians’ satisfaction with the generated autoplans.
The aim of this study was to investigate the dosimetric characteristics of the electron beams generated by the light intraoperative accelerator, Liac® (SORDINA, Italy), using Monte Carlo (MC) ...calculations. Moreover we investigated the possibility of characterizing the Liac® dosimetry with a minimal set of dosimetric data. In fact accelerator commissioning requires measurements of both percentage depth doses (PDDs) and off-axis profiles for all the possible combinations of energy, applicator diameter and bevelled angle. The Liac® geometry and water phantom were simulated in a typical measurement setup, using the MC code EGSnrc/BEAMnrc. A simulated annealing optimization algorithm was used in order to find the optimal non-monoenergetic spectrum of the initial electron beam that minimizes the differences between calculated and measured PDDs. We have concluded that, for each investigated nominal energy beam, only the PDDs of applicators with diameters of 30, 70 and 100 mm and the PDD without an applicator were needed to find the optimal spectra. Finally, the output factors of the entire set of applicator diameters/bevelled angles were calculated. The differences between calculated and experimental output factors were better than 2%, with the exception of the smallest applicator which gave differences between 3% and 4% for all energies. The code turned out to be useful for checking the experimental data from various Liac® beams and will be the basis for developing a tool based on MC simulation to support the medical physicist in the commissioning phase.
We show that measurements of stellar proper motions in dwarf spheroidal galaxies provide a powerful probe of the nature of dark matter. Allowing for general dark matter density profiles and stellar ...velocity anisotropy profiles, we show that the log slope of the dark matter profile at about twice the stellar core (King) radius can be measured to within c0.2 when the proper motions of 200 stars are added to standard line-of-sight velocity dispersion data. This measurement of the log slope provides a test of cold and warm dark matter theories at a sensitivity not possible with line-of-sight velocity dispersion measurements alone. The upcoming SIM PlanetQuest will have the sensitivity to obtain the required number of proper motions in Milky Way dwarf spheroidal galaxies.
Neutrinos could be mistaken for dark matter by certain types of detectors, so researchers are outlining ways to differentiate the two signals. Direct detection dark matter experiments looking for ...WIMP-nucleus elastic scattering will soon be sensitive to an irreducible background from neutrinos which will drastically affect their discovery potential. Here we explore how the neutrino background will affect future ton-scale experiments considering both spin-dependent and spin-independent interactions. We show that combining data from experiments using different targets can improve the dark matter discovery potential due to target complementarity. We find that in the context of spin-dependent interactions, combining results from several targets can greatly enhance the subtraction of the neutrino background for WIMP masses below 10 GeV /c super(2) and therefore probe dark matter models to lower cross sections. In the context of target complementarity, we also explore how one can tune the relative exposures of different target materials to optimize the WIMP discovery potential.
Purpose
To estimate and reduce uncertainties of a self-consistent set of radiobiological parameters based on the outcome of head and neck cancer (HNC) patients treated with radiotherapy (RT).
Methods
...Published studies comparing at least two RT schedules for HNC patients were selected. The method used to estimate the radiobiological parameters consists of three sequential steps that allow a significant reduction of uncertainties: the first, in which the intrinsic (
α
) and the repair (
β
) radio-sensitivities were estimated together with the doubling time (
T
d
) by an analytical/graphical method; the second, in which the kick-off time for accelerated proliferation (
T
k
) was estimated applying the hypothesis of activation for sub-populations of stem cells during the RT; the third, in which the number of clonogens (
N
) was obtained by the Tumor Control Probability (TCP) model. Independent clinical data were used to validate results.
Results
The best estimate and the 95 % confidence intervals (95 % CIs) were:
α
= 0.24 Gy
−1
(0.23–0.26),
β
= 0.023 Gy
−2
(0.021–0.025),
α
/
β
= 10.6 Gy (8.4–12.6),
T
d
= 3.5 days (3.1–3.9),
T
k
= 19.2 days (15.1–23.3),
N
= 7 × 10
7
(4 × 10
7
–1 × 10
8
). From these data, the dose required to offset repopulation occurring in 1 day (
D
prolif
) and starting after
T
k
was also estimated as 0.69 Gy/day (0.52–0.86).
Conclusions
The estimation of all the radiobiological parameters of HNC was obtained based on the hypothesis of activation for specifically tumorigenic sub-populations of stem cells. The similarity of results to those from other studies strengthens such a hypothesis that could be very useful for the predictivity of the TCP model and to design new treatment strategies for HNC.
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