Patterns in ano-rectal dose maps and the risk of late toxicity after prostate IMRT.

Purpose: The aim of this work was to determine how the spatial pattern of dose in the ano-rectal wall is related to late gastro-intestinal toxicity for prostate cancer patients treated with mainly IMRT.Patients and methods: Patients from the DUE-01 multicentre study with patient-reported (prospective) follow-up and available dosimetric data were included. Conventionally fractionated patients received 74-80 Gy and hypofractionated patients received 65-75.2 Gy. A large majority of the patients were treated with intensity-modulated radiotherapy (IMRT). Dose-surface maps (DSMs) for the anal canal and rectum as a single structure, and for the anal canal and the rectum separately, were co-registered rigidly in two dimensions and, for the patients with and without toxicity, respectively, the mean value of the dose in each pixel was calculated. A pixel-wise t-test was used to highlight the anatomical areas where there was a significant difference between the 'mean dose maps' of each group. Univariate models were also fitted to a range of spatial parameters. The endpoints considered were a mean grade ≥1 late fecal incontinence and a maximum grade ≥2 late rectal bleeding.Results: Twenty-six out of 213 patients had fecal incontinence, while 21/225 patients had rectal bleeding. Incontinence was associated with a higher dose in the caudal region of the anal canal; the most relevant spatial parameter was the lateral extent of the low and medium isodoses (5-49 Gy in EQD2). Bleeding was associated with high isodoses reaching the posterior rectal wall. The spatial dose parameters with the highest AUC value (.69) were the lateral extent of the 60-70 Gy isodoses.Conclusions: To avoid fecal incontinence it is important to limit the portion of the anal canal irradiated. Our analysis confirms that rectal bleeding is a function of similar spatial dose parameters for patients treated with IMRT, compared to previous studies on patients treated with three-dimensional conformal radiotherapy.

The rotational spectrum of 15ND. Isotopic-independent Dunham-type analysis of the imidogen radical.

The rotational spectrum of 15ND in its ground electronic X3Σ- state has been observed for the first time. Forty-three hyperfine-structure components belonging to the ground and ν = 1 vibrational states have been recorded with a frequency-modulation millimeter-/submillimeter-wave spectrometer. These new measurements, together with the ones available for the other isotopologues NH, ND, and 15NH, have been simultaneously analysed using the Dunham model to represent the ro-vibrational, fine, and hyperfine energy contributions. The least-squares fit of more than 1500 transitions yielded an extensive set of isotopically independent Ulm parameters plus 13 Born-Oppenheimer Breakdown coefficients Δlm. As an alternative approach, we performed a Dunham analysis in terms of the most abundant isotopologue coefficients Ylm and some isotopically dependent Born-Oppenheimer Breakdown constants δlm [R. J. Le Roy, J. Mol. Spectrosc., 1999, 194, 189]. The two fits provide results of equivalent quality. The Born-Oppenheimer equilibrium bond distance for the imidogen radical has been calculated [rBOe = 103.606721(13) pm] and zero-point energies have been derived for all the isotopologues.

Baseline status and dose to the penile bulb predict impotence 1 year after radiotherapy for prostate cancer.

AIM: To assess the predictors of the onset of impotence 1 year after radiotherapy for prostate cancer. PATIENTS AND METHODS: In a multi-centric prospective study, the International Index of Erectile Function (IIEF) questionnaire-based potency of 91 hormone-naïve and potent patients (IIEF1-5 > 11 before radiotherapy) was assessed. At the time of this analysis, information on potency 1 year after treatment was available for 62 of 91 patients (42 treated with hypofractionation: 2.35-2.65 Gy/fr, 70-74.2 Gy; 20 with conventional fractionation: 74-78 Gy). Prospectively collected individual information and Dmax/Dmean to the penile bulb were available; the corresponding 2 Gy-equivalent values (EQD2_max/EQD2_mean) were also considered. Predictors of 1­year impotency were assessed through uni- and multi-variable backward logistic regression: The best cut-off values discriminating between potent and impotent patients were assessed by ROC analyses. The discriminative power of the models and goodness-of-fit were measured by AUC analysis and the Hosmer-Lemeshow (H&L) test. RESULTS: At 1­year follow-up, 26 of 62 patients (42 %) became impotent. The only predictive variables were baseline IIEF1-5 values (best cut-off baseline IIEF1-5 ≥ 19), Dmax ≥ 68.5 Gy and EQD2_max ≥ 74.2 Gy. The risk of 1­year impotence may be predicted by a two-variable model including baseline IIEF1-5 (OR: 0.80, p = 0.003) and EQD2_max ≥ 74.2 Gy (OR: 4.1, p = 0.022). The AUC of the model was 0.77 (95% CI: 0.64-0.87, p = 0.0007, H&L: p = 0.62). The 1­year risk of impotency after high-dose radiotherapy in potent men depends on the EQD2_max to the penile bulb and on baseline IIEF1-5 values. CONCLUSION: A significant reduction in the risk may be expected mainly when sparing the bulb in patients with no/mild baseline impotency (IIEF1-5 > 17).

Rotational spectroscopy of isotopologues of silicon monoxide, SiO, and spectroscopic parameters from a combined fit of rotational and rovibrational data.

Pure rotational transitions of silicon monoxide, involving the main ((28)Si(16)O) as well as several rare isotopic species, were observed in their ground vibrational states by employing long-path absorption spectroscopy between 86 and 825 GHz (1 ≤ J" ≤ 18). Fourier transform microwave spectroscopy was used to study the J" = 0 transition frequencies in the ground and several vibrationally excited states. The vibrational excitation of the newly studied isotopologues extend to between υ = 9 and 29 for (28)Si(17)O and (30)Si(16)O, respectively. Data were extended for some previously investigated species up to υ = 51 for the main isotopologue. The high spectral resolution allowed us to resolve the hyperfine structure in (28)Si(17)O caused by the nuclear electric quadrupole and magnetic dipole moments of (17)O for the first time, and to resolve the much smaller nuclear spin-rotation splitting for isotopic species containing (29)Si. These data were combined with previous rotational and rovibrational (infrared) data to determine an improved set of spectroscopic parameters of SiO in one global fit which takes the breakdown of the Born-Oppenheimer approximation into account. Highly accurate rotational transition frequencies for this important astronomical molecule can now be predicted well into the terahertz region with this parameter set. In addition, a more complete comparison among physical properties of group 14/16 diatomics is possible.

Development of a Ready-to-Use Graphical Tool Based on Artificial Neural Network Classification: Application for the Prediction of Late Fecal Incontinence After Prostate Cancer Radiation Therapy.

PURPOSE: This study was designed to apply artificial neural network (ANN) classification methods for the prediction of late fecal incontinence (LFI) after high-dose prostate cancer radiation therapy and to develop a ready-to-use graphical tool. MATERIALS AND METHODS: In this study, 598 men recruited in 2 national multicenter trials were analyzed. Information was recorded on comorbidity, previous abdominal surgery, use of drugs, and dose distribution. Fecal incontinence was prospectively evaluated through self-reported questionnaires. To develop the ANN, the study population was randomly split into training (n = 300), validation (n = 149), and test (n = 149) sets. Mean grade of longitudinal LFI (ie, expressed as the average incontinence grade over the first 3 years after radiation therapy) ≥1 was considered the endpoint. A suitable subset of variables able to better predict LFI was selected by simulating 100,000 ANN configurations. The search for the definitive ANN was then performed by varying the number of inputs and hidden neurons from 4 to 5 and from 1 to 9, respectively. A final classification model was established as the average of the best 5 among 500 ANNs with the same architecture. An ANN-based graphical method to compute LFI prediction was developed to include one continuous and n dichotomous variables. RESULTS: An ANN architecture was selected, with 5 input variables (mean dose, previous abdominal surgery, use of anticoagulants, use of antihypertensive drugs, and use of neoadjuvant and adjuvant hormone therapy) and 4 hidden neurons. The developed classification model correctly identified patients with LFI with 80.8% sensitivity and 63.7% ± 1.0% specificity and an area under the curve of 0.78. The developed graphical tool may efficiently classify patients in low, intermediate, and high LFI risk classes. CONCLUSIONS: An ANN-based model was developed to predict LFI. The model was translated in a ready-to-use graphical tool for LFI risk classification, with direct interpretation of the role of the predictors.

Unusual case of spindle cell sarcoma metastases to right ventricle: a case report and a literature review.

Cardiac metastases from sarcoma are uncommon. Due to their rarity there is not a standard of care. However, complete cardiac metastases resection is the best option but most of patients has widespread disease. In these patients palliative radiotherapy (RT) might improve symptoms and prevent further cardiac function decline. Here we present the case of a symptomatic 30-year-old woman with spindle cell sarcoma metastasis of right ventriculum and widespread disease. The patient received radiotherapy to the heart with palliative intent. Cardiac metastases represent a challenging clinic problem. Treatment should be individualized in a multidisciplinary setting, when possible surgery seems to be the best options. However, radiotherapy even in case of widespread disease can improve clinical control symptoms by reducing the mass effect.

Multi-variable models of large International Prostate Symptom Score worsening at the end of therapy in prostate cancer radiotherapy.

PURPOSE/OBJECTIVE: Prospectively assessing clinical/dosimetry factors affecting the acute worsening of urinary functionality after radiotherapy for prostate cancer. MATERIAL/METHODS: DUE01 population was considered, including patients treated with conventional or moderate hypo-fractionation (2.2-2.7 Gy/fr). Relevant clinical factors were collected, urinary symptoms were self-reported through the International Prostate Symptom Score (IPSS) before and at the end of radiotherapy; while absolute weekly dose-surface histograms (DSHw) were chosen as dosimetry descriptors. An IPSS increase of at least 10 and 15 points (ΔIPSS ⩾ 10 and ΔIPSS ⩾ 15) were chosen as endpoints. Patients with baseline IPSS>20 were excluded. Relevant factors were chosen through a bootstrap-based in silico methodology. RESULTS: Complete information was available for 380 patients: 77/380 (20%) and 28/380 (7%) with ΔIPSS ⩾ 10 and ΔIPSS ⩾ 15, respectively. Neoadjuvant hormone was protective (OR=0.49 and 0.69). DSHw at 8.5 Gy/week and 12 Gy/week were risk factors, with additional risk for patients who use cardiovascular drugs and anti-hypercholesterolemia drugs. In the hypo-fractionated subgroup (n=209) the role of cardiovascular drugs (OR=2.16) for ΔIPSS ⩾ 10 and anti-hypercholesterolemia drugs (OR=2.80) for ΔIPSS⩾15, together with DSHw (10 Gy/week and 12.5 Gy/week, respectively), was confirmed. CONCLUSION: Current study shows a dose-surface/volume effect for acute large worsening of urinary functionality; several clinical variables largely impact the risk and especially all the factors related with vascular diseases.

Analysis of inter-fraction setup errors and organ motion by daily kilovoltage cone beam computed tomography in intensity modulated radiotherapy of prostate cancer.

BACKGROUND: Intensity-modulated radiotherapy (IMRT) enables a better conformality to the target while sparing the surrounding normal tissues and potentially allows to increase the dose to the target, if this is precisely and accurately determined. The goal of this work is to determine inter-fraction setup errors and prostate motion in IMRT for localized prostate cancer, guided by daily kilovoltage cone beam computed tomography (kVCBCT). METHODS: Systematic and random components of the shifts were retrospectively evaluated by comparing two matching modalities (automatic bone and manual soft-tissue) between each of the 641 daily kVCBCTs (18 patients) and the planning kVCT. A simulated Adaptive Radiation Therapy (ART) protocol using the average of the first 5 kVCBCTs was tested by non-parametric bootstrapping procedure. RESULTS: Shifts were < 1 mm in left-right (LR) and in supero-inferior (SI) direction. In antero-posterior (AP) direction systematic prostate motion (2.7 ± 0.7 mm) gave the major contribution to the variability of results; the averages of the absolute total shifts were significantly larger in anterior (6.3 ± 0.2 mm) than in posterior (3.9 mm ± 0.2 mm) direction. The ART protocol would reduce margins in LR, SI and anterior but not in posterior direction. CONCLUSIONS: The online soft-tissue correction based on daily kVCBCT during IMRT of prostate cancer is fast and efficient. The large random movements of prostate respect to bony anatomy, especially in the AP direction, where anisotropic margins are needed, suggest that daily kVCBCT is at the present time preferable for high dose and high gradients IMRT prostate treatments.