Pelvic bone marrow dose-volume predictors of late lymphopenia following pelvic lymph node radiation therapy for prostate cancer.

BACKGROUND AND PURPOSE: Given the substantial lack of knowledge, we aimed to assess clinical/dosimetry predictors of late hematological toxicity on patients undergoing pelvic-nodes irradiation (PNI) for prostate cancer (PCa) within a prospective multi-institute study. MATERIALS AND METHODS: Clinical/dosimetry/blood test data were prospectively collected including lymphocytes count (ALC) at baseline, mid/end-PNI, 3/6 months and every 6 months up to 5-year after PNI. DVHs of the Body, ileum (BMILEUM), lumbosacral spine (BMLS), lower pelvis (BMPELVIS), and whole pelvis (BMTOT) were extracted. Current analysis focused on 2-year CTCAEv4.03 Grade ≥ 2 (G2+) lymphopenia (ALC < 800/µL). DVH parameters that better discriminate patients with/without toxicity were first identified. After data pre-processing to limit overfitting, a multi-variable logistic regression model combining DVH and clinical information was identified and internally validated by bootstrap. RESULTS: Complete data of 499 patients were available: 46 patients (9.2 %) experienced late G2+ lymphopenia. DVH parameters of BMLS/BMPELVIS/BMTOT and Body were associated to increased G2+ lymphopenia. The variables retained in the resulting model were ALC at baseline [HR = 0.997, 95 %CI 0.996-0.998, p < 0.0001], smoke (yes/no) [HR = 2.9, 95 %CI 1.25-6.76, p = 0.013] and BMLS-V ≥ 24 Gy (cc) [HR = 1.006, 95 %CI 1.002-1.011, p = 0.003]. When acute G3+ lymphopenia (yes/no) was considered, it was retained in the model [HR = 4.517, 95 %CI 1.954-10.441, p = 0.0004]. Performances of the models were relatively high (AUC = 0.87/0.88) and confirmed by validation. CONCLUSIONS: Two-year lymphopenia after PNI for PCa is largely modulated by baseline ALC, with an independent role of acute G3+ lymphopenia. BMLS-V24 was the best dosimetry predictor: constraints for BMTOT (V10Gy < 1520 cc, V20Gy < 1250 cc, V30Gy < 850 cc), and BMLS (V24y < 307 cc) were suggested to potentially reduce the risk.

Acute patient-reported intestinal toxicity in whole pelvis IMRT for prostate cancer: Bowel dose-volume effect quantification in a multicentric cohort study.

BACKGROUND AND PURPOSE: To assess bowel dose-volume relationships for acute patient-reported intestinal symptoms of patients treated with whole-pelvis intensity-modulated radiotherapy (WPRT) for prostate cancer. MATERIALS AND METHODS: Complete data of 415 patients enrolled in a multi institute, prospective trial (#NCT02803086) treated with radical (31%), adjuvant (33%) and salvage (36%) intent at a median dose to pelvic nodes/lymph-nodal area of 53 Gy were available. The most severe changes between baseline and radiotherapy mid-point/end toxicity assessed by Inflammatory Bowel Disease Questionnaire (only Bowel Domain) were considered (ΔIBDQ). The 25th percentile values of these score variations were set as endpoints. DVHs of bowel loops for patients with/without toxicity were compared for each endpoint, having excluded patients with baseline scores <5 (rate ranging between 2% and 7% according to the endpoint): the resulting best dosimetric predictors were combined with selected clinical parameters through multivariate logistic regression (MVA) to derive predictive models. RESULTS: ΔIBDQ ranged between 0.2-1.5 points considering separately each IBDQ symptom. Only four symptoms (IBDQ1 = frequency, IBDQ5 = diarrhea, IBDQ17 = gas passage, IBDQ24 = urgency) showed a median worsening ≥ 1; DVH predicted the risk of worse symptoms for IBDQ5, IBDQ24 and overall Bowel Domain. At multivariable analysis DVHs (best cut-off: V46Gy ≥80 cc) and baseline scores (Odd-Ratio:0.35-0.65) were independently associated to the three end-points. The resulting models were reliable (H&L test: 0.453-0.956), well calibrated (calibration plot: slope = 0.922-1.069, R2 = 0.725-0.875) and moderately discriminative (Area Under the Curve:0.628-0.669). A bootstrap-based validation confirmed their robustness. CONCLUSION: Constraining the bowel loops (V46 < 80 cc) may reduce the risk of several moderate intestinal symptoms, with a much greater impact for patients with lower IBDQ baseline scores.

The contribution of interventional cardiology procedures to the population radiation dose in a 'health-care level I' representative region.

This study evaluates per-procedure, collective and per capita effective dose to the population by interventional cardiology (IC) procedures performed during 2002-11 at the main hospital of Aosta Valley Region that can be considered as representative of the health-care level I countries, as defined by the UNSCEAR, based on its socio-demographic characteristics. IC procedures investigated were often multiple procedures in patients older than 60 y. The median extreme dose-area product values of 300 and 22 908 cGycm(2) were found for standard pacemaker implantation and coronary angioplasty, respectively, while the relative mean per-procedure effective dose ranged from 0.7 to 47 mSv. A 3-fold increase in frequency has been observed together with a correlated increase in the delivered per capita dose (0.05-0.27 mSv y(-1)) and the collective dose (5.8-35 man Sv y(-1)). Doses increased particularly from 2008 onwards mainly because of the introduction of coronary angioplasty procedures in the authors' institution. IC practice contributed remarkably in terms of effective dose to the population, delivering ∼10% of the total dose by medical ionising radiation examination categories.

Laparoscopic total mesorectal excision for extraperitoneal rectal cancer: long-term results of a 18-year single-centre experience.

BACKGROUND AND OBJECTIVES: The oncologic efficacy of laparoscopic total mesorectal excision (TME) for middle-low rectal cancer is still under discussion because of the few long-term data. This study reports the results arising from a single-institution experience during a 18-year period. METHODS: Data about 132 consecutive laparoscopic TME performed between January 1994 and January 2012 were analysed with Kaplan-Meier method and a uni- and multi-variate analysis was conducted to define independent survival predictors. RESULTS: A total of 116 sphincter-preserving operations and 16 abdominoperineal resections were performed. Postoperative mortality and morbidity were 0.8 and 18.2%, with a rate of anastomotic leakage of 13.8%. Average follow-up was 85.9 months (range 13-210). Actuarial local recurrence rate was 4.13% at 5 years (any pelvic recurrence developed after 3 years from surgery). Overall and disease-free survival was respectively 83 and 79.8% at 5 years, 71 and 73% at 10 years and then remained constant until 18 years. Survival was correlated only to tumour stage and the type of surgery. CONCLUSIONS: Laparoscopic TME for extraperitoneal rectal cancer shows long-term oncologic outcomes similar to open rectal resections.

Does TomoDirect 3DCRT represent a suitable option for post-operative whole breast irradiation? A hypothesis-generating pilot study.

BACKGROUND: This study investigates the use of TomoDirect™ 3DCRT for whole breast adjuvant radiotherapy (AWBRT) that represents a very attractive treatment opportunity, mainly for radiotherapy departments without conventional Linacs and only equipped with helical tomotherapy units. METHODS: Plans were created for 17 breast cancer patients using TomoDirect in 3DCRT and IMRT modality and field-in-field 3DCRT planning (FIF) and compared in terms of PTV coverage, overdosage, homogeneity, conformality and dose to OARs. The possibility to define patient-class solutions for TD-3DCRT employment was investigated, correlating OARs dose constraints to patient specific anatomic parameters. RESULTS: TD-3DCRT showed PTV coverage and homogeneity significantly higher than TD-IMRT and FIF. PTV conformality was significantly better for FIF, while no differences were found between TD-3DCRT and TD-IMRT. TD-3DCRT showed mean values of the OARs dosimetric endpoints significantly higher than TD-IMRT; with respect to FIF, TD-3DCRT showed values significantly higher for lung V(20Gy), mean heart dose and V(25Gy), while contralateral lung maximum dose and contralateral breast mean dose resulted significantly lower. The Central Lung Distance (CLD) and the maximal Heart Distance (HD) resulted as useful clinical tools to predict the opportunity to employ TD-3DCRT: positive correlations were found between CLD and both V(20Gy) and mean lung dose and between HD and both V25Gy and the mean heart dose. TD-3DCRT showed a significantly shorter mean beam-on time than TD-IMRT. CONCLUSIONS: The present study showed that TD-3DCRT and TD-IMRT are two feasible and dosimetrically acceptable treatment approach for AWBRT, with an optimal PTV coverage and adequate OARs sparing. Some concerns might be raised in terms of dose to organs at risks if TD-3DCRT is applied to a general population. A correct patients clusterization according to simple quantitative anatomic measures, would help to correctly allocate patients to the appropriate treatment planning strategy in terms of target coverage, but also of normal tissue sparing.

Interventional radiology at a single institution over 9 years: a comprehensive evaluation of procedures and an estimation of collective effective dose.

PURPOSE: To investigate the exposure parameters, effective dose, frequency, and collective dose for interventional radiology (IR) procedures performed at a single institution during a 9-year period. MATERIALS AND METHODS: According to the anatomic region imaged, seven diagnostic and 16 therapeutic IR procedures performed between 2002 and 2010 were retrospectively investigated with regard to exposure setting parameters and frequency. Dose-area products (DAPs), cumulative doses (CDs), and irradiation time values were analyzed on a sample of 1,100 examinations. DAP distributions (median, mean, and percentiles) were adjunctively determined by using bootstrap resampling in PCXMC software to estimate patient effective dose. Data provided by the Radiological Information System allowed collective effective and per-capita doses to obtained. RESULTS: The exposure parameters showed widespread variability. The median DAP values for pelvic arteriography and pelvic arterial angioplasty/stent placement were 10,015 and 19,424 cGy·cm(2), respectively. For the 23 procedures studied, the estimated average per-procedure effective dose ranged from 0.34 to 104.9 mSv. The pelvis (37%) was the region most often imaged in diagnostic procedures, and angioplasty/stent treatment of vessels was the most frequently performed therapeutic procedure (44%). During the study period, IR procedures increased in frequency (+137%), with a consequent increase in the per-capita dose (0.172 to 0.461 mSv) and collective dose (21 to 58 man-Sv/y). CONCLUSIONS: A comprehensive Monte Carlo-aided analysis, which allowed evaluation of contributions in terms of per-procedure and collective doses to the population for the practice of IR, showed a significant growth rate during the study period.

Digital mammography: quality and dose control.

PURPOSE: For almost 3 years, Radiologists and Physicists from Padova and Ferrara Universities have collaborated together, with the aim of collecting and comparing experimental data useful to define the most significant parameters for quality controls in digital mammography. Successively, radiologists and physicists working in other sites where a digital mammography unit was installed joined the work-group. MATERIALS AND METHODS: In this study we report the results obtained from measurements of linearity, uniformity, short- and long-term reproducibility, AEC stability performed on 5 digital equipment by using a simple test object. X-ray beam quality and tube yield were preliminarily checked in such a way that possible uncertainties of digital system responses could be separated from those due to differences among X-ray tubes. RESULTS: Results showed that the equipment considered, comparable in terms of both beam quality (HVL) and tube yield, always displayed linear response and reproducibility errors lower than 5%. Uniformity was very good and the grey level compensation as a function of exposure parameters remained within 5%. Differences in choice of parameters by exposure control system (AOP) were emphasised, especially for crossing between track/filter combinations (from Mo/Mo to Mo/Rh and from Mo/Rh to Rh/Rh); those differences were attributed to the +/-2 mm tolerance of breast thickness measurement (mechanically obtained) greater than the AOP tolerance (+/-1 mm). DISCUSSION AND CONCLUSIONS: Obtained results can be useful, as comparison and reference values, for users employing a digital mammography unit of the same kind reported in this paper. Moreover, the same results could be used as "orientation" also by other users having different digital mammography technologies, whose operation should be nevertheless specifically studied and understood in order to find the most useful parameters for quality controls. The acquired experience clearly showed us that years of investigations will be necessary in order to be able to write reliable protocols. This should induce people to contemplate the necessity of not improvising "theoretical" protocols, that are unreliable and dangerous for their negative clinical implications.