Multiple Brain Metastases Radiosurgery with CyberKnife Device: Dosimetric Comparison between Fixed/Iris and Multileaf Collimator Plans

Purpose

In our institution, stereotactic radiosurgery of multiple brain metastases is performed with the CyberKnife® (CK) device, using fixed/Iris collimators. In this study, nineteen fixed/Iris plans were recalculated with the multileaf collimator (MLC), to assess if it is possible to produce plans with comparable dosimetric overall quality.

Materials and Methods

For consistent comparisons, MLC plans were re-optimized and re-normalized in order to achieve the same minimum dose for the total planning target volume (PTVtot). Conformation number (CN), homogeneity index (HI) and dose gradient index (DGI) metrics were evaluated. The dose to the brain was evaluated as the volume receiving 12 Gy (V12) and as the integral dose (ID). The normal tissue complication probability (NTCP) for brain radionecrosis was calculated as a function of V12.

Results

The reoptimized plans were reviewed by the radiation oncologist and were found clinically acceptable according to the The American Association of Physicists in Medicine (AAPM) Task Group-101 protocol. However, fixed/Iris plans provided significantly higher CN (+8.6%), HI (+2.2%), and DGI (+44.0%) values, and significantly lower ID values (-35.9%). For PTVtot less than the median value of 2.58cc, fixed/Iris plans provided significantly lower NTCP values. On the other side, MLC plans provided significantly lower treatment times (-18.4%), number of monitor units (-33.3%), beams (-46.0%) and nodes (-21.3%).

Conclusions

CK-MLC plans for the stereotactic treatment of brain multi metastases could provide an important advantage in terms of treatment duration. However, to contain the increased risk for brain radionecrosis, it could be useful to calculate MLC plans only for patients with large PTVtot.

Artificial Intelligence and Advanced Melanoma: Treatment Management Implications

Artificial intelligence (AI), a field of research in which computers are applied to mimic humans, is continuously expanding and influencing many aspects of our lives. From electric cars to search motors, AI helps us manage our daily lives by simplifying functions and activities that would be more complex otherwise. Even in the medical field, and specifically in oncology, many studies in recent years have highlighted the possible helping role that AI could play in clinical and therapeutic patient management. In specific contexts, clinical decisions are supported by "intelligent" machines and the development of specific softwares that assist the specialist in the management of the oncology patient. Melanoma, a highly heterogeneous disease influenced by several genetic and environmental factors, to date is still difficult to manage clinically in its advanced stages. Therapies often fail, due to the establishment of intrinsic or secondary resistance, making clinical decisions complex. In this sense, although much work still needs to be conducted, numerous evidence shows that AI (through the processing of large available data) could positively influence the management of the patient with advanced melanoma, helping the clinician in the most favorable therapeutic choice and avoiding unnecessary treatments that are sure to fail. In this review, the most recent applications of AI in melanoma will be described, focusing especially on the possible finding of this field in the management of drug treatments.

Exploring CT Texture Parameters as Predictive and Response Imaging Biomarkers of Survival in Patients With Metastatic Melanoma Treated With PD-1 Inhibitor Nivolumab: A Pilot Study Using a Delta-Radiomics Approach

In the era of artificial intelligence and precision medicine, the use of quantitative imaging methodological approaches could improve the cancer patient’s therapeutic approaches. Specifically, our pilot study aims to explore whether CT texture features on both baseline and first post-treatment contrast-enhanced CT may act as a predictor of overall survival (OS) and progression-free survival (PFS) in metastatic melanoma (MM) patients treated with the PD-1 inhibitor Nivolumab. Ninety-four lesions from 32 patients treated with Nivolumab were analyzed. Manual segmentation was performed using a free-hand polygon approach by drawing a region of interest (ROI) around each target lesion (up to five lesions were selected per patient according to RECIST 1.1). Filtration-histogram-based texture analysis was employed using a commercially available research software called TexRAD (Feedback Medical Ltd, London, UK; https://fbkmed.com/texrad-landing-2/) Percentage changes in texture features were calculated to perform delta-radiomics analysis. Texture feature kurtosis at fine and medium filter scale predicted OS and PFS. A higher kurtosis is correlated with good prognosis; kurtosis values greater than 1.11 for SSF = 2 and 1.20 for SSF = 3 were indicators of higher OS (fine texture: 192 HR = 0.56, 95% CI = 0.32–0.96, p = 0.03; medium texture: HR = 0.54, 95% CI = 0.29–0.99, p = 0.04) and PFS (fine texture: HR = 0.53, 95% CI = 0.29–0.95, p = 0.03; medium texture: HR = 0.49, 209 95% CI = 0.25–0.96, p = 0.03). In delta-radiomics analysis, the entropy percentage variation correlated with OS and PFS. Increasing entropy indicates a worse outcome. An entropy variation greater than 5% was an indicator of bad prognosis. CT delta-texture analysis quantified as entropy predicted OS and PFS. Baseline CT texture quantified as kurtosis also predicted survival baseline. Further studies with larger cohorts are mandatory to confirm these promising exploratory results.

The role of dosimetry and biological effects in metastatic castration-resistant prostate cancer (mCRPC) patients treated with 223Ra: first in human study

BACKGROUND

223Ra is currently used for treatment of metastatic castration resistant prostate cancer patients (mCRPC) bone metastases with fixed standard activity. Individualized treatments, based on adsorbed dose (AD) in target and non-target tissue, are absolutely needed to optimize efficacy while reducing toxicity of α-emitter targeted therapy. This is a pilot first in human clinical trial aimed to correlate dosimetry, clinical response and biological side effects to personalize 223Ra treatment.

METHODS

Out of 20 mCRPC patients who underwent standard 223Ra treatment and dosimetry, in a subset of 5 patients the AD to target and non-target tissues was correlated with clinical effects and radiation-induced chromosome damages. Before each 223Ra administrations, haematological parameters, PSA and ALP values were evaluated. Additional blood samples were obtained baseline (T0), at 7 days (T7), 30 days (T30) and 180 days (T180) to evaluate chromosome damage. After administration WB planar 223Ra images were obtained at 2-4 and 18-24 h. Treatment response and toxicity were monitored with clinical evaluation, bone scan, 18F-choline-PET/CT, PSA value and ALP while haematological parameters were evaluated weekly after 223Ra injection and 2 months after last cycle.

RESULTS

1. a correlation between AD to target and clinical response was evidenced with threshold of 20 Gy as a cut-off to obtain tumor control; 2. the AD to red marrow was lower than 2 Gy in all the patients with no apparently correlation between dosimetry and clinical toxicity. 3. a high dose dependent increase of the number of dicentrics and micronuclei during the course of 223Ra therapy was observed and a linear correlation has been found between blood AD (BAD) and number of dicentrics.

CONCLUSIONS

This study provides some interesting preliminary evidence to be further investigated: dosimetry may be useful to identify a more appropriate 223Ra administered activity predicting AD to target tissue; a dose dependent complex chromosome damage occurs during 223Ra administration and this injury is more evident in heavily pre-treated patients; dosimetry could be used for radioprotection purpose.

TRIAL REGISTRATION

The pilot study has been approved from the Ethics Committee of Regina Elena National Cancer Institute (N:RS1083/18-2111).

Sarcopenia Worsening One Month after Transarterial Radioembolization Predicts Progressive Disease in Patients with Advanced Hepatocellular Carcinoma

Simple Summary

Sarcopenia measured at one-month CT follow up after TARE (transarterial radioembolization) treatment is a predictive factor for the best tumor response in patients with locally advanced HCC.

Abstract

(1) Background: To demonstrate correlation between skeletal muscle depletion measured before and after one month of TARE treatment and its induced local response rate. (2) Material and methods: For this retrospective, single center study, we evaluated 86 patients with HCC treated with TARE. Sarcopenia status was measured using the psoas muscle index (PMI). The PMI was calculated according to the formula: PMI [mm/m²]: [(minor diameter of left psoas + major diameter of left psoas + minor diameter of right psoas + major diameter of right psoas)/4]/height in m². Population was divided in two groups according to the delta value of PMI measured at the time of TARE and one month after TARE, a group in which the delta PMI was stable or increased (No-Sarcopenia group; n = 42) vs. a group in which the delta-PMI decreased (Sarcopenia group; n = 44). Patient response was evaluated at 1, 3 and 6 months after TARE treatment with CT/MRI. (3) Results: When the radiological response of the tumor was evaluated according to the mRECIST criteria, the two groups were similar in terms of rates of complete response (p = 0.42), partial response (p = 0.26) and stable disease (p = 0.59). Progressive disease (PD) was more commonly observed in the Sarcopenia group (38.6% vs. 11.9%; p = 0.006). (4) Conclusions: Worsening of sarcopenia status measured one month after TARE is able to predict patients who will undergo disease progression.

Precision Medicine and Melanoma: Multi-Omics Approaches to Monitoring the Immunotherapy Response

The treatment and management of patients with metastatic melanoma have evolved considerably in the "era" of personalized medicine. Melanoma was one of the first solid tumors to benefit from immunotherapy; life expectancy for patients in advanced stage of disease has improved. However, many progresses have yet to be made considering the (still) high number of patients who do not respond to therapies or who suffer adverse events. In this scenario, precision medicine appears fundamental to direct the most appropriate treatment to the single patient and to guide towards treatment decisions. The recent multi-omics analyses (genomics, transcriptomics, proteomics, metabolomics, radiomics, etc.) and the technological evolution of data interpretation have allowed to identify and understand several processes underlying the biology of cancer; therefore, improving the tumor clinical management. Specifically, these approaches have identified new pharmacological targets and potential biomarkers used to predict the response or adverse events to treatments. In this review, we will analyze and describe the most important omics approaches, by evaluating the methodological aspects and progress in melanoma precision medicine.

Stereotactic body radiotherapy for T1 glottic cancer: dosimetric data in 27 consecutive patients

AIM

Because the clinical feasibility of stereotactic body radiotherapy (SBRT) for early glottic cancer (T1) is controversial, we report dosimetric results in 27 consecutive patients from a prospective phase I and II study that started in 2017.

METHODS

In our approach, only the parts of the true vocal cord containing cancer and those immediately adjacent are planned to be treated to 36 Gy and 30 Gy, respectively, in 3 fractions. Several dosimetric metrics for both target volumes and organs at risk were extracted from individual plans and results were compared to those achieved by other authors in a similar setting.

RESULTS

Proper coverage was reached at planning in 2/3 of planning treatment volume 30 Gy, but only 4 planning treatment volume 36 Gy; conversely, the maximum dose objective was met for most of the patients on either arytenoid cartilage, but this was not the case for 51.9% and 96.3% of cricoid and thyroid cartilages, respectively. Our dosimetric results are similar to if not better than those achieved by others.

CONCLUSION

SBRT in 3 fractions for T1 glottic lesions is dosimetrically challenging. Clinical validation is awaited.

Novel cancer therapies for advanced cutaneous melanoma: The added value of radiomics in the decision making process-A systematic review

Advanced malignant melanoma represents a public health matter due to its rising incidence and aggressiveness. Novel therapies such as immunotherapy are showing promising results with improved progression free and overall survival in melanoma patients. However, novel targeted and immunotherapies could generate atypical patterns of response which are nowadays a big challenge since imaging criteria (ie Recist 1.1) have not been proven to be always reliable to assess response. Radiomics and in particular texture analysis (TA) represent new quantitative methodologies which could reduce the impact of these limitations providing most robust data in support of clinical decision process. The aim of this paper was to review the state of the art of radiomics/TA when it is applied to the imaging of metastatic melanoma patients.

Absorbed dose measurements from a 90Y radionuclide liquid solution using LiF:Mg,Cu,P thermoluminescent dosimeters

In the last few years there has been an increasing interest in the measurement of the absorbed dose from radionuclides, with special attention devoted to molecular radiotherapy treatments. In particular, the determination of the absorbed dose from beta emitting radionuclides in liquid solution poses a number of issues when dose measurements are performed using thermoluminescent dosimeters (TLD). Finite volume effect, i.e. the exclusion of radioactivity from the volume occupied by the TLD is one of these. Furthermore, TLDs need to be encapsulated into some kind of waterproof envelope that unavoidably contributes to beta particle attenuation during the measurement. The purpose of this study is twofold: I) to measure the absorbed dose to water, D_w, using LiF:Mg,Cu,P chips inside a PMMA cylindrical phantom filled with a homogenous ⁹⁰YCl₃ aqueous solution II) to assess the uncertainty budget related to D_w measurements. To this purpose, six cylindrical PMMA phantoms were manufactured at ENEA. Each phantom can host a waterproof PMMA stick containing 3 TLD chips encapsulated by a polystyrene envelope. The cylindrical phantoms were manufactured so that the radioactive liquid environment surrounds the whole stick. Finally, D_w measurements were compared with Monte Carlo (MC) calculations. The measurement of absorbed dose to water from ⁹⁰YCl₃ radionuclide solution using LiF:Mg,Cu,P TLDs turned out to be a viable technique, provided that all necessary correction factors are applied. Using this method, a relative combined standard uncertainty in the range 3.1-3.7% was obtained on each D_w measurement. The major source of uncertainty was shown to be TLDs calibration, with associated uncertainties in the range 0.7-2.2%. Comparison of measured and MC-calculated absorbed dose per emitted beta particle provided good results, with the two quantities being in the ratio 1.08.

Radiobiological Optimization in Lung Stereotactic Body Radiation Therapy: Are We Ready to Apply Radiobiological Models?

Lung tumors are often associated with a poor prognosis although different schedules and treatment modalities have been extensively tested in the clinical practice. The complexity of this disease and the use of combined therapeutic approaches have been investigated and the use of high dose-rates is emerging as effective strategy. Technological improvements of clinical linear accelerators allow combining high dose-rate and a more conformal dose delivery with accurate imaging modalities pre- and during therapy. This paper aims at reporting the state of the art and future direction in the use of radiobiological models and radiobiological-based optimizations in the clinical practice for the treatment of lung cancer. To address this issue, a search was carried out on PubMed database to identify potential papers reporting tumor control probability and normal tissue complication probability for lung tumors. Full articles were retrieved when the abstract was considered relevant, and only papers published in English language were considered. The bibliographies of retrieved papers were also searched and relevant articles included. At the state of the art, dose–response relationships have been reported in literature for local tumor control and survival in stage III non-small cell lung cancer. Due to the lack of published radiobiological models for SBRT, several authors used dose constraints and models derived for conventional fractionation schemes. Recently, several radiobiological models and parameters for SBRT have been published and could be used in prospective trials although external validations are recommended to improve the robustness of model predictive capability. Moreover, radiobiological-based functions have been used within treatment planning systems for plan optimization but the advantages of using this strategy in the clinical practice are still under discussion. Future research should be directed toward combined regimens, in order to potentially improve both local tumor control and survival. Indeed, accurate knowledge of the relevant parameters describing tumor biology and normal tissue response is mandatory to correctly address this issue. In this context, the role of medical physicists and the AAPM in the development of radiobiological models is crucial for the progress of developing specific tool for radiobiological-based optimization treatment planning.

The usefulness of sLORETA in evaluating the effect of high-dose ARA-C on brain connectivity in patients with acute myeloid leukemia: an exploratory study

Cytosine arabinoside (Ara-C) is one of the key drugs for treating acute myeloid leukemia (AML). High intravenous doses may produce a number of central nervous system (CNS) toxicities and contribute to modifications in brain functional connectivity. sLORETA is a software used for localizing brain electrical activity and functional connectivity. The aim of this study was to apply sLORETA in the evaluation of possible effects of Ara-C on brain connectivity in patients with AML without CNS involvement. We studied eight patients with AML; four were administered standard doses of Ara-C while the other four received high doses. sLORETA was computed from computerized EEG data before treatment and after six months of treatment. Three regions of interest, corresponding to specific combinations of Brodmann areas, were defined. In the patients receiving high-dose Ara-C, a statistically significant reduction in functional connectivity was observed in the fronto-parietal network, which literature data suggest is involved in attentional processes. Our data highlight the possibility of using novel techniques to study potential CNS toxicity of cancer therapy.

[Conservative... and non conservative... treatment of renal blunt injuries]

Whether patients with blunt renal trauma should be managed conservatively without surgery or undergo surgery is often hard to decide. We describe three clinical cases of blunt renal trauma, all involving the left kidney. All three patients had abdominal ultrasound studies and computerized tomographic (CT) scans. In the first case, an accidental fall led to severe injury of the renal hilus causing massive retroperitoneal extravasation. The patient underwent emergency nephrectomy and survived. The second case concerned a patient who was involved in a road accident, suffered injuries mainly affecting the spleen, and underwent splenectomy. A postoperative CT scan showed left renal vein thrombosis functionally excluding the inferior pole of the kidney. The patient received conservative non surgical treatment. A follow-up imaging study showed that although the thrombosis had resolved the renal pole had failed to regain normal function. In the third case, mild apparently unimportant trauma led to a massive hemorrhage responsible for a severe shock state. Despite prompt nephrectomy, renal failure and and pulmonary complications developed and one month after the injuries the patient died. The medical history referred to a "chronic hematoma" secondary to a childhood injury. In this case, the pre-existing hematoma probably led to a permanent communication with the vascular and excretory tree thus resulting in a kind of "silent" fistula that the relatively mild injury unexpectedly disrupted. For the two left nephrectomies we used a midline approach after isolating the renal Treitz vessels; special care was taken to mobilize the left colon. Although blunt renal trauma often responds to non surgical conservative treatment, some patients should undergo prompt surgery. All patients must be scheduled for long-term clinical and imaging follow-up.

[Splenic artery rupture in pancreatic pseudocyst]

Hemorrhage is one of the most threatening complication of pancreatic pseudocyst. It results from erosion of adjacent vessels. Splenic, gastroduodenal, pancreaticoduodenal and middle colic vessels are predominantly involved. Hemorrhage may present different feature: intra and/or extraperitoneal collection, gastrointestinal bleeding. The authors report the rupture of splenic artery into pseudocyst, with the formation of pulsating pseudoaneurysm, increasing progressively until the final rupture. For the diagnosis the authors utilized: ultrasounds (US) which showed the cyst but not its nature and content; the CT scan which disclosed haematic contents; finally the US Color Doppler which proved the dynamic feature of hemorrhage. This technique allows to identify the arterious or venous source of bleeding and the possible presence of arteriovenous fistula. Arteriography was not performed due to circumstances, although it would permit bleeding vessel embolization and the control of hemorrhage. This procedure is not ever achievable, and doesn't exclude the possibility of rebleeding. On surgery, since the intraoperative rupture of the pseudoaneurysm occurred with severe hypovolemic shock, only a timely posterior mesogastric mobilization and the medially displacement of spleen-body-tail pancreatic complex, allowed to clamp the mass and the hemostasis. When such lesion are approached, it is mandatory to be prepared to carry on this maneuver: the severity of bleeding cannot allow intracystic ligature of bleeding vessel.