Advancements in photodynamic therapy of esophageal cancer.

The poor prognosis of patients with esophageal cancer leads to the constant search for new ways of treatment of this disease. One of the methods used in high-grade dysplasia, superficial invasive carcinoma, and sometimes palliative care is photodynamic therapy (PDT). This method has come a long way from the first experimental studies to registration in the treatment of esophageal cancer and is constantly being improved and refined. This review describes esophageal cancer, current treatment methods, the introduction to PDT, the photosensitizers (PSs) used in esophageal carcinoma PDT, PDT in squamous cell carcinoma (SCC) of the esophagus, and PDT in invasive adenocarcinoma of the esophagus. For this review, research and review articles from PubMed and Web of Science databases were used. The keywords used were "photodynamic therapy in esophageal cancer" in the years 2000-2020. The total number of papers returned was 1,000. After the review was divided into topic blocks and the searched publications were analyzed, 117 articles were selected.

Dosimetric Comparison of Ultra-Hypofractionated and Conventionally Fractionated Radiation Therapy Boosts for Patients with High-Risk Prostate Cancer.

Recent comparison of an ultra-hypofractionated radiotherapy (UF-RT) boost to a conventionally fractionated (CF-RT) option showed similar toxicity and disease control outcomes. An analysis of the treatment plans for these patients is needed for evaluating calculated doses for different organs, treatment beam-on time, and requirements for human and financial resources. Eighty-six plans for UF-RT and 93 plans for CF-RT schemes were evaluated. The biologically equivalent dose, EQD2, summed for the first phase and the boost, was calculated for dose-volume parameters for organs at risk (OARs), as well as for the PTV1. ArcCHECK measurements for the boost plans were used for a comparison of planned and delivered doses. Monitor units and beam-on times were recorded by the Eclipse treatment planning system. Statistical analysis was performed with a significance level of 0.05. Dosimetric parameter values for OARs were well within tolerance for both groups. EQD2 for the PTV1 was on average 84 Gy for UF-RT patients and 76 Gy for CF-RT patients. Gamma passing rate for planned/delivered doses comparison was above 98% for both groups with 3 mm/3% distance to agreement/dose difference criteria. Total monitor units per fraction were 647 ± 94 and 2034 ± 570 for CF-RT and UF-RT, respectively. The total delivery time for boost radiation for the patients in the UF-RT arm was, on average, four times less than the total time for a conventional regimen with statistically equal clinical outcomes for the two arms in this study.

Continuous glucose monitoring systems in well-controlled children with type 1 diabetes mellitus.

INTRODUCTION: Numerous studies have demonstrated the clinical benefits of using continuous glucose monitoring (CGM) systems among patients with type 1 diabetes (T1D). Aim of the study was to assess the effectiveness of CGM on metabolic control in children with T1D and well-controlled disease prior to the study. MATERIAL AND METHODS: This prospective analysis included 99 children (46 girls) at the median age of 11.23 years and diabetes duration of at least 1 year (median: 5.16 years), generally well controlled metabolically (median HbA1c: 7.0%), and treated with continuous subcutaneous insulin infusion (CSII). The patients had used CGM for at least 150 days. We analysed the participants in subgroups based on baseline HbA1c < 7%, ≥ 7%, age, and sex. RESULTS: Children with baseline HbA1c < 7% were characterized by significantly increased HbA1c after the median of 273 days (217; 320) of CGM usage (6.3% vs. 6.6%, respectively; p = 0.002). No significant change in HbA1c was noted in children with baseline HbA1c ≥ 7% (7.5% vs. 7.4%, respectively; p = 0.191), but 20% of the group reached the target of HbA1c < 7.0%. The analysis of CGM data revealed that no group achieved the CGM targets of good metabolic control. Total daily insulin requirements remained stable in both groups (p = 0.752; p = 0.274), but the amount of basal insulin increased statistically in both groups (p = 0.009; p ≤ 0.001). CONCLUSIONS: The application of CGM provides detailed information concerning glycaemic control and is beneficial in some, but not all, T1D children with good diabetes control.

Software simulation of tumour motion dose effects during flattened and unflattened ITV-based VMAT lung SBRT.

PURPOSE: Restricted studies comparing different dose rate parameters are available while ITV-based VMAT lung SBRT planning leads to perform the analysis of the most suitable parameters of the external beams used. The special emphasis was placed on the impact of dose rate on dose distribution variations in target volumes due to interplay effects. METHODS: Four VMAT plans were calculated for 15 lung tumours using 6 MV photon beam quality (flattening filter FF vs. flattening filter free FFF beams) and maximum dose rate of 600 MU/min, 1000 MU/min and 1400 MU/min. Three kinds of motion simulations were performed finally giving 180 plans with perturbed dose distributions. RESULTS: 6FFF-1400 MUs/min plans were characterized by the shortest beam on time (1.8 ±â€¯0.2 min). Analysing the performed motion simulation results, the mean dose (Dmean) is not a sensitive parameter to related interplay effects. Looking for local maximum and local minimum doses, some discrepancies were found, but their significance was presented for individual patients, not for the whole cohort. The same was observed for other verified dose metrics. CONCLUSIONS: Generally, the evaluation of VMAT robustness between FF and FFF concepts against interplay effect showed a negligible effect of simulated motion influence on tumour coverage among different photon beam quality parameters. Due to the lack of FFF beams, smaller radiotherapy centres are able to perform ITV-based VMAT lung SBRT treatment in a safe way. Radiotherapy department having FFF beams could perform safe, fast and efficient ITV-based VMAT lung SBRT without a concern about significance of interplay effects.

Feasibility of intensity-modulated radiotherapy to treat gastric cancer.

AIM: To present a proposed gastric cancer intensity-modulated radiotherapy (IMRT) treatment planning protocol for an institution that have not introduced volumetric modulated arc therapy in clinical practice. A secondary aim was to determine the impact of 2DkV set-up corrections on target coverage and organ at risk (OAR). METHODS AND MATERIALS: Twenty consecutive patients were treated with a specially-designed non-coplanar 7-field IMRT technique. The isocenter-shift method was used to estimate the impact of 2DkV-based set-up corrections on the original base plan (BP) coverage. An alternative plan was simulated (SP) by taking into account isocenter shifts. The SP and BP were compared using dose-volume histogram (DVH) plots calculated for the internal target volume (ITV) and OARs. RESULTS: Both plans delivered a similar mean dose to the ITV (100.32 vs. 100.40%), with no significant differences between the plans in internal target coverage (5.37 vs. 4.96%). Similarly, no significant differences were observed between the maximal dose to the spinal cord (67.70 and 67.09%, respectively) and volume received 50% of the prescribed dose of: the liver (62.11 vs. 59.84%), the right (17.62 vs. 18.58%) and left kidney (29.40 vs. 30.48%). Set-up margins (SM) were computed as 7.80 mm, 10.17 mm and 6.71 mm in the left-right, cranio-caudal and anterior-posterior directions, respectively. CONCLUSION: Presented IMRT protocol (OAR dose constraints with selected SM verified by 2DkV verification) for stomach treatment provided optimal dose distribution for the target and the critical organs. Comparison of DVH for the base and the modified plan (which considered set-up uncertainties) showed no significant differences.

Stereotactic body radiation therapy for liver metastasis - The linac-based Greater Poland Cancer Centre practice.

AIM: The main purpose of this work is to give a technical description and present the properties of the liver SBRT protocol implemented in the Greater Poland Cancer Centre (GPCC) in Poznan, Poland. BACKGROUND: Stereotactic body radiation therapy (SBRT) for liver metastasis is a non-invasive therapeutic option which enables irradiation of a small target in the body with a high dose. MATERIALS AND METHODS: This study presents details of our linac-based liver SBRT protocol. Special emphasis has been placed on fiducial implantation, patient preparation (CT scanning, immobilization), treatment planning, and its implementation. RESULTS: The liver SBRT treatment course implemented in the GPCC consists of three fractions to deliver a total of 45 Gy. Fraction delivery details with description of patient positioning (localization of liver metastasis) are presented below. CONCLUSIONS: The literature validation of the assumptions concerning the steps of the GPCC linac-based liver SBRT procedure show their potential for an effective and patient friendly implementation.

Staged Radiosurgical Ablation for Choroid Melanoma: A Case Report with Emphasis on the Role of Patient Preparation, Treatment Planning, and Precision of Delivery.

The aim of reporting this case of choroid melanoma of the left eye is to introduce the in-house-designed treatment planning protocol for fractionated radiosurgical ablation of an intraocular lesion. This is a clinical case with emphasis on treatment preparation and delivery using the Accuray CyberKnife Robotic Radiosurgery System (Accuray, Sunnyvale, CA, USA) for a patient immobilized with a head mask and our in-house-made eye fixation system.

Estimation of the planning organ at risk volume for the lenses during radiation therapy for nasal cavity and paranasal sinus cancer.

INTRODUCTION: To establish the optimal planning risk volume (PRV) of the lenses for patients who are receiving radiotherapy to the nasal cavity and paranasal sinus (NCPSC). METHODS: Geometrical uncertainties of the lenses were evaluated for a prospective group of patients (G1). Differences between planned and delivered maximum doses to the lenses were evaluated for every fraction. The relationship between dose differences and geometrical uncertainties were analysed to establish an optimal PRV for the lenses. Obtained results were verified in the second group (G2) of patients for whom calculated PRV was applied. RESULTS: Data of 426 observations for 15 patients from G1 were investigated. The systematic and random errors equalled, respectively, 0.6 mm and 2.3 mm in the medio-lateral direction; 0.8 mm and 1.6 mm in the cranio-caudal direction; and 0.4 mm and 1.5 mm in the anterio-posterior direction. The clinical PRV for the lenses was established at 2 mm. Applied margin was evaluated for 10 patients from G2. The dose distribution in the planning target volume (PTV) for G1 and for G2 was comparable (P = 0.122), whereas the differences between planned and delivered doses in the lenses were significantly smaller for G2 (P = 0.013). CONCLUSION: The study showed that for radiotherapy of NCPSC, the PRV for the lenses could be defined as 2 mm. This margin does not affect the dose distribution in the PTV and effectively reduces the differences between planned and delivered doses in the lenses.

Stereotactic body radiation therapy for liver metastasis--case report and review of the literature. The role of patient preparation, treatment planning and its delivery.

BACKGROUND: Stereotactic body radiation therapy (SBRT) is reported as a well-tolerated treatment modality, which offers a long-term tumor control. AIMS: The aim of the following study is to present the place of proposed treatment preparation and its delivery for liver metastases with conventional linear accelerator among reported SBRT protocols. MATERIALS AND METHODS: We present our treatment preparation, planning and set-up verification procedure performed for liver metastasis. The prescription dose of 45 Gy was delivered in 3 fractions with cone beam computed tomography and 2-dimensional guidance. RESULTS: The conventional 3-dimensional conformal plan, which fulfilled all dose constraints for target and organs at risk, was accepted for the treatment. Almost for all performed patient position verifications, on-line evaluated results were kept under 5 mm. CONCLUSIONS: The analysis presents the possible way of treating patients with liver metastasis. The SBRT treatment prepared and verified according our protocol can be implemented in clinical practice for a vast majority of such patients. The literature validation of our liver SBRT protocol showed that it has the potential for ensuring the effective and patient-friendly delivery.

Dosimetric consequences of prostate-based couch shifts on the precision of dose delivery during simultaneous IMRT irradiation of the prostate, seminal vesicles and pelvic lymph nodes.

INTRODUCTION: To evaluate the impact interfraction prostate (CTV1) motion corrections on doses delivered to seminal vesicles (CTV2) and lymph nodes (CTV3), and to determine ideal planning target volume (PTV) margins for these targets with prostate-based position verification. MATERIAL AND METHODS: Retrospective analysis based on 253 cone beam computed tomography (CBCT) studies of 28 patients. The isocenter-shift method was used to estimate the interfraction prostate and bony shift effects on the original plan coverage. Friedman's test was used to assess statistical significance between dose-volume histogram (DVH) parameters which were calculated for prostate-based sum plans, bony-based sum plans and original treatment plans. The van Herk formula was used to determine the set-up margin size for prostate-based verification. RESULTS: The tracked shifts influenced the minimum, maximum and mean CTV2 and CTV3 doses, with a range differential of 0.17%-2.63% (prostate shifts) and 0.13%-1.92% (bony shifts) compared to the corresponding original parameters. Friedman's test revealed significant differences in the minimum doses to the CTV3 and maximum doses to both the CTV2 and CTV3. The calculated set-up margins of 1.22 cm (vertical), 0.19 cm (longitudinal) and 0.39 cm (lateral) should be added to CTV3 while performing prostate-based positioning. CONCLUSION: To avoid geographical miss during simultaneous irradiation of independently moving targets (CTV1-3) appropriate margins should be used in accordance with the position verification method used. Based on our findings the following margin sizes should be used: 0.7 cm for the CTV1, 0.8-0.9 cm for the CTV2 , and asymmetric 1.0 cm (vertically) and 0.5 cm (other axes) for the CTV3.

Evaluation of clinical benefits achievable by using different optimization algorithms during real-time prostate brachytherapy.

BACKGROUND AND PURPOSE: High dose rate (HDR) brachytherapy is a clinically used procedure in prostate cancer treatment. The purpose of this study was to present the influence of using different optimization algorithms in 3D-CBRT planning on the treatment plan quality. MATERIALS AND METHODS: Treatment plans were calculated for 15 patients--three plans for each patient using: geometrical optimization (GO), inverse optimization (IO) and blind inverse optimization (BIO). For each patient, PTV and OAR volumes, number of needles and geometry of the implant were set equal. Differences between dose distributions were tracked using: D90, V100, V200, Dmax (for prostate); D10, Dmax (for urethra); D10, V100, Dmax (for rectum). RESULTS: The analysis of mean values of D90 and V100 in the prostate showed that inverse algorithms gave the best results (mean D90 was 12.1% for BIO and 9.3% for IO better than for GO, mean V100 was 8.2% for BIO and 6.3% for IO better than for GO). From a clinical point of view, GO diminished the doses in the PTV and urethra in all analyzed parameters. The lowest mean doses in the rectum were achieved for plans optimized with IO and BIO (mean D10: 61.2% for GO, 58.1% for IO, 58.0% for BIO; mean Dmax: 92.8% for GO, 85.1% for IO, 83.6% for BIO). CONCLUSIONS: Application of the blind inverse optimization (BIO) algorithm led to clinically best dose parameters for PTV and the rectum. Use of geometrical optimization (GO) led to smaller doses in the urethra, which was however associated with a certain dose decrease also in PTV.

Evaluation of combining bony anatomy and soft tissue position correction strategies for IMRT prostate cancer patients.

BACKGROUND: Radiotherapy treatment requires delivering high homogenous dose to target volume while sparing organs at risk. That is why accurate patient positioning is one of the most important steps during the treatment process. It reduces set-up errors which have a strong influence on the doses given to the target and surrounding tissues. AIM: The aim of this study was to investigate the efficiency of combining bony anatomy and soft tissue imaging position correction strategies for patients with prostate cancer. MATERIALS AND METHODS: The study based on pre-treatment position verification results determined for 10 patients using kV images and CBCT match. At the same patients' position, two orthogonal kV images and set of CT scans were acquired. Both verification methods gave the information about patients' position changes in vertical, longitudinal and lateral directions. RESULTS: For 93 verifications, the mean values of kV shifts in vertical, longitudinal and lateral directions equaled: -0.11 ± 0.54 cm, 0.26 ± 0.38 cm and -0.06 ± 0.47 cm, respectively. The same values achieved for CBCT matching equaled: 0.07 ± 0.62 cm, 0.22 ± 0.36 cm and -0.02 ± 0.45 cm. Statistically significant changes between the values of shifts received during the first week of treatment and the rest time of the irradiation process were found for 2 patients in the lateral direction and 2 patients in vertical direction among kV results and for 3 patients in the longitudinal direction among CBCT results. A significant difference between kV and CBCT match results was found in the vertical direction. CONCLUSIONS: In clinical practice, CBCT combined with kV or even portal imaging improves precision and effectiveness of prostate cancer treatment accuracy.