核医学と放射線治療

Introduction: Aim of the current study was to compare gross tumour volume delineation for radiation therapy planning by PET/CT and CT scan in head and neck tumour patients.
Methods: 70 oncological patients with primary head and neck cancer were enrolled in the study. CT and 18F-FDGPET/ CT scans were performed within 3 weeks of enrolment in the planned irradiation position. For radiation therapy planning delineation of the target volumes was performed manually both in conventional topometric CT slides and in FDG-PET/CT images. Gross tumour target volume was calculated (GTVcm3) using both modalities. Numerical and geometrical (intersection divided union ratio) comparisons were assessed. Intraobserver, interobserver, and intermodality variation analyses were performed.
Results: Intra- and interobserver agreement (intraclass correlation coefficients: 0.99 and 0.97) of tumour volume delineation with 18F-FDG-PET/CT was excellent. Radiotherapy target volume as assessed by FDG-PET/ CT differed in 98% (69/70) from target volumes calculated by the CT scans. According to the metabolic information, the target volume was larger in 12 cases (18%) and smaller in 58 cases (82%). Significant differences were found between CT and PET/CT based tumour volume (paired t-test, p<0.0001). Intersection divided union ratio showed low overlap (0.32).
Conclusions: Tumour delineation for radiation therapy planning with PET/CT shows good reproducibility in patients with head and neck cancer. CT based morphologic information compared to PET/CT overestimates the tumour volume in larger lesions and may underestimate it in smaller target lesions. Differences are not only evident in tumour volume, but in geometry: Morphology of tumour volume and position.

Purpose: To our knowledge, no study specifically assessed anxiety and depression in Moroccan cancer population undergoing radiotherapy. The objective of this study was to assess the prevalence of anxiety and depression in patients with cancer prior to the first session of radiotherapy and to identify predictor factors.
Material and methods: It is a cross-sectional single center study. An interview was conducted using the Hospital Anxiety and Depression Scale.
Results: 150 patients filled the study inclusion criteria. The mean age was 54.9 ± 12.8 years, 12% of patients were in current employment. 42% of the participants had a positive family history of cancer. Out of study participants, 58% scored abnormal on the anxiety scale and 52% on the depression scale. Statistically significant predictors of anxiety and depression were similar to those reported in published studies, such as the presence of family history of cancer, received radiotherapy in family, employment status and treatment intention.
Conclusions: The results of this study suggest that a large proportion of cancer patients have psychiatric comorbidities. There is an urgent need for psychosocial support programs and psychological screening for patients diagnosed with cancer and candidate for radiation therapy.

Aim: To study the effect of various planning parameters viz field width (FW), pitch factor (PF) on breast tumor and evaluate the relation among these parameters and their influence on the quality of plan and the treatment time.
Material and method: Nine plans for each of the ten breast cancer patients were created taking various combinations of field width (FW) and pitch keeping the Modulation factor (MF) constant 3. The reference plan selected for the study is field width of 1, pitch 0.215. Other plans were created keeping the same constraints and penalty as the reference plan and 1000 iterations. Target coverage was evaluated in terms of conformity index (CN) and homogeneity index (HI) while the sparing of organs at risk (OARs) were evaluated in terms of mean, maximum and relevant dose volumes. Low dose spillages in normal tissues were also evaluated. The plans are compared with the reference plan using the Wilcoxon Signed Ranks Test. Concept of plan Quality index is also used to evaluate the plans qualitatively.
Results: The mean treatment delivery time for 5, 2.5 and 1.0 cm FW plans were 5.04 ± 0.4, 8.51 ± 0.87 and 20.67 ± 2.02 minutes respectively. There was no significant variation in doses for OARs and COIN and HI of targets for 1 cm and 2.5 cm plans except for 5 cmplans. But the low dose spillage increased by 9-14% and 23-43% for 2.5 and 5 cm respectively.
Conclusion: Dose to the OARs was not significantly higher for 2.5_FW plans from the reference plan but, significantly higher for 5_FW. Larger the FW and higher the pitch, spillage were more. On the basis of our analysis, 2.5_0.215 plan with MF=3, can be considered as the optimum plan for unilateral breast treatment using Tomotherapy.

Purpose: The present study is to investigate the measured and calculated doses for different malignant tumours utilizing various gamma criteria and QA for confirmation of IMRT/VMAT with portal dosimetry and 2D array.
Methods: Different malignant tumors are treated by IMRT/VMAT techniques on Varian IX linear accelerator with 6 MV photon beams. Treatment planning system (TPS) is used to plan Patient’s charts. Gamma Index (GI) variation is compared to the procedure of pre-treatment verification in IMRT/VMAT plans.
Results: The gamma criteria (DD/ DTA) of IMRT for (3%/3 mm), mean ± SD are γ≤ 1%=99.41% ± 0.67%, γmax=2.11 ± 0.56 and γavg=0.23 ± 0.03 by EPID, and γ% ≤ 1=98.55% ± 0.79%, γmax=1.65 ± 0.45 and γavg=0.27 ± 0.04 by using 2D array. For VMAT mean ± SD are γ% ≤ 1= 99.42% ± 0.67%, γmax=2.11 ± 0.56 and γavg= 0.19 ± 0.05 using portal dosimetry, and γ% ≤ 1=99.36% ± 0.53%, γmax=1.65 ± 0.45 and γavg=0.22 ± 0.05 using 2D array.
Conclusions: Specific QA of IMRT/VMAT patient using (portal dosimetry or 2D array) to verify IMRT/VMAT fields. 3%/3 mm is the most appropriate of gamma criteria (DD/DTA) for IMRT/VMAT plans quality assurance. The control chart is an effective tool to detect uncontrolled variation.

Introduction: The doses received by the contralateral breast, lung and heart either directionally or full blocked techniques in Hi-Art Tomotherapy systems in partial or whole breast radiotherapy has been studied.
Method: In 20 breast cancer patients 3 plans with non-blocked, directionally blocked and full blocked methods were designed in Hi-Art planning system. In all planning method the dose received by the contralateral breast, the heart volume percentages V5 and V30 and the lung volume percentages V5 and V20 were compared.
Results: The mean doses received by contralateral breast were 6.24 Gy (4.50-8.74 Gy) in unblocked group 3.85 Gy (2.08-5.81 Gy) in directionally blocked group and 0.99 Gy (0.69-1.39 Gy) in full blocked group. The mean Lung V5 values were 98% (79-100%) in unblocked group and it was 98% (91-100%) in directionally blocked group while it was 93% (89-97%) in full blocked group. The mean V20 values were 16% (7-23%), 20% (17-24%) and 22% (18-28%) in unblocked, directionally blocked and full blocked groups respectively. The mean Heart V5 value 100% (99-100%) in unblocked group, and it was 99% (85-100%) in directionally blocked group while it was 92% (73- 100%) in full blocked group. The mean V30 values were 11% (2-25%), 6% (0-12%) and 9% (1-22%) in unblocked, directionally blocked and full blocked groups respectively. The mean beam-on time was 261.6 s (237.6-318.2) for unblocked, 277.9 s (237.6-338.5) for directionally blocked and 314.2 s (272.6-429.1) full blocked group. The mean numbers of MUs were 3712 (3353-4536) for unblocked, 3951 (3357-4834) for directionally blocked and 4506 (3866- 6168) for full blocked group. In full blocked group both beam on time and MU values were higher.
Conclusion: We propose that further efforts needed to reduce low dose volumes to normal tissues, meanwhile when using directionally and full blocked plans all parameters should be considered together.