Amr Taha

PURPOSE: To compare volumetric-modulated arc therapy (VMAT) with 3D-conformal radiation therapy (3D-CRT) mediastinal irradiation for stage I-II supra-diaphragmatic Hodgkin's Lymphoma (HL).

PATIENTS AND METHODS: Eleven patients were planned for RT after 4-6 cycles of ABVD chemotherapy: conventional 3D-CRT (AP/PA) and VMAT plans were conformed to the same PTV. Objective was to choose the best PTV coverage plan with the least OAR dose. The 2 plans were compared for: PTV coverage, mean dose and V5,V20lung, mean dose and V30heart, V5, V10, V15breast (female patients), and the integral body dose.

RESULTS: Both techniques achieved adequate PTV coverage. Mean lung and heart dose was consistently lower in VMAT plans. The lung V20 dose was acceptable for VMAT, but exceeded the tolerance threshold in 6 cases with 3DCRT plans. A mean difference of 15.9% for both lungs V20 favored VMAT plans; average MLD difference was 2.3Gy less for VMAT plans. Similarly, lower maximum and mean heart doses with a 3.3Gy dose reduction and a 9.4% difference in V30 favored VMAT plans. Mean V5lung/female breast and integral dose were invariably higher in VMAT plans because of the low-dose spread.

CONCLUSIONS: VMAT is a valuable technique for treatment of large mediastinal HL. VMAT spares the lung and heart compared to 3DCRT using ISRT in select HL cases. VMAT allows dose escalation for post-chemotherapy residual disease with minimal dose to OARs. VMAT low radiation dose (V5) to the normal tissues, and the increased integral dose should be considered.

BACKGROUND: The pediatric diffuse intrinsic pontine glioma (DIPG) outcome remains dismal despite multiple therapeutic attempts.

PURPOSE: To compare the results of treatment of pediatric diffuse intrinsic pontine glioma (DIPG) using hypofractionated versus conventional radiotherapy.

PATIENTS AND METHODS: Seventy-one newly diagnosed DIPG children were randomized into hypofractionated (HF) (39Gy/13 fractions in 2.6weeks) and conventional (CF) arm (54Gy/30 fractions in 6weeks).

RESULTS: The median and one-year overall survival (OS) was 7.8months and 36.4±8.2% for the hypofractionated arm, and 9.5 and 26.2±7.4% for the conventional arm respectively. The 18-month OS difference was 2.2%. The OS hazard ratio (HR) was 1.14 (95% CI: 0.70-1.89) (p=0.59). The hypofractionated arm had a median and one-year progression-free survival (PFS) of 6.6months and 22.5±7.1%, compared to 7.3 and 17.9±7.1% for the conventional arm. The PFS HR was 1.10 (95% CI: 0.67-1.90) (p=0.71). The 18-month PFS difference was 1.1%. These differences exceed the non-inferiority margin. The immediate and delayed side effects were not different in the 2 arms.

CONCLUSIONS: Hypofractionated radiotherapy offers lesser burden on the patients, their families and the treating departments, with nearly comparable results to conventional fractionation, though not fulfilling the non-inferiority assumption.

BACKGROUND: The pediatric diffuse intrinsic pontine glioma (DIPG) outcome remains dismal despite multiple therapeutic attempts.

PURPOSE: To compare the results of treatment of pediatric diffuse intrinsic pontine glioma (DIPG) using hypofractionated versus conventional radiotherapy.

PATIENTS AND METHODS: Seventy-one newly diagnosed DIPG children were randomized into hypofractionated (HF) (39Gy/13 fractions in 2.6weeks) and conventional (CF) arm (54Gy/30 fractions in 6weeks).

RESULTS: The median and one-year overall survival (OS) was 7.8months and 36.4±8.2% for the hypofractionated arm, and 9.5 and 26.2±7.4% for the conventional arm respectively. The 18-month OS difference was 2.2%. The OS hazard ratio (HR) was 1.14 (95% CI: 0.70-1.89) (p=0.59). The hypofractionated arm had a median and one-year progression-free survival (PFS) of 6.6months and 22.5±7.1%, compared to 7.3 and 17.9±7.1% for the conventional arm. The PFS HR was 1.10 (95% CI: 0.67-1.90) (p=0.71). The 18-month PFS difference was 1.1%. These differences exceed the non-inferiority margin. The immediate and delayed side effects were not different in the 2 arms.

CONCLUSIONS: Hypofractionated radiotherapy offers lesser burden on the patients, their families and the treating departments, with nearly comparable results to conventional fractionation, though not fulfilling the non-inferiority assumption.

AIM: To compare the accuracy of radiotherapy set-up using an electronic portal imaging device (EPID) versus megavoltage cone beam computed tomography (MV-CBCT) in paediatric patients.

MATERIALS AND METHODS: In total, 204 pairs of EPID and MV-CBCT were carried out for 72 patients in the first 3 treatment days and weekly thereafter.

RESULTS: For the whole group, the mean systematic EPID set-up errors were 1.8 (±1.7), 1.6 (±1.3), 1.4 (±1.5) mm and 2.3 (±1.7), 1.6 (±1.3), 2.4 (±1.6) mm for MV-CBCT in the longitudinal, lateral and vertical directions, respectively, whereas the mean EPID random errors were 2.0 (±1.7), 1.4 (±1.5), 1.2 (±1.6) and 1.9 (±1.5), 1.5 (±1.3), 2.1 (±1.7) mm for MV-CBCT in the longitudinal, lateral and vertical directions, respectively. For systematic errors of head and neck patients, there was a statistically significant difference in the lateral and vertical directions (P=0.027, 0.003), whereas in the non-head and neck patients there was a statistically significant difference in the lateral direction only (P=0.031). In head and neck patients, the mean random errors were significantly different in the vertical and lateral directions, whereas in non-head and neck patients, they were significantly different in the vertical direction only. The larger values alternate between the two modalities. The systematic and random errors (detected by EPID and MV-CBCT) were significantly correlated in almost all direction in all tumour sites.

CONCLUSIONS: The comparison between set-up error in EPID and MV-CBCT was not in favour of any of the two modalities. However, the two modalities were strongly correlated but fairly agreed and the differences between the shifts reported were small and hardly influenced the recommended planning target volume margin.