Current practices of craniospinal irradiation techniques in Turkey: a comprehensive dosimetric analysis.

OBJECTIVE: This study evaluates various craniospinal irradiation (CSI) techniques used in Turkish centers to understand their advantages, disadvantages and overall effectiveness, with a focus on enhancing dose distribution. METHODS: Anonymized CT scans of adult and pediatric patients, alongside target volumes and organ-at-risk (OAR) structures, were shared with 25 local radiotherapy centers. They were tasked to develop optimal treatment plans delivering 36 Gy in 20 fractions with 95% PTV coverage, while minimizing OAR exposure. The same CT data was sent to a US proton therapy center for comparison. Various planning systems and treatment techniques (3D conformal RT, IMRT, VMAT, tomotherapy) were utilized. Elekta Proknow software was used to analyze parameters, assess dose distributions, mean doses, conformity index (CI), and homogeneity index (HI) for both target volumes and OARs. Comparisons were made against proton therapy. RESULTS: All techniques consistently achieved excellent PTV coverage (V95 > 98%) for both adult and pediatric patients. Tomotherapy closely approached ideal Dmean doses for all PTVs, while 3D-CRT had higher Dmean for PTV_brain. Tomotherapy excelled in CI and HI for PTVs. IMRT resulted in lower pediatric heart, kidney, parotid, and eye doses, while 3D-CRT achieved the lowest adult lung doses. Tomotherapy approached proton therapy doses for adult kidneys and thyroid, while IMRT excelled for adult heart, kidney, parotid, esophagus, and eyes. CONCLUSION: Modern radiotherapy techniques offer improved target coverage and OAR protection. However, 3D techniques are continued to be used for CSI. Notably, proton therapy stands out as the most efficient approach, closely followed by Tomotherapy in terms of achieving superior target coverage and OAR protection.

Dosimetric evaluation of different radiotherapy techniques in mastectomized left-sided breast cancer.

CONTEXT: Inclusion of internal mammary lymph nodes in mastectomized left breast cancer radiotherapy may lead to high dose receiving risk of the heart, lung, and contralateral breast. AIM: The aim of this study is to compare the dosimetric differences of field-in-field (FIF), volumetric-modulated arc therapy (VMAT), seven-field intensity-modulated radiotherapy (7F-IMRT), and helical tomotherapy (HT) planning techniques for mastectomized left breast cancer. MATERIALS AND METHODS: Computed tomography images of ten patients treated with the FIF technique were used to compare four different treatment planning techniques. Planning target volume (PTV) included chest wall and regional lymph nodes. The heart, left anterior descending coronary artery (LAD), left and whole lung, thyroid, esophagus, and contralateral breast were identified as organs-at-risks (OARs). Except for HT, a single isocenter in PTV and bolus of thickness 0.3 cm on the chest wall was used. Complete and directional blocks were applied in HT, and the dosimetric parameters of PTV and OARs for four different techniques were analyzed using the Kruskal-Wallis test. RESULTS: 7F-IMRT, VMAT, and HT were superior to the FIF technique in providing homogeneous dose distribution covering the PTV (P < 0.0001). Mean doses (Dmean) of the contralateral breast and esophagus, lung, and body-PTV V5 (volume receiving 5 Gy) were reduced in FIF, whereas in the HT, Heart Dmean, LAD Dmean , Dmax, healthy tissue (body-PTV) Dmean , heart and left lung V20, and thyroid V30 were significantly reduced (P < 0.0001). CONCLUSIONS: FIF and HT techniques were found to be significantly advantageous over 7F-IMRT and VMAT for OARs. Using those three multiple-beam techniques reduced high-dose volumes of healthy tissues and organs in mastectomized left breast cancer radiotherapy but also increased low-dose volumes and contralateral lung and breast doses. Complete and directional blocks applied in HT reduce heart, lung, and contralateral breast doses.