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Background/Aim: To compare implant sparing irradiation with conventional radiotherapy (RT) using helical (H) and TomoDirect (TD) techniques in breast cancer patients undergoing immediate breast reconstruction (IBR). Patients and Methods: The dosimetric parameters of 40 patients with retropectoral implants receiving 50.4 Gy delivered in 28 fractions were analyzed. Three plans were created: H plan using conventional planning target volume (PTV) that included the chest wall, skin, and implant; TD plan using conventional PTV; and Hs plan using implantsparing PTV. The H, TD, and Hs plans were compared for PTV doses, organ-at-risk (OAR) doses, and treatment times. Results: Dose distribution in the Hs plan was less homogeneous and uniform than that in the H and TD plans. The TD plan had lower lung, heart, contralateral breast, spinal cord, liver, and esophagus doses than the Hs plan. Compared to the Hs plan, the H plan had lower lung volume receiving 5Gy (V5) (39.1±3.9 vs. 41.2±3.9 Gy; p<0.001), higher V20 (12.3±1.3 vs. 11.5±2.6 Gy; p=0.02), and higher V30 (7.5±1.6 vs. 4.4±1.7 Gy; p<0.001). H plan outperformed Hs plan in heart dosimetric parameters except V20. The Hs plan had significantly lower mean implant doses (43.4±2.1 Gy) than the H plan (51.4±0.5 Gy; p<0.001) and the TD plan (51.9±0.6 Gy; p<0.001). Implementing an implant sparing technique for silicone dose reduction decreases lung doses. Conclusion: Conventional H and TD plans outperform the implant sparing helical plan dosimetrically. Because capsular contracture during RT is unpredictable, long-term clinical outcomes are required to determine whether silicon should be spared. [ABSTRACT FROM AUTHOR]

Background: We examined the effects of reducing the planning target volume (PTV) margin in MR‐guided radiotherapy (MRgRT) on the distribution of radiation dose to target volumes and organs‐at‐risk (OARs). Thus, we compared MR‐Linac (MRL) plans with and without reduced margin and intensity‐modulated radiotherapy (IMRT) plan with conventional linac for low‐risk prostate cancer patients receiving 36.25 Gy in five fractions of ultra‐hypofractionated radiation therapy. Materials and Methods: Twenty low‐risk prostate cancer patients treated with 1.5 T MR‐Linac were evaluated. The same planning CT images were used for four plans: the MRL‐R plan with reduced margin planning target volume (PTV‐R) and the MRL‐N plan with normal margin PTV (PTV‐N), which is also used for IMRT plan. In four plans, PTV doses, organs‐at‐risk (OARs) doses, the homogeneity index (HI), and monitor units were compared. Results: All plans met the criteria for PTV coverage and OARs dose constraints. The maximum and mean PTV doses were significantly higher in the MRL‐R and MRL‐N plans compared to the IMRT plan. The HI was lowest in the IMRT plan (0.040 ± 0.013) and highest in the MRL‐N plan (0.055 ± 0.012; p < 0.001). There was no significant difference in the PTV dosimetric parameters between the MRL‐R and the MRL‐N plans. The high doses in the rectum was significantly lower in the MRL‐R compared to other plans. The bladder V36.25 Gy was significantly lower in the MRL‐R plan (2.43 ± 1.87 Gy) compared to MRL‐N (4.50 ± 2.42 Gy; p < 0.001), and IMRT plans (4.76 ± 2.77 Gy; p < 0.001). There was no significant difference in the low‐dose volumes of the body, maximum femur doses, or monitor units across each plan. Conclusions: Ultra‐hypofractionated MR‐guided RT with 1.5 T MRL is dosimetrically feasible for patients with prostate cancer. The improved soft tissue contrast and the online adaptive plan for 1.5 T MR‐Linac allows for PTV margin reduction resulted in a significant dose reduction in OARs. [ABSTRACT FROM AUTHOR]

This study aims to compare dosimetric 3D-CRT, Tomo-helical IMRT and Direct IMRT methods in intact breast irradiation. METHODS Radiotherapy was planned with three different techniques simulated images of 30 breast cancer patients with negative lymph nodes who underwent breast-conserving surgery. RESULTS The maximum and minimum doses, homogeneity and conformity index and cold-zone volumes were found to be different in all three techniques (p<0.001). The PTV boost maximum doses and homogeneity index were found to be different (p<0.001). The maximum non-PTV dose (110% volume) and the hot zone volumes grasped by these doses, the V5 volume of the body and V5 volumes, outer of PTV were found to be statistically significant for all three techniques (p<0.001). A statistically significant difference was found between the three techniques concerning the ipsilateral lung V5 and V20 volumes, the contralateral lung V5 and V10 volumes and the counter breast maximum and mean doses (p<0.001). The mean and V10 volume of the heart was statistically significant (p<0.001), while the left breast irradiation and mean values were not statistically significant between the three techniques (p=0.529). However, there was a statistically significant difference in the V10 volume of the left breast irradiation between the three techniques (p=0.033). CONCLUSION According to 3D-CRT, it is possible to achieve better dose distribution and dose homogeneity with Tomo- helical and direct IMRT. Low dose volumes are high with tomo-helical IMRT. Tomo-helical IMRT planning provides better ipsilateral lung and heart doses but causes an increase in heart dose/contralateral breast and for right breast irradiation causes an increase in heart dose. [ABSTRACT FROM AUTHOR]

Amaç: Meme koruyucu cerrahi sonrası helikal tomoterapi (HT) uygulanmış erken evre meme kanseri hastalarında tedavi planlama sisteminde (TPS) karşı meme dozlarını ölçmeyi ve MOSFET dedektörleri ile karşılaştırmayı hedefledik. Gereç ve Yöntem: Meme kanseri tanısıyla 28 fraksiyonda tüm memeye 50.4 Gy ve tümör yatağına 64.4 Gy ile tedavi edilmiş 30 hasta (15 sağ, 15 sol) değerlendirmeye alınmıştır. TPS dozları ölçülmüş, karşı memede kraniyal, kaudal, santral ve merkezin 2 cm laterali olacak şekilde MOSFET dozları not edilmiştir. Tüm hastalarda TPS ve MOSFET dozları karşılaştırılmış, ayrıca tümör yerleşimine göre (iç vs dış kadran) ve meme planlanan tümör hacmine göre de (<1200 cc vs. =1200 cc) karşılaştırma yapılmıştır. Bulgular: Hastaların ortalama yaşı 54'tür (range: 31-73 years). 14 hastada (%46.7) T1N0 hastalık izlenirken, 16 (%53.3) hastada T2N0 hastalık bulunmaktadır. 15 hastada (%50) tümör iç kadran yerleşimli, kalan 15 hastada da dış kadran yerleşimlidir. Meme için ortanca CTV ve PTV sırasıyla 950 cc (range: 300-2210 cc) ve 1200 cc'dir (range: 425-2600 cc). Boost için CTV ve PTV sırasıyla 18 cc (range: 5-117 cc) ve 68 cc'dir (19-170 cc). Kranial, kaudal, santral ve lateral noktalarda TPS ile ölçülen dozları sırasıyla, 0.26 ± 0.15 cGy, 0.21 ± 0.09 cGy, 0.65 ± 0.14 cGy, ve 0.50 ± 0.11 cGy iken, MOSFET ile sırasıyla, 0.37 ± 0.16 cGy, 0.34 ± 0.12 cGy, 0.60 ± 0.18 cGy, and 0.34 ± 0.15 cGy ölçülmüştür. Santral nokta haricinde TPS ve MOSFET değerlerinde farklılık görülmüştür. İç ve dış kadran tümörlerinde karşı meme dozları arasında anlamlı farklılık görülmemiştir. Büyük hacimli memelerde, MOSFET dozları kraniyal ve lateral noktalarda TPS'den daha yüksek ölçülürken, kaudal noktalarda TPS dozları daha yüksek okunmuştur. Küçük ve büyük hacimli memelerde iç veya dış kadran tümörleri olan hastalarda MOSFET ölçümleri, TPS'de hesaplanandan daha yüksek okunmuştur. Sonuç: TPS ve MOSFET ile ölçülen dozlar arasında çok ufak bir farklılık bulunmaktadır. MKC sonrası HT ile tedavi edilen erken evre meme kanseri hastalarında karşı memeye uygulanan en yüksek doz santral noktada 1.8 Gy olarak TPS'de ölçülmüş ve MOSFET dedektörleri ile doğrulanmıştır. Bulgularımız, HT ile tedavi edilen hastalarda TPS verilerinin güvenilir olduğunu göstermektedir. [ABSTRACT FROM AUTHOR]