2Deparment of Radiation Oncology, Yeni Yüzyıl University, Private Gaziosmanpaşa Hospital Faculty of Medicine, İstanbul-Türkiye DOI : 10.5505/tjo.2022.3479 OBJECTIVE
The purpose of our study is to compare composite and synchronous planning approaches in prostate radiotherapy in terms of dosimetric and radiobiology.
METHODS
Fifteen prostate patients previously treated at our clinic were used to conduct this study. For each patient,
two different types of planning were performed on the Monaco-TPS; a primary plan with an independently
planned boost (Synchronous Planning: SP) and a secondary plan with a dependently planned
boost (Composite Planning: CP). Dose distributions obtained by two techniques were compared.
RESULTS
Both of the summed plans were achieved according to the original planning goals. At the D99 dose (75.76
Gy versus 76.81 Gy; P=0.017), CI (0.91 versus 0.96; p=0.002), HI (0.08 versus 0.05; p=0.001) and MU
(1448 versus 719; p=0.001) were found to be significantly better with SP. Better results were obtained
in CP at V5, V10 and V20 doses of the body, rectal and bladder doses. When only the boost plans were
compared, the results were 11.8% lower at the D1 dose and 12.01% higher at the D99 dose with the SP. In
addition, more conformal (CI: 0.96 versus 0.70; p=0.001) and more homogenous (HI: 0.06 versus 0.24;
p=0.001) plans were obtained.
CONCLUSION
When the phase1+phase2 total dose distribution was evaluated, better results were obtained with CP.
However, if there is a heterogeneous dose distribution in phase1 planning, there may be very low or very
high fraction doses within the target volume only in phase2 planning. Even if the defined dose is applied in
total, hot or cold dose volumes can directly affect the radiobiological gain and the result of the treatment.