| Abstract (english) | Introduction: Within the past two decades, we made significant progress in radiation therapy for prostate cancer. At UH Rijeka IMRT became the technique of choice for radiation therapy following radical prostatectomy since 2016. Previously, an advanced 3-DCRT technique using the field-in-field (FiF) method was used for dose distribution optimization around target volumes and organs-at-risk. This research has been performed to investigate the influence of planning technique choice (FiF or IMRT) on coverage of target volumes with prescribed dose and organs-at-risk sparing.
Materials and methods: Comparison of dose distributions calculated using FiF and IMRT techniques was performed retrospectively for ten patients who underwent postoperative radiotherapy. The prescribed dose for all patients was delivered using IMRT, and for this research, we also calculated dose distributions using the FiF technique. For FiF and IMRT
techniques, we used linear accelerator photon beams. To determine the influence of planning technique on dose distribution parameters related to target volumes (GTV, CTV, PTV1, PTV2) were analyzed. For organs-at-risk sparing evaluation (rectum, bladder, femoral heads), we used dose-volume constraints.
Results and discussion: The analysis of parameters related to target volumes has shown that most of them had no statistically significant difference (V100%(GTV), V100%(CTV), V95%(PTV2), V95%(PTV1)). For both planning techniques, internationally set dose constraints were achieved. Statistically, we found a significant difference for V100%(PTV2), p=0,000534, and V100%(PTV1), p=0,042944 in favor of IMRT. A statistically significant difference (p=0,045966) was found for the volume of the rectum, which receives 40Gy, and for the volume of femoral heads, which receives 30Gy (p=0,000385), where the sparing is better for IMRT. For dose-volume constraints related to the bladder, no statistically significant differences were found.
Conclusion: Results of this research show a statistically significant difference for V100% target volume coverage for PTV1 and PTV2, with better dose coverage accomplished by IMRT. Concerning organs-at-risk sparing, a statistically significant difference in favor of IMRT was found for rectum volume, which receives 40Gy. Expectedly, IMRT was superior to the FiF technique. However, differences between the two planning techniques were relatively small, which points to the fact that the FiF technique is viable as a technique of choice. |
| Abstract (croatian) | Uvod: U posljedna dva desetljeća, u liječenju raka prostate radioterapijom postignut je veliki napredak. U KBC-u Rijeka, od 2016., jakosno modulirana radioterapija (IMRT) postaje tehnika izbora kod radioterapije operiranog raka prostate. Do tada je tehnika izbora bila napredna 3D konformalna radioterapija (3DCRT) korištenjem tehnike „polja u polju” (FiF). Istraživanje je provedeno s ciljem ispitivanja utjecaja izbora tehnike planiranja (FiF ili IMRT) na doznu pokrivenost ciljnih volumena i poštedu organa rizika.
Metode i materijali: Usporedba raspodjela doze izračunate koristeći FiF i IMRT retrospektivno je učinjena kod deset bolesnika kojima je indicirana postoperativna radioterapija. Svim je bolesnicima predana propisana doza IMRT tehnikom, a za potrebe ovog istraživanja izračunate su i raspodjele doze FiF tehnikom. Da bi se utvrdilo utječe li tehnika planiranja na raspodjelu doze, analizirani su parametri važni za ciljne volumene (GTV, CTV, PTV1, PTV2), a kod analize poštede organa rizika (rektum, mokraćni mjehur i glavice femura) korištena su dozno-volumna ograničenja.
Rezultati i diskusija: Analizom parametara vezanih za ciljne volumene utvrđeno je da kod većine (V100%(GTV), V100%(CTV), V95%(PTV2), V95%(PTV1) nema statistički značajne razlike. Kod obje tehnike postignuta su dozna ograničenja propisana međunarodnim smjernicama.
Statistički značajna razlika utvrđena je kod V100%(PTV2), p=0,000534 i V100%(PTV1), p=0,042944 u prilog korištenja IMRT tehnike. Utvrđena je statistički značajna razlika (p=0,045966) za volumen rektuma koji prima 40Gy, kao i za volumen glavica femura koji prime apsorbiranu dozu 30Gy. U oba slučaja pošteda organa rizika bolja je korištenjem IMRT tehnike. Za promatrana dozno-volumna ograničenja vezana uz mokraćni mjehur nije utvrđena statistički značajna razlika.
Zaključak: Rezultati istraživanja pokazuju statistički značajnu razlikukod usporedbe volumena kojemu je predana propisana apsorbirana doza (V100%) za PTV1 i PTV2, tako da je bolja dozna pokrivenost kod IMRT tehnike. Pri poštedi organa rizika statistički značajna razlika u korist IMRT-a utvrđena je kod analize volumena rektuma kojem je predana apsorbirana doza od 40Gy i volumena glavica femura kojima je predana apsorbirana doza od 30Gy. Prema očekivanju, IMRT daje bolje rezultate. Međutim, razlike u analiziranim parametrima između dvije tehnike planiranja (FiF ili IMRT) kod većine analiziranih parametara nisu statistički značajne što upućuje da kvalitetno planirana radioterapija FiF tehnikom može također biti tehnika izbora. |
