Dosimetric And Clinical Studies Of Intensity Modulated Radiation Therapy (IMRT) For Prostate Cancer

Partâ… :The Preliminary Results and Toxicity of Prostate Cancer Treated with Three-Dimensional Conformal Radiotherapy(3D-CRT) or Intensity Modulated Radiation Therapy(IMRT)Purpose:To investigate preliminary results and toxicity of prostate cancer treated with three-dimensional conformal radiotherapy(3D-CRT) or intensity modulated radiation therapy(IMRT).Methods and materials:Between March 1999 and July 2004,36 patients with stage T_1-4N_0-1M₀ prostate cancer treated with 3D-CRT or IMRT were retrospectively reviewed. Of the 36 patients,35 received androgen deprivation therapy as well.Clinical target volume(CTV) included whole prostate and seminal vesicles in 23 patients.Thirteen patients received radiation to the pelvis and prostate/seminal vesicles.Results:Median dose to CTV and PTV were 76.0 Gy(52.5-83.0Gy) and 45.0Gy (40-50Gy),respectively.The overall survival rate at 3 and 5 years were 91.4%and 83.7%, respectively.Disease-free survival rate at 3 and 5 years were both 91.4%.Twelve patents did not have any Grade of acute gastrointestinal toxicity(33.3%),whereas 20 patients had Grade 1(55.6%),3 Grade 2(8.3%),and 1 Grade 3 toxicity(2.8%).None had Grade 4 acute gastrointestinal toxicity.Nine(25.0%) patients had Grade 0 acute genitourinary toxicity,22 Grade 1(61.1%),3 Grade 2(8.3%),and 2 Grade 3(5.6%).There was no Grade 4 toxicity.80.6%of the patients had no late gastrointestinal toxicity.Four patients had Grade 1(11.1%) and 3 had Grade 2 of late gastrointestinal toxicity.There were no patients with Grade 3 or higher late gastrointestinal toxicity.The proportion of late genitourinary toxicity was low.Twenty-eight patients experienced no late genitourinary toxicity(77.8%),6 patients with Grade 1(16.7%),1 patient with Grade 2(2.8%),and 1 patient with Grade 3(2.8%). Conclusion:Patients with prostate cancer treated with 3D-CRT or IMRT at high dose level were safe.The acute and late toxicities were acceptable and no serious late toxicities were observed. Partâ…¡:Toxicities of Patients with Prostate Cancer Treated with Hypofractionated Intensity-Modulated RadiotherapyPurpose:To analyze the acute and late toxicities in patients with prostate cancer treated with hypofractionated intensity-modulated radiotherapy(IMRT).Methods:Between June 2006 and June 2008,37 patients were treated with hypofractionated IMRT.The clinical target volume(CTV) included the prostate and seminal vesicles in 12 patients,the tumor bed in 1 patient,and the prostate,seminal vesicles and pelvic lymph nodes in 24 patients.Twenty-six patients were treated at 2.7 Gy per fraction,and the others were treated at 2.5-2.8Gy per fraction.The minimal dose was 62.5-75Gy to the 95%PTV of the prostate and seminal vesicles,and 50 Gy to the 95%PTV of the pelvic lymph nodes.Results:With median follow-up of 14 months,none of the patients experienced Grade 4 acute gastro-intestinal(GI) toxicity.Grade 0,grade 1,grade 2 and grade 3 acute GI toxicities were occurred in 37.8%,24.3%,35.1%and 2.7%of 37 patients,respectively. The rectal V50＞27%and V55＞20%were highly significantly associated with Grade 1 or higher acute GI toxicity.Grade 0,grade 1,grade 2 and grade 3 acute genito-urinary (GU) toxicities were occurred in 29.7%,67.6%,0%and 2.7%,respectively.The bladder V60＞10%was significantly associated with Grade 1 or higher acute GU toxicity.The incidence of GI late toxicities were low,without any Grade 3 or higher toxicity.The incidence of Grade 1 and 2 GI late toxicities was 24.3%and 5.4%,respectively.The rectal V65＞10%was highly significantly with Grade 1 or higher late GI toxicity.No Grade 4 late GU toxicity was observed.The incidence of Grade 0,grade 1,grade 2 and grade 3 GU late toxicities were 37.8%,48.6%,10.8%and 2.7%,respectively.Grade 2 or higher late GU toxicity was correlated with the bladder V 40＞32%and V50＞29%and mean dose to the bladder＞40 Gy. Conclusion:Hypofractionated IMRT with neoadjuvant and concomitant hormone therapy is acceptable without severe acute or late toxicity. Partâ…¢:Dosimetric Advantages of IMRT Simultaneous Integrated Boost to Prostate For High-risk Prostate CancerPurpose:To compare the dosimetric advantages of simultaneous and sequential integrated boost(SIB) to the prostate with intensity modulated radiation therapy(IMRT) for high-risk prostate cancer patients who were irradiated with pelvic lymph nodes.Methods:A Pinnacle 3 inverse planning system was used to generate IMRT SIB plans and IMRT sequential two-phase boost plans for a sample patient case.The SIB is designed to deliver the same dose(50 Gy/25f/1.8 Gy) as the conventional method to the pelvic nodes(PTV2) and to deliver higher doses to prostate and seminal vesicles(PTV1) in the same 25 fractions(67.5Gy/2.7Gy/25f).For the sequential two-phase boost plan, whole-pelvis was irradiated to 50Gy/2Gy/25f followed by a boost to the prostate and seminal vesicles with 26Gy/2Gy/13f.The conformal index(CI) and dose homogeneity index(HI) of the PTV for the SIB plan and sequential two-phase boost plan were compared.The dose-volume histogram(DVH),equivalent uniform dose(EUD) normalized total dose(NTD),and normal tissue complication probability(NTCP) of the normal structures for the SIB plan and sequential two-phase boost plan were also compared.Results:IMRT SIB plan improved CI of PTV1 and PTV2 compared with sequential two-phase boost plan.The CI of PTV1 was 0.85 and 0.47,respectively.The corresponding CI of PTV2 was 0.62 and 0.33 respectively.The DVH,EUD and NTD for rectum of SIB plan were lower than those of sequential two-phase boost plan.The NTCP for rectum of SIB plan was a little higher than that of sequential plan,but the difference was not statically significant.DVHs data demonstrated the less volume of bladder receiving＞40Gy for the SIB plan.The EUD,NTD and NTCP for bladder of SIB plan were significant better than those of sequential two-phase boost plan.For the SIB plan, the EUD and volume of small bowl received 40-50Gy were decreased significantly, compared with those of sequential plan.The differences of NTD and NTCP between these two kinds of strategy were not significant.The volume of femurs received 50-60Gy was significantly smaller for SIB plan than that of sequential plan.Conclusion:A new IMRT simultaneous integrated boost strategy that irradiates prostate via hypofractionation while irradiating pelvic nodes with the conventional fractionation is proposed for high-risk prostate cancer.Compared to the conventional two-phase treatment,the proposed SIB technique offers potential advantages,including better sparing of critical structures,more efficient delivery,and shorter treatment duration.