ObjectiveTo compare the dosimetric differences among the double-arc volumetric-modulated arc therapy (VMAT), 7 field intensity-modulated radiotherapy (IMRT) and 3-dimensional conformal radiotherapy (3D-CRT) techniques in treatment planning for cervical cancer as adjuvant radiotherapy. MethodFifteen patients who underwent adjuvant chemotherapy for cervical cancer between March 1st and September 30th, 2013 were chosen to be our study subjects through random sampling. Under Pinnacle 9.2 planning system, the same CT image was designed through three different techniques:VMAT, IMRT and 3D-CRT. We then compared target zone fitness index, evenness index, D98%, D2%, D50% among those different techniques. Monitor unit (MU) and treatment time were also analyzed. ResultsThree techniques showed similar target dose coverage. The IMRT and VMAT plans achieved better target dose conformity, which reduced the V20 of the pelvic, the V50 of the rectum and bladder, as well as the V40/50 of the small intestine (P<0.05). The VMAT technique showed few dosimetric advantages over the IMRT technique. VMAT technique had the advantages of less MU (P>0.05) and shorter overall treatment time (P<0.01) compared with IMRT technique. ConclusionsThe IMRT and VMAT plans achieve similar dose distribution to the target, and are superior to the 3D-CRT plans, in adjuvant radiotherapy for cervical cancer. VMAT technique has the advantages of less MU and shorter overall treatment time.
Objective To analyze the advantages and disadvantages of various neoadjuvant therapy , provide reference for clinical diagnosis and treatment, and provide direction for further research and exploration. Method The recent domestic and international medical databases (PubMed, EMBASE, Cochrane Library, VIP database, CNKI, WanFang database, etc.) were searched and the relevant literature on neoadjuvant therapy for locally advanced rectal cancer (LARC) were reviewed. Results Neoadjuvant therapy could decrease tumor staging, increase anal reserving rate, and reduce local recurrence rate, but it does not significantly reduce the rates of distant metastasis and lateral lymph node metastasis, nor does it improve long-term survival. More and more optimization neoadjuvant therapy had emerged. Molecular targeted drugs and immunotherapy were being attempted for clinical using, combined with research on emerging biomarkers, to improve the therapeutic efficacy of LARC patients, reduce treatment related side effects, and improve patient survival benefits. Conclusions Neoadjuvant therapy is the standard treatment strategy for LARC, and the exploration of neoadjuvant treatment models is expected to further improve treatment effectiveness, reduce toxic side effects, and improve survival prognosis. By combining tumor molecular biology indicators to identify and screen beneficiaries, it is expected to become an important direction for future research.
ObjectiveTo analyze the clinical and dosimetric impacts on radiation pneumonitis (RP), and provides data for radiotherapy planning. MethodsWe reviewed 59 non-operative esophageal cancer patients who underwent radiotherapy from October 2010 to November 2012 to identify the correlation between the clinical and dosimetric parameters with acute radiation pneumonitis (ARP) and severe acute radiation pneumonitis (SARP) by t-Test, Chi-Square Test and logistic regression analysis. ResultsAmong the 59 patients, 33 (55.9%) developed ARP, in whom 9 (15.3%) developed SARP. Univariate analysis showed that lung infection during radiotherapy, mean lung dose (MLD), and dosimetric parameters are significantly correlated with RP. Multivariate analysis revealed lung infection during radiotherapy, MLD≥13 Gy, and V30≥13% were significantly correlated with the increasing risk RP. ConclusionLung infection during radiotherapy, MLD, and V30 are the influencing factors of RP, which should be seriously considered when formulating radiotherapy plan to avoid RP.
ObjectiveTo compare the static intensity-modulated radiation therapy (IMRT) plans using different beams sets and segments number, and find the better static IMRT plan sets on beams and segments in gastric surgical adjuvant radiotherapy.MethodsFifteen patients who underwent adjuvant radiotherapy for gastric cancer between February 1st and August 30th, 2013 were chosen as subjects through random sampling. Based on the 5 beams static IMRT plans already used in clinical practice, four different static IMRT plans used diverse beams sets for each patient were designed in the same treatment planning system (Pinnacle 9.2). The beams sets of static IMRT plans were as follows: 7 coplanar equal beams; 5 coplanar equal beams; 4 coplanar beams of 310, 20, 90 and 180°; 3 coplanar beams of 310, 65 and 180°. Sufficient segments 65 was set as the max segments number in order to compare the plans’ difference just resulting from beams. In the second step, the max segments number was changed from 65 to 45 and 25 to design two different static IMRT plans for the 4 coplanar beams static IMRT plans. The dosimetric parameters were compared for the planning target volume (PTV) and organs at risk (OARs). The monitor units and treatment times of the different static IMRT plans were also evaluated.ResultsWhen the max segments number was set to 65, the 4 coplanar beams static IMRT plans were a little better on PTV conformability than the 5 coplanar beams static IMRT plans used in clinical practice (0.74±0.04 vs. 0.73±0.05, P<0.01). Meanwhile, better OARs dose sparing especially for liver and kidneys were gained by the 4 coplanar beams static IMRT plans, for example, the percent volume gained 30 Gy for liver [(22.71±6.10)%vs. (24.03±6.84)%, P<0.01] and the percent volume gained 20 Gy for the right kidney [(14.97±6.72)%vs. (19.41±6.14)%, P<0.01]. The PTV conformability of the 4 coplanar beams static IMRT plans reduced as the max segments number became smaller (0.74±0.04vs. 0.73±0.04 vs. 0.71±0.04, P<0.05). However, they were still acceptable in clinical practice. And the better dose sparing for liver and kidneys were retained. The average reductions of 1.8 and 4.3 minutes on the irradiation time were get by the 4 coplanar beams static IMRT plans with the max segments number 45 and 25 compared to that with the max segments number 65 [(494.66±26.79)vs. (384.26±14.99) vs. (235.00±9.21) s, P<0.01]. And the raises of treatment efficiency were 22.3% and 52.4%, respectively (P<0.05).ConclusionsThe 4 coplanar beams static IMRT plans with fewer segments could ensure plan quality, and protect the OARs better in the meanwhile, especially for liver and kidneys. The treatment time is reduced as well. The 4 coplanar beams static IMRT plans could improve the treatment efficiency.