Clinical target volume (CTV) delineation is crucial for tumor control and normal tissue protection. This study aimed to define the locoregional extension patterns of nasopharyngeal carcinoma (NPC) and to improve CTV d...Clinical target volume (CTV) delineation is crucial for tumor control and normal tissue protection. This study aimed to define the locoregional extension patterns of nasopharyngeal carcinoma (NPC) and to improve CTV delineation. Magnetic resonance imaging scans of 2366 newly diagnosed NPC patients were reviewed. According to incidence rates of tumor invasion, the anatomic sites surrounding the nasopharynx were classified into high-risk (>30%), medium-risk (5%-30%), and low-risk (<5%) groups. The lymph node (LN) level was determined according to the Radiation Therapy Oncology Group guidelines, which were further categorized into the upper neck (retropharyngeal region and level Ⅱ), middle neck (levels Ⅲ and Va), and lower neck (levels Ⅳ and Vb and the supraclavicular fossa). The high-risk anatomic sites were adjacent to the nasopharynx, whereas those at medium- or low-risk were separated from the nasopharynx. If the high-risk anatomic sites were involved, the rates of tumor invasion into the adjacent medium-risk sites increased; if not, the rates were significantly lower (P < 0.01). Among the 1920 (81.1%) patients with positive LN, the incidence rates of LN metastasis in the upper, middle, and lower neck were 99.6% , 30.2%, and 7.2%, respectively, and skip metastasis happened in only 1.2% of patients. In the 929 patients who had unilateral upper neck involvement, the rates of contralateral middle neck and lower neck involvement were 1.8% and 0.4%, respectively. Thus, local disease spreads stepwise from proximal sites to distal sites, and LN metastasis spreads from the upper neck to the lower neck. Individualized CTV delineation for NPC may be feasible.展开更多
Let R be a Noetherian ring, I and J two ideals of R, M an R-module and t an integer. Let S be a Serre subcategory of the category of R-modules satisfying the co ondition CI, and N be a finitely generated R-module with...Let R be a Noetherian ring, I and J two ideals of R, M an R-module and t an integer. Let S be a Serre subcategory of the category of R-modules satisfying the co ondition CI, and N be a finitely generated R-module with SuppRN= V（a） for some a ∈ W（I, J）. It is shown that if ExtR^J（N,HI^i,J（M）） ∈ S for all i 〈 t and all j 〈 t - i, then Ha^i（M） ∈ S for all i 〈 t. Let S be the class of all R-modules N with divmR N ≤ k, where k is an integer. It is proved that if Ha^i（M） ∈ S for all i 〈 t and all a ∈ W（I, J）, then HI^i,j（M） ∈ S for all i 〈 t. It follows that inf{i ： HI^i,j（M） S} = inf（inf{i ： Ha^i（M） S）： a ∈W（I,J）}.展开更多
The Eisenstein Criterion is a sharp tool, i.e. a sufficient condition to judge a polynomial irreducible by using the coefficients of the polynomial. In particular, it plays an important role in studying totally ramifi...The Eisenstein Criterion is a sharp tool, i.e. a sufficient condition to judge a polynomial irreducible by using the coefficients of the polynomial. In particular, it plays an important role in studying totally ramified extensions of local fields. In this report, we shall generalize the Eisenstein Criterion for totally ramified extensions of local fields, and then we can get some results about extensions of local fields, that is to say, the conditions of tamely ramified extensions are cyclic or metacyclic.展开更多
文摘Clinical target volume (CTV) delineation is crucial for tumor control and normal tissue protection. This study aimed to define the locoregional extension patterns of nasopharyngeal carcinoma (NPC) and to improve CTV delineation. Magnetic resonance imaging scans of 2366 newly diagnosed NPC patients were reviewed. According to incidence rates of tumor invasion, the anatomic sites surrounding the nasopharynx were classified into high-risk (>30%), medium-risk (5%-30%), and low-risk (<5%) groups. The lymph node (LN) level was determined according to the Radiation Therapy Oncology Group guidelines, which were further categorized into the upper neck (retropharyngeal region and level Ⅱ), middle neck (levels Ⅲ and Va), and lower neck (levels Ⅳ and Vb and the supraclavicular fossa). The high-risk anatomic sites were adjacent to the nasopharynx, whereas those at medium- or low-risk were separated from the nasopharynx. If the high-risk anatomic sites were involved, the rates of tumor invasion into the adjacent medium-risk sites increased; if not, the rates were significantly lower (P < 0.01). Among the 1920 (81.1%) patients with positive LN, the incidence rates of LN metastasis in the upper, middle, and lower neck were 99.6% , 30.2%, and 7.2%, respectively, and skip metastasis happened in only 1.2% of patients. In the 929 patients who had unilateral upper neck involvement, the rates of contralateral middle neck and lower neck involvement were 1.8% and 0.4%, respectively. Thus, local disease spreads stepwise from proximal sites to distal sites, and LN metastasis spreads from the upper neck to the lower neck. Individualized CTV delineation for NPC may be feasible.
文摘Let R be a Noetherian ring, I and J two ideals of R, M an R-module and t an integer. Let S be a Serre subcategory of the category of R-modules satisfying the co ondition CI, and N be a finitely generated R-module with SuppRN= V（a） for some a ∈ W（I, J）. It is shown that if ExtR^J（N,HI^i,J（M）） ∈ S for all i 〈 t and all j 〈 t - i, then Ha^i（M） ∈ S for all i 〈 t. Let S be the class of all R-modules N with divmR N ≤ k, where k is an integer. It is proved that if Ha^i（M） ∈ S for all i 〈 t and all a ∈ W（I, J）, then HI^i,j（M） ∈ S for all i 〈 t. It follows that inf{i ： HI^i,j（M） S} = inf（inf{i ： Ha^i（M） S）： a ∈W（I,J）}.
文摘The Eisenstein Criterion is a sharp tool, i.e. a sufficient condition to judge a polynomial irreducible by using the coefficients of the polynomial. In particular, it plays an important role in studying totally ramified extensions of local fields. In this report, we shall generalize the Eisenstein Criterion for totally ramified extensions of local fields, and then we can get some results about extensions of local fields, that is to say, the conditions of tamely ramified extensions are cyclic or metacyclic.
