- 関
- hyperfractionate、hyperfractionated、multipartite
WordNet
- involving more than two parties
Wikipedia preview
出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2018/01/04 20:22:40」(JST)
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Experiments in radiation biology have found that as the absorbed dose of radiation increases, the number of cells which survive decreases. They have also found that if the radiation is fractionated into smaller doses, with one or more rest periods in between, fewer cells die. This is because of self-repair mechanisms which repair the damage to DNA[1][2] and other biomolecules such as proteins. These mechanisms can be over expressed in cancer cells, so caution should be used in using results for a cancer cell line to make predictions for healthy cells if the cancer cell line is known to be resistant to cytotoxic drugs such as cisplatin. The DNA self repair processes in some organisms is exceptionally good; for instance, the bacterium Deinococcus radiodurans can tolerate a 15 000 Gy (1.5 MRad) dose.
In the graph below, called a cell survival curve, the dose vs. surviving fraction have been drawn for a hypothetical group of cells with and without a rest time for the cells to recover. Other than the recovery time partway through the irradiation, the cells would have been treated identically.
The human body contains many types of cells, and the human can be killed by the loss of a single type of cells in a vital organ. For many short-term radiation deaths due to what is commonly known as radiation sickness (3 to 30 days after exposure), it is the loss of bone marrow cells (which produce blood cells), and the loss of other cells in the wall of the intestines, that is fatal.
Radiation fractionation as cancer treatment
Fractionation also refers to a method of treating cancer with radiation therapy. When the total dose of radiation is divided into several, smaller doses over a period of several days, there are fewer toxic effects on healthy cells. This maximizes the effect of radiation on cancer and minimizes the negative side effects. Typical fractionation schemes divide the dose into 30 units delivered every weekday over six weeks, though current research is considering the benefits of accelerated fractionation (two deliveries per day and/or deliveries on weekends as well). Hypofractionation is a treatment regimen that delivers higher doses of radiation in fewer visits. The logic behind this treatment is that applying greater amounts of radiation works to lower the effects of accelerated tumor growth that typically occurs during the later stages of radiotherapy.[3]
Notes and references
- ^ John Kimball (8 April 2012). "DNA repair". Retrieved 2012-06-24.
- ^ Ben Best. "Mechanisms of Aging". Retrieved 2012-06-24.
- ^ Pollack, Alan, and Mansoor Ahmed . Hypofractionation: Scientific Concepts and Clinical Experiences. 1st. Ellicot City: LimiText Publishing, 2011
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UpToDate Contents
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English Journal
- [Radioresistance parameters in head and neck cancers and methods to radiosensitize].
- Biau J1, Chautard E2, Miroir J3, Lapeyre M3.
- Cancer radiotherapie : journal de la Societe francaise de radiotherapie oncologique.Cancer Radiother.2015 Jun 25. pii: S1278-3218(15)00094-3. doi: 10.1016/j.canrad.2015.02.014. [Epub ahead of print]
- Head and neck cancers have been widely studied concerning their sensitivity to radiation therapy. Several parameters affect tumour response to radiation therapy. Some parameters are linked to the tumour. Large or invasive tumours, localization, such as oral cavity or adenopathy, are factors of radio
- PMID 26119219
- Accelerated hyperfractionated radiotherapy for small cell carcinoma of the nasopharynx.
- Takahashi S1, Miyashita T, Hoshikawa H, Haba R, Togami T, Shibata T.
- Head & neck.Head Neck.2015 May;37(5):E63-5. doi: 10.1002/hed.23888. Epub 2015 Mar 29.
- BACKGROUND: The purpose of this study was to report the treatment outcome of a patient with nasopharyngeal small cell carcinoma.METHODS: The patient received concurrent chemoradiotherapy (CRT). Chemotherapy consisted of 4 cycles of cisplatin and etoposide. Accelerated hyperfractionated radiotherapy
- PMID 25270910
- Concomitant chemoradiotherapy versus altered fractionation radiotherapy in the radiotherapeutic management of locoregionally advanced head and neck squamous cell carcinoma: An adjusted indirect comparison meta-analysis.
- Gupta T1, Kannan S, Ghosh-Laskar S, Agarwal JP.
- Head & neck.Head Neck.2015 May;37(5):670-6. doi: 10.1002/hed.23661. Epub 2014 Apr 30.
- BACKGROUND: Treatment intensification by using chemoradiotherapy (CRT) or altered fractionation radiotherapy (RT) improves outcomes in locoregionally advanced head and neck squamous cell carcinoma (HNSCC).METHODS: Two comprehensive meta-analyses with similar control arms (conventionally fractionated
- PMID 24596112
Japanese Journal
- 限局型小細胞肺癌に対する化学療法同時併用加速過分割照射の後方視的検討―照射線量45 Gyと54 Gyとの比較―
- 限局型小細胞肺癌に対する放射線化学療法 (特集 呼吸器悪性腫瘍の集学的治療)
- 早期喉頭癌根治的放射線治療における分割照射法による入院期間の検討
Related Links
- hyperfractionation /hy·per·frac·tion·a·tion/ (-frak″shun-a´shun) a subdivision of a radiation treatment schedule with some reduction of dose per exposure so as to decrease side effects while still delivering an equal or greater total dose of ...
- コンセンサス癌治療 VOL.1 NO.3 137 正常組織が照射後の亜致死障害か ら回復する時間間隔である4～6時 間あけるため，日常臨床では時間 的制約から1日2回が一般的であ る。多分割照射法には過分割照射 法hyperfractionation（1.1 ...
★リンクテーブル★
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- 英
- hyperfractionation、hyperfractionate、multipartite、hyperfractionated
- 関
- 過分割、多くの部分に分かれている
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- 関
- hyperfractionate、hyperfractionated、hyperfractionation
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- 関
- hyperfractionated、hyperfractionation、multipartite
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- 関
- hyperfractionate、hyperfractionation、multipartite
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- 英
- hyperfractionation、hyperfractionate
- 関
- 多分割