1. A patient has uncompleted radiotherapy say 10 fractions out of 30 (2Gy/fraction), how we compensate/manage the remaining dose in following situations?
i) LAMA/absent for 15 days.
ii) LAMA/absent for more than 15 days and less than 3 months.
iii) LAMA/absent for 3-12 months or more.
2. If the patient has completed his full radiotherapy say 60Gy and came with recurrent mass. What will be the management in case of radiotherapy as patient cant tolerate chemotherapy?
3. Are all above situations/management can be applied to all type of cancer (head&neck, breast, cervix, urinary bladder, prostate etc.)
Radiobiology is not one of my well know subject areas, however there are some resources which can aid you in performing some calculations. I am pretty sure the IAEA RPOP website has some examples that you can follow. If I remember correctly you are looking for the LQ Time model which should give you an approximation of the dose "lost" due to the break. The IAEA also publish online Radiobiology: A handbook for teachers and students (TCS-42_web.pdf) that discusses retreatment. Not agreat deal of help but maybe a little.
If patient defaults for less than 15 days the compensation is not very significant and one can easily continue on the course of planned treatment.
However, in case of prolonged gap a BED calculation and gap correction is required. Them you may add the remaining dose. However, attention should also be paid to the OAR dose limit as many structures (spine) exceed the dose.
Re-irradiation is being increasingly employed now a days with more con-formal therapy. However, attention should be paid to the OAR and temporal association.
If gap between the primary radiation and re-irradiation is 1 year re-irradiation may be more useful.
Chemotherapy may not always beneficial (like in H&N)
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