Special Topics: Hyperthermia and Computers

, Foster D. Lasley2, Indra J. Das2, Marc S. Mendonca2 and Joseph R. Dynlacht2



(1)
Department of Radiation Oncology, CHRISTUS St. Patrick Regional Cancer Center, Lake Charles, LA, USA

(2)
Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN, USA

 




Hyperthermia


If ionizing radiation is good at killing cells, and microwaves are good at cooking food, why not do both to the tumors? (see Chapt. 30 for more details).



  • The use of temperatures between 39 °C (102 °F) and 47 °C (116 °F) to achieve selective cell killing but does NOT use ablative temperatures >50 °C (122 °F) that might cook a tumor and surrounding tissue.


  • There are many benefits to providing hyperthermia concurrently with ionizing radiation, discussed in much greater detail in Chapt. 30.


  • Heat (thermia) may be applied externally or using implantable device inside the tumor using the following techniques:



    • hot water


    • microwave


    • radiofrequency


    • ultrasound


  • Primary limitation of heat therapy is the technical limitations:



    • Applying heat selectively to the tumor while sparing normal tissues.


    • Applying heat within the proper time frame of radiation therapy.


    • Reducing invasive techniques, especially if they would be required on a daily basis.


    • Expensive devices or power requirements.


  • Another limitation is the inability to achieve uniformity (some areas will be heated more than others) due to thermal diffusion of tissue.



    • Heat can be carried away by the heat-sink effect of venous blood flow (think of water-cooled machinery).


    • Heat sink effect has a slight benefit to normal tissues so they will not receive as much heat as tumor cells, and tumors that do experience vasodilatation can become better oxygenated, but this makes heat dosing logistically difficult.


  • Overall, hyperthermia has many benefits but is so technically difficult that it is usually reserved for academic studies or for superficial tumors (melanoma, neck nodes, or superficial breast cancers) or recurrent tumors. Even in these cases, it is not standard of care.


Computers: Miscellaneous Topics That Are Important!






  • DICOM – Digital Imaging and Communications in Medicine – this is the standard format for medical imaging. Version 3.0 was developed in 1993 but for some reason, there are still departments that do not use this. If you ever request films from an outside facility, it would be wise to request that they are in either DICOM or DICOM-RT format.



    • DICOM files also batch important information about the file such as patient name, ID, date of birth, slice thickness, kVp, and pixel representation.


    • DICOM-RT files can include contouring structures, dose, and radiotherapy plans.


    • Pixel representation is how the data is sent – either big bytes first (big Endian) or little bytes first (little Endian).


    • There are many variations of the DICOM features. Many free-ware programs on the internet are available that can read non-standard imaging files. Usually imaging studies when loaded on a compact disk also carry the read in format data that may be slightly different than DICOM-RT format.


  • PACS – Patient Archiving and Communication System – PACS provide massive data storage from any imaging device on a single platform. Every hospital usually has its own PACS system and just about all of them will accept DICOM files (though not all will generate them naturally unfortunately, but they can usually convert their own file format into DICOM). Huge amount of storage and further reading any study is made possible by a PACS.


Image Registration




Tags:
Apr 2, 2016 | Posted by in GENERAL RADIOLOGY | Comments Off on Special Topics: Hyperthermia and Computers

Full access? Get Clinical Tree
Get Clinical Tree app for offline access